From the inside out: a new species of armoured catfish Corydoras with the description of poorly-explored character sources (Teleostei, Siluriformes, Callichthyidae)

Abstract

A new species of the armoured catfish genus Corydoras is described from the Xingu-Tapajos ecore-gion, Brazilian Amazon. The new species can be distinguished from its congeners by having the following combination of features: short mesethmoid, with anterior tip poorly developed, smaller than 50% of bone length; posterior margin of pectoral spine with serrations directed towards spine tip or perpendicularly oriented; infraorbital 2 only in contact with sphenotic; ventral laminar expansion of infraorbital 1 poorly or moderately developed; flank midline covered by small dark brown or black saddles with similar size to remaining markings on body; relatively larger, scarcer and more sparsely distributed dark brown or black spots on body; absence of stripe on flank midline; caudal fin with conspicuous dark brown or black spots along its entire surface; slender body; and strongly narrow frontals. A more comprehensive description of poorly-explored internal character sources, such as the gross morphology of the brain, Weberian apparatus and swimbladder capsule elements is presented.

Full text

Journal of Fish Biology (2018)
doi:10.1111/jfb.13602, available online at wileyonlinelibrary.com
From the inside out: a new species of armoured catsh
Corydoras with the description of poorly-explored character
sources (Teleostei, Siluriformes, Callichthyidae)
V. C. E*†,L.F.C.T‡,F.M.P§,L.V-V§
 M. R. B§
*Museu de Zoologia, Setor de Ictiologia, Universidade de São Paulo, São Paulo, Brazil,
‡Departamento de Biologia, Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura,
Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais,
Universidade Estadual de Maringá, Maringá, Paraná, Brazil and §Universidade Federal do
Rio de Janeiro, Museu Nacional, Departamento de Vertebrados, Setor de Ictiologia, Rio de
Janeiro, Brazil
urn:lsid:zoobank.org:pub:BB2A81EB-EBD2-47B6-A1E2-D1D19360F389
(Received 15 October 2017, Accepted 22 February 2018)
A new species of the armoured catsh genus Corydoras is described from the Xingu– Tapajos ecore-
gion, Brazilian Amazon. The new species can be distinguished from its congeners by having the
following combination of features: short mesethmoid, with anterior tip poorly developed, smaller than
50% of bone length; posterior margin of pectoral spine with serrations directed towards spine tip or
perpendicularly oriented; infraorbital 2 only in contact with sphenotic; ventral laminar expansion of
infraorbital 1 poorly or moderately developed; ank midline covered by small dark brown or black
saddles with similar size to remaining markings on body; relatively larger, scarcer and more sparsely
distributed dark brown or black spots on body; absence of stripe on ank midline; caudal n with
conspicuous dark brown or black spots along its entire surface; slender body; and strongly narrow
frontals. A more comprehensive description of poorly-explored internal character sources, such as the
gross morphology of the brain, Weberian apparatus and swimbladder capsule elements is presented.
© 2018 The Fisheries Society of the British Isles
Key words: Brazilian Amazon; Corydoradinae; Corydoras sp. C22; gross brain morphology;
taxonomy; Xingu– Tapajos ecoregion.
INTRODUCTION
There are currently approximately 180 valid species of the armoured catsh genus
Corydoras Lacépède 1803, which correspond to 85% of species in the subfamily Cory-
doradinae (Eschmeyer et al., 2017). Corydoras species are widely distributed through-
out cis-Andean South America in diverse habitats such as shallow marginal areas of
rivers, pools and smaller tributaries (Reis, 2003). Although several new Corydoras
species have been described in recent decades, many taxa are still undescribed (Füller
†Author to whom correspondence should be addressed. Tel.: +55 11 2065 8119; email: espindolavc@
gmail.com
1
© 2018 The Fisheries Society of the British Isles

2V. C. ESPÍNDOLA ET AL.
& Evers, 2005). According to Britto (2003), Corydoras can be readily recognized and
supported by the following synapomorphies: complex vertebra compact in shape; pos-
terior expansion of ceratobranchial 3 with a notch; dorsal lamina on anguloarticular
triangular in shape; medial expansion of scapulocoracoid exposed. Alexandrou et al.
(2011) generated a molecular hypothesis for Corydoras and recognized nine distinctive
lineages.
The Xingu and Tapajos ecoregions (sensu Abell et al., 2008) are adjacent tributaries
to the Amazon River and possess a substantial number of endemic sh species (Buckup
et al., 2011). Four species of Corydoras have been described from the Xingu–Tapajos
ecoregion (sensu Buckup et al., 2011): Corydoras xinguensis Nijssen 1972, from the
Rio Xingu basin and Corydoras bifasciatus Nijssen 1972, Corydoras ornatus Nijssen
& Isbrücker 1976 and the relatively recent Corydoras apiaka Espíndola, Spencer,
Rocha & Britto 2014 from the Rio Tapajós basin.
Examination of Corydoras specimens from this region revealed an undescribed,
roughly spotted and saddled Corydoras sp., recorded from relatively few localities in
both the Rio Xingu and Rio Tapajós basins (excluding the lower Rio Tapajós basin; see
Discussion), which is formally described herein. Considering the broad geographic
distribution of the new species, both basins are herein treated as a single ecoregion,
following Buckup et al. (2011).
Historically, some anatomical structures, particularly soft tissue structures, have been
poorly-explored in systematic studies. Datovo & Vari (2014), summarizing Wiley &
Johnson (2010), revealed that within 180 major groups of Teleostei, 6% of synapo-
morphies are based on myology, 5% on splanchnology and 1% on neurology. Of the
last, the rst attempts to understand the neural-complex date back to the beginning of
the 20th century, but only from the mid-1990s has neuroanatomy been used in system-
atic works on Antarctic shes (Eastman & Lannoo, 1995, 2001, 2003, 2008, 2011) and
more recently on Neotropical groups (Albert, 2001; Pupo, 2011; Abrahão & Shibatta,
2015; Pupo, 2015; Pereira & Castro, 2016). Likewise with other structures, such as the
swimbladder capsule and Weberian apparatus, many studies were provided in the 19th
century (Birindelli et al., 2012) and there has more recently been renewed interested
in describing them (Birindelli et al., 2009, 2012; Birindelli & Shibatta, 2011). Some-
times, this anatomy is supercially included in taxonomic studies in which osteology
was described. Thus, descriptions of the gross brain morphology, swimbladder capsule
and Weberian apparatus of the new species are provided herein to broaden knowledge
about these character sources and provide a reference for future systematic analyses of
the Callichthyidae and of catsh morphology as a whole.
