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Accepted by J. Armbruster: 6 Oct. 2017; published: 10 Nov. 2017
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN
1175-5334
(online edition)
Copyright © 2017 Magnolia Press
Zootaxa 4347 (1): 151
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168
http://www.mapress.com/j/zt/
Article
151
https://doi.org/10.11646/zootaxa.4347.1.9
http://zoobank.org/urn:lsid:zoobank.org:pub:DD5FC393-AFE1-4DEF-8261-FA54663E2B06
Description of two new species of Lithoxus (Hypostominae: Loricariidae)
from rio Jari and rio Amapá basins, Brazilian Guiana Shield
GABRIEL S. C. SILVA¹, RAPHAEL COVAIN², CLAUDIO OLIVEIRA
1
& FÁBIO F. ROXO¹
¹Universidade Estadual Paulista, Departamento de Morfologia, Laboratório de Biologia e Genética de Peixes, Prof. Dr. Antônio
Celso Wagner Zanin, 250, Rubião Júnior, 18618–689, Botucatu, São Paulo State, Brazil. E-mail: roxoff@hotmail.com.br
²Museum d’histoire naturelle, Département d’herpétologie et d’ichtyologie, route de Malagnou 1, case postale 6434, CH-1211 Genève
6, Switzerland.
Abstract
Two new species of Lithoxus, a genus diagnosed by possessing a dorsoventrally depressed body, a large round oral disk,
and small tooth cusps with few teeth, are described from two drainages of the Guiana Shield: Lithoxus jariensis from the
rio Jari basin and L. raso from the rio Raso, rio Amapá basin. The new species, L. jariensis, is distinguished from conge-
ners by having an adipose fin, by the number of branched anal-fin and caudal-fin rays, by color pattern of the body, number
of teeth, adipose-fin length, dorsal adipose-caudal distance, caudal peduncle depth, cleithral width, and dorsal-anal dis-
tance. Lithoxus raso can be diagnosed from congeners by coloration pattern, by having an adipose fin, by the number of
branched anal-fin rays, number of teeth, adipose-fin length, dorsal adipose–caudal distance, caudal peduncle depth, and
cleithral width. Greater genetic divergence in mitochondrial cytochrome oxidase subunit I (COI) confirms L. jariensis and
L. raso as two new species.
Key words: COI gene, DNA barcode, Guiana Shield, Amapá State, Neotropical fish
Introduction
Loricariidae is a large group of suckermouth armored catfish, with over 950 valid species (Eschmeyer & Fong
2017) divided into six subfamilies: Delturinae, Hypostominae, Hypoptopomatinae, Lithogeninae, Loricariinae and
Rhinelepinae (sensu Lujan et al. 2015). Loricariids are easily distinguished from other fishes by having bodies
covered in ossified dermal plates, an abundance of integumentary teeth known as odontodes (Garg et al. 2010), and
ventral oral disk that facilitates surface attachment and feeding (Geerinckx et al. 2011).
Eigenmann in 1910 transferred the type species of the genus (L. lithoides) to Lithoxus, but this species was
only formally described in 1912 by the same author. This genus includes rheophilic fishes recognized by
possessing a dorsoventrally depressed body, a large round oral disk, and small tooth cusps with few teeth (Lujan
2008). Currently, this genus has eight valid species, which are distributed across rivers in Venezuela, Suriname,
Guyana and French Guiana. These include: L. lithoides Eigenmann, 1912, type species of the genus, that has the
type locality at Amatuk, on the Lower Potaro River, tributary of the Essequibo River, in Guyana; L.
pallidimaculatus Boeseman, 1982 that was described from Kwambaolo Creek, a tributary of Sara Creek (Suriname
River drainage), Suriname; L. planquettei Boeseman, 1982 described from the Comté, Mana, Maroni, and
Approuage river systems, all in French Guiana; L. surinamensis Boeseman, 1982 described from Awaradam (type
locality) and Grandam, Gran Rio, upper Suriname River in Suriname; L. bovallii (Regan, 1906) that according to
Boeseman (1982) was described from the Ireng River, Guyana; Lithoxus boujardi Muller & Isbrücker, 1993 from
Arataye River Approuague Basin, , French Guiana; L. jantjae Lujan, 2008 described from the Ventuari River,
Orinoco River basin, Venezuela; and L. stocki Nijssen & Isbrücker, 1990 described from the Maroni River, in
French Guiana and Suriname.
The recent molecular phylogenetic hypothesis of Lujan et al. (2015) revealed that Lithoxus is a paraphyletic
group, in which L. lithoides (the type species of the genus) is more close related with species of Exastilithoxus (E.
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fimbriatus and possibly four new species), than with other species of the genus, such as: Lithoxus cf. stocki, L.
planquettei and L. pallidimaculatus (see Fig. 3 in Lujan et al. 2015). This last study is one of the largest molecular
study for the genus, including most of its species. In the morphological phylogenetic study of Armbruster (2004)
the author included only two species of Lithoxus (L. lithoides and L. gr. bovallii) that formed a sister group to two
species of Exastilithoxus (E. fimbriatus and Exastilithoxus). Therefore, a more comprehensive study of the genus
Lithoxus is necessary, including all its species, to better elucidate the evolutionary history among its members.
In the present study, we described two new species of Lithoxus, one from the rio Jari, Amazon basin, and the
other one from rio Amapá, Atlantic coastal drainages in northern Brazil. Furthermore, we performed a
morphometric and genetic analysis of five described Lithoxus species from the eastern Guiana Shield and the two
new species described herein.
Material and methods
Morphological analysis. After capture, fish were anesthetized using 1% benzocaine in water, fixed in 10%
formaldehyde, and preserved in 70% ethanol for morphological study. Institutional acronyms follow Fricke &
Eschmeyer (2017). Vouchers were deposited in the collection of the Laboratório de Biologia e Genética de Peixes
(LBP); Museu de Zoologia da Universidade de São Paulo (MZUSP); and Museum of Natural History of the City of
Geneva (MHNG). Zoological nomenclature follows the International Code of Zoological Nomenclature (4th Ed.).
Measurements and counts were taken on the left side of specimens. Measurements follow Armbruster (2003),
except for mouth width, and were taken point to point to the nearest 0.1 mm with digital caliper.
