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A Multilocus Molecular Phylogeny for Chaetostoma Clade Genera and Species with a Review of Chaetostoma (Siluriformes: Loricariidae) from the Central Andes

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The rubbernose-pleco genus Chaetostoma comprises 47 currently valid and many undescribed species distributed along Atlantic and Pacific slopes of the Andes Mountains from Panama to southern Peru, the Coastal Mountains of Venezuela, and drainages of the Guiana and Brazilian shields. We present a five-locus molecular phylogeny for 21 described and six undescribed species of Chaetostoma spanning the geographic range of the genus. Bayesian and maximum likelihood analyses found Chaetostoma to be well supported as monophyletic and sister to a clade of central and northern Andean genera that have also been hypothesized to be closely related based on morphology (i.e., Andeancistrus, Cordylancistrus, Dolichancistrus, Leptoancistrus, and Transancistrus). Species of Chaetostoma were divided into a trichotomy consisting of: a Pacific Coast, Central American, Magdalena Basin, Lake Valencia, and Guiana Shield clade a western Orinoco, Lake Maracaibo, and Lake Valencia clade and a widespread upper Amazon/Orinoco clade inclusive of a single species on the Brazilian Shield. We also conducted a systematic review of species from the central Andes of northern Peru and Ecuador. Based on our phylogenetic results and direct examination of historical and recently collected type and non-type material, we describe two new species of Chaetostoma (C. bifurcum, from the Pacific Coast, and C. trimaculineum, from the Atlantic Slope), redescribe four species (C. breve, C. carrioni, C. dermorhynchum, and C. microps, all from the Atlantic Slope), transfer four species from Chaetostoma to Ancistrus and find two species to be junior synonyms. © 2015 by the American Society of Ichthyologists and Herpetologists.
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A Multilocus Molecular Phylogeny for Chaetostoma Clade Genera and
Species with a Review of Chaetostoma (Siluriformes: Loricariidae) from
the Central Andes
Nathan K. Lujan
1,2,3
, Vanessa Meza-Vargas
4,5
, Viviana Astudillo-Clavijo
1,2
,
Ramiro Barriga-Salazar
6
, and Herna´n Lo´ pez-Ferna´ ndez
1,2
The rubbernose-pleco genus Chaetostoma comprises 47 currently valid and many undescribed species distributed along
Atlantic and Pacific slopes of the Andes Mountains from Panama to southern Peru, the Coastal Mountains of
Venezuela, and drainages of the Guiana and Brazilian shields. We present a five-locus molecular phylogeny for
21 described and six undescribed species of Chaetostoma spanning the geographic range of the genus. Bayesian and
maximum likelihood analyses found Chaetostoma to be well supported as monophyletic and sister to a clade of central
and northern Andean genera that have also been hypothesized to be closely related based on morphology (i.e.,
Andeancistrus,Cordylancistrus,Dolichancistrus,Leptoancistrus, and Transancistrus). Species of Chaetostoma were divided
into a trichotomy consisting of: a Pacific Coast, Central American, Magdalena Basin, Lake Valencia, and Guiana Shield
clade; a western Orinoco, Lake Maracaibo, and Lake Valencia clade; and a widespread upper Amazon/Orinoco clade
inclusive of a single species on the Brazilian Shield. We also conducted a systematic review of species from the central
Andes of northern Peru and Ecuador. Based on our phylogenetic results and direct examination of historical and
recently collected type and non-type material, we describe two new species of Chaetostoma (C. bifurcum, from the
Pacific Coast, and C. trimaculineum, from the Atlantic Slope), redescribe four species (C. breve,C. carrioni,
C. dermorhynchum, and C. microps, all from the Atlantic Slope), transfer four species from Chaetostoma to Ancistrus
and find two species to be junior synonyms.
Las carachamas nariz de goma del ge´nero Chaetostoma comprenden 47 especies va´lidas y algunas especies no descritas
distribuidas a lo largo de las vertientes Atla´ntico y Pacı´fico de la Cordillera de los Andes desde Panama´ hasta el sur de
Peru´, las montan˜as costeras de Venezuela, y cuencas de los escudos de Guayana y Brasil. Presentamos una filogenia
molecular de cinco loci para 21 especies descritas y seis no descritas de Chaetostoma, que abarcan el a´ rea de
distribucio´ n geogra´fica del ge´nero. Los ana´ lisis de probabilidad bayesiana y ma´xima verosimilitud muestran que
Chaetostoma esta´ bien soportado como grupo monofile´ tico y grupo hermano del clado de los ge´ neros andinos del
centro y norte, que tambie´ n se ha hipotetizado que esta´ n estrechamente relacionados en base a la morfologı´a (p.e.,
Andeancistrus, Cordylancistrus, Dolichancistrus, Leptoancistrus yTransancistrus). Las especies de Chaetostoma se dividieron
en una tricotomı´a que consiste en: un clado de la costa del Pacı´fico, Centroame´rica, cuenca del Magdalena, Lago de
Valencia y del Escudo Guayane´s; un clado del oeste del Orinoco, Lago de Maracaibo y Lago de Valencia; y un clado
ampliamente distribuido del alto Amazonas/Orinoco incluyendo la u´ nica especie en el Escudo Brasilen˜ o. Realizamos
tambie´n una revisio´ n sistema´ tica de las especies de los Andes centrales del norte de Peru´ y Ecuador. Basados en
nuestros resultados filogene´ ticos y en la examinacio´ n directa de colectas histo
´ ricas y recientes de material tipo y no
tipo, se describen dos nuevas especies de Chaetostoma (C. bifurcum, de la costa Pacı´fica y C. trimaculineum, de la vertiente
del Atla´ntico), se redescriben cuatro especies (C. breve, C. carrioni, C. dermorhynchum, C. microps, todas de la vertiente
del Atla´ntico), se transfieren cuatro especies de Chaetostoma aAncistrus y se encuentran dos especies que son sino´ nimo
junior.
THE genus Chaetostoma was erected by Tschudi (1846)
for the new species Ch. loborhynchos from the Ucayali
River drainage in east-central Peru. For nearly a
century, Chaetostoma was used as a catch-all taxon to which
many new species that are now broadly distributed through-
out the subfamily Hypostominae were assigned (e.g.,
Chaetostomus aspidolepis Gu¨nther, 1867 5Hypostomus
aspidolepis;Chaetostomus nigrolineatus Peters, 1877 5
Panaque nigrolineatus;Chaetostomus furcatus Fowler, 1940
5Peckoltia furcata; Lujan et al., 2015a). Taxonomic revisions
by Eigenmann and Eigenmann (1889, 1890), Eigenmann
(1922), Regan (1904), Isbru¨cker (1980), and Burgess (1989),
and morphology-based phylogenetic analyses by Armbrus-
ter (2004, 2008) restricted the genus to species having the
following five internal osteological synapomorphies (from
Armbruster, 2004): 1) hyomandibular free from the com-
pound pterotic posterior to the cartilaginous condyle of the
hyomandibular (character 34, state 0), 2) posterior region of
the hyomandibular not greatly deflected (character 42,
state 0), 3) anterior process of the compound pterotic absent
or only slightly deflected (character 111, state 0), 4)
sphenotic with a thin ventral process less than one fourth
as wide as the main body of the sphenotic (character 116,
state 0), 5) tip of transverse process of the Weberian complex
1
Department of Natural History, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario, Canada M5S 2C6; E-mail: (HLF)
h.lopez.fernandez@utoronto.ca.
2
Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada M5S 3B2; E-mail:
(VAC) viviana.astudillo@utoronto.ca.
3
Present address: Center for Systematic Biology and Evolution, Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin
Parkway, Philadelphia, Pennsylvania 19103; E-mail: nklujan@gmail.com. Send reprint requests to this address.
4
Departamento de Vertebrados, Museu Nacional, Quinta da Boa Vista, 20940-040 Rio de Janeiro, RJ, Brazil; E-mail: meza.sv@gmail.com.
5
Departamento de Ictiologı´a, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Av. Arenales 1256, Lima, Peru´.
6
Instituto de Ciencias Biologicas, Escuela Polite´ cnica Nacional, Quito, Ecuador; E-mail: ramiro.barriga@epn.edu.ec.
Submitted: 14 November 2014. Accepted: 7 May 2015. Associate Editor: R. E. Reis.
F2015 by the American Society of Ichthyologists and Herpetologists DOI: 10.1643/CI-14-194 Published online: September 25, 2015
Copeia 103, No. 3, 2015, 664–701
centrum at least partially contacting the compound pterotic
(character 135, state 0). Several more recent species descrip-
tions and taxonomic revisions have helped to further clarify
boundaries of both the genus, clades within the genus, and
species (e.g., Ballen, 2011; Salcedo, 2006a, 2006b, 2013).
In a molecular phylogenetic study examining two mito-
chondrial (Cyt b, 16S) and three nuclear (RAG1, RAG2,
MyH6) loci and 12 species of Chaetostoma among a wide
range of other Hypostominae taxa, Lujan et al. (2015a) found
strong support for monophyly of the genus as defined by
Armbruster (2004, 2008; i.e., inclusive of the genera
Lipopterichthys and Loraxichthys, which are therefore treated
herein as junior synonyms). Both morphological and
molecular phylogenetic evidence support a sister relation-
ship between Chaetostoma and a clade consisting of five
northern Andean genera: Andeancistrus,Cordylancistrus,
Dolichancistrus,Leptoancistrus, and Transancistrus.
Externally, all but one of the 47 currently valid species of
Chaetostoma can be distinguished from most other loricar-
iids by having at least one vertical column of five plate rows
at the thinnest part of the caudal peduncle (vs. three in
Ancistrus), by having eight or more branched dorsal-fin rays
(vs. seven in Ancistrus), and by having the anterior and
anterolateral snout margins free of plates, with this region
insteadbeingcoveredbyabroadbandofnaked
(i.e., unplated) skin lacking tentacles (vs. tentacles present
in Ancistrus). Chaetostoma platyrhyncha, which is unique in
the genus for having a plated snout, is the only exception
to the last characteristic. Variation in the extent or pattern
of snout platation distinguishes Chaetostoma from Transan-
cistrus aequinoctialis,T. santarosensis,Paulasquama callis, and
Pseudolithoxus stearleyi. The naked snout region of Chaetos-
toma generally takes the shape of a broad crescent around
the anterior and anterolateral margins of the snout, whereas
in T. aequinoctialis and T. santarosensis, the anteriormost
unplated snout region is almost absent (Tan and Armbrus-
ter, 2012), and in Paulasquama and Pseudolithoxus stearleyi
the unplated region is limited to medial lobes extending
posteriorly from the anterior snout margin to the nares
(Lujan and Armbruster, 2011).
In this study, we reexamine and expand upon relation-
ships found by Lujan et al. (2015a) by conducting a molec-
ular phylogenetic analysis inclusive of more species and
populations of Andeancistrus,Chaetostoma,Cordylancistrus,
Dolichancistrus,Leptoancistrus, and Transancistrus. We also
present new morphometric, meristic, geographic range, and
live color data for two new and four described species of
Chaetostoma distributed along the Pacific and Atlantic slopes
of the Andes from central Peru to southern Colombia. We
redescribe the Atlantic slope species Ch. breve Regan, 1904,
Ch. carrioni (Norman, 1935), Ch. dermorhynchum Boulenger,
1887, and Ch. microps Gu¨nther, 1864, based on combina-
tions of original type specimens and recently collected
material from at or near type localities. We describe the new
Atlantic Slope species Ch. trimaculineum based on material
from the Maran˜on and Santiago river drainages, and
describe the new Pacific Slope species Ch. bifurcum based
on material from the Esmeraldas, Guayas, Santa Rosa, and
Tumbes river drainages in Ecuador and Peru. In addition to
these phylogenetic and taxonomic results, we provide as
comprehensive an overview of the distinguishing morpho-
logical characteristics of Chaetostoma from throughout the
Amazon Basin as is possible given limitations on the
availability of specimens of certain rare species. Finally, we
present a summary of all genera and species that we
conclude are valid within the Chaetostoma Clade (sensu
Lujan et al., 2015a), including several taxonomic changes
based on our direct and photographic examination of type
specimens.
MATERIALS AND METHODS
Phylogenetic taxon sampling.—We sampled as broadly as
possible throughout Chaetostoma Clade genera and species,
including all valid genera, approximately half of all valid
species (Tables 1, 2), several undescribed species, and
representatives from almost the entire geographic range of
the clade. Lots that have been examined in our molecular
phylogenetic analysis are indicated with an asterisk (*, text)
or bullet (N, Table 1). As with any attempt to comprehen-
sively sample a diverse, widespread, and relatively poorly
known group of organisms, there are species and drainages
missing from our analysis.
Tissue and DNA sources.—Newly generated sequence data
(Table 2) were obtained from tissue samples or DNA extracts
collected by the authors or provided by the Academy of
Natural Sciences of Drexel University in Philadelphia,
Pennsylvania (ANSP), the Auburn University Museum in
Auburn, Alabama (AUM), the Muse´um d’Histoire Naturelle
in Geneva, Switzerland (MHNG), the Museo de Historia
Natural de la Universidad Nacional Mayor de San Marcos in
Lima, Peru (MUSM), the Royal Ontario Museum in Toronto,
Canada (ROM), and the Smithsonian Tropical Research
Institute in Panama (STRI), or obtained through the
ornamental fish trade. Voucher specimens (Table 2) were
identified either directly by the first author, directly by
curators and collection managers at contributing institu-
tions, or by exchange of photographs.
Molecular markers, DNA extraction, amplification, and
sequencing.—Molecular methods followed those of Lujan et
al. (2015a) and will only be briefly reviewed here. We
amplified and sequenced an approximately 600 base pair
(bp) fragment of the mitochondrial 16S gene, an approxi-
mately 1150 bp fragment of the mitochondrial Cyt bgene,
an approximately 1020 bp fragment of the nuclear gene
RAG1, an approximately 950 bp fragment of the nuclear
RAG2 gene, and an approximately 660 bp fragment of the
nuclear MyH6 gene. Each fragment was amplified using
combinations of previously published (Sullivan et al., 2006;
Li et al., 2007) and recently developed primers (Lujan et al.,
2015a). The total alignment equaled 4293 base pairs.
Whole genomic DNA (gDNA) was extracted from fin or
muscle tissues preserved in 95%ethanol following manu-
facturer’s instructions for the DNeasy Blood & Tissue Kit
(Qiagen N.V., Venlo, Netherlands). Fragment amplifi-
cations were performed following the methods of Lujan et
al. (2015a). For all genes, the entire volume of PCR product
was run on a 1%agarose gel with 0.01%SYBR Safe DNA gel
stain (LTI: Life Technologies Inc., Carlsbad, CA). For all
markers, the band corresponding to the target locus was cut
from the gel and the target PCR product extracted by
centrifuge filtration through the top of a P-200 pipette filter
tip in a labeled 1 ml snap-top tube (5 min at 15,000 rpm).
Forward and reverse sequencing reactions followed the
manufacturer’s recommendations for sequencing on an
Applied Biosystems 3730 DNA analyzer (LTI).
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 665
Table 1. Summary of valid genera and species in the Chaetostoma Clade (sensu Lujan et al., 2015). Species included in our molecular phylogenetic
analysis are designated with a bullet (N) after their name. Institutional abbreviations follow Sabaj Pe´rez (2014). Drainages indicated are those for the
principal type locality only, followed by the following larger watershed abbreviations: AD =Amazon Drainage (n=19), CC =Caribbean Coastal
(n=6), MD =Magdalena Drainage (n=9), OD =Orinoco Drainage (n=5), PC =Pacific Coastal (n=13). Taxonomic conclusions for Dolichancistrus
from Ballen and Vari (2012). Abbreviation: syn =syntype.