MATERIAL AND METHODS
Morphometric measurements were taken from the left side of specimens whenever possible
and were recorded to the nearest 0·1 mm. Morphometric and meristic measurements follow
Reis (1997), with modications by Tencatt et al. (2013). Morphometrics are reported as per-
cents of standard length (LS) and head length (LH). Teeth and vertebral counts were made from
cleared-and-stained (c&s) specimens prepared according to Taylor & van Dyke (1985). Vertebral
counts include only free centra, with the compound caudal centra (preural 1 +ural 1) counted as
a single element. Lateral plate counts include all dorso-lateral and ventro-lateral plates, except
for the small, irregular plates on the caudal peduncle. In the description, numbers in parentheses
following each count represent total of specimens with that respective value and an asterisk indi-
cates data for the holotype. Nomenclature of latero-sensory canals follows Schaefer & Aquino
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 3
(2000) and that of pre-opercular pores follows Schaefer (1988). Osteological terminology fol-
lows Reis (1998), except for parieto-supraoccipital is used instead of supraoccipital (Arratia &
Gayet, 1995), compound pterotic is used instead of pterotic-supracleithrum (Aquino & Schaefer,
2002) and scapulocoracoid is used instead of coracoid (Lundberg, 1970). The supra-preopercle
(sensu Huysentruyt & Adriaens, 2005) was herein treated as a part of the hyomandibula accord-
ing to Vera-Alcaraz (2013). The Weberian complex vertebra was considered to include vertebrae
2–4 following Fink & Fink (1981). The Weberian apparatus is restricted to the tripus and con-
cha scaphium, as described for Callichthyidae (Chardon, 1968). Homology of barbels follows
Britto & Lima (2003).
Six specimens were dissected for brain description. The dissection protocol followed Abrahão
& Pupo (2014). Nomenclature of brain subunits follows Meek & Nieuwenhuys (1998). Figures
of the c&s-bone structures and brain topography were made using a Leica DFC 450 digital
camera attached to a Leica M205C auto-stacking multifocus stereomicroscope, with the help of
Leica application suite 4.8 software to obtain an all-in-focus image (www.leica-microsystems
.com). Subsequently, all images were improved using the Pixelmator 3.6 software (www
.pixelmator.com). The map was generated using Quantum GIS 2.8.2 software (www.quantum-
gis.en.lo4d.com).
Institutional abbreviations follow Sabaj (2016): AI, Asociación Ictiológica, Museo de La
Plata, La Plata, Argentina; ANSP, The Academy of Natural Sciences, Philadelphia, PA, U.S.A.;
BMNH, Natural History Museum, London, U.K.; LBP, Laboratório de Biologia e Genética de
Peixes, Departamento de Morfologia, Universidade Estadual Paulista ‘Júlio de Mesquita Filho’,
Campus de Botucatu, Brazil; MCP, Museu de Ciências e Tecnologia, Pontifícia Universidade
Católica do Rio Grande do Sul, Porto Alegre, Brazil; MCZ, Museum of Comparative Zoology,
Harvard University, Cambridge, MA, U.S.A.; MNRJ, Museu Nacional, Universidade Federal
do Rio de Janeiro, Rio de Janeiro, Brazil; MZUSP, Museu de Zoologia da Universidade de
São Paulo, São Paulo, Brazil; NRM, Naturhistoriska Riksmuseet, Department of Vertebrate
Zoology, Stockholm, Sweden; NUP, Coleção Ictiológica do Núcleo de Pesquisas em Limnolo-
gia, Ictiologia e Aquicultura (Nupélia), Universidade Estadual de Maringá, Maringá, Brazil;
ROM, Royal Ontario Museum, Department of Natural History, Toronto, Canada; ZUFMS-PIS,
Coleção Zoológica de Referência (shes) da Universidade Federal de Mato Grosso do Sul,
Campo Grande, Brazil.
RESULTS
CORYDORAS BENATTII,SP.NOV.
(Figs 1–3 and Table I)
urn:lsid:zoobank.org:act:AA22A641-6DD5-41A8-BEDA-6B32C9E6E707
Corydoras sp. 4. Castilhos & Buckup, 2011: 241 (species list). Corydoras sp. C22.
Evers, 1994: 755, Fig. 2 (species catalogue). Glaser et al., 1996: 92 (photos, species
catalogue). Evers & Schäfer, 2004: 11, 12 (photos, species catalogue). Füller & Evers,
2005: 281, 285, 294 (species catalogue). Corydoras sp. aff. C22. Glaser et al., 1996:
90 (photos, species catalogue).
Holotype
MZUSP 121671, 25·4mmLS, Brazil, Mato Grosso, between Canarana and Gaúcha
do Norte, Rio Culuene, a tributary to the Rio Xingu, 13∘30′52′′ S; 53∘05′34′′ W; 19
October 2004, O. Oyakawa, J. Birindelli & C. Nolasco.
Paratypes
All from Brazil, Rio Xingu basin: MNRJ 35425 (6, 22·3–30·9mmLS), Pará, Cumaru
do Norte, Rio Trairão (Rio Fresco subdrainage), tributary to Rio da Ponte, 15km S; of
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

4V. C. ESPÍNDOLA ET AL.
(a)
(b)
F. 1. Corydoras benattii sp. nov. in (a) aquarium and (b) natural habitat, uncatalogued specimens, both near
Altamira, lower Rio Xingu Basin, 3∘37′20′′ S; 51∘49′13′′ Wand3
∘35′2·4′′ S; 51∘49′22·8′′ W,
respectively.
Cumaru do Norte, 7∘56′34·3′′ S; 50∘47′48·7′′ W; 9 October 2008, P. Buckup, J.
Birindelli, C. Chamon, J. Gomes, J. Maldonado, C. Zawadski, F. Jerep, F. Carvalho &
L. Fries. MNRJ 35426 (6, 21·2–28·0mmLS), Pará, São Felix do Xingu, Igarapé Man-
guari (km 28), an afuent to Rio Fresco basin, 6∘35′41·8′′ S; 51∘48′48·5′′ W; 12 Octo-
ber 2008, M. Britto, C. Chamon, J. Maldonado, F. Jerep, C. Zawadski. MNRJ 35427
(4, 19·0–22·7mmLS), Pará, Altamira, Page Beach, Rio Xingu upstream to Altamira
and Igarapé Panela, 3∘14′07·9′′ S; 52∘13′21·2′′ W; 25 September 2008, P. Buckup,
J. Birindelli, L. Fries, F. Carvalho, V. Felzman. MNRJ 50710 (2, 23·7–24·2mmLS);
MZUSP 87015 (20, 16·1–29·1mmLS, 2 c&s, 22·1–27·4mmLS), NUP 19106 (1,
23·0mmLS); ZUFMS-PIS 5352 (1, 23·1mmLS), collected with the holotype. MZUSP
111582 (31, 14·3–28·8mmLS), Pará, Altamira, black water stream tributary to Rio
Xingu, near Espelho Falls, 3∘42′32′′ S; 52∘27′11′′ W; 17 November 2011, O.
Oyakawa, J. Birindelli, C. Moreira, A. Akama, L. Sousa & H. Varela. MZUSP 111700
(443, 14·3–27·0mmLS), Pará, Altamira, Rio Xingu at Pajé Beach, 3∘14′12′′ S; 52∘
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 5
F. 2. Corydoras benattii sp. nov., MZUSP 121671, holotype, 25·4 mm standard length, Brazil, Mato Grosso,
Canarana– Gaúcha do Norte, Rio Culuene, tributary to Rio Xingu Basin.
13′21′′ W; 8 November 2011, O. Oyakawa, J. Birindelli, C. Moreira, A. Akama, L.
Sousa & H. Varela.