DNA sequencing and gene tree analysis. The total DNA extraction was performed using the Wizard
Genomic DNA Purification Kit (Promega, Madison, Wisconsin, U.S.A.) from ethanol-preserved muscle, fin, and
liver. Partial sequences of the cytochrome oxidase C subunit I (COI) gene were amplified using the following
primers: Fish F1 (5’-TCA ACC AAC CAC AAA GAC ATT GGC AC-3’) and Fish R1 (5’-TAG ACT TCT GGG
TGG CCA AAG AAT CA-3’) (Ward et al. 2005). Polymerase chain reactions (PCR) were performed in a total
reaction mixture volume of 12.5 µl. Each reaction included 1.25 µl of 10 X Buffer, 0.25 μl of MgCl2 (50 mM), 0.2
μl dNTPs (2 mM), 0.5 μl of each primer (5 mM), 0.1 μl of Pht Taq DNA polymerase (Phoneutria Biotecnologia e
Serviços Ltda, Belo Horizonte, Brazil), 1 μl of genomic DNA (20 ng) and 8.7 ml ddH2O. The conditions for the
PCR reaction consisted of an initial denaturation (5 min at 94°C), followed by 30 cycles of chain denaturation (40
s at 94 °C), primer hybridization (30 s at 50 – 54°C), nucleotide extension (1 min at 68°C) and final extension (8
min at 72°C). The amplified products were checked on 1% agarose gels and purified using ExoSap-IT (USB
Corporation, Cleveland, USA) following the manufacturer’s instructions. We accomplished the sequencing
reactions using the Big DyeTM Terminator v 3.1 Cycle Sequencing Ready Reaction Kit (Applied Biosystems,
Austin, USA). DNA sequencing was conducted in an automatic sequencer ABI 3130 DNA Analyzer (Applied
Biosystems, California, USA).
All individual sequences for each species were initially analyzed and assembled using the software Geneious
7.1.4 (http://www.geneious.com; Kearse et al. 2012). The alignment among all sequences was generated with the
algorithm Muscle (Edgar 2004) under default parameters. To evaluate the occurrence of substitution saturation in
our molecular data, we estimated whether the Iss (index of substitution saturation) was significantly lower than
Iss.cAsym (assuming asymmetrical topology) using the method described by Xia et al. (2003) and Xia & Lemey
(2009) with the software DAMBE 5.3.38 (Xia 2013). Nucleotide variation, substitution patterns, and genetic
distances were examined using MEGA v.6.06 (Tamura et al. 2013).
The best-fit nucleotide substitution model for the entire data set was selected under the Akaike information
criterion (AICc) and Maximum Likelihood (ML) analyses were performed using the software MEGA v.6.06
(Tamura et al. 2013). Bootstrap (BS) resampling (Felsenstein 1985) was applied to assess support for individual
nodes using 1,000 replicates. Random starting trees were used for each independent ML tree search and all other
parameters were set to default values. The calculation of genetic variation within and among species groups under
the best fit nucleotide model was also performed in the MEGA v.6.06 software (Tamura et al. 2013).
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Results
Morphometric and meristic analysis. The new species, Lithoxus jariensis and L. raso, were distinguished from
congeners by the combination of several morphometric and meristic characters (Table 1), such as: the presence of
five branched anal-fin rays, 14 branched caudal-fin rays, a smaller number of dentary teeth, a greater adipose-fin
length, a greater dorsal adipose-caudal distance, a smaller caudal peduncle depth, a shorter cleithral width and a
greater dorsal-anal distance. Furthermore, the two new species described in the present study can be distinguished
from each other mainly by the presence in L. raso of light spots on the body (a character absent in L. jariensis).
FIGURE 1. Maximum likelihood – ML (LogL = -2497.55) tree of Lithoxus species using T92+G nucleotide model and based
on the analysis of partial sequences of cytochrome oxidase C subunit I (COI). Numbers at nodes are bootstrap values based on
1,000 pseudoreplicates. Values below 50% are not shown.
Genetic analysis. We sequenced the COI gene for 46 samples of Lithoxus (representing five described species
and two new) and one outgroup sample (Hypostomus ancistroides). The combined sequence data resulted in a
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matrix of 866 base pairs. All sequences were deposited in GenBank (Table 2). No sequences showed any
insertions, deletions or stop codons. The best nucleotide model selected for the matrix was T92+G (AICc =
5940.763). The nucleotide frequencies under T92+G model were 0.299 (A), 0.299 (T), 0.201 (C), and 0.201 (G).
The overall transition/transversion rate was R = 4.54. Saturation was not observed considering that the Iss < Iss.c
for all NumOTU in the Xia et al. (2003) and Xia & Lemey (2009) test.
The gene tree represented is a 50% majority-rule consensus obtained by ML analysis (LogL = -2497.55, Fig.
1). In this tree, we recognize seven clusters that correspond to five described species and the two new species
described herein. Genetic distances among Lithoxus species, and among specimens of each nominal species, are
shown in Table 3. The rate of genetic variation ranges from 1.8% between L. raso and L. jariensis, to 7.9% between
L. stocki and L. jariensis.
Lithoxus jariensis, sp. n.
Fig. 2; Table 1
Holotype. MZUSP 123131, 60.7 mm SL, municipality of Laranjal do Jari, Amapá State, rio Itapuru, cachoeira de
São Raimundo, rio Jari, rio Amazonas basin, 00°33’59” S, 52°34’40” W, 20 February 2009, J.L Birindelli, L.S.
Sousa, & M. Soares.
Paratypes. All specimens from Brazil: Amapá State: rio Jari: rio Amazon basin: LBP 19553 (3, 33.8–45.5 mm
SL, 1 c&s, 47.1 mm SL), collected with holotype. LBP 20468 (1, 32.2 mm SL), municipality of Laranjal do Jari,
igarapé Iratapuru, 00°32’01”S, 52°35’05”W, 26 September 2015, C. Oliveira & B.F. Melo. LBP 20512 (10, 29.3–
48.1 mm SL, 1 c&s, 45.6 mm SL), municipality of Laranjal do Jari, rio Jari, rio Amazonas basin, 00°38’33”S,
52°30’27”W, 28 September 2015, C. Oliveira & B.F. Melo. MHNG 2767.051 (2, 48.1–48.9 mm SL), municipality
of Almeirim, rio Jari, rio Amazonas basin, 00°37’25”S, 52°32’48”W, 19 February 2009, J.L Birindelli, L.S. Sousa,
& M. Soares. MZUSP 103396 (24, 30.0–50.7 mm SL), municipality of Almeirim, rio Jari, rio Amazonas basin,
00°37’25”S, 52°32’48”W, 19 February 2009, J.L Birindelli, L.S. Sousa, & M. Soares. MZUSP 103491 (40, 19.5–
53.2 mm SL), collected with holotype. MZUSP 101528 (17, 29.2–53.3 mm SL), municipality of Laranjal do Jari,
rio Jari, rio Amazonas basin, 00°38’44”S, 52°30’34”W, 19 September 2008, C. Moreira & A. Akama.
