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A new catfish species of Microcambeva Costa & Bockmann 1994 (Siluriformes: Trichomycteridae) from a coastal basin in Rio de Janeiro State, southeastern Brazil


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Microcambeva bendego, a small psammophilous catfish species, is described from the rio Guapi-Macacu basin at Guanabara Bay in Rio de Janeiro State, an Atlantic Forest remnant. This coastal drainage has been explored by several naturalists and fish researchers since the 19th century. It is a drainage with remarkably high endemism and species richness, and some recently-described and threatened species. The new species is distinguished from all congeners by two distinctive characters: long finger-like projections in the branchial isthmus and a large opercular patch of odontodes with 19 odontodes. Due to the paucity of specimens (n=3) osteological features of the new species were accessed by CT-Scan images of the holotype. Microcambeva bendego shares putative synapomorphies with two congeners, M. ribeirae and M. filamentosa, such as the fusion of supraorbital pore s6, the absence of ossification in the anterior autopalatine cartilage, the presence of an elongated and wide posterior process of the autopalatine, and a concavity on the dorsal process of the opercle. Those characters suggest that M. bendego is more closely related to those two species from the rio Ribeira de Iguape basin than to other congeners. The biogeography and conservation status of M. bendego are also discussed.
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ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Accepted by J. Armbruster: 3 Nov. 2020; published: 14 Dec. 2020 111
Zootaxa 4895 (1): 111–123
Copyright © 2020 Magnolia Press Article
A new catfish species of Microcambeva Costa & Bockmann 1994 (Siluriformes:
Trichomycteridae) from a coastal basin in Rio de Janeiro State, southeastern
1Laboratório de Ictiologia Sistemática e Evolutiva, Departamento de Botânica e Zoologia, Centro de Biociências, Universidade Fed-
eral do Rio Grande do Norte, 59978–970 Natal, RN, Brazil.
2Museu Nacional, Universidade Federal do Rio de Janeiro, Departamento de Vertebrados, Quinta da Boa Vista, 20940-040 Rio de
Janeiro, RJ, Brazil.;
3Museu de Zoologia da Universidade de São Paulo, Universidade de São Paulo, Av. Nazaré, 481, 04263–000 São Paulo, SP, Brazil.;
Microcambeva bendego, a small psammophilous catfish species, is described from the rio Guapi-Macacu basin at
Guanabara Bay in Rio de Janeiro State, an Atlantic Forest remnant. This coastal drainage has been explored by several
naturalists and fish researchers since the 19th century. It is a drainage with remarkably high endemism and species
richness, and some recently-described and threatened species. The new species is distinguished from all congeners by two
distinctive characters: long finger-like projections in the branchial isthmus and a large opercular patch of odontodes with
19 odontodes. Due to the paucity of specimens (n=3) osteological features of the new species were accessed by CT-Scan
images of the holotype. Microcambeva bendego shares putative synapomorphies with two congeners, M. ribeirae and M.
filamentosa, such as the fusion of supraorbital pore s6, the absence of ossification in the anterior autopalatine cartilage,
the presence of an elongated and wide posterior process of the autopalatine, and a concavity on the dorsal process of the
opercle. Those characters suggest that M. bendego is more closely related to those two species from the rio Ribeira de
Iguape basin than to other congeners. The biogeography and conservation status of M. bendego are also discussed.