Non-types
All from Brazil, Rio Tapajós basin: MNRJ 35424 (1, 12·5–28·9mm LS,16c&s,
14·2–24·3mm LS), Mato Grosso, Guarantã do Norte, Strege Balneary, Braço Rio
Norte, tributary to right margin of Rio Peixoto de Azevedo, a tributary to Rio Teles
Pires, 9∘56′56′′ S; 55∘2′9′′ W; 2 October 2008, P. Buckup, J. Maldonado, J.
Birindelli, C. Chamon & V. Felzman. MZUSP 116758 (5, 17·1–23·3mmLS), Pará,
beach at Rio Cururu, 8∘53′42′′ S; 57∘14′27′′ W; 6 December 2005, A. Datovo,
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

6V. C. ESPÍNDOLA ET AL.
F. 3. Juvenile specimen of Corydoras benattii sp. nov., MNRJ 35424, 12·5 mm standard length, Brazil, Mato
Grosso, Guarantã do Norte, Rio Braço Norte, right bank tributary of the Rio Peixoto de Azevedo. Scale
bar =1·0 mm.
M. Carvalho & M. Rodrigues. MZUSP 116768 (1, 24·2mmLS), Pará, Rio Cururu, 8∘
52′27′′ S; 57∘15′9′′ W; 6 December 2005, A. Datovo, M. Carvalho & M. Rodrigues.
MZUSP 96764 (64, 15·3–28·7mm LS), Mato Grosso, Rio Peixoto de Azevedo, a
tributary to Rio Teles Pires, 10∘17′14′′ S; 54∘50′57′′ W; 17 October 2007, J.
Birindelli, L. Sousa, A. Netto-Ferreira, M. Sabaj-Pérez & N. Lujan. MZUSP 96584
(27, 17·8–26·8mmLS), Mato Grosso, Rio Peixoto de Azevedo, a tributary to Rio
Teles Pires, 10∘13′14′′ S; 54∘58′02′′ W; 16 October 2007, J. Birindelli, L. Sousa, A.
Netto-Ferreira, M. Sabaj-Pérez & N. Lujan. MZUSP 116653 (1, 21·2mmLS), Mato
Grosso, Paranaíta, Rio São Benedito, a tributary to Rio Teles Pires, 9∘07′00′′ S; 57∘
00′35′′ W; 12 January 2015, W. Ohara.
Diagnosis
Corydoras benattii can be distinguished from its congeners, with the exception of
species from lineages 4, 5, 6, 7 and 9 sensu Alexandrou et al. (2011), by having a short
mesethmoid with anterior tip poorly developed, smaller than 50% of bone length (v.
mesethmoid long, with anterior tip well developed, larger than 50% of bone length),
resulting in a blunt, short snout. From the species of lineages 4 and 5, with the excep-
tion of Corydoras hastatus Eigenmann & Eigenmann 1888 and Corydoras pygmaeus
Knaack 1966, by having the posterior margin of the pectoral spine with serrations
directed towards the spine tip or perpendicularly oriented (Fig. 4; v. directed towards
spine origin); from C. hastatus and C. pygmaeus by having infraorbital 2 only in contact
with sphenotic (Fig. 5; v. contacting sphenotic and compound pterotic). It differs from
the species of lineage 7 by having the ventral laminar expansion of infraorbital 1 poorly
or moderately developed (Fig. 5; v. well or very well developed). The new species can
be distinguished from the species of lineage 6 and 9, with the exception of Corydo-
ras albolineatus Knaack 2004, Corydoras armatus (Günther 1868), Corydoras breei
Isbrücker & Nijssen 1992, Corydoras loretoensis Nijssen & Isbrücker 1986, Corydo-
ras osteocarus Böhlke 1951, Corydoras potaroensis Myers 1927 and C. xinguensis,
by having the ank midline covered by small dark brown or black saddles similar in
size to remaining markings on the body (v. ank midline with longitudinal series of
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 7
T I. Morphometric data of the holotype (MZUSP 121671) and 56 paratypes (MNRJ
50710, 2; MZUSP 87015, 14; MZUSP 111582, 10; MZUSP 111700, 30) of Corydoras benattii
sp. nov.
Holotype Paratypes Mean S.D.
Standard length (LS; mm) 25·421·1–29·125·61·8
Head length (LH; mm) 12·08·6–13·511·00·9
%LS
Depth of body 33·730·0–35·734·31·6
Predorsal distance 48·745·3–50·249·81·8
Prepelvic distance 45·344·7–46·247·31·4
Preanal distance 77·375·4–79·880·51·8
Preadipose distance 77·775·4–84·481·81·7
Length of dorsal spine 31·021·7–29·627·22·5
Length of pectoral spine 32·124·3–29·130·32·4
Length of adipose-n spine 9·67·7–9·510·91·3
Depth of caudal peduncle 15·614·0–16·115·60·8
Dorsal to adipose distance 17·616·0–22·719·91·6
Length of dorsal-n base 16·516·6–20·819·51·5
Maximum cleithral width 10·76·7–10·59·21·1
Head length 47·433·6–43·443·22·3
Length of longer barbel 14·57·9–16·314·72·2
%LH
Head depth 66·965·0–78·774·94·5
Least interorbital distance 25·618·8–27·726·82·0
Horizontal orbit diameter 19·717·0–24·321·72·5
Snout length 32·829·2–40·634·42·5
Least internareal distance 16·514·3–21·518·22·2
large, dark brown or black blotches, clearly larger than remaining markings on body;
or conspicuous longitudinal dark brown or black stripe). It differs from C. albolineatus,
C. loretoensis,C. osteocarus and C. potaroensis by having caudal n with conspicuous
dark brown or black spots along its entire surface (vs. hyaline or with dark brown or
black spots only on its proximal third in C. loretoensis; entirely hyaline in remaining
species); from C. armatus and C. xinguensis by having clearly slender body (v. clearly
robust).
F. 4. Pectoral-n spine of a cleared-and-stained specimen of Corydoras benattii sp. nov., MZUZP 87015,
paratype, 22·1 mm standard length, showing serrations directed towards tip of spine or perpendicularly
oriented on posterior margins of the right pectoral-n spine (7·5 mm length). Scale bar =1·0 mm.
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

8V. C. ESPÍNDOLA ET AL.
sph
cpt
io2
io1
F. 5. Lateral view of the head of a cleared-and-stained specimen of Corydoras benattii sp. nov., MZUSP 87015,
paratype, 22·1 mm standard length, showing infraorbital 2 (io2) only in contact with sphenotic (sph). A
moderately ventral laminar expansion of infraorbital 1 (io1; ). cpt, Compound pterotic. Scale bar =1·0 mm.
Corydoras benattii can be distinguished from C. breei by having the following
combination of features: absence of conspicuous concentration of dark brown or
black blotches along ank midline, forming longitudinal stripe (v. stripe variably
present, fragmented in some specimens) and by slightly larger, scarcer and clearly
more distant dark brown or black irregular spots on anks (v. anks densely covered
by closely-spaced roundish dark brown or black spots). Corydoras benattii differs
from C.apiaka by having strongly narrow frontals (v. relatively narrow but clearly
thicker; see Britto, 2003:126, character 6, states 2 and 1, respectively).