Diagnosis. Lithoxus jariensis differs from L. surinamensis and L. pallidimaculatus by the presence of an
adipose fin (vs. adipose fin absent); from L. bovallii by the absence of an irregular concentration of chromatophores
around the anal-fin origin and adjacent region (vs. presence), and by the coloration pattern of caudal fin with three
dark bands (vs. five dark bands); from L. lithoides and L. jantjae by the presence of five branched anal-fin rays (vs.
four); from L. pallidimaculatus and L. raso by absence of light spots on the body (vs. presence of light spots on the
body); from L. jantjae by having 14 branched caudal-fin rays (vs. 12); and from L. stocki by having medial
premaxillary teeth with an enlarged and widened cusp (vs. cusps of all premaxillary teeth similar in size, not
enlarged), and by a small number of dentary teeth 5–8 (vs. 10–12). Moreover, the new species differs from L.
boujardi by having a greater adipose–spine length, 6.2–10.1% SL (vs. 3.6–4.7% SL), and by having a greater
dorsal adipose-caudal distance, 12.0–16.5% SL (vs. 10.3–11.7% SL); from L. planquettei by smaller caudal
peduncle depth, 7.6–8.7% SL (vs. 9.7–10.5% SL), and by having a straight adipose-fin spine (vs. a curved adipose-
fin spine); and from L. stocki by having a shorter cleithral width, 27.8–31.2% SL (vs. 32.6–34.2% SL), and a
greater dorsal–anal distance, 10.4–13.7% SL (vs. 8.8–10.4% SL).
Description. Morphometric data presented in Table 1. Medium sized loricariids (41–60 mm SL). In lateral
view, dorsal profile convex from snout tip to dorsal-fin origin; straight and gradually descending from dorsal-fin
origin to end of caudal peduncle insertion. Ventral profile slightly concave from snout tip to pectoral-fin origin;
convex from pectoral-fin origin to pelvic-fin origin; concave from pelvic-fin origin to insertion of lower caudal-fin
spine.
Head and snout broadly rounded. Snout elongated (49–57% HL); anterior region slightly depressed. Posterior
nostril small, almost reaching same diameter of eyes; no concavity between nostrils. Eyes small (orbit diameter 11–
15% HL), dorsally positioned. Superior margin of orbits not elevated. Oral disk occupying entire ventral surface of
head. Ventral surface of disk covered with low and wide papillae; margin of disk fringed with low triangular
papillae. Maxillary barbel relatively long and projected anterolaterally to upper lip. Teeth bicuspid with deep
division between cusps; four to five left premaxillary teeth, five to eight left dentary teeth; premaxillary tooth cusps
increasing in size from lateralmost to medialmost tooth; medialmost tooth cusp two to four times larger than
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lateralmost tooth cusp. Lateralmost premaxillary tooth cusps similar in size to dentary tooth cusps; dentary teeth all
similar in size.
TABLE 1 . Morphometric data for the two new species L. jariensis and L. raso, and for the comparative material of L.
boujardi, L. gr. bovallii, L. planquettei and L. stocki. Abbreviations used in the table are: SD = standard deviation; L =
length; D = distance; Dp = depth; Dia = diameter; W = width; SL = standard length; HL = head length.
L. jariensis, n = 20 L. raso, n = 3
Holotype Min Max Mean SD Holotype Min Max Mean SD
Standard length (SL) 60.6 41.6 60.6 47.9 3.3 44.3 42.9 46.4 44.5 1.7
Percents of SL
Predorsal L. 42.8 42.8 48.1 45.9 1.4 44.0 43.3 46.1 44.5 1.4
Head L. (HL) 31.3 32.2 35.7 34.3 1.0 34.0 33.8 34.9 34.4 0.5
Head-dorsal L. 10.0 9.1 13.2 11.5 1.1 8.3 7.9 9.5 8.6 0.8
Cleithral W. 30.0 27.8 31.2 29.9 1.0 30.9 30.9 31.2 31.0 0.1
Head-pectoral L. 26.5 19.2 30.2 26.3 2.4 26.6 26.6 27.9 27.1 0.7
Thorax L. 22.4 22.4 28.2 25.0 1.4 22.8 22.8 24.0 23.5 0.6
Pectoral-spine L. 30.0 23.4 30.0 25.2 1.2 29.3 27.9 29.3 28.4 0.7
Abdominal L. 22.1 20.2 23.4 21.9 1.0 20.9 19.4 20.9 19.9 0.8
Pelvic-spine L. 25.5 22.5 28.0 24.8 1.4 25.9 25.0 29.1 26.7 2.1
Postanal L. 32.3 30.6 36.7 33.1 1.8 32.7 32.7 33.1 32.9 0.1
Anal-fin spine L. 8,0 6.6 10.4 8.1 1.0 8.1 8.1 10.5 9.5 1.2
Dorsal-pectoral D. 24.5 24.5 28.5 26.5 1.0 24.1 23.9 25.1 24.4 0.6
Dorsal-spine L. 19.9 17.2 21.3 19.9 1.2 23.0 20.9 23.0 22.0 1.0
Dorsal-pelvic D. 20.3 15.5 22.9 18.6 1.8 14.4 12.9 14.4 13.4 0.8
Dorsal-fin base L. 20.4 18.6 22.6 20.2 1.1 17.8 15.8 17.8 17.1 1.1
Dorsal-adipose D. 23.4 15.8 23.5 21.2 2.0 21.6 20.9 23.0 21.8 1.1
Adipose-spine L. 6.2 6.2 10.1 7.9 0.9 7.2 7.2 8.1 7.6 0.4
Dorsal-adipose caudal D. 12.0 12.0 16.5 14.5 1.1 14.6 13.1 14.6 13.7 0.8
Caudal peduncle Dp. 8.4 7.6 8.7 8.2 0.3 8.5 8.4 8.6 8.5 0.1
Ventral adipose-caudal D. 17.6 16.1 22.9 19.0 1.6 18.2 17.0 18.2 17.6 0.6
Adipose-anal D. 20.1 16.9 21.5 19.4 1.3 17.6 17.4 18.7 17.9 0.7
Dorsal-anal D. 11.7 10.4 13.7 11.1 0.8 9.7 9.7 11.8 10.6 1.1
Pelvic-dorsal D. 23.1 19.0 23.6 20.7 1.3 16.4 16.0 16.4 16.2 0.2
Percents of HL Holotype Min Max Mean SD Holotype Min Max Mean SD
Head-eye L. 41.0 38.5 46.0 42.3 1.8 43.0 38.0 43.0 40.6 2.5
Orbital Dia. 10.0 11.0 15.3 12.6 1.2 13.9 13.3 15.9 14.3 1.3
Snout L. 54.2 49.7 57.1 53.5 1.8 50.3 50.3 54.6 52.4 2.17
Internares W. 11.0 11.0 17.0 14.8 1.4 8.6 8.6 11.3 9.8 1.3
Interorbital W. 28.9 25.4 31.0 27.6 1.3 27.1 27.1 28.6 27.7 0.8
Head Dp. 57.3 53.8 58.1 56.3 1.2 58.9 57.6 58.4 58.3 0.5
Mouth L. 58.4 50.0 58.4 53.5 2.3 47.6 47.6 54.1 51.9 3.6
Barbel L. 14.7 10.4 17.2 13.4 1.9 13.2 13.2 15.9 14.1 1.5
Dentary tooth cup L. 5.7 4.9 9.9 6.5 1.3 5.3 4.4 5.3 4.8 0.4
Premaxillary tooth cup L. 4.7 4.7 10.2 8.2 1.0 3.3 3.3 4.0 3.7 0.3
......continued on the next page
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Continued.