Key words: Taxonomy, Microcambevinae, Fluminense ecoregion, Atlantic Forest, Guanabara bay, CT-Scan
Microcambeva bendego, é uma pequena espécie de bagre psamófilo descrita da bacia do rio Guapi-Macacu na Baía de
Guanabara, no Estado do Rio de Janeiro, em um remanescente da Mata Atlântica. Essa bacia costeira tem sido explorada
por vários naturalistas e pesquisadores de peixes desde o século 19 e possui alto endemismo e riqueza de espécies, com
algumas espécies recentemente descritas e ameaçadas. A nova espécie se distingue de todos os congêneres por possuir
um barbilhão digitiforme longo, na região do istmo branquial e por uma grande placa opercular de odontódeos com
19 odontódeos dispostos em cinco fileiras. Devido à escassez de espécimes (n = 3), as características osteológicas da
nova espécie foram analisadas por tomografia computadorizada (CT-Scan). Microcambeva bendego compartilha várias
sinapomorfias com dois congêneres, M. ribeirae e M. filamentosa, como a fusão do poro supraorbital s6, a ausência
de ossificação na cartilagem anterior do autopalatino, um processo posterior alongado e amplo do autopalatino e uma
concavidade no processo dorsal do opérculo, sugerindo uma relação mais próxima com espécies da bacia do rio Ribeira
de Iguape que com outras espécies do gênero. A biogeografia e o estado de conservação de M. bendego também são
Palavras chaves: Taxonomia, Microcambevinae, Ecorregião Fluminense, Floresta Atlântica, Baia de Guanabara, CT-
112 · Zootaxa 4895 (1) © 2020 Magnolia Press
Microcambeva Costa & Bockmann 1994 is a genus of small psammophilous translucent catfishes endemic to coast-
al streams of the Atlantic Forest (Costa & Bockmann 1994; Sarmento-Soares et al. 2019; Costa et al. 2019a; 2020a;
2020b). The genus was originally assigned to the trichomycterid subfamily Sarcoglanidinae based on morphology
(Costa & Bockmann 1994). However, recent proposals place Microcambeva as the sister group to Listrura de Pinna
1988 (formerly in Glanapteryginae), also from the eastern Atlantic basins, in a separate clade distinct from the other
Amazonian taxa they convergently resemble (Costa et al. 2020a, Ochoa et al. 2020). As a consequence, Costa et al.
(2020a) proposed a new subfamily, the Microcambevinae, to comprise the two genera.
Currently, Microcambeva includes six species distributed in three freshwater ecoregions (sensu Abell et al.
2008, Sarmento-Soares et al. 2019). The type species of the genus is M. barbata Costa & Bockmann 1994 from rio
São João basin, in Rio de Janeiro State, Fluminense ecoregion (Costa & Bockmann 1994). Microcambeva ribeirae
Costa, Lima & Bizerril 2004 and M. filamentosa Costa, Katz & Vilardo 2020 were described from the rio Ribeira do
Iguape basin and ecoregion, in São Paulo and Paraná states (Costa et al. 2004; 2020b). Microcambeva draco Mattos
& Lima 2010 are recorded from rio Jucuruçu and rio Peruípe basins (Mattos & Lima 2010), M. jucuensis Costa,
Katz, Mattos & Rangel-Pereira 2019 from rio Jucu basin, in Bahia State, and M. mucuriensis; Costa, Katz, Mattos
& Rangel-Pereira 2019 from rio Mucuri basin, in Espírito Santo State (Costa et al. 2019b), all in the Northeastern
Mata Atlantica ecoregion. Half of those species came to light in the last two years, indicating that knowledge on the
genus is still incipient, a situation unfavorable for the conservation of these cryptic and easily overlooked catfishes.
According to IUCN criteria, M. barbata and M. ribeirae are considered ‘near threatened’, M. draco is ‘endangered’,
and the remaining species have not yet had their conservation status evaluated (ICMBio, 2018; Sarmento-Soares et
al. 2019).
During a taxonomic revision of Microcambeva conducted by the first author, three specimens of a single lot
located in the Museu Nacional fish collection (MNRJ) proved to be a new species. Those small catfishes were
collected in the rio Guapi-Macacu basin in Rio de Janeiro State in 2016, and constitute a remarkable discovery
considering that the area has been extensively sampled since the 19th century (Bizerril & Primo 2001, Koerber &
Reis 2020). The species is herein described and its putative phylogenetic relationships and conservation status are
Material and methods
Counts and measurements followed Costa (1992). Measurements were taken with digital calipers, calibrated to
one-tenth millimeter precision under binocular stereomicroscope. Measurements are presented as percentages of
standard length (SL), except for head measurements which are expressed as percentages of head length (HL).