Species Author Year Holotype Paratypes Country Drainage
Andeancistrus Lujan, Meza-Vargas, and Barriga-Salazar, 2015
A. eschwartzae NLujan et al. 2015 MEPN 14780 19 Ecuador Pastaza (AD)
A. platycephalus N(Boulenger) 1898 BMNH 1898.11.4.42 2 (syn) Ecuador Santiago (AD)
Chaetostoma Tschudi, 1846
Ch. aburrensis Posada 1909 type unknown Colombia Cauca (MD)
Ch. anale (Fowler) 1943 ANSP 70525 Colombia Caqueta (AD)
Ch. anomalum NRegan 1903 BMNH syntypes 13 (syn) Venezuela L. Maracaibo
Ch. bifurcum n. sp. NLujan et al., this study 2015 MEPN 14687 136 Ecuador Guayas (PC)
Ch. branickii Steindachner 1881 NMW syntypes 5 (syn) Peru Maran˜on (AD)
Ch. breve NRegan 1904 BMNH, MSNM, MZUT 12 (syn) Ecuador Santiago (AD)
Ch. brevilabiatum NDahl 1942 ZMUL Colombia Magdalena (MD)
Ch. carrioni N(Norman) 1935 BMNH 1933.5.29.1 4 Ecuador Santiago (AD)
Ch. changae NSalcedo 2006a ANSP 179125 16 Peru Huallaga (AD)
Ch. daidalmatos NSalcedo 2007 MUSM 25552 7 Peru Huallaga (AD)
Ch. dermorhynchum NBoulenger 1887 BMNH 1880.12.8.64–66 3 (syn) Ecuador Pastaza (AD)
Ch. dorsale NEigenmann 1922 CAS 77093 Colombia Meta (OD)
Ch. dupouii Ferna´ndez-Ye´pez 1945 AFY 11 Venezuela Tuy (CC)
Ch. fischeri NSteindachner 1879 NMW 47170–73 7 (syn) Panama Chepo (PC)
Ch. floridablancaensis Ardila Rodriguez 2013 CAR 633.1 19 Colombia Lebrija (MD)
Ch. formosae NBallen 2011 ICNMHN 17114 many Colombia Meta (OD)
Ch. guariense NSteindachner 1882 NMW 47183–85 7 (syn) Venezuela Tuy (CC)
Ch. jegui Rapp Py-Daniel 1991 INPA 2822 83 Brazil Uraricoera (AD)
Ch. leucomelas Eigenmann 1918 CAS 60167 2 Colombia Patı´a (PC)
Ch. lepturum Regan 1912 BMNH 1910.7.11.116–118 3 (syn) Colombia San Juan (PC)
Ch. lexa NSalcedo 2013 ANSP 179128 17 Peru Huallaga (AD)
Ch. leucomelas Eigenmann 1917 CAS 60167 2 Colombia Patı´a (PC)
Ch. lineopunctatum NEigenmann
and Allen
1942 CAS 64650 1 Peru Ucayali (AD)
Ch. loborhynchos NTschudi 1845 NMW 47190 Peru Ucayali (AD)
Ch. machiquense Ferna´ndez-Ye´pez
and Martin S.
1953 MHNLS 1558 1 Venezuela L. Maracaibo
Ch. marginatum Regan 1904 BMNH 1901.8.3/27–28 3 (syn) Ecuador Mira (PC)
Ch. marmorescens NEigenmann and Allen 1942 IU 15403 Peru Huallaga (AD)
Ch. microps NGu¨nther 1864 BMNH 1860.6.16.137–143 7 (syn) Ecuador Santiago (AD)
Ch. milesi Fowler 1941 ANSP 69330 Colombia Magdalena (MD)
Ch. niveum Fowler 1944 ANSP 71432 Colombia Jurubida´ (PC)
Ch. nudirostre NLu¨tken 1874 ZMUC P30168 Venezuela L. Valencia (CC)
Ch. palmeri Regan 1912 BMNH 1910.7.11.120–121 2 (syn) Colombia San Juan (PC)
Ch. patiae Fowler 1945 ANSP 71716 1 Colombia Patia (PC)
Ch. paucispinis Regan 1912 BMNH 1910.7.11.119 Colombia San Juan (PC)
Ch. pearsei Eigenmann 1920 CAS 64655 4 Venezuela L. Valencia (CC)
Ch. platyrhynchus (Fowler) 1943 ANSP 70512 3 Colombia Caqueta´ (AD)
Ch. sovichthys Schultz 1944 USNM 121053 171 Venezuela L. Maracaibo
Ch. stanii Lu¨tken 1874 ZMUC P30169 Venezuela Yaracuy (CC)
Ch. stroumpoulos NSalcedo 2006b MUSM 23491 many Peru Huallaga (AD)
Ch. tachiraense Schultz 1944 USNM 121052 1 Venezuela L. Maracaibo
Ch. taczanowskii Steindachner 1883 NMW 47219 1 Peru L. Maracaibo
Ch. thomsoni Regan 1904 BMNH 1902.5.15.28–30 3 (syn) Colombia Magdalena (MD)
Ch. trimaculineum n. sp. NLujan et al., this study 2015 MEPN 14688 6 Ecuador Santiago (AD)
Ch. vagum Fowler 1943 ANSP 70521 3 Colombia Caqueta´ (AD)
Ch. vasquezi NLasso and Provenzano 1998 MHNLS 8791 57 Venezuela Caura (OD)
Ch. venezuelae Schultz 1944 NYZS 30064 Venezuela San Juan (CC)
Ch. yurubiense Ceas and Page 1996 INHS 34942 15 Venezuela Yaracuy (CC)
Cordylancistrus Isbru¨ cker, 1980
Co. torbesensis N(Schultz) 1944 USNM 121001 173 Venezuela Apure (OD)
666 Copeia 103, No. 3, 2015
Sequence assembly, alignment, and phylogenetic inference.—
Sequence data were assembled, edited, aligned, and
concatenated following the methods of Lujan et al.
(2015a). Phylogenetic analysis of the concatenated align-
ment was conducted using both Bayesian inference (BI)
and maximum likelihood (ML) methods with Vandellia sp.
(Trichomycteridae) designated as the outgroup. A Bayesian
Markov chain Monte Carlo search of tree space was
conducted using MrBayes (v3.2.2; Ronquist and Huelsen-
beck, 2003) on the CIPRES supercomputing cluster (Miller
et al., 2010). MrBayes was programmed to run for 40
million generations using eight chains (nchains 58; with
default temperature parameter), sampling every 2666 trees
with the first 30%of trees (4500) being discarded as burn-
in. The Bayesian search was determined to have reached
stationarity when cold chains randomly fluctuated within
a stable range of posterior probabilities and when effective
sample size for all metrics exceeded 200 as determined by
the program Tracer (v1.6; Rambaut et al., 2007). Maximum
likelihood analysis was conducted using RAxML (v8.0.0;
Stamatakis, 2014) programmed to first conduct a 200
generation search for the best tree and then generate
bootstrap support values based on a 2000 generation search
of tree space.
Scope of taxonomic research.—This study is based largely on
fresh material collected by the authors during expeditions to
the Atlantic and Pacific slopes of the Andes mountains of
Ecuador in 2012 and 2014 and to the Maran˜on (2006) and
Madre de Dı´os (2010) river drainages of Peru. Our choice of
species to formally redescribe is based largely on the material
that we had at our disposal as a result of this field work and
by our desire to avoid duplicating ongoing work by other
researchers.
Morphometrics and meristics.—Morphometric and meristic
data are presented in tables. Measurement landmarks follow
Armbruster (2003); lateral trunk plate row terminology
follows Schaefer (1997). Standard length (SL) is expressed in
mm and other measurements are expressed as percentages of
either standard length or head length. Measurements and
counts were taken on the left side of specimens when possible.
Institutional abbreviations follow Sabaj Pe´ rez (2014).
Sexual dimorphism.—Urogenital pore morphologies differ
between male and female Chaetostoma, with males having
a more elongate and tubular genital pore (Fig. 1; Rapp Py-
Daniel, 1991). These primary sexual differences were used to
determine sex and to elucidate secondary sexual character-
istics.
Type specimens.—We directly examined original types of
Chaetostoma alternifasciatum Fowler, 1945 (ANSP 71711), Ch.
anale (Fowler, 1941; holotype: ANSP 70525), Ch. anomalum
Regan, 1903 (holotype: USNM 133135), Ch. breve Regan,
1904 (syntypes: BMNH 1898.11.4.33–36), Ch. carrioni (Nor-
man, 1935; holotype: BMNH 1933.5.29.1), Ch. changae
Salcedo, 2006a (holotype: ANSP 179125), Ch. dermor-
hynchum Boulenger, 1887 (syntypes: BMNH 1880.12.8.64–
66), Ch. microps Gu¨nther, 1864 (syntypes: BMNH
1860.6.16.137–143), Ch. milesi Fowler, 1941 (holotype:
ANSP 69330), Ch. mollinasum Pearson, 1937 (syntypes [8]:
CAS 64653), Ch. niveum Fowler, 1944 (holotype: ANSP
71432), Ch. patiae Fowler, 1945 (holotype: ANSP 71716),
Ch. platyrhynchus (Fowler, 1943; holotype: ANSP 70512), Ch.
sericeum Cope, 1872 (holotype: ANSP 22005), Ch. sovichthys
Schultz, 1944 (holotype: USNM 121053), Ch. tachiraense
Schultz, 1944 (holotype: USNM 121052), and Ch. vagum
Fowler, 1943 (holotype: ANSP 70521). We also directly
examined live or recently collected topotypes (see non-type
material listed below) of Ch. breve Regan, 1904, Ch. carrioni
(Norman, 1935), Ch. dermorhynchum Boulenger, 1887, Ch.
jegui Rapp Py-Daniel, 1991 (INPA 33840), and Ch. microps
Gu¨nther, 1864. Original types of Ch. guairense Steindachner,
1881, Ch. lepturum Regan, 1912, Ch. leucomelas Eigenmann,
1918, Ch. marginatum Regan, 1904, Ch. palmeri Regan, 1912,
and Ch. paucispinis Regan, 1912 were examined via high
resolution digital images hosted by the All Catfish Species
Project website.
L-numbers.—Several taxa examined in this study are unde-
scribed genera or species that have previously been recog-
nized as distinct by aquarium fish hobbyists and been
assigned a standardized alphanumeric code (an L-number;
Dignall, 2014) as a way of tracking them pending official
description. Given the utility and generally standardized
Species Author Year Holotype Paratypes Country Drainage
Dolichancistrus Isbru¨ cker, 1980
D. atratoensis (Dahl) 1960 ICNMHN 51 42 Colombia Atrato
D. carnegiei N(Eigenmann) 1916 FMNH 58350 11 Colombia Magdalena (MD)
D. cobrensis (Schultz) 1944 USNM 121036 160 Venezuela L. Maracaibo
D. fuesslii N(Steindachner) 1911 NMW 48026 Colombia Meta (OD)
Leptoancistrus Meek and Hildebrand, 1916
L. canensis N(Meek and Hildebrand) 1913 FMNH 7581 44 Panama Tuira (PC)
L. cordobensis Dahl 1964 type missing Colombia Magdalena (MD)
Transancistrus Lujan, Meza-Vargas, and Barriga-Salazar, 2015
T. aequinoctialis N(Pellegrin) 1909 MNHN 1904–0017 Ecuador Esmeraldas (PC)
T. santarosensis N(Tan and Armbruster) 2012 MECN-DP 2061 5 Ecuador Santa Rosa (PC)
incertae sedis
Co. daguae (Eigenmann) 1912 FMNH 56052 84 Colombia Magdalena (MD)
Co. perijae Pe´rez and Provenzano 1996 MBLUZ 4413 47 Venezuela L. Maracaibo
D. setosus (Boulenger) 1887 BMNH 1880.2.26.9–10 2 (syn) Colombia Cesar (MD)
Table 1. Continued.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 667
Table 2. Loci sequenced, voucher catalog number, and country and river drainage of origin for the tissue samples analyzed in this study. Non-Chaetostoma Clade taxa were included in the analysis only as
outgroups and were omitted from Figure 2.
Taxa Tissue #Topotype 16S Cyt bRAG1 RAG2 MyH6 Voucher cat. #Country Drainage
Loricariidae
Chaetostoma Clade
Andeancistrus eschwartzae T14249 X X X X X AUM 64664 Ecuador Pastaza R.
Andeancistrus platycephalus T14019 * X X X X X ROM 93847 Ecuador Santiago R.
Chaetostoma aff. lineopunctatum PE08-545 X X X X X MHNG 2712.069 Peru Huallaga R.
Chaetostoma anomalum T631 X X X X INHS 55455 Venezuela L. Maracaibo
Chaetostoma bifurcum n. sp. T13602 * X X X X X ROM 93687 Ecuador Esmeraldas R.
Chaetostoma bifurcum n. sp. T13665 X X X X X ROM 93721 Ecuador Guayas R.
Chaetostoma bifurcum n. sp. T13896 X X X X X ROM 93787 Ecuador Santa Rosa R.
Chaetostoma breve PE08-648 X X X X X MHNG 2712.074 Peru Huallaga R.
Chaetostoma breve P6292 * X X X X X AUM 46515 Peru Maran˜on R.
Chaetostoma breve T14360 X X X X ROM 93950 Ecuador Napo R.
Chaetostoma breve T14224 X X ROM 93923 Ecuador Pastaza R.
Chaetostoma carrioni T14016 * X X X X X ROM 93845 Ecuador Santiago R.
Chaetostoma cf. fischeri T9034 X X X X X STRI 11581 Panama Tuira R.
Chaetostoma cf. loborhynchus CH204 X X X X X MUSM 44889 Peru Huallaga R.
Chaetostoma changae PE08-543 * X X X X X MHNG 2712.067 Peru Huallaga R.
Chaetostoma daidalmatos PE08-347 * X X X X X MHNG 2712.055 Peru Huallaga R.
Chaetostoma dermorhynchum T14258 X X X X X ROM 93656 Ecuador Pastaza R.
Chaetostoma dorsale T12929 X X X X ROM 94926 Colombia Meta R.
Chaetostoma fischeri T9036 * X X X X X STRI 12274 Panama Bayano R.
Chaetostoma fischeri T9026 X X X X X STRI 7604 Panama Chagres R.
Chaetostoma guairense VZ122 * X X X X INHS 34786 Venezuela Limon R.
Chaetostoma lexa PE08-591 * X X X X X MHNG 2712.071 Peru Huallaga R.
Chaetostoma lineopunctatum T10088 X X X X X AUM 51166 Peru Madre de Dios R.
Chaetostoma lineopunctatum PE08-047 * X X X X X MHNG 2712.041 Peru Ucayali R.
Chaetostoma marmorescens CH198 X X X X X MUSM unknown Peru Huallaga R.
Chaetostoma microps PE08-190 X X X X X MHNG 2712.046 Peru Huallaga R.
Chaetostoma microps P6034 X X X X AUM 45518 Peru Maran˜on R.
Chaetostoma microps T14364 X X X X X ROM 93949 Ecuador Napo R.
Chaetostoma microps T14125 * X X X X X ROM 93895 Ecuador Santiago R.
Chaetostoma microps T14097 X X X X ROM 93877 Ecuador Yungantza R.
Chaetostoma n. sp. L402 T621 X X X INHS 56147 Venezuela Apure R.
Chaetostoma n. sp. L402 T08955 X X X X AUM 54034 Venezuela Apure R.
Chaetostoma n. sp. L445 T12930 X X X X X ROM 94925 Colombia Meta R.
Chaetostoma n. sp. Ucayali PE08-121 X X X X X MHNG 2712.042 Peru Ucayali R.
Chaetostoma n. sp. Xingu B1487 X X X X X ANSP 199686 Brazil Jarauc¸u R.
Chaetostoma nudirostre T2084 X X X ANSP 191471 Venezuela L. Valencia
Chaetostoma stroumpoulos PE08-307 * X X X X X MHNG 2712.056 Peru Huallaga R.