L. boujardi, n = 6 L. gr. bovallii, n = 8
Min Max Mean SD Min Max Mean SD
Standard length (SL) 36.1 62.5 53.0 9.84 36.3 46.5 41.3 3.36
Percents of SL
Predorsal L. 42.4 43.6 43.0 0.38 42.3 45.5 44.4 1.14
Head L. (HL) 31.9 33.8 32.5 0.73 31.6 34.4 33.5 1.06
Head-dorsal L. 8.5 10.7 9.9 0.77 8.2 10.6 9.5 0.74
Cleithral W. 27.3 29.9 28.4 0.71 29.5 32.7 31.1 1.27
Head-pectoral L. 24.4 26.5 25.6 0.83 26.9 29.9 28.3 1.18
Thorax L. 23.2 25.2 23.8 1.02 21.1 25.3 22.9 1.52
Pectoral-spine L. 23.6 26.2 25.0 0.95 24.3 29.4 26.8 1.82
Abdominal L. 20.2 22.8 20.8 1.28 20.1 22.4 21.0 0.85
Pelvic-spine L. 22.4 25.4 24.8 1.30 22.3 24.6 23.2 0.88
Postanal L. 31.5 34.8 33.5 1.37 31.0 33.2 32.0 0.76
Anal-fin spine L. 4.96 8.7 7.05 1.36 7.1 10.4 8.2 1.25
Dorsal-pectoral D. 23.5 25.7 24.7 0.87 23.3 27.1 25.5 1.16
Dorsal-spine L. 17.6 19.6 18.9 0.70 18.0 21.8 19.5 1.33
Dorsal-pelvic D. 13.0 16.4 15.2 1.17 14.0 18.7 16.6 1.71
Dorsal-fin base L. 19.3 20.6 19.8 0.61 17.3 20.6 18.8 1.03
Dorsal-adipose D. 21.7 24.8 22.5 1.51 20.1 22.5 21.3 0.87
Adipose-spine L. 3.6 4.7 4.3 0.44 3.3 5.3 4.2 0.65
Dorsal-adipose caudal D. 10.3 11.7 11.1 0.53 9.4 13.5 11.5 1.66
Caudal peduncle Dp. 7.2 8.3 7.5 0.40 7.5 8.5 8.0 0.34
Ventral adipose-caudal D. 15.3 17.1 16.2 0.73 13.2 17.9 16.4 1.50
Adipose-anal D. 18.1 20.6 19.2 1.08 18.0 22.9 20.1 1.49
Dorsal-anal D. 10.0 11.2 10.2 0.47 10.4 13.3 11.2 1.01
Pelvic-dorsal D. 19.3 21.3 20.1 0.87 17.3 22.5 19.4 1.69
Percents of HL Min Max Mean SD Min Max Mean SD
Head-eye L. 37.7 41.4 39.6 1.30 40.8 44.6 42.4 1.52
Orbital Dia. 10.2 12.5 11.7 1.37 11.5 14.3 13.1 0.89
Snout L. 50.8 54.3 53.1 1.31 45.5 49.6 48.7 1.35
Internares W. 7.3 8.5 7.9 0.42 8.2 10.5 9.6 0.72
Interorbital W. 23.7 26.8 25.4 1.16 27.2 29.6 28.0 0.74
Head Dp. 53.7 61.4 58.2 2.93 56.6 61.1 59.5 1.52
Mouth L. 53.0 61.2 56.0 4.02 51.3 61.9 56.5 3.47
Barbel L. 9.8 11.8 10.6 0.77 8.0 15.2 10.2 2.22
Dentary tooth cup L. 5.1 10.6 7.5 1.91 3.7 6.4 4.8 0.80
Premaxillary tooth cup L. 6.7 11.4 8.3 1.75 3.6 6.7 5.0 0.93
......continued on the next page
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Body dorsoventrally depressed. In dorsal view, greatest body width at cleithral region and greatest body depth
at dorsal-fin origin. Body progressively narrow from opercular region to caudal fin. Cross-section of body between
pectoral and pelvic fins rounded dorsally and flat ventrally. Body almost entirely covered by plates, except at
ventral portions of head, abdomen and along dorsal-fin base. Dorsal surface of body entirely covered by plates;
three to four predorsal plates; five interdorsal plates, eight plates below dorsal-fin base; four plates between dorsal
Continued.