Osteological structures were examined in the CT-scanning Laboratory of the Museu de Zoologia da Universi-
dade de São Paulo (Phoenix v | tome | x M—General Electric Company), applying the following parameters, voxel
size X= 0.2395892, number of images 4400 voltage 60Kv and current 220mA. Osteological nomenclature follows
de Pinna (1989) and Adriaens et al. (2010). Bones of the orbital region, barbular and lachrymal-antorbital, follow de
Pinna et al. (2020). Counts of procurrent caudal-fin rays, branchiostegal rays, ribs, precaudal and caudal vertebrae,
opercular and interopercular odontodes, and premaxillary and dentary teeth were performed on the micro-tomo-
graphed holotype. Vertebrae involved in the Weberian apparatus and compound caudal centrum were not included
in counts. Nomenclature of the latero-sensory canal system and pores followed Arratia & Huaquin (1995). Mor-
phological, meristic and osteological data for M. barbata, M. ribeirae, M. draco, M. filamentosa and M. jucuensis
were obtained from type and non-type specimens deposited in Museu de Zoologia da Universidade de São Paulo,
São Paulo (MZUSP); Museu Nacional, Universidade Federal do Rio de Janeiro (MNRJ); Coleção Ictiológica da
Universidade Federal do Rio Grande do Sul, Porto Alegre (UFRGS); and Universidade Estadual Paulista - Campus
São José do Rio Preto Instituto de Biociências, Letras e Ciências Exatas, São José do Rio Preto (DZSJRP) (see
Sarmento-Soares et al. 2019). Data on M. mucuriensis were obtained from published sources (Costa et al. 2019a;
Costa et al. 2020b).
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Microcambeva bendego new species
(Fig. 1, Table 1)
Holotype. MNRJ 52042, 28.1 mm SL; Brazil: Rio de Janeiro State, Guapimirim Municipality; rio Guapiaçu near
Cachoeiras de Macacu, rio Guapi-Macacu basin, 22°35’33”S 42°53’20”W, P. A. Buckup, D. F. Moraes-Jr and V.
Brito, 31 Aug 2016.
Paratypes. MNRJ 48616, 1, 26.9 mm SL, collected with holotype. MZUSP 125789, 1, 27.8 mm SL, collected
with holotype.
Diagnosis. Microcambeva bendego is distinguished from all congeners by the long finger-like projections, as
long as orbital diameter (vs. projections absent in M. filamentosa and smaller than orbital diameter in the remaining
congeners), and the more numerous opercular odontodes (19 vs. 6–7 in M. barbata, 9–12 in M. mucuriensis, 9–14
in M. ribeirae, 11–12 in M. draco and M. filamentosa, and 13–15 in M. jucuensis). It is also distinguished from
all congeners, except M. ribeirae, by the unmodified first pectoral-fin ray (vs. first pectoral-fin ray filamentous). It
differs from all species of the genus, except M. ribeirae and M. filamentosa, by the absence of ossification in the
anterior cartilage of the autopalatine (vs. presence), and by the supraorbital pores (s6) fused into a single median
pore, positioned on the middle of head (vs. paired s6 pore). The new species differs further from M. filamentosa by
having 8 interopercular odontodes (vs. 6) and 33 vertebrae (vs. 36), and from M. ribeirae by the rictal barbels reach-
ing the anterior portion of the interopercular patch of odontodes (vs. reaching middle of orbit), and the three first
rays of the dorsal-fin unbranched (vs. two).
Description. Morphometric data of holotype and two paratypes presented in Table 1. Body elongated, cylin-
drical immediately posterior to head to pelvic-fin origin, gradually compressed towards caudal peduncle (Fig. 1a).
Dorsal profile gently convex from snout to dorsal-fin origin, and straight along caudal peduncle. Ventral profile
convex from jaw to pelvic-fin insertion, straight from that point to terminus of caudal peduncle.
FIGURE 1. Microcambeva bendego, new species, holotype, MNRJ 52042, 28.1 mm SL. Rio Guapiaçu, near Cachoeiras de
Macacu, rio Guapi-Macacu basin, Guapimirim Municipality, Rio de Janeiro State, southeastern Brazil. a. lateral view; b. dorsal
view; c. ventral view. Scale: 10 mm.
114 · Zootaxa 4895 (1) © 2020 Magnolia Press
TABLE 1. Morphometric data of holotype (MNRJ 52042, 28.1 mm SL) and two paratypes (MNRJ 48616, 26.94 mm SL
and MZUSP 125789, 27.8 mm SL) of Microcambeva bendego.