Description
Measurements of holotype and paratypes in Table I. Head compressed (Fig. 2);
roughly triangular in dorsal view. Rounded snout prole from upper lip to horizontal
through anterior nares; bluntly round in juveniles (Fig. 3). Head prole slightly convex
from upper lip to tip of parieto-supraoccipital expansion. Moderate ascent of dorsal
prole nearly straight from nares to base of dorsal spine. Body concave from last
dorsal-n ray to base of adipose-n spine; straight to slightly concave from that point
to caudal-n base. Ventral prole of body straight from isthmus to pelvic-n origin,
convex from that point to caudal-n base. Body approximately triangular in cross
section at pectoral girdle, gradually becoming more compressed toward caudal n.
Eyes rounded, dorso-lateral on head; orbit bordered dorsally by frontal, lateral
ethmoid and sphenotic, ventrally by infraorbitals. Anterior and posterior nares very
close, only detached by ap of skin. Anterior naris tubular; eshy ap. Posterior naris
close to antero-dorsal margin of orbit, separated from orbit by distance slightly smaller
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CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 9
than naris diameter. Mouth small, subterminal; width nearly equal to bony orbit
diameter. Maxillary barbel moderately developed, not reaching antero-ventral limit of
gill opening. Outer mental barbel slightly larger than maxillary barbel. Inner mental
barbel eshy, with base close to its counterpart. Small rounded papillae scattered over
entire surface of all barbels, upper and lower lips, snout and isthmus. Gill membranes
united to isthmus.
Posterior portion of mesethmoid, frontal, sphenotic, compound pterotic and
parieto-supraoccipital externally visible, covered by thin layer of skin and bear-
ing minute scattered odontodes. Long frontal fontanel, ellipsoid, sheltered by thin
layer of skin; posterior portion extending into parieto-supraoccipital. Nasal slender,
curved laterally, mesial border contacting mesethmoid and frontal. Frontal rectan-
gular; anterior expansion in contact with nasal bone, posterior portion bordered by
sphenotic and parieto-supraoccipital. Posterior area of mesethmoid wide. Sphenotic
somewhat trapezoidal in shape, contacting parieto-supraoccipital dorsally, compound
pterotic posteriorly, second infraorbital ventrally and frontal anteriorly. Compound
pterotic roughly pipe-shaped, with posterior expansion limited by rst lateral-line
ossicle. Ventral margin of compound pterotic cofned by opercle and cleithrum.
Parieto-supraoccipital wide, posterior process well developed, contacting nuchal plate.
Two laminar infraorbitals with minute odontodes; infraorbital 1 large, ventral lami-
nar expansion ranging from poorly to relatively well developed; anterior portion with
moderately to well developed expansion, reaching to or slightly surpassing middle por-
tion of nasal capsule; inner laminar expansion poorly developed (Fig. 5). Infraorbital 2
small, slender; with posterior laminar expansion from poorly to moderately developed;
inner laminar expansion generally poorly developed; postero-ventral margin contact-
ing postero-dorsal ridge of hyomandibula; dorsal tip contacting only sphenotic (Fig. 5).
Postero-dorsal ridge of hyomandibula close to its articulation with opercle oblong;
exposed, relatively slender; dorsal ridge of hyomandibula between compound pterotic
and opercle exposed or covered by thinner to thicker layer of skin in some specimens;
exposed areas bearing small odontodes. Interopercle entirely covered by thick layer of
skin; posterior portion exposed in some specimens; somewhat triangular, anterior pro-
jection moderately developed. Preopercle relatively slender, elongated, minute odon-
todes sparse on external surface. Opercle slender in shape, width equal to or slightly
smaller than half of its length; free margin convex; postero-dorsal region with smoothly
concave area in some specimens; without serrations and covered by small odontodes;
some portions of bony distal margin irregular in some specimens.
Four branchiostegal rays decreasing in size posteriorly. Hypobranchial 2 somewhat
triangular, tip ossied and directed towards anterior portion, posterior margin carti-
laginous; ossied portion well developed, about twice size of cartilaginous portion.
Five ceratobranchials with increasing posterior expansions; ceratobranchial 1 with
small process on anterior margin of mesial portion; ceratobranchial 3 notched on
postero-lateral margin; ceratobranchial 5 toothed on postero-dorsal surface, 26– 37(5)
teeth aligned in one row. Four epibranchials with comparable size; epibranchial
2 slightly larger than others, with small pointed process on laminar expansion of
posterior margin; epibranchial 3 with curved mesially uncinate process on laminar
expansion of posterior margin. Two wide pharyngobranchials (3 and 4); pharyngo-
branchial 3 with irregular laminar expansion on posterior margin. Upper tooth plate
oval; 27– 44(5) teeth aligned in two rows on postero-ventral surface.
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10 V. C. ESPÍNDOLA ET AL.
Trunk lateral line with two or three latero-sensory canals; two anteriormost canals
reduced to small ossicles; rst ossicle tubular, second ossicle laminar; third lateral-line
canal, if present, encased in third dorso-lateral body plate. Lateral-line canal conned
on neurocranium through compound pterotic, branching twice before entering sphe-
notic; pterotic and preoperculo-mandibular branches, each with single pore. Sensory
canal passes along compound pterotic, through sphenotic as temporal canal, then splits
into two branches: one branch rises to infraorbital canal, another branch passes through
frontal and supraorbital canal. Single supraorbital canal, along nasal bone. Epiphyseal
pore opening at supraorbital main canal. Nasal canal with three openings, rst on pos-
terior edge, second on postero-lateral portion and third on anterior edge; second pore
generally fused with rst pore. Infraorbital canal through entire infraorbital 2, extended
to infraorbital 1 and opening into two or three pores. Preoperculo-mandibular branch
emerges into preoperculo-mandibular canal, along entire preopercle with three open-
ings (pores 3, 4 and 5, respectively).
Body plates with minute odontodes restricted to posterior margins. Nuchal plate
exposed. Posterior extremity of cleithrum along vertical through dorsal-n spinelet.
Cleithrum and mesial process of scapulocoracoid exposed. Body plates not delimited
by counterparts ventrally, instead, narrow naked area. Dorso-lateral body plates 22(21)
or 23*(75); ventro-lateral body plates 20(12) or 21*(85); dorso-lateral body plates
along dorsal-n base six(18) or seven*(79); dorso-lateral body plates from adipose n
to caudal-n base seven*(77) or eight(20); pre-adipose platelets two(16), three*(69), or
four(12); small platelets positioned dorsally and ventrally between junctions of lateral
plates on posterior portion of caudal peduncle. Anterior margin of orbit, above region
of junction of frontal with lateral ethmoid, region of lateral ethmoid in ventral margin
of nasal capsule and region of mesethmoid generally with small platelets; ventro-lateral
portion of snout with platelets in some specimens. Ventral surface of trunk with scarce
small and irregular platelets, generally restricted to pectoral girdle area; this area naked
in some specimens.