L. planquettei, n = 13 L. stocki, n = 5
Min Max Mean SD Min Max Mean SD
Standard length (SL) 39.6 71.0 51.8 9.83 36.8 65.4 47.2 11.2
Percents of SL
Predorsal L. 42.6 46.7 44.5 0.99 43.4 45.9 44.9 0.99
Head L. (HL) 31.6 34.8 33.1 0.96 32.2 34.2 33.7 0.83
Head-dorsal L. 9.6 12.1 10.7 0.71 8.4 11.9 10.3 1.40
Cleithral W. 28.1 32.5 30.4 1.29 32.6 34.2 33.2 0.61
Head-pectoral L. 24.8 28.9 27.1 1.57 27.4 28.0 27.7 0.32
Thorax L. 19.6 24.7 22.3 1.54 21.7 27.9 24.4 2.34
Pectoral-spine L. 24.9 29.8 27.5 1.78 29.7 34.7 32.4 2.10
Abdominal L. 18.3 22.6 20.8 1.30 19.1 23.7 20.9 1.67
Pelvic-spine L. 23.8 28.7 25.5 1.41 21.0 23.6 22.5 1.18
Postanal L. 30.6 37.0 33.6 2.07 31.3 35.9 33.5 2.21
Anal-fin spine L. 7.5 10.6 9.1 0.82 6.4 8.1 7.2 0.82
Dorsal-pectoral D. 24.1 27.1 25.9 0.87 24.4 26.4 25.6 0.97
Dorsal-spine L. 20.2 23.8 21.9 1.01 17.9 21.4 19.4 1.38
Dorsal-pelvic D. 15.1 19.4 17.8 1.24 11.9 19.6 14.6 3.08
Dorsal-fin base L. 15.3 20.1 18.0 1.31 17.7 21.7 20.3 1.52
Dorsal-adipose D. 20.2 24.1 22.6 1.25 18.4 22.7 21.0 1.67
Adipose-spine L. 5.6 13.6 7.6 1.99 6.8 9.5 7.8 1.08
Dorsal-adipose caudal D. 9.8 16.0 12.7 1.80 10.7 13.9 12.7 1.35
Caudal peduncle Dp. 9.7 10.5 10.0 0.28 7.8 8.6 8.0 0.36
Ventral adipose-caudal D. 17.0 22.9 19.0 1.64 17.1 18.1 17.8 0.40
Adipose-anal D. 18.4 23.1 20.2 1.40 15.2 19.5 17.7 1.61
Dorsal-anal D. 11.0 14.3 12.9 0.93 8.8 10.4 9.7 0.74
Pelvic-dorsal D. 17.7 22.1 19.6 1.31 18.9 20.8 20.0 0.67
Percents of HL
Head-eye L. 35.9 42.0 39.3 1.58 40.4 43.6 42.1 1.18
Orbital Dia. 10.4 14.1 12.5 1.15 14.2 17.3 15.8 1.14
Snout L. 51.2 55.2 53.6 1.10 47.3 52.3 49.6 1.95
Internares W. 8.2 11.7 9.7 0.95 7.7 9.4 8.6 0.59
Interorbital W. 29.5 35.9 32.0 1.94 24.4 26.1 25.4 0.84
Head Dp. 57.8 62.0 59.9 1.39 62.0 63.4 62.7 0.62
Mouth L. 50.0 60.7 53.9 3.48 42.0 52.3 49.1 4.17
Barbel L. 6.7 12.7 9.8 2.26 9.0 11.9 10.4 1.20
Dentary tooth cup L. 3.4 6.9 4.8 1.05 5.2 7.9 6.7 1.01
Premaxillary tooth cup L. 3.0 5.2 4.1 0.60 7.1 8.7 7.7 0.8
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fin and adipose fin. Lateral surface of body entirely covered by plates; mid-dorsal plate series developed, reaching
end of adipose fin; lateral median plates 23−24; mid-ventral plate series developed (six plates), reaching end of
adipose-fin base. Body plates with minute odontodes. Odontodes slightly hypertrophied on pectoral-fin spines,
becoming gradually larger distally. Longest odontodes on posteriormost evertible cheek plates.
Dorsal-fin II,7; dorsal-fin spinelet V-shaped, locking mechanism present; dorsal-fin origin approximately at
midpoint between pectoral- and pelvic-fin origins; last dorsal-fin ray not reaching adipose fin when depressed.
Pectoral-fin I,6; pectoral-fin spine reaching slightly beyond base of pelvic-fin spine when depressed. Pelvic-fin I,5;
reaching anal-fin origin when depressed. Anal-fin I,5. Adipose-fin present, with single azygous preadipose plate;
posterior margin of adipose-fin membrane convex, extending posteriorly beyond adipose-fin spine. Cross-section
of caudal peduncle ellipsoid, flat dorsally and ventrally. Three lateral plate rows at base of caudal peduncle.
Caudal-fin I,7−I,7; obliquely forked, lower lobe longer than upper.
FIGURE 2. Lithoxus jariensis, holotype, MZUSP 123131, male 60.6 mm SL, from rio Jari (rio Amazon basin), municipality of
Laranjal do Jari, Amapá State, Brazil.
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FIGURE 3. Map showing the type locality of (A) L. jariensis, rio Jari basin, rio Amazonas basin, Amapá State, Brazil; and (B)
Lithoxus raso in igarapé Balneário Raso, rio Amapá basin, Amapá State, Brazil.
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FIGURE 4. Upper picture showing the habitat of the type locality where the species Lithoxus jariensis lives at cachoeira de
São Raimundo, 00°33’59” S, 52°34’40” W. Lower picture showing the habitat of the type locality where the species of L. raso
lives at igarapé Balneário Raso, 02°05’25” N, 50°53’20” W.
Color in alcohol. Background color dark brown dorsally and laterally, and light brown ventrally. Four dark
saddles along dorsal portion of body: first at dorsal-fin origin, second at end of dorsal-fin base, third at the middle
of caudal peduncle, and fourth reaching anteriormost caudal procurrent ray. Fins with irregular and poorly defined
bars: three or four on anal-, pectoral-, dorsal- and pelvic-fin rays. Caudal-fin dark with a large hyaline bar in middle
portion of rays. Hypertrophied odontodes on posteriormost evertible cheek plates and on pectoral-fin spines
yellowish.
Sexual dimorphism. Males possess a papilla posterior to urogenital opening (absent in females).
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Etymology. The specific epithet jariensis is in reference to the type-locality, the rio Jari, a large tributary of the
rio Amazon basin.
Distribution. Lithoxus jariensis is only known from rio Jari and small tributaries, at municipality of Almerim
and Laranjal do Jari, Amapá State, Brazil (see Fig. 3).
Habitat. The new species L. jariensis is found in the bottom of a fast-flowing clear-water rivers of median to
large size, such as rio Jari (Fig. 4). The bottom of the rivers was composed of small to large-sized rocks, loose
stones, and sand.
Lithoxus raso, sp. n.
Fig. 5; Table 1
Holotype. MZUSP 123132, 44.3 mm SL, Brazil, municipality of Amapá, Amapá States, igarapé Balneário Raso,
rio Amapá basin, 02°05’25” N, 50°53’20” W, 02 December 2015, C. Oliveira & B.F. Melo.
Paratypes. LBP 21184 (5, 28.8–42.9 mm SL), collected with holotype. MHNG 2767.052 (2, 25.3–44.8 mm
SL), collected with holotype.
Diagnosis. Lithoxus raso differs from all congeners, except L. pallidimaculatus by the presence of large light
spots all over the body, spots similar in size with orbit diameter, (Fig. 5; vs. absence of light spots over the body or
light spots very small, similar to size of a tooth, covering only the dorsal portion of the head in L. boujardi; see Fig.
6 for coloration pattern among Lithoxus species); from L. surinamensis and L. pallidimaculatus by having an
adipose fin (vs. adipose fin absent); from L. lithoides and L. jantjae by having five branched anal-fin rays (vs. four);
and from L. jantjae by having 14 branched caudal-fin rays (vs. 12). Moreover, the new species differs from L.
bovallii by having a lower premaxillary tooth cup length, 3.3–4.0% HL (vs. 4.2–10.4% HL, personal
communication with J.W. Armbruster for measurements of L. bovallii specimens from the type locality); from L.
boujardi by having a greater adipose–spine length, 7.2–8.1% SL (vs. 3.6–4.7% SL), and a greater dorsal adipose–
caudal distance, 13.1–14.6% SL (vs. 10.3–11.7% SL); from L. planquettei by smaller caudal peduncle depth, 8.4–
8.6% SL (vs. 9.7–10.5% SL); and from L. stocki by having medial premaxillary teeth with an enlarged and widened
cusp (vs. cusps of all premaxillary teeth similar in size, not enlarged), and by having a shorter cleithral width, 30.9–
31.2% SL (vs. 32.6–34.2% SL).