Holotype MNRJ
Paratype MNRJ
Paratype MZUSP
Standard length—SL 28.1 26.9 27.8 27.5
Percentage of SL
Body depth 3.7 3.2 3.5 3.5
Caudal peduncle depth 2.6 2.1 2.1 2.3
Body width 2.5 1.0 1.0 1.5
Caudal penduncle width 2.2 0.6 0.6 1.1
Caudal penduncle length 8.8 5.0 5.7 6.5
Dorsal-fin base length 3.3 2.8 2.6 2.9
Anal-fin base length 2.1 2.3 2.5 2.3
Pelvic-fin length 4.7 4.1 4.3 4.4
Distance between pelvic-fin bases 1.1 0.6 1.0 0.9
Pectoral-fin length 5.6 3.8 4.3 4.5
Predorsal length 17.0 13.9 14.8 15.2
Prepelvic length 14.9 12.5 12.3 13.2
Head length (HL) 6.0 5.1 5.8 5.7
Percentage of HL
Head depth 3.0 2.3 2.4 2.6
Head width 4.9 4.1 4.3 4.4
Interorbital width 0.8 0.9 1.2 1.0
Preorbital length 2.7 2.4 2.6 2.6
Eye diameter 1.2 1.1 0.7 1.0
Mouth width 1.3 1.5 1.2 1.3
Internarial width 0.1 0.4 0.4 0.3
Head triangular in dorsal view, moderately depressed, longer than wide (Fig. 1b). Mouth subterminal. Snout
rectangular, with slight lateral compression after origin of maxillary barbel. Nostrils circular, posterior ones larger
than anterior ones. Anterior nostril surrounded by skin continuous with nasal barbel, posterior nostril with small
half-moon skin fold, approximately as large as nasal opening. Posterior nostril closer to anterior nostril than to mar-
gin of eye, anterior nostril closer to upper lip than posterior nostril. Barbels tapering distally. Nasal barbel originat-
ing on median portion of anterior nostril, reaching posterior portion of posterior nostril. Maxillary barbel reaching
posterior half of interopercular patch of odontodes. Rictal barbel reaching anterior half of interopercular patch of
odontodes. Pair of finger-like projections approximately as long as eye diameter, inserted anterior to branchial isth-
mus (Fig. 2). Eyes round, positioned dorsally at middle distance between snout and posterior portion of opercular
patch of odontodes.
Pectoral fin subtriangular, with seven rays (i+6). First unbranched ray not filamentous, approximately 60% as
long as first branched ray, last branched ray shortest. Tips of rays extending beyond interradial membrane. Adipose
organ round, translucent, dorsal to pectoral fin. Dorsal fin semicircular, nine rays (iii+6), origin at vertical through
14th vertebrae. Pelvic fins subtriangular, with five rays (i+4) extending beyond interradial membrane; pelvic-fin ori-
gin at vertical through 10th vertebrae, its tip not reaching urogenital papilla. Urogenital papilla conic. Anal fin with
seven rays (iii+4) and semicircular distal margin, originating at vertical through 19th vertebrae. Caudal fin truncated,
with 13 rays (i+11+i), six in dorsal plate (i+5) and seven in ventral plate (6+i). Six procurrent caudal-fin rays dor-
sally and ventrally. Vertebrae 33, 27 caudal and six precaudal. Five pleural ribs. Six branchiostegal rays.
Mesethmoid long, cornua short, straight and pointed; slight depression at anterior portion of the mesethmoid;
main body of bone compressed at posterior portion, and pointed. Lateral margin straight along mid-length (Fig.3).
Frontals slender; progressively more spaced from each other posteriorly. Two pores of supraorbital canal present,
s3 pore opening at anterior portion of frontal, and median s6 pore at center of neurocranium, near anterior edge of
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cranial fontanel. Cranial fontanel extending for approximately 75% of neurocranium length, with rounded anterior
and posterior ends. Sphenotic+ pterosphenoid+ prootic trapezoid, prominent, with elongated and pointed lateral
process at middle portion, bearing part of laterosensory canal, opening as single pore i11. Pterotic square-like, with-
out lateral process, bearing preopercle pore i11. Epioccipital rectangular. Posttemporo-supracleithrum rectangular,
with small lateral process near its proximal portion. Vomer long, arrow-shaped, with lateral constriction at anterior
portion and forked anteriorly; thin lateral projections anterior to constriction. Lateral ethmoid rectangular, without
lateral projections. Basioccipital fused with exoccipital anteriorly and with Weberian complex posteriorly.