Chaetostoma trimaculineum n. sp. P6047 X X X X X AUM 45524 Peru Maran˜on R.
Chaetostoma trimaculineum n. sp. T14136 X X X X X ROM 93894 Ecuador Santiago R.
Chaetostoma vasquezi V27 X X X X X AUM 36555 Venezuela Caroni R.
668 Copeia 103, No. 3, 2015
Taxa Tissue #Topotype 16S Cyt bRAG1 RAG2 MyH6 Voucher cat. #Country Drainage
Chaetostoma vasquezi T09945 * X X X X X AUM 53812 Venezuela Caura R.
Cordylancistrus torbesensis T674 * X X X X INHS 55478 Venezuela Torbes R.
Dolichancistrus carnegiei 6647 X X X X X ANSP 189598 Colombia Magdalena R.
Dolichancistrus fuesslii T14621 * X X X X X ROM 94484 Colombia Guaviare R.
Leptoancistrus canensis T9033 * X X X X X STRI 11580 Panama Tuira R.
Leptoancistrus cf. canensis T9031 X X X X X STRI AM-55 Panama Cocle del Norte R.
Leptoancistrus cf. canensis T9029 X X X X STRI 11050 Panama Cocle del Sur R.
Leptoancistrus cf. canensis T9039 X X X X STRI 6058 Panama Indio R.
Transancistrus aequinoctialis T13525 X X X X X ROM 93661 Ecuador Esmeraldas R.
Transancistrus santarosensis T13980 * X X X X X ROM 93798 Ecuador Santa Rosa R.
Ancistrini
Ancistrus leucostictus T08143 X X X X ROM 88561 Guyana Essequibo R.
Ancistrus ranunculus B1500 * X X X X X ANSP 199525 Brazil Xingu R.
Ancistrus clementinae T13829 * X X X X X ROM 93737 Ecuador Guayas R.
Lasiancistrus schomburgkii P6125 X X X X X AUM 45548 Peru Maran˜on R.
Lasiancistrus tentaculatus T09686 X X X X X AUM 53895 Venezuela Ventuari R.
Pseudolithoxus kelsorum T09895 * X X X X X AUM 51644 Venezuela Orinoco R.
Pseudolithoxus stearleyi V5533 * X X X X X AUM 43872 Venezuela Soromoni R.
Corymbophanes kaiei T12637 X X X X X ROM 89856 Guyana Potaro R.
Hopliancistrus tricornis T9017 X X X X X AUM 39853 Brazil aquarium trade
Guyanancistrus brevispinis 86.1 * X X X X X MHNG 2725.099 French Guiana Maroni R.
Dekeyseria scaphirhyncha T09540 X X X X X AUM 54309 Venezuela Ventuari R.
Neblinichthys brevibrachium T06068 * X X X X X ROM 83692 Guyana Mazaruni R.
Paulasquama callis T06189 * X X X X X ROM 83784 Guyana Mazaruni R.
Peckoltia Clade
Panaqolus nocturnus P6126 * X X X X X AUM 45500 Peru Maran˜on R.
Peckoltia furcata P6200 X X X X X AUM 45593 Peru Maran˜on R.
Hypancistrus debilittera T09279 * X X X X X AUM 53528 Venezuela Orinoco R.
Aphanotorulus squalinus T09528 X X X X X AUM 54305 Venezuela Ventuari R.
Hypostomini
Cochliodon macushi T07038 * X X X X X ROM 85939 Guyana Essequibo R.
Hypostomus niceforoi T10282 X X X X X AUM 51404 Peru Madre de Dios R.
Hemiancistrus Clade
‘Baryancistrus’ beggini T09392 * X X X X X AUM 54990 Venezuela Orinoco R.
‘Baryancistrus’ demantoides T09361 * X X X X X ROM 93339 Venezuela Ventuari R.
Hemiancistrus medians 6948 * X X X X X ANSP 187122 Suriname Maroni R.
Panaque nigrolineatus T09018 * X X X X X AUM 53764 Venezuela Apure R.
Acanthicus Clade
Acanthicus adonis T9001 X X X X X AUM 44605 aquarium trade
Lithoxus Clade
Exastilithoxus fimbriatus V049 * X X X X X AUM 36632 Venezuela Caroni R.
incertae sedis
Pseudancistrus genisetiger 86.2 X X X X X MHNG 2593.061 Brazil Sa˜o Francisco R.
Table 2. Continued.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 669
application of these codes, we have adopted them through-
out this study.
Taxonomic diagnoses.—Due to the broad geographic range
and high species richness of Chaetostoma and the paucity
of institutionally curated specimens from many parts of its
range, a comprehensive taxonomic revision of the genus is
not currently possible. We therefore restrict our taxonomic
diagnoses to valid congeners described from arbitrarily
defined geographic regions. For Ch. bifurcum, new species,
we restrict our diagnosis to the eight Chaetostoma currently
described from the Pacific Coast of South America. For Ch.
carrioni,Ch. breve,Ch. dermorhynchum,Ch. microps,andCh.
trimaculineum, new species—all species with type localities
in Atlantic Slope headwaters of the Amazon Basin within
Ecuador—we restrict our diagnoses to all 17 naked-snouted
Chaetostoma currently recognized as valid from the
Amazon Basin. For ease of reference, we present the
diagnosesofAmazonBasinspeciesinbothatextand
tabular format. Chaetostoma platyrhynchus,theonlyAma-
zon Basin species excluded from our diagnoses, is easily
distinguished from all other Chaetostoma by having a fully
plated snout and will therefore not be considered further
herein.
Color descriptions.—To the extent possible, we focus on
descriptions and images of live specimens—information
that has been scarce in the recent literature on this group.
As with most fish, coloration of Chaetostoma changes
dramatically after preservation, including the frequent loss
of most or all color and color pattern on the body. Fin
color patterns are usually more resistant to the fading
effects of long-term preservation. Illustrations and photo-
graphs of preserved specimens of most of the species in this
paper can be found in the original descriptions and/or
online repositories of type images (e.g., the All Catfish
Species Inventory Image Base: http://acsi.acnatsci.org/
base/).
RESULTS
Phylogeny.—With the addition of more species and popula-
tions of Andeancistrus,Chaetostoma,Cordylancistrus,Doli-
chancistrus,Leptoancistrus,andTransancistrus (Fig. 2; vs.
Lujan et al., 2015a), statistical support for the sister
relationship between Chaetostoma and the Cordylancistrus
Clade (Clade OP) changed little (Table 3, Node 52: BI:
0.70, ML: 53; vs. BI: 0.66, ML: 64), support for monophyly of
Fig. 1. Illustrations of representative female (left) and male (right)
urogenital pores of Chaetostoma. Illustrations by VAC.
Taxa Tissue #Topotype 16S Cyt bRAG1 RAG2 MyH6 Voucher cat. #Country Drainage
Callichthyidae
Corydoradinae
Corydoras aeneus T12836 X X X X ROM 90346 Bolivia Mamore´R.
Corydoras panda T12932 X X X X ROM 94924
Corydoras stenocephalus T12839 X X X X X ROM 90345 Bolivia Mamore´R.
Callichthyinae
Callichthys callichthys T10404 X X X MUSM unknown Peru Huallaga R.
Trichomycteridae
Vandellia sp. V5509 X X X AUM 43867 Venezuela Orinoco R.
Table 2. Continued.
670 Copeia 103, No. 3, 2015
Chaetostoma remained strong (Node 41: BI: 1.0, ML: 99; vs.
BI: 1.0, ML: 100), and support for monophyly of Cordylan-
cistrus Clade genera declined slightly (Node 51; BI: 0.80, ML:
60; vs. BI: 0.87, ML: 72).
Basal relationships within Chaetostoma consisted of a tri-
chotomy between the geographically widespread Clade A–J,
the northwestern South American Clade N, and the
northern South American/Panamanian Clade KLM (Node
41). Clade N also consisted of a strongly monophyletic
trichotomy (Node 38: BI: 1.0, ML: 100), in this case between
an undescribed species from the upper Meta River drainage
in Colombia (Ch. n. sp. Meta L445), and respective species
from the Lake Maracaibo (Ch. anomalum) and Lake Valencia
(Ch. nudirostre) drainages in western and northern Vene-
zuela. Clade KLM consisted of species distributed from
central Panama (Ch. fischeri) in the northwest to the Pacific
Coast of southern Ecuador (Ch. bifurcum, new species) in the
southwest and the Caroni River drainage (Ch. vasquezi)of
eastern Venezuela in the east. Within Clade KLM, Ch.
brevilabiatum (Clade M) from the Magdalena River drainage
in Colombia was moderately supported as sister to all other
species (Node 37: BI: 0.97, ML: 61). The remaining clades K
and L were moderately supported as sister (Node 36: BI: 0.89,
ML: 46), with each clade being strongly well supported as
monophyletic (Nodes 33 and 35: BI: 1.0, ML: 100).
Clade K was the only Chaetostoma clade that contained
species from either Central America or the Pacific Coast of
South America, and it appears to be entirely restricted to this
marginal zone. Within Clade K, the apparently undescribed
southeastern Panamanian species Ch. aff. fischeri (from the
Tuira River) was found to be sister (Node 33) to a weakly
supported clade containing species distributed to both the
northwest (Ch. fischeri) and southwest (Ch. bifurcum, new
species; Node 32: BI: 0.68, ML: –). Specimens of Ch. bifurcum,
new species, from across the entire Pacific Coast of Ecuador
were strongly monophyletic (Node 30: BI: 1.0, ML: 100) and
showed little sequence divergence (i.e., short branchlengths).
However, the two more southerly populations from the
Guayas and Santa Rosa drainages were more closely related to
each other than either were to populations in the Esmeraldas
River drainage to the north (Node 29: BI: 0.97, ML: 75).
In contrast to Chaetostoma clades K, L, M, and N, Clade
A–J comprised species that are broadly distributed across
headwaters of the Amazon and Orinoco, from the Meta and
Apure river drainages in the north to the Madre de Dios
River drainage in the south and the Xingu River in the east.
Basal relationships within Clade A–J consisted of a trichot-
omy (Node 28: BI: 1.0, ML: 100) including Ch. lexa (Clade J),
a weakly supported Clade A–D (Node 13: BI: 0.56, ML: 57),
and a strongly supported Clade E–I (Node 26: BI: 1.0, ML:
99). Of these, Clade J (Ch. lexa) was the most geographically
restricted, being known only from the upper Huallaga River
drainage in central Peru (Salcedo, 2013). Clade A–D
comprised species from mostly southwestern headwaters of
the Amazon Basin, bounded by the Napo River in the north
(Ch. microps) to the Madre de Dios River drainage (Ch.
lineopunctatum)—the southernmost limit to the range of
Chaetostoma.
Within Clade A–D, Clade A (Node 5: BI: 1.0, ML: 100)
comprised the widely distributed and strongly monophylet-
ic species Ch. microps (Node 4: BI: 1.0, ML: 89) and its sister
species Ch. carrioni, which is narrowly endemic to the
Santiago River drainage in southeastern Ecuador. Clade
A was well supported as sister to Clade B (Node 7: BI: 91, ML:
70), which comprised the Huallaga River sister species Ch.
marmorescens and Ch. cf. loborhynchos (Node 6: BI: 1.0,
ML: 100). The strongly supported Clade C (Node 11: BI: 1.0,
ML: 100) comprised species having rows of longitudinal
spots along the body, including the Huallaga River sister
species Ch. daidalmatos and Ch. stroumpoulos (Node 8: BI:
1.0, ML: 100), and Ch. lineopunctatum from the Ucayali and
Madre de Dios rivers (Node 10: BI: 1.0, ML: 100). A possibly
new species (Ch. aff. lineopunctatum) from the Huallaga River
was found to be more closely related to Ch. daidalmatos and
Ch. stroumpoulos than to Ch. lineopunctatum sensu stricto
(Node 9: BI: 0.81, ML: 94; see Other undescribed species
below). The Huallaga River species Ch. changae (Clade D) was
ambiguously supported as sister to Clade C (Node 12: BI:
0.97, ML: 49).
Fig. 2. Phylogenetic relationships within the Chaetostoma Clade
(sensu Lujan et al., 2015) based on Bayesian analysis of a 4293 base
pair alignment consisting of two mitochondrial (16S, Cyt b) and three
nuclear loci (RAG1, RAG2, MyH6). Taxa from Pacific Coast drainages in
blue and Brazilian or Guiana Shield drainages in green. Node numbers
correspond to Bayesian posterior probability (BI) and maximum
likelihood (ML) support values in Table 3. Numbers in red indicate
indicate BI: ,90; numbers in italics indicate ML: ,50. Samples taken
from at or near the type locality for a given species are indicated by
asterisks and species that are types for the given genus are indicated
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 671
Clade E–I (Node 26) comprised species distributed across
almost the entire Atlantic Slope range of the genus
Chaetostoma, from the Meta and Apure rivers in the north
to the Huallaga River in the south and the Xingu River in
the east. Basal relationships within this clade consist of
a four-way polytomy between an undescribed species from
the Ucayali River drainage (Clade I), an undescribed and
strongly monophyletic species from the Meta and Apure
river drainages (L402, Clade H, Node 24: BI: 1.0, ML: 94), the
geographically widespread and strongly monophyletic spe-
cies Ch. breve (Clade G, Node 23: BI: 1.0, ML: 100), and the
weakly supported Clade EF (Node 18: BI: 0.60, ML: –). Clade
E comprised only Ch. dorsale from the upper Meta River
drainage in central Colombia. Clade F was found to be
strongly monophyletic (Node 17: BI: 1.0, ML: 96) and
contained species from the upper Meta River drainage
(Ch. formosae), the Pastaza River drainage (Ch. dermo-
rhynchum), an undescribed species (L416) from the Xingu
River drainage in Brazil, and a new species from the
Maran˜ on and Santiago river drainages of southern Ecuador
and northern Peru (described herein as Ch. trimaculineum,
new species). The first three of these species comprise
a previously morphologically defined subclade within
Chaetostoma called the Ch. anale species group (Ballen,
2011); molecular data supported their monophyly (Node 15:
BI: 0.99, ML: 71) and their sister relationship to Ch.
trimaculineum, new species.
Monophyly of the Cordylancistrus Clade (Clade OP) was
moderately supported (Node 51: BI: 0.80, ML: 60). This clade
comprised the respectively strongly supported clades O and P
(Nodes 47 and 50: BI: 1.0, ML: 100). Clade O comprised three
genera (Cordylancistrus,Dolichancistrus, and Leptoancistrus)
distributed from northwestern Panama to western head-
waters of the Orinoco River in central Colombia and western
Venezuela. The entirely Panamanian and northwestern
Colombian genus Leptoancistrus was found to be strongly
monophyletic (Node 44: BI: 1.0, ML: 100) and to comprise the
type species, L. canensis (from the Tuira River drainage in
southeastern Panama), plus a likely undescribed species, L. cf.
canensis (from the Cocle and Indio rivers in northwestern
Panama; Node 43: BI: 1.0, ML: 100). Leptoancistrus was sister
(Node 47) to a strongly supported clade (Node 46: BI: 0.98,
ML: 81) comprising two species of Dolichancistrus (Node 45:
BI: 1.0, ML: 100) and Cordylancistrus torbesensis (type species of
Cordylancistrus). This latter clade spans the Cordillera Central
of the northern Andes Mountains, being present in the
Table 3. Support values for each of the nodes in Figure 2, derived from Bayesian inference (BI) and maximum likelihood (ML) optimality criteria.
Support values in bold indicate BI: ,0.90 or ML: ,50.