Description. Morphometric data presented in Table 1. Medium sized loricariid (42–46 mm SL). In lateral
view, dorsal profile convex from snout tip to dorsal-fin origin; straight and gradually descending from dorsal-fin
origin to adipose-fin origin; concave from adipose-fin origin to upper caudal-fin spine. Ventral profile slightly
concave from snout tip to anal-fin origin; slightly convex from anal-fin origin to insertion of lower caudal-fin
spine.
Head and snout broadly rounded. Snout elongated (50–54% HL), anterior region depressed. Area around tip of
snout free of plates and odontodes. Posterior nostril small, half of eye diameter. Dorsal profile of head ascending
approximately 45° to parieto-supraoccipital. Eye small (orbit diameter 13–15 % HL), dorsolaterally positioned.
Superior margin of orbit not elevated. Mouth moderate in size; oral disk occupying almost entire ventral surface of
head. Lips without odontodes; lower lip larger than upper lip, but far from reaching cleithrum region. Margin of
oral disk fringed, with low triangular papillae. Maxillary barbel relatively long and projecting anterolaterally from
upper lip. Teeth bicuspid with deep division between cusps; four left premaxillary teeth, six to eleven left dentary
teeth. Premaxillary tooth cusps increasing in size from lateralmost to medialmost tooth with medialmost tooth cusp
two times as large as lateralmost tooth cusp. Dentary tooth cusps similar in size to lateralmost premaxillary tooth
cusps. Dentary teeth of same size.
Body dorsoventrally depressed. In dorsal view, greatest body depth at dorsal-fin origin. Greatest body width at
cleithral region; body progressively narrowing from opercular region to caudal fin. Cross-section of body between
pectoral and pelvic fins rounded dorsally and flat ventrally. Body almost entirely covered by plates; except in
ventral portions of head, abdomen and along dorsal-fin base.
Dorsal surface of body entirely covered by plates; three predorsal plates; seven plates below dorsal-fin base;
four plates between dorsal fin and adipose fin. Lateral surface of body entirely covered by plates; mid-dorsal plate
series developed, reaching end of adipose fin; lateral median plates 23–25; mid-ventral plate series developed,
reaching end of adipose fin. Body plates with minute odontodes. Odontodes slightly hypertrophied on pectoral-fin
spines, becoming gradually larger distally. Longest odontodes on posteriormost evertible cheek plates.
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FIGURE 5. Lithoxus raso, holotype, MZUSP 123132, 42.9 mm SL, from igarapé Balneário Raso (rio Amapá basin),
municipality of Amapá, Amapá State, Brazil.
Dorsal-fin II,7; dorsal-fin spinelet V-shaped, dorsal-fin locking mechanism present; dorsal-fin origin
approximately at midpoint between pectoral- and pelvic-fin origins; last dorsal-fin ray not reaching adipose fin
when depressed. Pectoral-fin I,6; pectoral-fin spine reaching slightly beyond base of pelvic-fin spine when
depressed. Pelvic-fin I,5; reaching anal-fin origin when depressed. Anal-fin I,5. Adipose fin with single azygous
preadipose plate; posterior margin of adipose-fin membrane convex, extending posteriorly beyond adipose-fin
spine. Cross-section of caudal peduncle ellipsoid, rounded dorsally and ventrally. Three caudal peduncle plate
rows. Caudal-fin I,7−I,7; caudal fin obliquely forked, lower lobe longer than upper.
Color in alcohol. Background color dark brown on dorsum and sides of body, becoming lighter ventrally.
Large white spots on trunk, becoming larger on posterior portion of body. Fins with irregular and poorly defined
bars: three or four on anal, pectoral, dorsal and pelvic-fin rays. Caudal-fin dark with one large hyaline bar in middle
portion. Hypertrophied odontodes on posteriormost evertible cheek plates and on pectoral-fin spines; pectoral-fin
spines reddish. Cross-section of caudal peduncle ellipsoid.
Sexual dimorphism. Males possess a papilla posterior to urogenital opening (absent in females).
Etymology. The specific epithet raso is in reference to the type-locality, the igarapé Balneário Raso, a tributary
of the rio Amapá, Atlantic coastal drainage. A noun in apposition.
Distribution. Lithoxus raso is only known from igarapé Raso, at the municipality of Amapá, in Amapá State,
Brazil (Fig. 3).
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Habitat. The new species L. raso is found associated with rocks and sand in the bottom of small to medium
sized rivers (Fig. 4).
FIGURE 6. Picture showing the variation in color pattern among Lithoxus species. A) L. gr. bovallii, MHNG 2704.043, 38.8
mm SL; B) L. boujardi, MHNG 2723.04, 58.5 mm SL; C) L. gr. pallidimaculatus, MHNG 2722.088, 39.9 mm SL; D) L.
planquettei, MHNG 2757.001, 66.3 mm SL; and E) L. stocki, MHNG 2767.051, 48.6 mm SL.
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Discussion
Lithoxus jariensis and L. raso are typical species of Lithoxus, both having the three diagnostic characters of the
genus: strongly dorsoventrally depressed body, a large rounded oral disk, and small tooth cups with few teeth
(Lujan 2008). Lithoxus jariensis is the first species of this genus reported for the rio Jari basin in Amapá State,
Brazil. This species is distinguished from congeners by the presence of the following characters: (1) an adipose fin;
(2) five branched anal-fin rays; (3) absence of light spots on the body; (4) having 14 branched caudal-fin rays; (5)
having medial premaxillary teeth with an enlarged and widened cusp; (6) small number of dentary teeth; and by
morphometric characters such as: (7) greater adipose-fin length; (8) greater dorsal adipose–caudal distance; (9)
smaller caudal peduncle depth; (10) straight adipose-fin spine; (11) a shorter cleithral width; and (12) greater
dorsal–anal distance.
Lithoxus raso is also the first species of this genus reported from the igarapé Balneário Raso, a tributary of the
rio Amapá, which is a river in northern Brazil that drains directly to the Atlantic Ocean. We are describing this new
species only based on a few specimens (three large 42–46 mm SL and five medium 28–35 mm SL). Access to the
type locality of this species is difficult because it is in the middle of the Brazilian rainforest. Furthermore, in the
period that we collected the specimens the climate was atypically dry and the level of the river was very low giving
us access to specimens in the igarapé Balneário Raso, which is a medium sized stream with fast flow that is not
normally accessible.
Despite having few specimens, Lithoxus raso can be easily distinguished from congeners by the following
characters: (1) presence of large light spots all over the body; (2) having an adipose fin; (3) having five branched
anal-fin rays; (4) having 14 branched caudal-fin rays; (5) a lower premaxillary tooth cup length; (6) having a
greater adipose-spine length; (7) having a greater dorsal adipose–caudal distance; (8) having smaller caudal
peduncle depth; and by (9) having medial premaxillary teeth with an enlarged and widened cusp.