FIGURE 2. Ventral view of holotype of Microcambeva bendego, new species, holotype, MNRJ 52042, 28.1 mm SL, white ar-
row indicates the finger-like projections. Scale bar: 1.0mm.
Premaxilla with two tooth rows. Eight conical teeth in labial row and 12 in lingual; premaxillary dorsal protu-
berance present and expanded near palatine cartilage (Fig. 3). Maxilla long, 50% larger than premaxilla, its distal
tip pointed and triangular expansion on its ventrolateral portion. Autopalatine long with moderately concave lateral
margin, and straight mesial margin. Posterior process of autopalatine long and pointed. Lacrimal-antorbital elon-
gated and cylindrical approximately 75% of barbular length. Barbular bone long and cylindrical; lacrimal-antorbital
and barbular disposed in line, separated by gap approximately equivalent to length of lacrimal-antorbital.
Metapterygoid small and elliptical. Quadrate elongated and concave, with small dorsally-directed process form-
ing distal synchondrosis with metapterygoid (Fig. 4). Quadrate-hyomandibula fenestra lacking defined shape. Hyo-
mandibula narrow, long, with pointed anterior process with slightly ventrally-curved anteriorly. Ventroposterior
116 · Zootaxa 4895 (1) © 2020 Magnolia Press
margin of hyomandibula with lateral condyle articulating with opercle. Preopercle narrow, pointed anteriorly and
round posteriorly, its anteromedial region concave with lateral extension articulating with interopercle, its central
portion with pointed process. Opercle narrow, with 19 conical, posteriorly-directed odontodes arranged obliquely in
five irregular rows on posterior region. Opercle with pronounced dorsomedial concavity and small pointed process
anteriorly. Opercle articulating dorsally with hyomandibula via small condyle on anterior medial process. Interoper-
cle narrow with eight conical, posteriorly-oriented odontodes arranged in two oblique irregular rows on posterior
region. Interopercle with deep concavity in dorsomedial region, with small pointed process on anterior portion.
Odontodes progressively larger and more strongly curved posteriorly, on both opercle and interopercle. Dentary
straight, with two rows of small conical teeth, seven teeth in inner row and nine in outer one. Prominent coronoid
process and associated Meckel’s cartilage.
Parurohyal with two long wings tapering gradually from base to tip, with slight concavity between them. Pos-
terior median process straight and pointed, shorter than lateral wings. Hypobranchial foramen small and circular.
Anterior portion of parurohyal with two small condyles articulating with ventral hypohyals (Fig. 3B). Ventral hypo-
hyal triangular, with gentle concavity on dorsal portion and slightly depression on ventral portion, accommodating
parurohyal condyles. Anterior ceratohyal cylindrical, with constriction at middle; its anterior margin nearly straight,
its posterior margin concave dorsally and convex ventrally with both ends lined with cartilage. Posterior ceratohyal
roughly triangular, with irregular margins. Six branchiostegal rays, cylindrical and pointed, three on posterior cera-
tohyal, one on interceratohyal cartilage and two on posterior ceratohyal.
FIGURE 3. Skull, Hyoid Arch, Jaws, Opercular Apparatus, pectoral fin and girdle, Suspensorium, anterior vertebrae and Webe-
rian complex of Microcambeva bendego, new species, holotype, MNRJ 52042, 28.1 mm SL. Dorsal view (A) and Ventral view
(B). Abbreviations: AAR, Anguloarticular; ACH: Anterior ceratohyal; BAR: Barbular; BAS+EXO: Basioccipital-exoccipital
bone; BRR: Branchiostegal rays; CLE: Cleithrum; DEN: Dentary; EPO: Epioccipital; HYO: Hyomandibula; IOP: Interopercle;
LAN: Lacrimal-antorbital; LAT: Lateral ethmoid; MAX: Maxilla; MET: Mesethmoid; MPT: Metapterygoid; OPE: Opercle;
ORB: Orbitosphenoid; PAT: Parietal; PAL: Autoplatine; PCH: Posterior ceratohyal; PMX: Premaxilla; POP, Preopercle; PSC:
Posttemporo-supracleithrum; PSO: Parieto-supraoccipital; PTE: Pterotic; PUH: Parurohyal; QUA: Quadrate; SCO, Scapulocor-
acoid; SPH+POT+PSF: Sphenotic + Prootic + Pterosphenoid complex; VHH: Ventral hypohyal; VOM: Vomer; WEB: Capsule
of Weberian apparatus; psp S6: Posterior supraorbital pore S6. Scale bar: 1.0mm.