Node BI ML Clade Node BI ML Clade Node BI ML Clade
10.84 66 19 — 13 37 0.97 61
Ch. brevilabiatum +
(Clades K +L)
21.00 100
Ch. microps Santiago +
Yungantza 20 1.00 99
Ch. breve Napo +
Pastaza 38 1.00 100 Clade N
30.91 50
Ch. microps Maran˜on +
Huallaga 21 43 39 — 43
Ch. anomalum +
Ch. n. sp. L445
41.00 89 Chaetostoma microps 22 1.00 100
Ch. breve Maran˜on +
Santiago 40 — 46 Clade N +Clade A–J
51.00 100
Ch. carrioni
+Ch. microps 23 1.00 100 Chaetostoma breve 41 1.00 99 Chaetostoma
61.00 100
Ch. marmorescens +
Ch. cf. lobo 24 1.00 94
Chaetostoma n. sp.
L402 42 62 L. cf. canensis Cocle
70.91 70 Clade A +B2513 43 1.00 100
L. cf. canensis (North/
Caribbean)
81.00 100
Ch. daidalmatos
+Ch. stroump 26 1.00 99 Clade E–I 44 1.00 100 Leptoancistrus
90.81 94 27 — 33 Ch. lexa +Clade A–D 45 1.00 100 Dolichancistrus
10 1.00 100
Ch. lineopunctatum
Ucayali +MdD 28 1.00 100
widespread
Chaetostoma clade 46 0.98 81
Co. torbesensis +
Dolichancistrus
11 1.00 100 Clade C 29 0.97 75
Ch. marginatum
Guay. +Sta. Ros. 47 1.00 100 Clade O
12 0.97 49 Ch. changae +Clade C 30 1.00 100
Chaetostoma
marginatum 48 1.00 100
Co.platycephalus +
Co.’ n. sp.
13 0.56 57 Clades A, B, C, D 31 1.00 100
Ch. fischeri Bayano +
Chagres 49 1.00 100
Co.aequinoctialis +
Co.santoros
14 0.79 53
Ch. formosae +
Ch. n. sp. Xingu 32 0.68
Ch. marginatum +Ch.
fischeri 50 1.00 100
all ‘Cordylancistrus’ of
Ecuador
15 0.99 71 33 1.00 100 Clade K 51 0.80 60
Subtribe:
Cordylancistrus
Clade
16 1.00 98
Ch. n. sp. Maran˜on +
Santiago 34 1.00 100
Ch. vasquezi Caura +
Caroni 52 0.70 53
Tribe: Chaetostoma
Clade
17 1.00 96 Clade F 35 1.00 100
Ch. guairense
+Ch. vasquezi 53 0.98 50 Hypostominae
18 0.60 — Ch. dorsale +Clade F 36 0.89 46 Clade K +L
672 Copeia 103, No. 3, 2015
Magdalena River drainage (Dolichancistrus carnegiei) and two
left-bank (western) tributaries of the Orinoco River: the upper
Apure River drainage in southwestern Venezuela (Cordylan-
cistrus torbesensis), and the upper Guaviare River drainage in
central Colombia (D. fuesslii). Clade P comprised two recently
described genera (Lujan et al., 2015b) from opposite sides of
the Andes Mountains in Ecuador. The Pacific Coastal genus
Transancistrus was strongly monophyletic (Node 49: BI: 1.0,
ML: 100) and sister (Node 50: BI: 1.0, ML: 100) to the Atlantic
Slope genus Andeancistrus, which was also strongly mono-
phyletic (Node 48: BI: 1.0, ML: 100).
Biogeography.An explicit, quantitative biogeographical
analysis of the Chaetostoma Clade is beyond the scope of
this paper and will be provided elsewhere. However, two
broad biogeographical trends can be inferred from the
phylogeny (Fig. 2). The first is suggestive of a northwestern
South American origin for the clade as a whole, with several
depauperate sister lineages that branch from basal nodes
being restricted to this region (e.g., clades K, L, M, and O)
and more species-rich and broadly distributed clades being
generally more deeply nested (e.g., clades A, B, C, D, G, J).
The second trend, within the broadly distributed Chaetos-
toma Clade A–J, is suggestive of a secondary point of origin
in the Huallaga River drainage of central Peru, with this
drainage being represented in six of the ten lettered
subclades A–J. Moreover, despite the poor resolution at
several points in this clade, it is clear that several de-
pauperate lineages restricted to the Huallaga (e.g., clades B,
D, J) are closely related to more geographically widespread
clades (e.g., A, C, E, F, G, H).
Sexual dimorphism.—Unlike many other loricariids (Rapp Py-
Daniel and Cox Fernandes, 2005), members of the genus
Chaetostoma generally do not display extensive hypertrophy
or elongation of odontodes when sexually mature. Instead,
males of many species develop a more enlarged and fleshy
unplated anterior snout region, an elongation of various fin
regions, sometimes accompanied by longitudinal dermal
folds along the dorsal or lateral ridges of fin rays (e.g., Ch.
dermorhynchum, Fig. 3, immature male [A] versus mature
male [B]). The coloration of some species can also change,
with base colors becoming more intensified and pattern
contrasts either increasing (e.g., Ch. breve,Fig.4A)or
decreasing (e.g., Ch. dermorhynchum, Fig. 3B).
We recognized four distinct types of sexual dimorphism
related to fin morphology in Chaetostoma, each of which is
illustrated either alone or in combination by species
described herein: Type 1 fin modifications involve the
elongation of proximal, branched pelvic-fin rays so that
the proximomedial posterior margin of the pelvic fin is
elongated into a lobe (e.g., Ch. dermorhynchum,Fig.3;
Chaetostoma microps, Fig. 5, male [A and B] vs. female
[C and D]). Type 2 modifications involve the development
of a dermal fold or flap along the proximal posterodorsal
margin of the unbranched pelvic-fin ray, with this fold
being deeper than all other skin folds on branched rays (if
present) and being adnate to the body at the pelvic-fin
insertion (e.g., Ch. dermorhynchum, Fig. 3). Type 3 modifica-
tions involve the development of low dermal folds along the
length of branched fin rays (e.g., Ch. dermorhynchum,
Fig. 3B). These dermal folds can develop on the dorsal
surfaces of pelvic-fin rays and on the lateral or posterior
surface of anal-fin rays, but have not been observed on rays
of either the pectoral, dorsal, or caudal fin. Type 4 fin
modifications involve the elongation of outer, unbranched
rays of the pelvic and/or anal fins into short filaments,
typically accompanied by the overall enlargement of the
anal fin (e.g., Ch. dermorhynchum, Fig. 3B).
Cheek odontode shape and size.—Chaetostoma exhibit a range
of taxonomically important cheek odontode morphologies
(Ballen, 2011; Salcedo, 2013). To facilitate diagnoses, we
categorize this variation into four distinct types (Fig. 6):
Type 1 cheek odontodes are thin, short, and straight; Type 2
cheek odontodes are thin, more elongate, and slightly
hooked; Type 3 odontodes are relatively short, thick, and
strongly hooked; and Type 4 cheek odontodes are more
elongate than all others and moderately hooked.
Taxonomic changes.—Based on our direct and photographic
examination of type material, we transfer the following
three species from Chaetostoma to the genus Ancistrus:
Chaetostoma greeni Isbru¨cker et al., 2001 (replacement name
for Chaetostomus maculatus Regan, 1904) is recognized as
Ancistrus greeni, new combination; Chaetostomus marcapatae
Regan, 1904 is recognized as Ancistrus marcapatae, new
combination; and Chaetostomus sericeus Cope, 1872 is
recognized as Ancistrus sericeus, new combination. The type
specimens of each of these species have unplated snout
margins, but only three plate rows at the thinnest part of the
caudal peduncle and seven branched dorsal-fin rays, con-
firming their proper placement in the genus Ancistrus.
Chaetostomus trinitatis Gu¨nther, 1864, described from the
island of Trinidad, is a fourth species that we believe should
be transferred to Ancistrus, based in part on its original
description stating that it only has seven branched dorsal-
fin rays. Unfortunately, the whereabouts of the syntypes of
Chaetostomus trinitatis are unknown. Further justification for
this transferral is derived from the absence of any vouchered
record of a Chaetostoma ever having been collected in
Trinidad, and the modern occurrence of only a single species
of ancistrine loricariid on this island: a species currently
referred to as Ancistrus maracasae (Phillip et al., 2013). We
Fig. 3. Chaetostoma dermorhynchum from the Pastaza River drainage,
Ecuador: (A) immature (type locality; ROM 93946, 84.4 mm SL) and (B)
adult male (ROM93656*, 171.7 cm SL). Scale bars 51 cm. Photos by NKL.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 673
Fig. 4. Chaetostoma breve from various drainages along the Atlantic Slope of the Andes: the (A, B) Napo (Ecuador: ROM 93950*, A: 117.4 mm, B:
137.1 mm SL), (C) Santiago (Ecuador: type locality; ROM 93848, 127.2 mm SL), and (D) Maran˜ on (Peru: AUM 46515*, 91.5 mm SL) river drainages.
Scale bars 51 cm. Photos by NKL.
674 Copeia 103, No. 3, 2015
Fig. 5. Chaetostoma microps from various Atlantic Slope drainages of the Andes: the (A) Napo (Ecuador, ROM 93948, 72.3 mm SL), (B, C) Santiago
(Ecuador, type locality; B: ROM 93902, 74.5 mm SL, C: ROM 93895*, 56.2 mm SL), and (D) Maran˜ on (Peru, AUM 45525) river drainages. Scale bars
51 cm. Photos by NKL.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 675
therefore recognize Chaetostomus trinitatis Gu¨nther, 1864 as
Ancistrus trinitatis, new combination, and agree with Phillip
et al. (2013) that this species is likely a synonym of Ancistrus
maracasae Fowler, 1946.
Within Chaetostoma, we consider Ch. alternifasciatum
Fowler, 1945 to be a junior synonym of Ch. vagum Fowler,
1943 based on a lack of characteristics differentiating the
type specimens and on their overlapping distribution in the
upper Japura´ River (Caqueta´ River drainage), Colombia. We
believe that the holotype of Ch. alternifasciatum (143.0 mm
SL) is an adult, and that of Ch. vagum (85.8 mm SL) is
a juvenile, of the same species. We also consider Ch.
mollinasum Pearson, 1937, from the upper Maran˜ on River
drainage in Peru, to be a synonym of Ch. microps Gu¨nther,
1864, from the Santiago River drainage in Ecuador, based on
a review of type and non-type specimens spanning the
geographic range between both type localities. Specimens of
Ch. microps spanning this geographic range are not only
morphologically similar, but also monophyletic in our
molecular phylogenetic analysis (Fig. 2, Node 4: BI: 1.0,
ML: 89). A summary of species that we consider valid within
the Chaetostoma Clade is provided in Table 1.
Finally, given the strong molecular phylogenetic evidence
for the nested position of Lipopterichthys carrioni Norman,
1935 and Loraxichthys lexa Salcedo, 2013 within Chaetos-
toma, and the overall morphological similarity of these
species to other species of Chaetostoma, we transfer these
species to genus Chaetostoma:Chaetostoma carrioni, new
combination; and Chaetostoma lexa, new combination.
Chaetostoma branickii and Ch. taczanowskii.—Specimens
correctly identified as either Chaetostoma branickii or Ch.
taczanowskii are rare in collections, and the two species
are challenging or impossible to distinguish based only on
original descriptions and the limited availability of type
or non-type material. Both species share a relatively tall
and slender body, Type 1 cheek odontodes, eight
branched dorsal-fin rays, absence of a supraoccipital
excrescence and absence of any detectable color pattern
or sexual dimorphism (Table 4). Both species were de-
scribed by Steindachner in sequential years (Ch. branickii
in 1881 and Ch. taczanowskii in 1882) from neighboring
drainages (Maran˜ on and Huallaga, respectively). For this
study, we had only two lots tentatively identified as Ch.
branickii (ROM 54720, ROM 54723) and no tissue avail-
able for genetic analysis. We therefore had little basis
from which to draw conclusions regarding differences
between these species and refer to them in diagnoses as
the undifferentiated species pair Ch. branickii/taczanow-
skii.Theinformationwehaveforthesespeciesapplies,to
the best of our knowledge, to both. More specimens, data,
and redescriptions of these species are needed in order to
clearly diagnose them from each other and other species.
Chaetostoma loborhynchos and Ch. marmorescens.—Dif-
ferentiating the sister species Chaetostoma loborhynchos from
Ch. marmorescens can also be a source of confusion. Both
share Type 1 cheek odontodes, marbled light and dark green
to gray coloration on the body, indistinct banding of the
dorsal- and paired-fin rays with all fin membranes being
hyaline, absence of a supraoccipital excresence, and Type 1
and 2 sexual dimorphism of the pelvic fins. Moreover they
were described from neighboring drainages (Ch. lobo-
rhynchos from the upper Ucayali River, and Ch. marmorescens
from the upper Huallaga River), but appear to have at least
partially overlapping ranges within the Huallaga River
drainage. In addition to the meristic differences listed in
Table 4 (e.g., non-overlapping ranges of premaxillary and
dentary teeth, differing numbers of branched anal- and
dorsal-fin rays), we found that Ch. loborhynchos can be
distinguished morphometrically from Ch. marmorescens by
having a smaller orbit diameter (3.160.4%SL, vs. 4.560.4),
a greater snout length (22.061.0%SL, vs. 19.461.4), and
greater pelvic-dorsal distance (22.261.4%SL, vs. 20.160.7).
See also Other undescribed species below for a description of
interdrainage morphological variation observed in Ch.
loborhynchos.
Chaetostoma bifurcum,new species
urn:lsid:zoobank.org:act:9349BF35-726C-43EA-AE4D-
C4708BBAAA78
Figure 7; Tables 5, 6
Holotype.—MEPN 14687 (ex. ROM 93721*), 132.4 mm SL,
Ecuador, Santo Domingo de las Tsa´chilas Province, Guayas
River drainage, Otongo River upstream of confluence with
Baba River, 00u21906.900S, 79u12952.320W, 24 August 2012,
H. Lo´ pez-Ferna´ ndez, D. Taphorn, N. Lovejoy, R. Barriga, F.
Hauser, J. Arbour, D. Brooks.
Paratypes.—Ecuador, Pacific Coast, Esmeraldas River drain-
age, Imbadura Province: ROM 93662, 2, 61.3–139.3 mm SL,
confluence of the Chontal and Guallabamba rivers,
00u14923.130N, 78u45952.100W, 20 August 2012, N. Lujan,
D. Taphorn, D. Brooks (electrofishing), local fisherman
(cast-netting). Pichincha Province: ROM 93668, 3, 58.2–
140.1 mm SL, Nanegalito, Pachijal River alongside road,
00u10908.010N, 78u56913.800W, 21 August 2012, N. Lujan, D.
Taphorn, H. Lo´pez-Ferna´ndez, J. Arbour, F. Hauser, D.
Brooks; ROM 93670, 2, 69.0–81.1 mm SL, Blanco River west
of Puerto Quito, 00u07912.770N, 79u14904.460W, 22 August
2012, D. Taphorn, N. Lovejoy, J. Arbour, F. Hauser, E.
Wagner Obando Mina; ROM 93687*, 3, 49.5–103.4 mm SL,
Silanchi River downstream of community of Silanchi,
00u09932.280N, 79u14936.420W, 22 August 2012, N. Lujan,
Fig. 6. Illustrations of four odontode shape and size types observed
across species of Chaetostoma. Illustrations by VAC.
676 Copeia 103, No. 3, 2015
Table 4A. Summary of characters variable across Amazon Basin species of Chaetostoma (exclusive of Ch. platyrhynchus). Data summarized from examination of types, comparative material, Rapp Py-
Daniel (1991), and Salcedo (2006a, 2006b, 2013).