Large light spots all over the body are also present in the species L. pallidimaculatus and the new species L.
raso (Fig. 5). The species L. gr. bovallii (Fig. 6A) also present this character, however it is absent in the specimens
of L. bovallii from the type locality (personal communication with J.W. Armbruster). The light spots of these
species are large, similar in size the orbit diameter and cover all the dorsal and lateral portion of the body. The
species L. boujardi presents very small spots (similar to the size of a tooth) in the dorsal portion and dorsolateral
portion of the head (Fig. 6B). Lithoxus lithoides has a body coloration pattern without spots, but with irregular
bands in the dorsal and lateral portions of the body (see Fig. 3 in Lujan 2008).
Results of our molecular genetic analysis were useful to discriminate the five already described species of
Lithoxus (i.e., L. planquettei, L. gr. pallidimaculatus, L. gr. bovallii, L. stocki and L. boujardi) and the two new
species (i.e., L. jariensis and L. raso) described in the present study (Fig. 1). These last two species of Lithoxus
have greater genetic divergence than all five described species (Table 3), however genetic divergence between L.
jariensis and L. raso is 1.8% the lowest value obtained. This could suggest that the divergence between these
species is recent. However, despite this low value, morphologically, L. raso can be distinguished from L. jariensis
by having a color pattern of large white spots over the body. This color pattern is also present in L.
pallidimaculatus.
TABLE 3. Genetic distance (and standard deviation) among Lithoxus species based on the T92+G nucleotide model. In
the main diagonal are the values of intragroup genetic divergences highlighted in bold. Below the main diagonal is the
values of interspecific genetic divergences. The values are shown in percentage.
1234567
1L. boujardi 0.2±0.1
2L. gr. bovallii 5.5±0.8 0.5±0.1
3L. gr. pallidimaculatus 5.6±0.9 4.6±0.6 1.4±0.3
4L. planquettei 5.1±0.9 4.0±0.6 4.1±0.6 0.2±0.1
5L. stock 2.7±0.6 5.4±0.8 5.9±0.9 5.2±0.8 0.1±0.1
6L. jariensis 7.6±1.1 6.8±1.2 7.0±1.1 5.4±1.0 7.9±1.2 0
7L. raso 6.1±0.9 6.0±1.0 5.8±0.9 4.3±0.8 6.5±1.0 1.8±0.6 0
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The group composed by specimens of L. pallidimaculatus in the molecular analysis includes samples from
three localities: Kumbu Creek (Brokopondo, Sarramacca River, Suriname), Cajana Creek in Gran Rio River
(Sipaliwini, Suriname River, Suriname) and a small forest Creek from Upper Mapana Creek (Commewijne River,
Suriname). The specimen that morphologically represents the species L. pallidimaculatus is from Cajana Creek a
tributary of the Gran Rio River (Sipaliwini, Suriname River, Suriname), despite the type locality of L.
pallidimaculatus being at Kwambaolo Creek, tributary of Sara Creek, Suriname River, Suriname (Boeseman 1982;
Nijssen & Isbrücker 1990). Given genetic divergence, the other two sampled localities of L. pallidimaculatus from
Kumbu Creek, a tributary of Saramacca River (Brokopondo, Saramacca River, Suriname), and the small Upper
Mapana Creek (Commewijne River, Suriname), could possibly represent a new species of Lithoxus closely related
to L. pallidimaculatus.
Similarly, Lithoxus gr. bovallii is represented by specimens from five localities: Kurupukari Cross (Rupununi
River, Guyana), Sir Walter Raleighvallen (Sipaliwini River, Suriname), Moi Moi Falls (Sipaliwini, Kabalebo
River, Suriname), Bakhuis Mountains (Nickerie River, Suriname) and Moses Creek (Nickerie River, Suriname).
The specimens of L. gr. bovallii used in this study, most similar to L. bovallii was from Kurupukari Cross
(Essequibo River, Guyana), despite the type locality being at the Kaat River, tributary of the Treng River, Upper
Potaro, Guyana (Regan 1906; Nijssen & Isbrücker 1990). Boeseman (1982) suggested that Treng River could be
recognized in Guyana and that Treng River of Regan (1906) is the Ireng River and designated that locality as the
type locality of L. bovallii. However, Nijssen & Isbrücker (1990) suggested that L. bovallii from Treng River could
represent more than one species. Therefore, a deeper revision of this species (L. bovallii) from Treng River in
Guyana is necessary to evaluate if this species represents a complex of species.
For our study, the other four specimens of L. gr. bovallii analyzed in the present work are from localities in
Suriname, which could represent also a possible new species of Lithoxus of the group L. gr. bovallii. However, we
decided not to describe these genetic units due to the lack of morphological evidence at this moment, however, in
future studies, such as a revision of the genus, may uncover morphological evidence that support these independent
lineages of Lithoxus gr. pallidimaculatus and Lithoxus gr. bovallii as new species.
Comparative material
Lithoxus boujardi Muller & Isbrücker, 1993: MHNG 2723.041 (4, 36.1–60.5 mm SL), French Guiana, Crique
Cascade & Crique du Barrage, Arataye River; MHNG 2662.090 (2, 48.0–62.5 mm SL), French Guiana,
Crique Arataye, Saut Grand Japigny, Approuage River.
Lithoxus gr. bovallii (Regan, 1906): MHNG 2704.042 (1, 46.5 mm SL), Suriname, Sipaliwini, Corantijn River;
MHNG 2704.043 (4, 36.3–36.3 mm SL), Suriname, Sipaliwini, Sipaliwini River; MHNG 2704.047 (1, 43.2
mm SL), Suriname, Sipaliwini, Corantijin River; MHNG 2736.030 (2, 39.3–44.9 mm SL), Suriname,
Sipaliwini, Cascade Moi Moi, Kabalebo River; MHNG 2724.065 (1, 24.1 mm SL), Guyana, Kurupukari
Cross, Essequibo River.
Lithoxus gr. pallidimaculatus Boeseman, 1982: MHNG 2722.088 (3, 36.0–46.5 mm SL), Suriname, Commewijne
River, Upper Mapana Creek.
Lithoxus planquettei Boeseman, 1982: MHNG 2756019 (2, 47.7–49.8 mm SL); MHNG 2722.060 (3, 46.9–53.7
mm SL), Crique Grillon, Orapu River; MHNG 2682.051 (1, 42.3 mm SL).
Lithoxus stocki Nijssen & Isbrücker, 1990: MHNG 2767.053, (4, 34.8–44.7 mm SL), French Guiana, Saut Capiai,
Mana River; MHNG 2767.050 (2, 41.4–65.6 mm) SL, French Guiana, Saut Fracas, Mana River; MHNG
2767.051 (2, 37.3–49.5 mm SL), French Guiana, station 5, Saut “S”, Inini River.