Dorsal n roughly triangular, located just posterior to second dorso-lateral body
plate. Dorsal spine shorter than rst branched ray. Anterior border of dorsal spine with
odontodes; posterior border with 10–24 minute serrations. Dorsal-n rays II,7(15) or
II,8*(82). Adipose n roughly triangular, separated from base of last dorsal-n ray by
six dorso-lateral body plates in all specimens. Anal n roughly triangular, located just
posterior to 13th ventro-lateral body plate and at vertical through anterior margin of
adipose-n spine. Anal n with eight rays in all specimens, ii,5,i or ii,6*. Pectoral n
triangular, its origin located just posterior to gill opening. Ossied portion of pectoral
spine shorter than rst branched ray. Distal tip of spine with minute, segmented, unos-
sied portion. Pectoral spine with 15–27 relatively small serrations along almost entire
posterior border (Fig. 4). Pectoral serrations more developed than those of dorsal spine;
directed towards tip of spine; presence of perpendicularly directed and bid serrations
in some specimens (Fig. 4). Pectoral-n rays I,7 in all specimens. Pelvic n ellipsoid, at
horizontal position just below rst ventro-lateral body plate and at vertical through rst
branched dorsal-n ray. Pelvic-n rays i,5 in all specimens. Caudal n forked; upper
lobe slightly longer. Principal caudal-n rays i,6/6,i in all specimens, with generally
four dorsal and ventral procurrent rays. All ns with minute odontodes scattered over
all rays. Vertebral count 21(5); ribs ve(4) or six(1), rst pair conspicuously larger than
others.
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CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 11
(a)
(b)
fron sph cpt swcso
F. 6. Mid-posterior part of head of cleared-and-stained specimen of (a) dorsal, (b) lateral views of Corydoras
benattii sp. nov., MZUSP 87015, paratype, 22·1 mm standard length, showing swimbladder capsule (swc)
and associated structures. Traced lines indicate the cephalic lateral line canal. fron, Frontal; sph, sphenotic;
cpt, compound pterotic; so, parieto-supraoccipital. Scale bar =1·0 mm.
Weberian apparatus and swimbladder capsule
Complex vertebra relatively compact. Swimbladder capsule bullae-like with dor-
sal elevation (Fig. 6). Lateral opening circular, similar diameter to proximal portion
and partially occluded by compound pterotic. Cleithrum near to swimbladder capsule
lateral opening. Transverse canal between bullae and near medial portion of swimblad-
der capsule. Swimbladder capsule posterior portion free from bone elements. Ventral
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12 V. C. ESPÍNDOLA ET AL.
F. 7. Weberian apparatus of cleared-and-stained specimen of Corydoras benattii sp. nov., MZUSP 87015,
paratype, 27·4 mm standard length. csc, Concha scaphium; tr, tripus. Scale bar=0·5 mm.
suture of swimbladder capsule and basioccipital diagonal to transverse canal between
bullae foramina; ventral suture limited by transverse canal between bullae suture and
basioccipital. Transverse canal between bullae larger than complex vertebra width.
Pneumatic duct absent. Transverse canal between bullae foramina under swimbladder
capsule, near medial portion and distant from complex vertebra. Support bone process
from aortic canal sheath robust. Ventral apophysis under both swimbladder capsule and
complex vertebra; anterior to transverse canal and among bullae, complex vertebra and
bone process support of aortic canal sheath. Sixth vertebra articulated with fth verte-
bra. Fifth and sixth vertebra parapophyses fused. Weberian apparatus inside complex
vertebra; concha scaphium connected to endolymphatic sinus; tripus proximal portion
connected to concha scaphium (Fig. 7); tripus distal portion with thin expansion, nearly
straight angle and connected to swimbladder through capsule foramen.
Gross brain morphology
Lobus vagi expanded in size with roughly spherical format (Fig. 8). Subunit larger
than corpus cerebelli, but smaller than tectum mesencephali and with anterior tip
rounded and above posterior portion of lobus facialis (Fig. 9). Bilateral lobus facialis
detached to medial margin of fourth ventricle and discontinuous to lobus vagi.
Subunit ventrally positioned and almost completely covered by corpus cerebelli,
with postero-lateral tip exposed in dorsal view. Subunit roughly divided in three
regions: medial (smallest); intermediate; and lateral (largest). Latter extended and
with lateral area above lobus vestibulolateralis. Corpus cerebelli roughly spherical
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CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 13
F. 8. (a) Dorsal, (b) lateral and (c) ventral views of the brain and associated olfactory organ of Corydoras
benattii sp. nov., MNRJ 35424, 27·5 mm standard length. bo, Bulbus olfactorius; cc, corpus cerebelli; gh,
ganglion habenulae; hyp, hypophysis; hyt, hypothalamus; lf, lobus facialis; lhl, lobus hypothalami later-
alis; lih, lobus inferior hypothalami; lv, lobus vagi; lvl, lobus vestibulolateralis; nol, nervus olfactorius;
nop, nervus opticus; nv, nervus vagi; olf, olfactory organ; tel., telencephalon; tm, tectum mesencephali; tr,
tegmentum rhombencephali. Scale bar =1·0 mm.
and smaller than tectum mesencephali and lobus vagi. Subunit in contact with tectum
mesencephali and positioned in central part of brain above lobus facialis. Tectum
mesencephali largest subunit of brain in dorsal view; bilateral dome located on
dorsal surface of tegmentum mesencephali. Nervus opticus more than three times
thicker than nervus olfactorius. Hypothalamus most conspicuous external subunit
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14 V. C. ESPÍNDOLA ET AL.
F. 9. Posterior half of brain of Corydoras benattii sp. nov., MNRJ 35424, 31·52 mm standard length, without
corpus cerebelli, showing the lobus facialis (lf) in dorsal view. Arrow indicates the anteriormost margin
of the lobus vagi (lv) above the posterior region of the lobus facialis. gh, Ganglion habenulae; lvl, lobus
vestibulolateralis; tm, tectum mesencephali. Scale bar=1·0 mm.
in ventral view and posteriorly positioned to chiasma opticum, ventral to tectum
mesencephali and truncus cerebri. Subunit divided in hypothalamus itself, lobus
lateralis hypothalami and lobus inferior hypothalami. Latter with invagination located
in posterior margin. Hypophysis spherical and anteriorly anchored to lobus inferior
hypothalami and above hypothalamus. Telencephalon located on dorsal surface of
brain as bilaterally-elongated structure, posterior to bulbus olfactorius and anterior to
tectum mesencephali; anterior area somewhat wider in dorsal view and lateral margin
almost straight. Bulbus olfactorius sessile and spherical, with posterior area ventrally
positioned on anterior tip of telencephalon. Nervus tractus olfactorius absent. Olfac-
tory organ circular with <15 lamellae and connected to bulbus olfactorius via nervus
olfactorius. Posterior lamellae with small ap toward dorsal surface and larger than
anterior lamellae. Nervus olfactorius length about twice of bulbus olfactorius diameter.
Colour in alcohol
Overall colour pattern in Fig. 2. Ground colour of body light or brownish yellow,
with top of head dark brown. Dorsal and lateral portions of head with scattered
small roundish or irregular dark-brown or black spots. Region between antero-ventral
margin of infraorbital 1 and lateral portion of mouth and between postero-ventral
portion of infraorbital 1 and antero-ventral portion of opercle with concentration
of dark brown or black chromatophores in some specimens. Upper lip, maxillary
barbel, opercle and cleithrum generally with dark brown or black chromatophores.