Chaetostoma anale
Ch. branickii/
taczanowskii Chaetostoma breve Chaetostoma carrioni Chaetostoma changae
n=1; Fowler, 1943 n=4n=26, Fig. 4 n=6, Fig. 10 n=27
Head
depth (%SL) — 22.661.3 26.661.2 23.461.3 24.860.7
spots (color;
distinct/indistinct;
shape; size; spacing)
black; distinct; 1/2
naris size; 1–2 spot
widths apart
absent absent or (rarely) white; indistinct;
irregularly reticulated; naris size
or smaller; variable spacing
white; indistinct; irregularly round to
vermiculate; ,1/2 size of naris;
2–3 spot widths apart
absent
male snout enlargement present none observed present present present
occipital excrescence present absent present absent present
Cheek odontodes
shape/length Type 2 Type 2 Type 3 Type 1 Type 2
number 5 6–10 3–16 5–13 3,4
Dentition
premaxillary teeth 60 87–90 123621 566675615
dentary teeth 75 115–132 170633 76610 105615
Body
cleithral width (%SL) — 31.161.7 35.662.7 33.761.1 32.961.8
spots (color;
distinct/indistinct;
shape; size; spacing)
black; distinct; round;
naris sized; 3–5
spot widths apart;
forming 4 linear
rows
absent absent black; indistinct; round; orbit
diameter or larger; 1 spot width
apart; anteriorly absent, more
distinct caudally; irregularly
distributed
absent
stripes/bands absent absent stripe along absent absent
Fins
branched dorsal-fin rays 8 8 7,(8),9 7,(8) 8,(9),10
dorsal-fin coloration uniform uniform uniform or (rarely) reticulated with
band width similar to naris
diameter
variable, indistinct black bands,
bands orbit diameter or smaller
uniform distinct white spots on rays,
spots half naris diameter
branched anal-fin rays 5 4 3,(4),5 fin absent or (1),2 (4),5
anal-fin odontodes present present present present if fin present absent
paired-fin coloration uniform uniform unpatterned or (rarely) reticulated
with band width similar to naris
diameter
variable, indistinct black spots/
bands, bands orbit diameter or
smaller
unpatterned
pelvic-fin dimorphism Type 1, 2, 3, 4 none observed Type 1 (weak), 2 (weak) Type 1, 2, 3 Type 1, 2 (weak), 3 (weak), 4
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 677
Table 4B. Summary of characters variable across Amazon Basin species of Chaetostoma (exclusive of Ch. platyrhynchus). Data summarized from examination of types, comparative material, Rapp Py-
Daniel (1991), and Salcedo (2006a, 2006b, 2013).
Chaetostoma
daidalmatos Chaetostoma
dermorhynchum
Chaetostoma
jegui Chaetostoma
lexa
Chaetostoma
lineopunctatum
Chaetostoma
loborhynchos
n=3; Salcedo,
2006b n=11, Fig. 3
Rapp Py-Daniel,
1991 n=2; Salcedo, 2013 n=10, Fig. 11 n=8
Head
depth (%SL) 22.360.9 22.560.6 14.960.9* 16.260.7* 25.461.0 23.861.0
spots (color;
distinct/indistinct;
shape; size; spacing)
black; distinct; round
to oblong; half size
of naris; densely
spaced ,1 spot
width apart
black; distinct; round; size of
naris; evenly distributed 1
spot width apart
uniform absent absent (Urubamba and Madre
de Dios) or black; distinct;
round to vermiculate; ,1/2
naris size; evenly spaced 1
spot width apart
light green to gray; indistinct;
round to oblong; ,1/2
naris diameter; ,1 spot
width apart
male snout
enlargement
absent present none observed present weak present (strong)
occipital excrescence present present present absent present absent
Cheek odontodes
shape/length Type 2 Type 2 Type 3 Type 4 Type 2 Type 1/2
number 5–8 2–5 2–5 9–14 3,4 6–17
Dentition
premaxillary teeth 60611 105614 46–102 31–41 105610 8768
dentary teeth 97621 131614 62–121 41–50 159618 13866
Body
cleithral width (%SL) 29.762.5 31.460.8 — 34.461.0 33.360.8 35.860.9
spots (color;
distinct/indistinct;
shape; size; spacing)
black; round or
irregularly
oblong; distinct;
orbit size or smaller;
evenly spaced 1
spot width apart;
loosely arranged in
5–6 rows
white to gray; indistinct; round;
diameter of orbit; arranged in
4–5 rows from pelvic to
caudal fin; more distinct
posteriorly
absent absent black; round to vermiculate;
distinct; 1/2 size of naris; 2–
4 spot widths apart; 5–7
irregular rows or series of
oblique columns
absent; indistinctly blotched or
marbled; pattern widths.
orbit diameter
stripes/bands absent absent absent midlateral stripe
(indistinct), width
of orbit
absent absent, see spots above
Fins
branched dorsal-fin
rays
8 8 9,10 (9),10 (8), 9 8
dorsal-fin coloration black spots; round;
diameter of naris;
,1 spot width
apart; centered on
rays; 6–8 per ray
white spots; up to 10; ,1/2
diameter of naris; on rays or
membranes; more distinct in
juveniles
absent 3–5 black bands
across all rays; band
as wide as orbit
diameter; spaced 1
band width apart;
membranes hyaline
two series of black spots ,1/2
diameter of naris on most or
all interradial membranes,
single series on most rays
4–6 irregular bands across all
rays; band width similar to
naris diameter; membranes
hyaline
678 Copeia 103, No. 3, 2015
Chaetostoma
daidalmatos Chaetostoma
dermorhynchum
Chaetostoma
jegui Chaetostoma
lexa
Chaetostoma
lineopunctatum
Chaetostoma
loborhynchos
n=3; Salcedo,
2006b n=11, Fig. 3
Rapp Py-Daniel,
1991 n=2; Salcedo, 2013 n=10, Fig. 11 n=8
branched anal-fin rays (4),5 4 2,3,4 fin absent or 1,(2),3 3,(4),5 3,(4)
anal-fin odontodes present present present absent present present
paired-fin coloration black spots; round or
merging into bands;
diameter or width
of naris
uniformly gray uniform uniform or rays
indistinctly banded,
membranes hyaline
indistinct black spots or lines
bordered by hyaline along
interradial membranes
approximately 5 indistinct
bands across all rays;
membranes hyaline
pelvic-fin dimorphism none observed Type 1, 2, 3, 4 Type 2, 4 Type 1 (crenulate),
2, 3
Type 1, 2 Type 1, 2
Table 4B. Continued.
Table 4C. Summary of characters variable across Amazon Basin species of Chaetostoma (exclusive of Ch. platyrhynchus). Data summarized from examination of types, comparative material, Rapp Py-
Daniel (1991), and Salcedo (2006a, 2006b, 2013).
Chaetostoma
marmorescens Chaetostoma microps
Chaetostoma
stroumpoulos
Chaetostoma trimaculineum,
new species Chaetostoma vagum
n=10 n=23, Figs. 5, 12 n=31; Salcedo, 2006b n=5, Figs. 13, 14 n=9
Head
depth (%SL) 23.661.5 24.861.4 23.761.0 23.360.2 23.560.6
spots (color;
distinct/indistinct;
shape; size; spacing)
none observed white, blue, or yellow;
distinct; round or
vermiculate; ,1/2 size
of naris; 3 or more spot
widths apart
absent or black; indistinct;
round to oblong; 1/3 or
1/4 size of naris; densely
spaced ,1 spot width
apart
black; distinct; round; 1/2 naris
size; 1–3 spot widths apart
black; distinct; round; 1/2
naris size; 1 spot width
apart
male snout enlargement present (weak) present weak absent present
occipital excrescence absent absent present present present
Cheek odontodes
shape/length Type 1/2 Type 1 Type 2 Type 2/3 Type 2
number 3–16 5–20 3–6 4,5 2–6
Dentition
premaxillary teeth 63615 49618 86621 100631 82614
dentary teeth 95615 80623 135627 138644 102613
Body
cleithral width (%SL) 36.462.4 34.662.0 32.062.2 31.761.2 32.562.3
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 679
Chaetostoma
marmorescens Chaetostoma microps
Chaetostoma
stroumpoulos
Chaetostoma trimaculineum,
new species Chaetostoma vagum
n=10 n=23, Figs. 5, 12 n=31; Salcedo, 2006b n=5, Figs. 13, 14 n=9
spots (color;
distinct/indistinct;
shape; size; spacing)
absent; indistinctly blotched
or marbled; pattern
widths.orbit diameter
white, blue, or yellow;
distinct; round or
vermiculate; ,1/2 size
of naris; 3 or more spot
widths apart;
anterodorsally clustered
black; indistinct; round or
irregularly oblong; 1/2
orbit size or less; evenly
spaced 1 spot width apart;
loosely arranged in rows
(sometimes absent)
black; distinct; round; naris size;
1–2 spot widths apart; 3–4
linear rows on median, mid-
dorsal, and dorsal plate series
black; distinct; round; 1/2
naris size; irregular, 1–
4 spot widths apart
stripes/bands absent, see spots above faint midlateral stripe absent absent absent
Fins
branched dorsal-fin rays 8,(9),10 8,(9),10 8 8 8
dorsal-fin coloration 3–4 irregular bands across all
rays; band width similar to
orbit diameter; membranes
hyaline
unpatterned or indistinctly
patterned rays; hyaline
membranes
uniform and hyaline or black
spots; round; diameter of
naris;
1 spot width apart;
centered on rays;
6–7 per ray
rays uniform, membranes
hyaline or with few black
spots
uniform
branched anal-fin rays 2,(3),4 2,(3) 3,4,(5) 4 3,4,(5)
anal-fin odontodes absent present present present present
paired-fin coloration uniform pectoral fins; 3–4
indistinct and irregular
bands on pelvic fins
uniform or (rarely)
irregularly banded,
bands indistinct and
broadly reticulate
uniform and hyaline or black
spots; round; diameter of
naris; 1–2 spot widths
apart; centered on rays
uniformly gray to light brown uniform
pelvic-fin dimorphism Type 1, 2 Type 1, 2, 3 Type 2, 4 none observed none observed
Table 4C. Continued.
680 Copeia 103, No. 3, 2015
Fig. 7. Chaetostoma bifurcum, new species, from three drainages along the Pacific Coast of Ecuador: (A) Esmeraldas (ROM 93662, 59.7 mm SL), (B,
C) Guayas (B: ROM 93721*, 83.7 mm SL; and C: ROM 93729, 91.9 mm SL), and (D) Santa Rosa (ROM 93787*, 96.3 mm SL) river drainages. Scale
bars 51 cm. Photos by NKL.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 681
Table 5. Selected morphometric characters and tooth counts for Chaetostoma bifurcum, new species, Chaetostoma breve Regan, 1904 (syntype: BMNH 1898.11.4.33–36), and Chaetostoma carrioni
(Norman, 1935; holotype: BMNH 1933.5.29.1). Interlandmarks (ILM) are the two points between which measurements were taken (from Armbruster, 2003). Morphometric characters other than standard
length presented as percents of either standard length or head length. Abbreviations: Min =minimum value, Max =maximum value, n=number of specimens examined, StDev =standard deviation.
Chaetostoma bifurcum, new species Chaetostoma breve Regan, 1904 Chaetostoma carrioni (Norman, 1935)
ILM Measurement Holotype nMean StDev Min Max Syntype nMean StDev Min Max Holotype nMean StDev Min Max
1–20 Standard length (mm) 132.4 12 71.5 132.4 126.2 26 56.1 134.8 55.9 7 46.9 60.2
Percents of standard length
1–10 Predorsal length 41.6 12 41.7 2.2 39.3 47.9 42.8 26 44.0 1.3 41.7 47.2 42.8 7 44.8 2.0 42.7 47.9
1–7 Head length 31.8 12 31.7 1.9 29.6 36.4 31.6 26 34.8 1.3 31.6 36.7 32.4 7 31.7 1.1 30.3 33.7
7–10 Head-dorsal length 10.1 12 10.5 1.3 9.5 14.2 12.7 26 10.0 0.9 8.3 12.7 9.7 7 14.0 2.1 9.7 15.7
8–9 Cleithral width 31.9 12 31.6 2.0 29.1 36.9 34.0 26 35.6 2.7 30.7 40.0 34.8 7 33.7 1.1 32.1 35.1
1–12 Head-pectoral length 27.3 12 26.8 1.3 25.2 30.1 28.1 26 29.3 1.1 27.3 31.9 30.3 7 29.8 1.3 27.4 31.3
12–13 Thorax length 19.4 12 21.3 1.5 19.0 24.2 20.7 26 22.0 1.8 19.3 25.8 26.7 7 24.0 2.0 20.8 26.7
12–29 Pectoral-spine length 28.5 12 28.6 1.0 27.2 30.3 29.1 26 29.0 2.0 24.7 32.9 27.4 7 26.6 1.2 24.3 27.8
13–14 Abdominal length 23.3 12 23.9 0.8 22.8 25.5 23.7 26 24.4 1.5 20.6 28.2 6 25.4 1.7 23.5 27.9
13–30 Pelvic-spine length 24.2 12 24.8 1.6 21.3 26.5 25.6 26 25.1 3.8 8.8 28.5 29.6 7 23.9 2.9 21.0 29.6
14–15 Postanal length 35.8 12 35.0 1.6 30.7 37.3 35.0 26 33.5 2.5 26.4 36.3 6 28.4 1.5 26.8 31.2
14–31 Anal-fin spine length 11.8 12 11.2 1.4 9.0 13.7 9.8 26 10.1 1.4 8.0 13.5 6 4.1 1.4 2.3 6.5
7–12 Head depth 22.2 12 22.9 1.6 21.0 26.8 24.3 26 26.6 1.2 24.3 28.9 21.3 7 23.4 1.3 21.3 25.3
10–12 Dorsal-pectoral depth 26.9 12 27.3 0.9 25.9 28.8 29.0 26 30.9 1.5 28.6 34.3 25.7 7 29.5 2.3 25.7 32.2
10–11 Dorsal spine length 26.1 12 27.2 2.1 24.0 30.0 29.1 26 26.9 1.9 24.2 31.0 26.6 7 22.5 2.3 18.8 26.6
10–13 Dorsal-pelvic depth 22.2 12 21.0 1.0 19.5 22.6 24.6 26 24.9 1.9 21.6 30.5 19.7 7 21.0 1.9 19.2 24.7
10–16 Dorsal-fin base length 25.8 12 25.2 1.0 22.9 26.6 26.7 26 27.3 1.6 24.2 31.8 24.0 7 26.7 1.6 24.0 28.4
16–17 Dorsal-adipose depth 16.7 12 17.1 1.7 14.4 20.9 16.3 26 15.3 1.3 13.0 18.9 3 14.8 0.8 13.9 15.6
17–18 Adipose-spine length 7.9 12 8.9 0.9 7.6 10.2 7.2 26 9.7 1.1 7.2 12.0 3 6.9 1.1 6.2 8.1
17–19 Adipose-upper caudal length 17.9 12 17.7 1.0 15.9 19.2 18.1 26 15.8 1.5 12.7 18.5 3 14.5 2.5 11.8 16.9
15–19 Caudal peduncle depth 14.6 12 13.3 0.6 12.5 14.6 16.9 26 15.4 0.8 13.5 16.9 11.5 7 12.0 0.7 11.3 13.3
15–17 Adipose-lower caudal depth 22.8 12 23.1 1.0 22.0 25.5 26.3 26 24.7 1.0 23.1 26.6 3 22.7 2.2 21.1 25.2
14–17 Adipose-anal depth 22.1 12 20.8 1.3 18.1 22.3 22.7 26 22.4 1.0 19.9 23.8 3 19.1 3.6 15.8 22.9
14–16 Dorsal-anal depth 15.5 12 15.5 0.4 14.7 16.1 20.2 26 18.3 0.9 16.1 20.2 6 14.8 0.5 14.4 15.8
13–16 Pelvic-dorsal depth 26.9 12 26.5 1.3 23.5 28.2 28.2 26 29.0 1.5 25.8 31.3 20.8 7 27.9 3.3 20.8 30.3
Percents of head length
5–7 Head-eye length 28.5 12 30.5 2.2 27.1 34.8 9.7 26 11.1 4.0 8.9 28.5 32.7 7 33.3 3.4 26.5 36.9
4–5 Orbit diameter 13.3 12 14.3 1.1 11.8 16.3 4.1 26 5.1 1.7 3.8 13.1 10.8 7 14.2 1.6 10.8 15.5
1–4 Snout length 67.3 12 64.3 2.5 61.5 68.2 20.8 26 25.1 8.9 20.4 68.4 66.6 7 65.5 2.4 61.8 69.5
2–3 Internares width 12.4 12 10.9 1.0 9.8 13.2 3.8 26 3.7 1.5 2.2 10.4 8.8 7 13.7 2.3 8.8 16.2
5–6 Interorbital width 29.3 12 30.8 1.7 28.0 34.3 10.0 26 11.7 3.9 9.9 30.5 32.8 7 44.0 5.3 32.8 48.7
1–24 Mouth length 61.3 12 54.9 3.8 49.2 61.3 62.3 26 60.8 2.6 55.7 67.3 20.8 7 20.2 0.5 19.5 20.9
21–22 Mouth width 77.7 12 74.6 4.2 68.8 83.9 78.0 26 83.1 5.0 74.4 90.4 25.5 7 25.3 1.2 23.1 26.7
22–23 Barbel length 8.4 12 8.2 2.8 3.5 14.1 8.1 26 9.0 1.4 5.4 12.0 4.3 7 3.0 0.8 1.9 4.3
25–26 Dentary tooth cup length 30.5 12 29.6 1.8 26.6 32.5 33.7 26 34.3 2.3 29.1 38.6 10.3 7 10.2 0.9 8.8 11.4
27–28 Premax. tooth cup length 26.3 12 25.4 1.4 22.4 27.0 28.4 26 29.4 1.8 26.3 32.3 9.0 7 8.7 0.7 7.3 9.5