Acknowledgments
We wish to thank Bruno F. Melo for help during the collection expeditions and for photos of the environment. We
also are grateful to Angelica C. Dias for held with molecular work. This research was supported by the Brazilian
agencies FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo; proc. 2014/05051–5 and 2015/
00691–9 to FFR) and CNPq (proc.150027/2017–6 to GSCS).
SILVA ET AL.
168
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Zootaxa 4347 (1) © 2017 Magnolia Press
References
Armbruster, J.W. (2003) Peckoltia sabaji, a new species from the Guiana Shield (Siluriformes, Loricariidae). Zootaxa, 344, 1–
12.
https://doi.org/10.11646/zootaxa.344.1.1
Armbruster, J.W. (2004) Phylogenetic relationships of the suckermouth armoured catfishes (Loricariidae) with emphasis on the
Hypostominae and the Ancistrinae. Zoological Journal of the Linnean Society, 141, 1–80.
https://doi.org/10.1111/j.1096-3642.2004.00109.x
Boeseman, M. (1982) The South American mailed catfish genus Lithoxus Eigenmann, 1910, with the description of three new
species from Surinam and French Guyana and records of related species (Siluriformes, Loricariidae). Proceedings of the
Koninklijke Nederlandse Akademie van Wetenschappen, Series C, Biological and Medical Sciences, 85, 41–58.
Edgar, R.C. (2004) MUSCLE: Multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Research,
32, 1792–1797.
https://doi.org/10.1093/nar/gkh340
Eigenmann, C.H. (1910) Catalogue of the fresh-water fishes of tropical and south temperate America. Report Princeton
University Expeditions to Patagonia, 1896–1899. Vol. 3. Indiana University, Bloomington, 137 pp. [pp. 375–511]
Eigenmann, C.H. (1912) The freshwater fishes of British Guiana, including a study of the ecological grouping of species, and
the relation of the fauna of the plateau to that of the lowlands. Memoirs of the Carnegie Museum, 5, 1–578.
https://doi.org/10.5962/bhl.part.14515
Eschmeyer, W.N. & Fong, J.D. (2017) Catalog of fishes. Available from: http://researcharchive.calacademy.org/research/
ichthyology/catalog/SpeciesByFamily.asp (accessed 24 May 2017)
Felsenstein, J. (1985) Confidence limits on phylogenies: an approach using the bootstrap. Evolution, 39, 783–791.
https://doi.org/10.1111/j.1558-5646.1985.tb00420.x
Fricke, R. & Eschmeyer, W.N. (2017) Catalog of fishes. Available from: http://researcharchive.calacademy.org/research/
ichthyology/catalog/collections.asp (accessed 23 August 2017)
Garg, T.K., Valdes Domingos, F.X., Almeida-Val, V.M.F. & Val, A.L. (2010) Histochemistry and functional organization of the
dorsal skin of Ancistrus dolichopterus (Siluriformes: Loricariidae). Neotropical Ichthyology, 8, 877–884.
https://doi.org/10.1590/S1679-62252010000400018
Geerinckx, T., Herrel, A. & Adriens, D. (2011) Suckermouth armoured catfish resolve the paradox of simultaneous respiration
and suction attachment: a kinematic study of Pterygoplichthys disjunctivus. Journal Exploration Biology, 315, 121–131.
Kearse, M., Moir, R., Wilson, A., Stones-Havas, S., Cheung, M., Sturrock, S., Buxton, S., Cooper, A., Markowitz, S., Duran,
C., Thierer, T., Ashton, B., Meintjes, P. & Drummond, A. (2012) Geneious Basic: an integrated and extendable desktop
software platform for the organization and analysis of sequence data. Bioinformatics, 28, 1647–1649.
https://doi.org/10.1093/bioinformatics/bts199
Lujan, N.K. (2008) Description of a new Lithoxus (Siluriformes: Loricariidae) from the Guayana highlands with a discussion of
Guiana Shield biogeography. Neotropical Ichthyology, 6, 413–418.
https://doi.org/10.1590/S1679-62252008000300014
Lujan, N.K., Armbruster J.W., Lovejoy, N.R. & López-Fernandez, H. (2015) Multilocus molecular phylogeny of the
suckermouth armored catfishes (Siluriformes: Loricariidae) with a focus on subfamily Hypostominae. Molecular
Phylogenetics and Evolution, 82, 269–288.
Muller, S. & Isbrücker, I.J.H. (1993) Lithoxus boujardi (Siluriformes, Loricariidae), une espèce nouvelle du Bassin de
l'Approuague, Guyane française. Cybium, 17, 71–76.
Nijssen, H. & Isbrücker, I.J.H. (1990) Lithoxus stocki, a species new to science of ancistrin loricariid catfish from the Maroni
River drainage, with a comparison of the primary type specimens of the six species of Lithoxus (syn. Paralithoxus)
(Pisces, Siluriformes, Loricariidae). Bijdragen tot de Dierkunde, 60, 327–333.
Regan, C.T. (1906) Notes on some loricariid fishes, with descriptions of two new species. Annals and Magazine of Natural
History, Series 7, 17 (97), 94–98.
https://doi.org/10.1080/00222930608562495
Tamura, K., Stecher, G., Peterson, D., Filipski, A. & Kumar, S. (2013) MEGA6: Molecular Evolutionary Genetics Analysis
version 6.0. Molecular Biology and Evolution, 30, 2725–2729.
https://doi.org/10.1093/molbev/mst197
Ward, R.D., Zemlak, T.S., Innes, B.H., Last, P.R. & Hebert, P.D.N. (2005) DNA barcoding Australia’s fish species
Philosophical transactions of the Royal Society of London Series B. Biological Sciences, 360, 1847–1857.
https://doi.org/10.1098/rstb.2005.1716
Xia, X. (2013) DAMBE5: a comprehensive software package for data analysis in molecular biology and evolution. Molecular
Biology and Evolution, 30, 1720–1728.
https://doi.org/10.1093/molbev/mst064
Xia, X. & Lemey, P. (2009) Assessing substitution saturation with DAMBE. In: Lemey, P., Salemi, M. & Vandamme, A.M.
(Eds.), The Phylogenetic Handbook: A Practical Approach to DNA and Protein Phylogeny. Cambridge University Press,
Cambridge, pp. 615–630.
https://doi.org/10.1017/CBO9780511819049.022
Xia, X., Xie, Z., Salemi, M., Chen, L. & Wang, Y. (2003) An index of substitution saturation and its application. Molecular
Phylogenetics and Evolution, 26, 1–7.
https://doi.org/10.1016/S1055-7903(02)00326-3