Dorso and ventro-lateral body plates with dark brown or black chromatophores,
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CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 15
generally forming small roundish or irregular spots; region around pelvic-n ori-
gin lacking chromatophores; dorso-lateral body plates on regions of anterior and
posterior portion of dorsal-n base, adipose-n base and caudal-n base with more
concentrated chromatophores in some specimens. Midline of ank with somewhat
aligned dark-brown or black blotches, forming longitudinal series; slightly larger
than remaining blotches on anks. Dorsal n covered by dark brown or black
small roundish or irregular spots; spine covered by dark-brown or black chro-
matophores. Pectoral n with sparse dark-brown or black chromatophores, generally
more evident on spine; hyaline in some specimens. Pelvic n hyaline. Adipose n
with dark-brown or black chromatophores, generally more concentrated on spine;
membrane hyaline in some specimens. Anal n with dark-brown or black chro-
matophores, generally restricted to proximal portion. Middle portion of caudal-n
base generally with small dark-brown or black spot; diffuse in some specimens;
Caudal n covered by small dark-brown or black spots, forming up to seven slender
transverse bars.
Colour in life
Based on eld observations, photographs and aquarium specimens. Similar to
preserved specimens but with ground colour of body greyish yellow. Region between
antero-ventral margin of infraorbital 1 and lateral portion of mouth and between
postero-ventral portion of infraorbital 1 and antero-ventral portion of opercle gen-
erally with conspicuously concentrated dark-brown or black chromatophores. Body
covered by greenish yellow iridescent coloration (Fig. 1).
Sexual dimorphism
Males have urogenital papilla, as is usual for corydoradine catshes (Nijssen &
Isbrücker, 1980; Britto, 2003).
Geographical distribution
Corydoras benattii occurs in both the Rio Xingu and Rio Tapajós basins, Brazilian
Amazon (Fig. 10). In the Rio Xingu basin, it is known in Mato Grosso State from
tributaries to the Rio Culuene, a clearwater tributary of the upper Rio Xingu (type
locality) and in Pará State from the Rio Fresco sub drainage (Rio Trairão and Igarapé
Manguari), middle Rio Xingu and from the lower Rio Xingu basin near Altamira. In
the Rio Tapajós basin, it occurs in the Rio Peixoto de Azevedo, a tributary to the Rio
Teles Pires, Mato Grosso and from Rio Cururu, a tributary to the Rio São Manuel, Pará.
Habitat notes
Specimens of Corydoras benattii were found in lotic habitats in the Rio Culuene, Rio
Xingu basin and Rio Braço Norte, tributary to Rio Peixoto de Azevedo, Rio Tapajós
basin (Fig. 11). Both localities have muddy-brown water with clay and sandy substrata.
Most specimens were captured in the small forest streams of black or clearwater, or in
marginal ponds.
Specimens from the Rio Braço Norte were caught on 2 October 2008, around
1100 hours, with air temperature 32∘C and from water with the following
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

16 V. C. ESPÍNDOLA ET AL.
Brazil
5°
15°
50°
60°
Bolivia
F. 10. Geographic distribution of Corydoras benattii sp. nov. Type locality in Rio Culuene, a tributary of the
upper Xingu Basin, Mato Grosso ( ), and paratype localities in middle and lower Rio Xingu, Pará State
(). Non-type localities in Rio Tapajós basin, Mato Grosso and Pará states ( ).
physic-chemical variables: pH 6·52, conductivity 0·092 𝜇Scm
−1and water tem-
perature 30·1∘C.
Etymology
The specic name, benattii, honours the late Laert Benatti for his humanitarian
work, providing fresh water from artesian wells to poor communities in Brazil. Case is
genitive.
Remarks
As mentioned by Tencatt & Evers (2016), the Corydoradinae are very popular in the
aquarium hobby, being kept and reproduced for many decades by hobbyists around the
world. Some species in the ornamental sh trade are recognized for the difculty in
determining their taxonomic status among those already described. To avoid the cre-
ation of nomina nuda by using trade names, Evers (1993) implemented a code system
for putative new species, giving each of them a C-number (where C stands for Cory-
doradinae) published in the Die Aquarien- und Terrarienzeitschrift (DATZ) German
aquarist magazine. After the C-number coding was nished with by DATZ magazine
with C159, this labelling system was taken over by the Corydoras World website (www
.corydorasworld.com) and changed to a CW-number coding (where CW stands for
Corydoras World), which restarted the count to include the many new morphotypes
known in the aquarium trade.
Corydoras benattii is already known in the hobby under the code C22 (Evers, 1994;
Glaser et al., 1996; Evers & Schäfer, 2004; Füller & Evers, 2005). Specimens of C.
benattii captured in the Rio Itata, a tributary to the Rio Xingu near Altamira, Pará have
been spawned and reared under aquarium conditions by H. Evers, who provided photos
of its fry with 1 and 4 weeks of life (Fig. 12), showing colour pattern variation during
initial stages of growth.
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CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 17
(a)
(b)
F. 11. Habitats of Corydoras benattii sp. nov. in (a) Rio Culuene, Xingu Basin, 13∘30′52′′ S; 53∘05′34′′ W,
type locality, and (b) Strege Balneary, Rio Braço Norte, a tributary of the Rio Peixoto de Azevedo, Tapajós
Basin, 9∘56′56′′ S; 55∘2′9′′ W, both in Mato Grosso State, Brazil.
DISCUSSION
The molecular phylogenetic hypothesis of Alexandrou et al. (2011) revealed nine
lineages of Corydoradinae species. Corydoras benattii presents a general morpholog-
ical pattern most similar to the species of lineage 9 sensu Alexandrou et al. (2011),
with characteristics such as: the presence of a short mesethmoid; posterior margin
of the pectoral-n spine with serrations generally directed towards the tip of the
spine; infraorbital 1 generally with moderately developed ventral laminar expansion;
infraorbital 2 generally not contacting compound pterotic, as cited by Tencatt & Britto
(2016) and Tencatt & Ohara (2016). Even though lineage 6 has a similar general
morphological pattern as lineage 9, the assignment of C.benattii to lineage 6 is less
plausible as all species of that clade exhibit a distinctive colour pattern on the midline
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

18 V. C. ESPÍNDOLA ET AL.
(a)
(b)
F. 12. Fry development of Corydoras benattii sp. nov. bred under aquarium conditions, showing the general
morphological and colour patterns after (a) 1 and (b) 4 weeks post-hatch.
of the ank (Tencatt et al., 2016) not observed in the new species. Additionally,
regarding general morphological and colour patterns, the two species most similar to
C. benattii (i.e., C. loretoensis and C. osteocarus) are among the members of lineage 9.
Regarding gross brain morphology, the increase in size of the lobus vagi among
Siluriformes occurs in Callichthyidae and, probably independently, in other lineages
[e.g. Claroteidade, Plotosidae, Loricariinae, Conorhynchos conirostris (Valenciennes
1840)] (Pupo, 2015). This area innervates chemical and mechanical taste buds present
in the oropharyngeal cavity indicating an enhancement of the sense of taste (Butler
& Hodos, 2005). Together with a large lobus facialis, which enervates taste buds on
body, ns, lips and barbels, it seems likely that this species has an enhanced sense of
taste. The tectum mesencephali size and the optic nerve (cranial nerve II) thickness
represent an enhancement in the vision sense in Corydoras. Pupo (2011) noticed that
some Corydoras species have a large tectum mesencephali and optic nerve gauge when
compared to other Callichthyidae. Corydoras benattii has both features. Nevertheless,
this paper is not intended to make precise phylogenetic inferences using these struc-
tures and those from the swimbladder capsule and Weberian apparatus, but to present
a preliminary description to encourage further research.