Tooth counts
Left premaxillary teeth 132 12 107 21 67 137 86 26 123 21 86 166 6 56 6 45 59
Left dentary teeth 185 12 151 34 52 185 92 26 170 33 92 223 6 76 10 63 84
682 Copeia 103, No. 3, 2015
D. Taphorn, H. Lo´ pez-Ferna´ ndez, J. Arbour, F. Hauser, E.
Wagner Obando Mina. Esmeraldas Province: ROM 93712, 1,
82.4 mm SL, Otongo River at bridge crossing, 00u22959.760N,
79u12926.200W, 24 August 2012, N. Lujan, D. Taphorn, V.
Meza, H. Lo´ pez-Ferna´ ndez, F. Hauser, D. Brooks. Guayas
River drainage, Los Rı´os Province: ANSP 182817, 10, 60.7–
104.4 mm SL, same data as holotype; AUM 64433, 10, 65.4–
97.1 mm SL, same data as holotype; FMNH 80708, 1, 91.6
mm SL, Palenque River at Centro Cientifico Rı´o Palenque,
1975, G. S. Glodek; FMNH 93101, 68, 83.8–137.2 mm SL,
Palenque River at Centro Cientifico Rı´o Palenque,
7 November 1978, G.S. Glodek, D. Taphorn, J. Gourley,
J. Carter; ROM 93729, 9, 43.2–114.1 mm SL, Umbe River at
bridge crossing in Las Palmitas, 01u12942.560S,
79u18940.250W, 25 August 2012, local children from com-
munity of Las Palmitas; ROM 93739, 2, 58.6–58.8 mm SL,
Clara River at La Clara around bridge and downstream,
01u40928.680S, 79u23913.220W, 26 August 2012, local chil-
dren from community of La Clara. Santo Domingo de las
Tsa´ chilas Province: ROM 93704, 2, 29.9–38.0 mm SL,
Chihuilpe River at bridge crossing and downstream,
00u19920.920S, 79u12959.110W, 23 August 2012, N. Lujan,
N. Lovejoy, V. Meza, J. Arbour, F. Hauser; ROM 93721*, 4,
58.2–74.7 mm SL, Ecuador, same data as holotype. Santa
Rosa River drainage, El Oro Province: ROM 93787*, 10, 61.3–
99.0 mm SL, Santa Rosa River at La Avanzada bathing area,
03u33931.180S, 79u56949.190W, 29 August 2012, N. Lujan,
D. Taphorn, V. Meza, R. Barriga, H. Lo´ pez-Ferna´ ndez, F.
Hauser, J. Arbour; ROM 93842, 9, 68.3–99.5 mm SL, Santa
Rosa River downstream of town of Avanzada, 9 km S of town
of Santa Rosa, 03u31949.800S, 79u57935.400W, 30 August
2012, D. Taphorn, N. Lovejoy, J. Arbour, V. Meza.
Non-type material.—Peru, Tumbes Region: AUM 21561, 3,
Puyango River 5 km W of Puyango, 19 km NW of Alamor,
approx. 03u549S, 80u079W; MHNG 2359.009, 2, Tumbes
River at Rica Playa; MUSM 5830, Tumbes River, Quebrada
Don Pablo; ROM 66743, 1, 119 mm SL, Tumbes River at Rica
Playa, Carillos, approx. 03u489S, 80u319W; ROM 66746, 3,
43105mmSL,QuebradaHonda,Ucumares,approx.
03u529S, 80u309W.
Diagnosis.—Chaetostoma bifurcum can be diagnosed from all
other Chaetostoma along the Pacific Coast of South America
except Ch. palmeri and Ch. paucispinis by having only one
or two evertible cheek odontodes (vs. three to six); from
Ch. niveum,Ch. palmeri,Ch. patiae, and Ch. paucispinis by
having most frequently four branched anal-fin rays (vs. five);
from Ch. palmeri and Ch. paucispinis by living adults having
body with black, indistinct, vertically elongate, irregularly
broken or complete bars Kto Owidth of orbit (vs. body
uniform or with transverse cross-bars wider than two times
orbit centered on dorsal midline, Fig. 8); and from Ch.
paucispinis by having eight branched dorsal-fin rays (vs. nine).
Description.—Morphometrics in Table 5 and meristics in
Table 6. Largest specimen 140.1 mm SL. Body depth
increasing from tip of snout to greatest body depth at
predorsal plates, decreasing to posterior margin of adipose
fin with slight increase at base of caudal fin. Dorsal profile
slightly convex between snout and predorsal plates then
straight and descending to base of dorsal fin. Ventral profile
flat from snout to base of caudal fin. Ossified dermal plates
with small odontodes covering head and body flanks. Plates
missing from broad crescent around snout margin and
abdomen. Cheek plates having zero, one, or two slightly
enlarged, distally hooked (Type 3, Fig. 6) odontodes;
odontodes typically obscured by thick fleshy lobe. Orbit
positioned dorsolaterally on head with opening sloped
ventrolaterally at approximately 45ufrom sagittal plane in
anterior view. Snout broadly triangular in dorsal view.
Oral disk occupying majority of ventral surface of head
anterior of cleithrum. Teeth minute, bicuspid, with cusps
bent 90utoward mouth opening. Single digitate papilla
Table 6. Selected meristic characters for Chaetostoma bifurcum, new species, Chaetostoma breve Regan, 1904 (syntype: BMNH 1898.11.4.33–36),
and Chaetostoma carrioni (Norman, 1935; holotype: BMNH 1933.5.29.1). Abbreviations: Min =minimum value, Max =maximum value, n=number
of specimens examined.
Chaetostoma bifurcum,
new species
Chaetostoma breve
Regan, 1904
Chaetostoma carrioni
(Norman, 1935)
Holotype nMode Min Max Syntype nMode Min Max Holotype nMode Min Max
Median plates 24 12 24 22 24 23 26 23 23 24 24 7 23 22 24
Supramedian plates 25 12 24 23 25 23 26 24 22 24 23 7 22 22 23
Inframedian plates 25 12 24 23 25 24 26 24 23 24 23 7 22 22 23
Caudal peduncle plate rows 5 12 5 5 5 5 26 5 5 5 5 7 5 5 5
Dorsal-fin branched rays 8 12 8 8 8 8 26 8 7 9 7 7 8 7 8
Pectoral-fin branched rays 6 12 6 6 6 6 26 6 6 7 6 7 6 6 6
Pelvic-fin branched rays 5 12 5 5 5 5 26 5 5 5 5 7 5 5 5
Anal-fin branched rays 4 12 4 4 5 4 26 4 3 5 0 7 0 0 2
Caudal-fin branched rays 14 12 14 14 14 14 26 14 14 14 12 7 12 12 12
Dorsal procurrent
caudal-fin rays
5 125 35 5265 26 6 74 36
Ventral procurrent
caudal-fin rays
4 123 24 2263 15 4 72 14
Preadipose plates 1 12 1 1 1 1 26 1 1 2 0 7 1 0 1
Dorsal–adipose plates 6 12 6 4 6 4 26 5 3 6 0 7 5 0 5
Infraorbital plates 5 12 5 5 6 6 26 6 5 6 5 7 5 5 5
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 683
extending ventrally from dorsal part of premaxillary
symphysis; single thick cluster of low papillae at middle of
interior surface of each mandible. Maxillary barbel short,
unattached along most of length; ventral surface of labial
disk with low hemispherical papillae decreasing in size
distally.
Dorsal-fin spinelet small and round; posteriormost dorsal-
fin ray free from body; reaching to within one plate width
from adipose-fin spine when adpressed. Pectoral fin reach-
ing just beyond pelvic-fin base when adpressed, spine
having modestly enlarged odontodes along posterodorsal
and distal surfaces. Pelvic-fin spine reaching middle of anal-
fin base when adpressed. Second unbranched anal-fin ray
longest; anal fin spanning total of six plate widths when
adpressed. Adipose-fin spine straight, adnate to caudal
peduncle via fleshy membrane. Caudal-fin margin
obliquely emarginate with ventral lobe slightly longer than
dorsal lobe.
Body broadest at cleithrum; posterior margin of exposed
posterior process of cleithrum rounded. First two to three
midventral plates gently bent forming rounded lateral ridge
between verticals through pectoral- and dorsal-fin origins.
Coloration in life.—Highly variable (Fig. 7). Base color of head
black to dark gray with white to cream colored, indistinct,
irregularly round to oblong spots; head spots size of naris or
smaller and spaced from less than one to three spot widths
apart. Body base color white to cream with black, indistinct,
vertically elongate, irregularly broken or complete bars, bars
width of orbit or smaller, spaced one spot or bar width apart.
Dorsal fin irregularly colored, sometimes uniformly light
brown to gray, sometimes with three to four white to cream
colored spots less than half naris diameter along branched
rays. Paired fins irregularly colored, sometimes uniformly
light brown to gray, sometimes with three to four alternat-
ing light and dark colored bands width of orbit or smaller,
bands sometimes irregularly broken into spots. Caudal
uniformly light brown to gray or with bands wider than
orbit diameter. Tips of caudal and/or dorsal fin often colored
red to orange.
Coloration in preservative.—Uniformly dark gray to black.
Sexual dimorphism.—None observed.
Distribution.—Known from piedmont elevations (approxi-
mately 100 to 650 masl) of Pacific Coast drainages of
western Ecuador and northwestern Peru (Fig. 9C), including
(from north to south) the Esmeraldas, Guayas, Santa Rosa,
and Tumbes river drainages.
Etymology.—The species epithet bifurcum is a Latin adjective
meaning “two-pronged,” which is in reference to the two
evertible cheek odontodes characteristic of this species.
Remarks.—Chaetostoma bifurcum displays relatively little
genetic divergence in the loci sequenced for this study from
the Esmeraldas River drainage in the north to the Santa Rosa
River drainage in the south (see branch lengths, Fig. 2).
However, molecular data do suggest that Guayas and Santa
Rosa river drainage populations are more closely related to
each other (Fig. 2, Node 29: BI: 0.97, ML: 75) than either are
to the Esmeraldas River population (Node 30: BI: 1.0, ML:
100).
Molecular phylogenetic evidence (Fig. 2) and morpholog-
ical similarities (i.e., only one to three evertible cheek
odontodes, reddish tinged fin tips, absence of sexual
dimorphism) place Ch. bifurcum with Ch. palmeri and Ch.
paucispinis as part of the Ch. fischeri group, which appears to
be limited to Panama and the Pacific Coast of South America
in Colombia, Ecuador, and Peru. Throughout its range, Ch.
bifurcum appears to be the only species of Chaetostoma
present, although at higher elevations it is often sympatric
with Transancistrus (i.e., T. aequinoctialis in the north and T.
santarosensis in the south) which may be confused with
Chaetostoma due to their both having a partially naked
snout, eight branched dorsal-fin rays, and five rows of
caudal-peduncle plates. However, Transancistrus can be
easily distinguished from Ch. bifurcum by having a more
narrowly restricted unplated snout region and by having
a much higher number of evertible cheek odontodes (16–31,
mode 19; Tan and Armbruster, 2012; Lujan et al., 2015b).
Fig. 8. Original illustrations (A, C–G) and photograph (B) of the types of
seven species of Chaetostoma from the Pacific Coast of South America.
Illustrations (A, G, E) from Regan (1912), (C) from Regan (1904), (D)
from Fowler (1944), and (F) from Fowler (1945). Photograph (B; CAS
60167) courtesy of the California Academy of Sciences.
684 Copeia 103, No. 3, 2015
Chaetostoma breve Regan, 1904
Figure 4; Tables 4, 5, 6
Syntypes.—All specimens eastern Ecuador, Santiago River
drainage: BMNH 1898.11.4.33–36, 4, Zamora River; MSNM
40 [ex MSNM 5592], 1, Zamora River; MZUT 1488, 2,
Bomboiza River; MZUT 1489, 13, Zamora River [15 total
specimens at MZUT but evidently only 1 designated as
syntype; see Tortonese (1940), type catalog].
Non-type material.—Ecuador, Napo River drainage, Napo
Province: ROM 93950*, 6, 68.2–135.3 mm SL, Tena River at
bridge crossing 9.3 km NW of Tena, 00u55927.620S,
77u52934.100W; ROM 93951, 2, 67.7–72.9 mm SL, Napo
River near Tena, 01u02938.080S, 77u47934.680W. Pastaza
River drainage, Morona-Santiago Province: ROM 93923*,
1, 61.5 mm SL, Lumbaime River at bathing area 27 km S of
Puyo, 01u42937.660S, 78u00903.530W; ROM 93930, 3, 81.4–
94.6 mm SL, Amundalo River 10.3 km WSW of Palora,
01u44954.900S, 78u02939.780W. Pastaza Province: ROM
93939, 6, 78.8–139.7 mm SL, Puyo River upstream of
confluence with Pastaza River, 20.4 km SSE of Puyo,
01u39909.590S, 77u55929.260W. Santiago River drainage,
Morona-Santiago Province: ROM 93879, 2, 93.4–117.4 mm
SL, Yungantza River downstream of bridge S of the town of
Limo´n, 02u58916.260S, 78u26929.880W; ROM 93888, 1, 72.5
mm SL, Yunquiantza River at bridge crossing on road
between Santiago and Mendez, just upstream of confluence
with Santiago River, 02u58956.160S, 78u13936.120W; ROM
93893, 2, 98.9–100.4 mm SL, confluence of the Changa-
changasa and Tutanangosa rivers and upstream in both,
02u35951.180S, 78u11910.380W; ROM 93921, 2, 123.6–127.5
mm SL, Upano River, 02u18905.760S, 78u06947.040W. Za-
mora-Chinchipe Province: ROM 93848, 3, 124.2–134.2 mm
SL, Bomboscara River 2.42 km SE of Zamora, downstream of
Podocarpus National Park, 04u05908.080S, 78u57926.980W;
ROM 93856, 1, 88.3 mm SL, Piunza River at bridge in
community of Piunza, 03u52928.120S, 78u52941.780W; ROM
93861, 8, 80.1–122.6 mm SL, Yacuambi River at community
of Piunza, upstream of mouth of Piunza R., 03u52944.480S,
78u53906.400W; ROM 93863, 23, 86.7–107.6 mm SL,
confluence of the Jambue and Zamora rivers,
03u57937.300S, 78u50949.180W. Peru, Maran˜ on River drain-
age, Amazonas Region: AUM 45583, 1, Maran˜on River at
pongo above Borja, 35.5 km NE of Santa Maria de Nieva,
04u27930.640S, 77u34953.520W; AUM 45597, 25, same data
as AUM 45583; AUM 45634, 17, Maran˜on River at Pongo de
Renema, 05u38916.660S, 78u31953.720W; AUM 45641, 2, Rı´o
Utcubamba, 23 km SE of Bagua Chica, 05u46932.340S,
78u22928.740W; AUM 46515*, 41, same data as AUM
45641. Huallaga River drainage, San Martı´n Region, Tocache
Province: MHNG 2712.074*, 2, Tocache River at Uchiza
(RFC 23), 08u10907.500S, 76u32932.500W. Hua´nuco Region,
Leoncio Prado Province: MHNG 2712.047, 2, Huallaga River
between Tingo Maria and Aucayacu (RFC 07), 09u049420S,
76u049440W; MHNG 2712.081, 10, Huallaga River at Tingo
Maria (RFC 25), 09u18953.80S, 76u00934.20W; MHNG
2712.048, 1, same data as MHNG 2712.047; MHNG
2712.078, 1, same data as MHNG 2712.081; MUSM 16471,
Tingo Maria, Huallaga River, 09u180S, 76u000W; MUSM
35826, Tingo Maria, Huallaga River; MUSM 35828, Huallaga
River between Tingo Maria and Aucayacu; MUSM 41082,
Hua´nuco District, Huallaga River, 09u40933.000S,
75u51901.070W.
Diagnosis.—Chaetostoma breve can be diagnosed from all
other Amazon Basin Chaetostoma except Ch. jegui and Ch.
trimaculineum, new species, by having Type 3 cheek
odontodes (vs. Types 1, 2, or 4); from all other Amazon
Basin species except Ch. dermorhynchum,Ch. lineopunctatum,
Ch. stroumpoulos, and Ch. trimaculineum, new species, by
Fig. 9. (A) Map of northwestern South America and southern Central America, and (B, C) enlargements of Ecuador and northern Peru showing the
distributions of specimens of (B) Chaetostoma breve and Ch. microps, and (C) Ch. bifurcum, new species, Ch. carrioni,Ch. dermorhynchum, and Ch.
trimaculineum, new species, that were examined in this study. Star 5type locality.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 685
having more teeth per premaxillary ramus (an average of
123621, vs. typically fewer than 102); from all other
Amazon Basin species except Ch. dermorhynchum,Ch. line-
opunctatum,Ch. loborhynchos,Ch. stroumpoulos, and Ch.
trimaculineum, new species, by having more teeth per
mandible (an average of 170633, vs. typically fewer than
137); from all other Amazon Basin species except Ch.
branickii/taczanowskii,Ch. changae,Ch. jegui,Ch. lexa,Ch.
loborhynchos, and Ch. marmorescens by lacking round spots
on the body (vs. black or white spots present on body); from
all other Amazon Basin species except Ch. anale,Ch.
branickii/taczanowskii,Ch. jegui,Ch. microps,Ch. stroumpou-
los, and Ch. vagum by lacking distinct spots or bands on the
dorsal fin (vs. dorsal-fin spots or bands present); from all
other Amazon Basin species except Ch. branickii/taczanow-
skii,Ch. daidalmatos,Ch. lineopunctatum,Ch. loborhynchos,
Ch. marmorescens,Ch. trimaculineum, new species, and Ch.
vagum by lacking Types 3 and 4 sexual dimorphism of the
pelvic and anal fins (vs. Type 3 and/or 4 sexual dimorphism
present); from Ch. daidalmatos,Ch. dermorhynchum,Ch. lexa,
Ch. stroumpoulos,Ch. trimaculineum, new species, and Ch.
vagum by having greater head depth (26.661.2%SL, vs.
#24.7); from Ch. anale,Ch. daidalmatos,Ch. dermorhynchum,
Ch. microps,Ch. trimaculineum, new species, and Ch. vagum
by lacking round spots or having indistinct and irregularly
reticulate white spots on the head (vs. distinct black spots or
distinctly round to vermiculate white, yellow, or blue spots
smaller than naris on head); from Ch. branickii/taczanowskii,
Ch. carrioni,Ch. lexa,Ch. loborhynchos,Ch. marmorescens,
and Ch. microps by having a supraoccipital excrescence (vs.
excrescence absent); from Ch. daidalmatos, and Ch. dermo-
rhynchum by having a wider cleithral width (35.662.7%SL,
vs. ,32.9); from Ch. carrioni and Ch. lexa by having an anal
fin with most frequently four branched rays (sometimes
three or five, vs. anal fin missing or if present with most
frequently one or two rays, rarely three).
Description.—Morphometrics in Table 5 and meristics in
Table 6. Largest specimen 139.7 mm SL. Body depth
increasing from tip of snout to greatest body depth at
predorsal plates or dorsal-fin origin, decreasing to posterior
margin of adipose fin then increasing slightly to base of
caudal fin. Dorsal profile convex between snout and dorsal-
fin origin then straight and descending to base of dorsal fin.
Ventral profile flat from snout to base of caudal fin. Ossified
dermal plates with small odontodes cover head and body
flanks. Plates missing from broad crescent around snout
margin and abdomen. Cheek plates having three to 16
slightly enlarged, distally hooked odontodes (Type 3, Fig. 6).
Orbit positioned dorsolaterally on head with opening sloped
ventrolaterally at approximately 45ufrom sagittal plane in
anterior view. Snout broadly rounded in dorsal view.
Oral disk occupying majority of ventral surface of head
anterior of cleithrum. Teeth minute, bicuspid, with cusps
bent 90utoward mouth opening. Single digitate papilla
extending ventrally from dorsal part of premaxillary
symphysis; clusters of low papillae at middle of interior
surface of each premaxilla and mandible, mandibular
clusters larger. Maxillary barbel short, adnate along most
or all of length; ventral surface of labial disk with low
hemispherical papillae decreasing in size distally.
Dorsal-fin spinelet small and triangular, sometimes cov-
ered with flesh; posteriormost dorsal-fin ray free from body;
reaching to within one plate width from adipose-fin spine
when adpressed. Pectoral fin reaching just beyond pelvic-fin
base when adpressed, spine having modestly enlarged
odontodes along posterodorsal and distal surfaces. Pelvic-
fin spine not reaching anal fin or reaching middle of anal-fin
base when adpressed. Second unbranched anal-fin ray
longest; anal fin spanning total of four to four and a half
plate widths when adpressed. Adipose-fin spine straight,
adnate to caudal peduncle via fleshy membrane. Caudal-fin
margin vertically or slightly obliquely emarginate with
ventral lobe coequal or slightly longer than dorsal lobe.
Body broadest at cleithrum; posterior margin of exposed
posterior process of cleithrum rounded or pointed. First one
to two midventral plates gently bent, forming rounded
lateral ridge between verticals through pectoral- and dorsal-
fin origins.
Coloration in life.—Highly variable (Fig. 4). Base color of head
dark brown to black with light gray to cream colored,
generally indistinct (excepting mature males, e.g., Fig. 4A),
irregularly round to reticulated spots; spots half size of naris
to half orbit diameter. Body sometimes uniformly light
brown to gray, sometimes with darker gray to black,
generally indistinct (excepting mature males, e.g., Fig. 4A),
irregular reticulations with patterns being width of orbit or
smaller. Dorsal fin irregularly colored, sometimes uniformly
light brown to gray, sometimes with irregular spotting
aligned with rays. Paired fins uniformly light brown to gray
or with irregular, indistinct bands or reticulations. Caudal
fin uniformly light brown to gray. Tips of caudal fin
sometimes colored white. Indistinct black spot sometimes
present along anterior base of dorsal fin, between second
unbranched and first branched ray.
Coloration in preservative.—Body uniformly dark gray to light
brown. Fins sometimes showing faint pattern of spots
aligned with rays.
Sexual dimorphism.—Mature males with slightly elongated
proximal, branched pelvic-fin rays so that proximomedial
posterior pelvic-fin margin is slightly elongated into a mod-
est lobe (Type 1 dimorphism), posterodorsal margin of
pelvic-fin spine with modest dermal fold (Type 2 dimor-
phism). Mature males may also display some enlargement of
the unplated, fleshy snout region and more intense color
pattern contrasts (e.g., Fig. 4A).
Distribution.—Chaetostoma breve is widespread across head-
waters of the western Amazon Basin in Ecuador and Peru,
from at least the Aguarico River in the north to the Huallaga
River in the south (Fig. 9B). It appears to be restricted to
piedmont habitats and elevations (approximately 250 to
1100 masl). Chaetostoma breve is not currently known from
the Ucayali River drainage, and it seems unlikely, given the
considerable sampling that has occurred in this drainage,
that Ch. breve exists there but remains undetected. It seems
more likely that the Huallaga River drainage forms the
southernmost extent of its range. Drainages to the imme-
diate north of the Aguarico River are poorly sampled, but it
seems plausible that the range of Ch. breve extends further
northward, possibly even into Colombia.
Chaetostoma carrioni (Norman, 1935)
Figure 10; Tables 4, 5, 6
Lipopterichthys carrioni Norman, 1935.
686 Copeia 103, No. 3, 2015
Holotype.—BMNH 1933.5.29.1, 78 mm SL, Rı´o Zamora near
Loja, upper Amazon River basin, eastern Ecuador.
Paratypes.—BMNH 1933.5.29.2–5, 4, same data as holotype.
Non-type material.—Ecuador, Santiago River drainage: AUM
4233, 1, Loja Province, tributary to San Lucas River at “El
Puente” 33 km N of Loja; ROM 93845*, 6, 48.0–61.1 mm SL,
Zamora-Chinchipe Province, Bomboscara River 2.42 km SE
of Zamora, downstream of Podocarpus National Park,
04u05910.080S, 78u57919.500W; ROM 93877*, 2, 54.4–72.7
mm SL, Morona-Santiago Province, Yungantza River down-
stream of bridge S of the town of Limo´n, 02u58916.260S,
78u26929.880W.
Diagnosis.—Chaetostoma carrioni can by diagnosed from all
other Amazon Basin Chaetostoma by having only 12
branched caudal-fin rays (vs. 14); from all other Amazon
Basin species except Ch. lexa by lacking an anal fin or (if
present) having most frequently one or two branched anal-
fin rays (vs. anal fin present, with most frequently three or
more branched rays) and by having the adipose fin often
absent or rudimentary; from all other Amazon Basin species
except Ch. loborhynchos,Ch. marmorescens, and Ch. microps
by having Type 1 cheek odontodes (vs. Types 2–4); from all
other Amazon Basin species except Ch. branickii/taczanow-
skii,Ch. breve, Urubamba and Madre de Dios populations of
Ch. lineopunctatum (Fig. 11), and Ch. microps by having
white, indistinct, irregularly round to vermiculate spots less
Fig. 10. Topotypes of Chaetostoma carrioni from the Zamora River (Ecuador, Santiago River drainage, Atlantic Slope, ROM 93845*): (A) 60.2 mm
and (B) 56.3 mm SL. Scale bars 51 cm. Photos by NKL.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 687
Fig. 11. Original illustration (A, from Eigenmann and Allen, 1942) and photos (B, C) of Chaetostoma lineopunctatum. Photographed specimen from
the Ucayali River drainage (Rio Coribeni, ANSP 180442, 80.5 mm SL). Photos by M. H. Sabaj Pe´rez.
688 Copeia 103, No. 3, 2015
than half naris size spaced two to three spot widths apart on
head (vs. head without spots or with black spots); from all
other Amazon Basin species except Ch. breve,Ch. carrioni,
Ch. lexa,Ch. loborhynchos,Ch. marmorescens, and Ch. microps
by having 11–13 evertible cheek odontodes (vs. typically
less than 11 or more than 13); from all other Amazon Basin
species except Ch. branickii/taczanowskii,Ch. lexa,Ch.
loborhynchos,Ch. marmorescens,andCh. microps by lacking
a supraoccipital excrescence (vs. excrescence present); from
all other Amazon Basin species except Ch. changae,Ch. jegui,
Ch. lexa,Ch. marmorescens, and Ch. microps by having most
frequently nine branched dorsal-fin rays (vs. eight); from all
other Amazon Basin species except Ch. anale,Ch. changae,
Ch. dermorhynchum,Ch. lexa, and Ch. microps by exhibiting
Type 3 sexual dimorphism of the pelvic fins (vs. lacking
Type 3 sexual dimorphism); from all other Amazon Basin
species except Ch. anale,Ch. daidalmatos,Ch. jegui,Ch.
marmorescens, and Ch. microps by having an average of
76610 teeth per mandible (vs. typically less than 66 or
greater than 86 teeth); from Ch. changae,Ch. daidalmatos,
Ch. dermorhynchum,Ch. lineopunctatum,Ch. stroumpoulos,
Ch. trimaculineum, new species, and Ch. vagum by having
a wider average cleithral width (36.361.1%SL, vs. ,35.2);
from Ch. breve,Ch. dermorhynchum,Ch. lexa,Ch. line-
opunctatum,Ch. loborhynchos,Ch. trimaculineum, new spe-
cies, and Ch. vagum by having an average of 5666 teeth per
premaxillary ramus (vs. less than 50 or more than 62 teeth);
from Ch. breve,Ch. changae,Ch. dermorhynchum,Ch. lexa,Ch.
loborhynchos,Ch. marmorescens,andCh. microps by having
indistinct black spots larger than orbit diameter on body (vs.
spots absent or white and naris size or smaller); from Ch.
anale,Ch. changae,Ch. dermorhynchum,Ch. jegui, and Ch.
stroumpoulos by lacking Type 4 sexual dimorphism of the
paired or anal fin (vs. having Type 4 sexual dimorphism);
and from Ch. breve by having a lesser head depth (24.461.6%
SL, vs. 26.661.2).
Description.—Morphometrics in Table 5 and meristics in
Table 6. Largest specimen 78.0 mm SL. Body depth in-
creasing from tip of snout to greatest body depth at
predorsal plates, decreasing to posterior margin of adipose
fin then remaining straight to base of caudal fin. Dorsal
profile convex between snout and dorsal-fin origin then
straight and descending to base of dorsal fin. Ventral profile
flat from snout to base of caudal fin. Ossified dermal plates
with small odontodes cover head and body flanks. Plates
missing from broad crescent around snout margin and
abdomen. Cheek plates having five to 13 slightly enlarged,
straight odontodes (Type 1, Fig. 6). Orbit positioned dorso-
laterally on head with opening sloped ventrolaterally at
approximately 45ufrom sagittal plane in anterior view.
Snout broadly rounded or triangular in dorsal view.
Oral disk occupying majority of ventral surface of head
anterior of cleithrum. Teeth minute, bicuspid, with cusps
bent 90utoward mouth opening. Digitate papilla generally
absent from mouth, very small if present. Maxillary barbel
short, adnate along most or all of length; ventral surface of
labial disk with low hemispherical papillae decreasing in size
distally.
Dorsal-fin spinelet obscured by flesh; posteriormost
dorsal-fin ray free from body; reaching to adipose-fin spine
when adpressed if adipose fin present. Adipose fin some-
times missing, with spine flush with dorsal ridge of caudal
peduncle; if present spine straight, adnate to caudal
peduncle via fleshy membrane. Pectoral fin reaching to
posterior pelvic-fin base when adpressed, spine having
modestly enlarged odontodes along posterodorsal and distal
surfaces. Pelvic-fin spine not reaching anal fin or just
reaching anal-fin base when adpressed, if anal fin present.