According to Dagosta & de Pinna (2017), numerous teleost species occur in both the
Rio Tapajós and Rio Xingu basins. These authors suggest that the lower Rio Tapajós
basin is more ichthyologically similar to other Amazonian basins than to the remainder
of the Xingu–Tapajos ecoregion. Notwithstanding, Corydoras benattii has not been
recorded from the lower Rio Tapajós basin, which corroborates the Dagosta & de
Pinna (2017) hypothesis. Although the Xingu–Tapajos ecoregion does not constitute
a biogeographical unit (Dagosta & de Pinna, 2017), the Simpson’s faunistic similarity
indices between the Rio Xingu and Rio Tapajós basins is about 53·8% (Buckup
et al., 2011). It indicates the two regions share a similar biogeographical history.
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CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 19
Knowledge about the distribution of this new species brings additional information to
help understand the historical biogeography of this enigmatic ecoregion.
ADDITIONAL SPECIMENS EXAMINED
Corydoras acutus Cope 1872: MNRJ 3985 (2, 47·1–54·8mmLS). Corydoras adol-
foi Burgess 1982: MZUSP 26641 (holotype, 32·5mmLS). Corydoras albolineatus
Knaack 2004: MNRJ 33864 (5, 21·7–27·2mmLS). Corydoras ambiacus Cope 1872:
MCP 26178 (1, 42·5mmLS); MCP 26209 (10 of 19, 25·0–33·3mm LS); MZUSP
26053 (2, 41·8–47·2mmLS). Corydoras apiaka Espíndola, Spencer, Rocha & Britto
2014: MNRJ 40720 (holotype, 28·4mmLS); MNRJ 23334 (paratype, 1, 31·6mmLS).
Corydoras approuaguensis Nijssen & Isbrücker 1983: MZUSP 27895–6 (paratypes,
2, 43·0–46·1mmLS). Corydoras araguaiaensis Sands 1990: MZUSP 87155 (4 of
33, 24·9–46·7mmLS, 2 c&s, 27·6–31·8mmLS); MZUSP 86248 (7, 36·2–54·6mm
LS). Corydoras areio Knaack 2000: ZUFMS-PIS 1314 (15, 34·4–41·9mm LS,2
c&s, 38·1–38·5mm LS). Corydoras armatus (Günther 1868): MNRJ 38436 (12,
28·5–40·9mmLS); MZUSP 49567 (1, 45·3mmLS). Corydoras aurofrenatus Eigen-
mann & Kennedy 1903: NRM 23529 (10 of 33, 31·4–45·7mm LS). Corydoras
cervinus Rössel 1962: MNRJ 33867 (1, 44·6mmLS). Corydoras bifasciatus Nijssen
1972: MZUSP 38976 (paratypes, 16, 23·6–30·0mm LS). Corydoras blochi Nijssen
1971: MZUSP 8580 (paratypes, 3, 31·0–42·6mm LS). Corydoras bondi Gosline
1940: ROM 66202 (7 of 134, 33·8–39·9mm LS, 3 c&s, 36·7–38·6mmLS). Cory-
doras brevirostris Fraser-Brunner 1947: LBP 3080 (10, 23·8–27·7mm LS, 3 c&s,
25·8–27·9mm LS). Corydoras britskii (Nijssen & Isbrücker 1983): ZUFMS-PIS
862 (12, 72·0–78·0mmLS). Corydoras brittoi Tencatt & Ohara 2016: MNRJ 43316
(holotype, 38·1mmLS). Corydoras carlae Nijssen & Isbrücker 1983: NUP 711 (1,
47·9mmLS); NUP 4425 (1 c&s, 45·0mmLS). Corydoras cochui Myers & Weitzman
1954: MZUSP 35838 (4 of 6, 16·1–18·5mmLS); MZUSP 89055 (6, 18·7–23·6mm
LS). Corydoras condiscipulus Nijssen & Isbrücker, 1980: MZUSP 38957 (paratypes,
7, 34·1–40·3mm LS). Corydoras coppenamensis Nijssen 1970: MZUSP 13995-99
(paratypes, 5, 29·31–37·60 mm LS). Corydoras crimmeni Grant 1997: MZUSP 52490
(holotype, 36·1mmLS). Corydoras davidsandsi Black 1987: MZUSP 110066 (4 of
40, 36·0–41·9mm LS, 2 c&s, 40·9–42·1mm LS). Corydoras diuviatilis Britto &
Castro 2002: MZUSP 75268 (holotype, 39·8mmLS). Corydoras diphyes Axenrot &
Kullander 2003: ANSP 169756 (2, 40·7–43·1mm LS). Corydoras ehrhardti Stein-
dachner 1910: NUP 11255 (15, 36·5–46·8mmLS). Corydoras elegans Steindachner
1876: MZUSP 26017 (6, 25·9–28·3mm LS). Corydoras ephippifer Nijssen 1972:
MZUSP 31605 (2, 44·9–49·1mm LS). Corydoras eques Steindachner 1876: MCZ
8204 (4 of 12, 37·6–44·4mmLS). Corydoras eversi Tencatt & Britto, 2016: MNRJ
43195 (holotype, 44·5mm LS). Corydoras aveolus Ihering 1911: MZUSP 424
(holotype, 33·4mmLS); MZUSP 111174 (7, 24·2–37·5mmLS). Corydoras fowleri
Böhlke 1950: LBP 12462 (9, 44·3–59·9mm LS, 1 c&s, 50·4mm LS). Corydoras
garbei Ihering 1911: MNRJ 18089 (14, 19·2–25·3mm LS, 2 c&s, 25·9–27·4mm
LS). Corydoras geoffroy Lacépède 1803: MZUSP 38984 (paratypes, 2, 38·7–45·2mm
LS). Corydoras gossei Nijssen 1972: MZUSP 38977 (paratypes, 6, 48·4–53·4mm
LS). Corydoras griseus Holly 1940: MZUSP 108896 (4 of 13, 31·5–36·2mm LS,2
c&s, 30·6–34·5mm LS). Corydoras guapore Knaack 1961: ZUFMS-PIS 4000 (5,
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