Anal fin typically reduced, sometimes missing; if present,
spanning total of one to two plate widths when adpressed.
Caudal-fin margin obliquely straight or slightly rounded
with ventral spine slightly longer than dorsal spine.
Body broadest at cleithrum; posterior margin of exposed
posterior process of cleithrum rounded or straight. First
three to four midventral plates gently bent forming rounded
lateral ridge between verticals through pectoral and pelvic-
fin origins.
Coloration in life.—Base color of head dark gray with white,
indistinct, irregularly round to vermiculate spots; spots less
than half size of naris and spaced two to three spot widths
apart. Body base color light gray with black, indistinct,
round spots; spots orbit diameter or larger and spaced one
spot width apart; spots absent or faded anteriorly and
increasingly distinct posteriorly; irregularly distributed.
Dorsal-, paired-, and caudal-fin coloration variable, often
with indistinct black bands width of orbit or smaller.
Distinct black spot present along anterior base of dorsal
fin, between second unbranched and first branched ray.
Coloration in preservative.—Uniformly dark gray with some
banding apparent in fins.
Sexual dimorphism.—Mature males with elongated proximal,
branched pelvic-fin rays so that proximomedial posterior
pelvic-fin margin is elongated into a lobe (Type 1 di-
morphism); posterodorsal margin of pelvic-fin spine with
modest dermal fold (Type 2 dimorphism); low fin folds also
along dorsal surface of branched pelvic-fin rays (Type 3
dimorphism). Mature males also often display some en-
largement of the unplated, fleshy snout region.
Distribution.—Chaetostoma carrioni is known only from
headwaters of the Santiago River drainage in southeastern
Ecuador (Fig. 9C), although additional records in the
Maran˜ on River drainage of northern Peru would not be
surprising.
Remarks.—Chaetostoma carrioni was originally assigned to
the then new genus Lipopterichthys by Norman (1935) based
on the absence of adipose and anal fins from the type series.
These and other morphological characters were assessed in
a phylogenetic analysis by Salcedo (2013), which found
support for continued recognition of Lipopterichthys as
a valid genus. However, recently collected topotypes (ROM
93845*) revealed continuous gradation in the development
of the adipose and anal fins. Comparison of live specimens
also showed striking similarities between Ch. carrioni
(Fig. 10) and Ch. microps (Fig. 5), which is consistent with
the sister relationship found for these species in our
molecular phylogenetic analysis.
Chaetostoma dermorhynchum Boulenger, 1887
Figure 3; Tables 4, 7, 8
Syntypes.—BMNH 1880.12.8.64–66, 3, Bobonaza River at
Canelos, eastern Ecuador.
Lujan et al.—Phylogeny and taxonomy of Chaetostoma 689
Table 7. Selected morphometric characters and tooth counts for Chaetostoma dermorhynchum Boulenger, 1887 (syntype: BMNH 1880.12.8.64–66), Chaetostoma microps Gu¨ nther, 1864 (syntypes:
BMNH 1860.6.16.137–143), and Chaetostoma trimaculineum, new species. Interlandmarks (ILM) are the two points between which measurements were taken (from Armbruster, 2003). Morphometric
characters other than standard length presented as percents of either standard length or head length. Abbreviations: Min =minimum value, Max =maximum value, n=number of specimens examined,
StDev =standard deviation.
Chaetostoma dermorhynchum Boulenger, 1887 Chaetostoma microps Gu¨ nther, 1864 Chaetostoma trimaculineum, new species
ILM Measurement Syntype nMean StDev Min Max Syntype Syntype nMean StDev Min Max Holotype nMean StDev Min Max
1–20 Standard length (mm) 107.3 11 68.4 107.3 43.7 62.3 26 28.8 78.2 128.1 4 68.4 128.1
Percents of standard length
1–10 Predorsal length 41.3 11 41.6 0.6 40.7 42.3 44.8 43.7 26 43.7 2.0 40.9 49.4 41.9 4 40.8 1.4 38.8 41.9
1–7 Head length 31.2 11 32.1 0.6 31.2 33.1 34.3 31.8 26 32.3 2.6 24.7 37.1 31.4 4 30.6 1.4 28.5 31.5
7–10 Head-dorsal length 10.4 11 10.0 0.4 9.3 10.7 12.2 11.7 26 12.3 1.3 9.4 15.4 11.2 4 10.7 0.4 10.4 11.2
8–9 Cleithral width 32.4 11 31.4 0.8 30.2 32.8 38.5 35.2 26 34.6 2.0 31.5 38.5 33.4 4 31.7 1.2 30.6 33.4
1–12 Head-pectoral length 26.8 11 26.0 0.8 24.4 27.0 29.7 28.0 26 28.7 1.6 25.7 32.3 26.7 4 28.0 1.2 26.7 29.0
12–13 Thorax length 21.3 11 21.6 1.4 19.8 23.7 25.4 23.3 26 24.2 1.5 21.8 27.5 21.7 4 21.9 0.7 21.1 22.6
12–29 Pectoral-spine length 31.6 11 28.2 1.5 25.5 31.6 28.8 29.1 26 29.6 1.9 26.8 34.4 30.6 4 28.9 1.3 27.6 30.6
13–14 Abdominal length 24.0 11 24.3 0.6 23.5 25.3 27.7 28.8 26 26.4 1.7 23.6 29.8 25.4 4 25.1 0.5 24.3 25.4
13–30 Pelvic-spine length 28.2 11 26.7 1.4 24.5 29.0 27.7 24.7 26 26.0 2.7 22.2 31.8 24.8 4 25.6 1.2 24.4 26.8
14–15 Postanal length 35.9 11 35.6 1.1 33.9 37.5 31.1 27.1 26 31.9 1.8 27.1 35.5 32.7 4 32.6 0.3 32.3 33.0
14–31 Anal-fin spine length 10.9 11 11.4 0.9 10.4 13.1 10.0 7.2 26 7.8 1.4 4.7 10.5 11.7 4 11.2 0.6 10.5 11.7
7–12 Head depth 21.7 11 22.5 0.6 21.7 23.6 25.3 22.5 26 24.8 1.4 22.5 29.0 23.1 4 23.3 0.2 23.1 23.7
10–12 Dorsal-pectoral depth 25.7 11 27.2 0.7 25.7 28.5 29.7 26.5 26 30.1 1.6 26.5 33.2 28.6 4 28.6 0.5 27.9 29.2
10–11 Dorsal spine length 34.3 11 31.4 1.3 29.6 34.3 26.6 25.9 26 24.3 2.4 19.5 28.1 29.9 4 21.1 14.1 0.0 29.9
10–13 Dorsal-pelvic depth 21.6 11 22.0 0.7 20.8 23.2 18.9 18.5 26 20.3 1.6 17.2 24.3 24.3 4 23.5 1.5 21.5 24.9
10–16 Dorsal-fin base length 27.1 11 26.4 0.8 24.7 27.4 28.6 31.8 26 29.8 2.3 24.9 35.2 26.0 3 25.7 0.3 25.2 26.0
16–17 Dorsal-adipose depth 16.9 11 16.8 0.5 16.1 17.7 11.9 13.5 26 14.1 2.2 11.1 18.4 19.3 4 16.7 1.7 15.5 19.3
17–18 Adipose-spine length 10.4 11 9.6 0.6 8.6 10.6 5.1 5.6 26 8.2 2.9 5.1 15.9 7.2 4 9.0 1.4 7.2 10.6
17–19 Adipose-upper caudal length 16.6 11 17.5 0.5 16.6 18.4 14.7 13.6 26 15.2 2.3 12.0 21.0 15.3 4 14.3 1.8 12.3 16.3
15–19 Caudal peduncle depth 14.3 11 14.2 0.4 13.7 15.1 12.5 12.2 26 13.0 0.7 11.9 14.6 14.1 4 15.2 0.8 14.1 16.1
15–17 Adipose-lower caudal depth 24.6 11 24.5 0.6 23.9 25.8 21.7 19.2 26 21.4 1.5 19.2 25.4 22.5 4 24.0 1.3 22.5 25.6
14–17 Adipose-anal depth 22.4 11 21.4 1.8 16.3 22.6 20.3 16.1 26 19.2 1.5 16.1 23.3 23.3 4 22.0 1.4 20.7 23.3
14–16 Dorsal-anal depth 16.6 11 16.6 0.5 16.0 17.6 17.2 13.3 26 14.1 1.2 11.0 17.2 17.4 4 17.6 0.4 17.2 18.2
13–16 Pelvic-dorsal depth 25.4 11 27.9 1.4 25.4 30.2 30.7 26.8 26 29.1 2.1 24.7 33.5 29.0 4 29.7 1.5 28.5 31.8
Percents of head length
5–7 Head-eye length 27.3 11 28.4 1.1 26.0 29.8 33.2 33.6 26 32.1 2.5 28.3 41.5 29.6 4 30.9 1.4 29.6 32.8
4–5 Orbit diameter 19.8 11 17.6 1.2 16.1 19.8 18.0 14.1 26 15.9 1.6 11.2 20.1 14.4 4 16.0 1.5 14.4 17.8
1–4 Snout length 68.5 11 64.2 2.7 59.8 68.5 63.5 64.0 26 63.9 4.5 55.9 81.3 65.7 4 64.6 1.3 62.7 65.7
2–3 Internares width 12.0 11 10.7 0.7 9.3 12.0 10.5 9.7 26 10.3 1.7 7.7 16.3 11.9 4 15.3 3.1 11.9 18.0
5–6 Interorbital width 29.5 11 28.8 1.2 27.5 30.9 32.1 31.2 26 32.4 2.8 27.5 42.2 31.5 4 47.9 11.0 31.5 54.3
1–24 Mouth length 49.9 11 52.3 2.5 47.5 56.5 62.7 65.2 26 61.0 6.2 44.7 69.9 56.2 4 58.6 1.8 56.2 60.3
21–22 Mouth width 78.6 11 76.5 2.9 70.5 79.5 83.3 83.5 26 87.3 8.3 74.2 113.5 89.5 4 82.5 5.3 77.3 89.5
22–23 Barbel length 13.5 11 9.6 2.0 7.3 13.5 12.9 8.5 26 11.1 4.3 4.0 24.1 6.3 4 10.1 2.6 6.3 12.0
25–26 Dentary tooth cup length 36.6 11 33.2 2.3 30.9 36.9 36.5 28.6 26 32.1 3.2 25.2 39.2 37.2 4 35.5 1.7 33.8 37.2
27–28 Premax. tooth cup length 31.0 11 28.2 2.0 26.3 31.5 29.5 26.3 26 27.6 2.0 23.5 31.7 31.7 4 30.9 0.9 29.8 31.7
Tooth counts
Left premaxillary teeth 95 11 105 14 86 126 20 35 26 49 18 20 90 147 4 100 31 83 147
Left dentary teeth 108 11 131 14 108 160 37 26 80 23 37 133 201 4 138 44 105 201
690 Copeia 103, No. 3, 2015
Non-type material.—Ecuador, Pastaza River drainage, Pastaza
Province: ROM 93946, 17, 69.1–95.2 mm SL, Bobonaza River
1.5 km W of Canelos downstream of bridge, 01u35926.280S,
77u45938.400W; ROM 93656*, 22, 80.6–182.1 mm SL, Puyo
River upstream of confluence with Pastaza River, 20.4 km
SSE of Puyo, 01u39910.020S, 77u55928.020W. Napo River
drainage, Napo Province: ROM 93952, 4, 78.8–100.1 mm SL,
Napo River near Tena, 01u02938.080S, 77u47934.680W.
Diagnosis.—Chaetostoma dermorhynchum can by diagnosed
from all other Amazon Basin Chaetostoma by having four to
five rows of white to gray indistinct round spots the diameter
of the orbit or larger on the body (vs. spots absent, black, or
diameter of naris or smaller); from all other Amazon Basin
species except Ch. changae by having up to ten distinct or
indistinct white spots less than half naris diameter on each
branched dorsal-fin ray or interradial membrane (vs. dorsal-
fin spots absent, black, or much fewer in series); from all
other Amazon Basin species except Ch. anale,Ch. changae,
Ch. jegui, and Ch. stroumpoulos by exhibiting Type 4 sexual
dimorphism of the pelvic and anal fins (vs. lacking Type 4
sexual dimorphism); from all other Amazon Basin species
except Ch. anale,Ch. daidalmatos, lower Ucayali populations
of Ch. lineopunctatum,Ch. stroumpoulos,Ch. trimaculineum,
new species, and Ch. vagum by having distinct, black, round,
naris-sized spots evenly distributed one spot width apart on
the head (vs. spots absent or white); from Ch. anale,Ch.
carrioni,Ch. changae,Ch. daidalmatos,Ch. lexa,Ch. marmor-
escens,andCh. microps by having more teeth per pre-
maxillary ramus (an average of 105614, vs. ,91); from Ch.
breve,Ch. carrioni,Ch. lexa,Ch. lineopunctatum,Ch. lobo-
rhynchos,Ch. marmorescens, and Ch. microps by having lesser
cleithral width (31.460.8%SL, vs..32.3); from Ch. anale,Ch.
carrioni,Ch. daidalmatos,Ch. lexa,Ch. marmorescens,Ch.
microps, and Ch. vagum by having more teeth per mandible
(an average of 131614, vs. ,117); from Ch. branickii/
taczanowskii,Ch. carrioni,Ch. lexa,Ch. microps,Ch. lobo-
rhynchos, and Ch. marmorescens by having a supraoccipital
excrescence (vs. excrescence absent); from Ch. breve,Ch.
carrioni,Ch. jegui,Ch. lexa, and Ch. microps by having Type 2
cheek odontodes (vs. Types 1, 3, or 4); from Ch. changae,Ch.
jegui,Ch. lexa,Ch. marmorescens, and Ch. microps by having
eight branched dorsal-fin rays (vs. most frequently nine or
more); from Ch. carrioni,Ch. lexa,Ch. microps, and Ch.
marmorescens by having four branched anal-fin rays (vs. anal
fin absent or having most frequently three or fewer branched
rays); from Ch. changae,Ch. lineopunctatum, and Ch. microps
by having lesser head depth (22.560.6%SL, vs. .23.1); and
from Ch. branickii/taczanowskii and Ch. lexa by having four or
five evertible cheek odontodes (vs. six or more).
Description.—Morphometrics in Table 7 and meristics in
Table 8. Largest specimen 182.1 mm SL. Body depth
increasing from tip of snout to greatest body depth at
predorsal plates or dorsal-fin origin, decreasing to posterior
margin of adipose fin then increasing slightly to base of
caudal fin. Dorsal profile convex between snout and dorsal-
fin origin then straight and descending to base of dorsal fin.
Ventral profile flat from snout to base of caudal fin. Ossified
dermal plates with small odontodes cover head and body
flanks. Plates missing from broad crescent around snout
margin and abdomen. Cheek plates having two to five
slightly enlarged, gently curved odontodes (Type 2, Fig. 6).
Cheek odontodes typically obscured by thick fleshy lobe.
Orbit positioned dorsolaterally on head with opening sloped
ventrolaterally at approximately 45ufrom sagittal plane in
anterior view. Snout broadly rounded in dorsal view.
Table 8. Selected meristic characters for Chaetostoma dermorhynchum Boulenger, 1887 (syntype: BMNH 1880.12.8.64–66), Chaetostoma microps
Gu¨ nther, 1864 (syntypes: BMNH 1860.6.16.137–143), and Chaetostoma trimaculineum, new species. Abbreviations: Min =minimum value, Max =
maximum value, n=number of specimens examined.
Chaetostoma dermorhynchum
Boulenger, 1887
Chaetostoma microps
Gu¨ nther, 1864
Chaetostoma trimaculineum,
new species
Syntype nMode Min Max Syntype Syntype nMode Min Max Holotype nMode Min Max
Median plates 22