20 V. C. ESPÍNDOLA ET AL.
26·9–33·6mmLS, 2 c&s, 28·8–29·2mmLS). Corydoras gryphus Tencatt, Britto &
Pavanelli 2014: MNRJ 40770 (holotype, 32·3mmLS); NUP 14676 (paratypes, 3 c&s,
27·7–32·4mm LS). Corydoras haraldschultzi Knaack 1962: MZUSP 94996 (299,
31·9–56·1mmLS). Corydoras hastatus Eigenmann & Eigenmann 1888: NUP 6862
(116, 13·1–20·7mm LS). Corydoras hephaestus Tencatt & Britto, 2016: MZUSP
119087 (holotype, 22·6mmLS). Corydoras incolicana Burgess 1993: MZUSP 45717
(holotype, 47·6mm LS). Corydoras julii Steindachner 1906: MNRJ 33869 (40,
21·2–28·6mmLS); MNRJ 33870 (4, 24·5–29·4mm LS); NUP 16225 (1, 46·8mm
LS). Corydoras kanei Grant 1998: MZUSP 52489 (holotype, 36·6mmLS). Corydoras
knaacki Tencatt & Evers 2016: MUSM 52730 (holotype, 35·6mm LS). Corydoras
lacrimostigmata Tencatt, Britto & Pavanelli 2014: MNRJ 40725 (holotype, 31·8mm
LS); NUP 14657 (paratypes, 3 c&s, 30·9–34·5mmLS). Corydoras longipinnis Knaack
2007: AI 221 (holotype, 59·5mmLS). NUP 14440 (2 c&s, 29·9–33·4mmLS). Corydo-
ras loretoensis Nijssen & Isbrücker 1986: MNRJ 19960 (paratypes, 2, 32·2–34·2mm
LS, 2 c&s, 31·0–31·2mm LS). Corydoras lymnades Tencatt, Vera-Alcaraz, Britto
& Pavanelli 2013: MNRJ 15765 (6, 15·8–17·7mmLS, 2 c&s, 18·1–18·4mm LS).
MNRJ 40186 (holotype, 29·7mm LS). Corydoras maculifer Nijssen & Isbrücker
1971: NUP 8970 (2, 42·0–46·0mmLS); MZUSP 89320 (1, 35·2mmLS). Corydoras
melanistius Regan 1912: BMNH 1864·1·21·86, (lectotype, 35·0mmLS). Corydoras
melini Lönnberg & Rendahl 1930: MZUSP 81163 (2, 37·0–45·0mmLS). Corydoras
multimaculatus Steindachner 1907: MCP 29025 (2, 20·1–25·4mmLS); MNRJ 16118
(6, 19·9–24·5mmLS); MZUSP 40183 (13, 21·6–31·1mmLS). Corydoras napoensis
Nijssen & Isbrücker 1986: MZUSP 26341 (paratype, 1, 27·8mm LS). Corydoras
nattereri Steindachner 1876: MZUSP 110255 (4 of 31, 32·0–32·8mm LS, 2 c&s,
32·3–34·4mm LS). Corydoras panda Nijssen & Isbrücker 1971: ROM 55815 (6,
26·5–39·7mm LS). Corydoras pantanalensis Knaack 2001: NUP 10188 (1 c&s,
46·4mm LS); NUP 12593 (21, 38·7–51·2mm LS). Corydoras parallelus Burgess
1993: MZUSP 45716 (holotype, 47·4mm LS). Corydoras pavanelliae Tencatt &
Ohara 2016: MNRJ 43317 (holotype, 45·1mmLS). Corydoras pinheiroi Dinkelmeyer
1995: MZUSP 48099 (holotype, 54·3mm LS). Corydoras polystictus Regan 1912:
MNRJ 12418 (9, 13·1–24·2mmLS). Corydoras potaroensis Myers 1927: ROM 61526
(3 of 15, 35·0–44·8mmLS, 2 c&s, 32·6–35·1mmLS). Corydoras pygmaeus Knaack
1966: MZUSP 26344 (4, 13·5–20·0mm LS). Corydoras reticulates Fraser-Brunner
1938: MZUSP 28752 (3, 37·3–45·1mm LS). Corydoras robineae Burgess 1983:
MZUSP 27175 (holotype, 33·7mmLS). Corydoras sarareensis Dinkelmeyer 1995:
MZUSP 48100 (holotype, 40·9mm LS). Corydoras septentrionalis Gosline 1940:
MZUSP 27953 (12, 28·7–41·9mmLS). Corydoras seussi Dinkelmeyer 1996: MZUSP
49323 (paratypes, 10, 44·3–54·0mmLS). Corydoras similis Hieronimus 1991: LBP
10648 (7, 21·4–34·3mmLS). Corydoras splendens (Castelnau 1855): NUP 12990 (1,
43·7mmLS); NUP 10195 (1 c&s, 54·6mmLS). Corydoras stenocephalus Eigenmann
& Allen 1942: MNRJ 3625 (3, 31·2–62·3mmLS). Corydoras sterbai Knaack 1962:
MZUSP 94998 (1, 39·9mmLS). Corydoras treitlii Steindachner 1906: NUP 16224
(3, 21·5–45·6mmLS). Corydoras trilineatus Cope 1872: MZUSP 30857 (3 of 25,
40·9–44·1mmLS, 2 c&s, 44·2–43·8mmLS). Corydoras tukano Britto & Lima, 2003:
MZUSP 82100 (holotype, 40·9mmLS). Corydoras xinguensis Nijssen 1972: MNRJ
24871 (1, 48·0mmLS); MZUSP 38974 (paratype, 1, 31·8mmLS); MZUSP 38980
(paratype, 1, 24·7mmLS); MZUSP 116030, (2, 26·0–32·1mmLS); MZUSP 38987
(paratype, 1, 37·1mmLS). Corydoras zawadzkii Tencatt & Ohara 2016: MNRJ 45565
© 2018 The Fisheries Society of the British Isles, Journal of Fish Biology 2018, doi:10.1111/jfb.13602

CORYDORAS SP. NOV. FROM RIO XINGU AND RIO TAPAJÓS 21
(holotype, 48·7mm LS); NUP 17824 (paratype, 1 c&s, 39·9mm LS). Corydoras
zygatus Eigenmann & Allen 1942: MZUSP 30858 (4 of 15, 41·7–47·3mmLS).
We thank M. de Pinna, A. Datovo, O. Oyakawa and M. Gianetti (MZUSP) for the loan of
specimens. We are also grateful to H. Evers and P. Petersen for kindly providing photos of
the living specimens, to J. Birindelli for the eld photos, to B. Frable (UCSD) for the English
revision and important considerations in the manuscript and to F. Dagosta (MZUSP) for his
good discussion and information, especially regarding the shes of Xingu– Tapajos ecoregion.
We also thank the staff of Setor de Herpetologia at MNRJ for use of the auto-stacking mul-
tifocus stereomicroscope facilities. Our collection permit was granted by ICMBIO (SISBIO
#13339-1). This work was supported by the Brazilian government via CAPES (Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior, Ministério da Educação) and CNPq (Conselho
Nacional de Desenvolvimento Cientíco e Tecnológico, Ministério de Ciência e Tecnologia), to
MRB: 305955/2015-2, LFCT: 141061/2014-6 and 304997/2016-1. M.R.B. is also supported by
a grant from ‘Edital Programa Institucional de Pesquisa nos Acervos da USP’.
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