MICROCAMBEVA BENDEGO, NEW TRICHOMYCTERID CATFISH Zootaxa 4895 (1) © 2020 Magnolia Press · 117
Basibranchial 1 absent. Basibranchial 2–3 rod-like with anterior and posterior tips cartilaginous; basibranchial-
4 fully cartilaginous, circular and flattened, with slight constriction at middle (Fig. 3B). Hypobranchial 1, rod-like,
anterior and posterior ends with globose cartilages; hypobranchial 2–3 conical, with constriction at middle. Cera-
tobranchial 1–4 cylindrical, with irregular dorsal margins. Ceratobranchial 1–2 with small laminar expansion at
ventromedial region; ceratobranchial 3 with small round process at ventromedial region; ceratobranchial 4 with
pointed process near anterodorsal margin. Five conical pharyngeal teeth irregularly arranged on ceratobranchial-5.
Epibranchial 1 Y-shaped, with pronounced concavity at distal portion. Epibranchial 2 rod-like, with two lateral ex-
pansions, a mid-dorsal one directed anteriorly, and an anteroventral one directed posteriorly. Epibranchial 3 laminar
with expansion distally at anteroventral portion; epibranchial 4 rectangular. Pharyngobranchials 1–2 absent; pha-
ryngobranchial 3 rod-like, with thin roundish cartilages at tips; pharyngobranchial 4 entirely cartilaginous, inserted
at anterior portion of upper pharyngeal tooth plate. Tooth plate large, trapezoid in shape, with 12 conical teeth dis-
tributed in single row on ventral surface.
FIGURE 4. Suspensorium, opercular apparatus and jaws of Microcambeva bendego, new species, holotype, MNRJ 52042, 28.1
mm SL. Left lateral view. Abbreviations: ACH: Anterior ceratohyal; BRR: Branchiostegal rays; DEN: Dentary; HYO: Hyo-
mandibula; IOP: Interopercle; LAT: Lateral ethmoid; MAX: Maxilla; MET: Mesethmoid; OPE: Opercle; ORB: Orbitosphenoid;
PMX: Premaxilla; POP: Preopercle; PUH: Parurohyal; QUA: Quadrate; VHH: Ventral hypohyal. Scale bar: 1.0mm.
Cleithrum triangular and flat; scapulacoracoid ossified, roughly triangular. Basipterygium square, excluding
anterior processes; internal and external processes long and slender with pointed tips; external process larger than
internal; posterior process rudimentary; pelvic splint pointed and small. Hypural complex composed of two plates
(Fig. 5). Lower plate rectangular, supposedly corresponding to fused parhypural plus hypurals 1–2, and upper plate
corresponding to hypurals 3–5. Uroneural long and equal in size to adjacent neural spine, in contact with, but not
fused to, upper hypural plate. Two procurrent rays associated with uroneural. Neural spine long and pointed, reach-
ing approximately half of upper hypural plate. Hemal spine larger than neural one, not contacting lower hypural
plate, and reaching to distal portion of lower hypural plate; two procurrent rays associated with hemal spine. Ventral
procurrent rays larger than dorsal ones (Fig. 5).
Color in alcohol. Dorsum, lateral and ventrum of body, almost yellowish pale. Four rows of large dark spots,
two along sides, one middorsal and one midventral. Lower lateral row midlateral, with nine unevenly-spaced spots
extending along longitudinal skeletogenous septum. First spot dorsoposteriorly to base of pectoral fin. Last spot of
midlateral series largest, covering hypural plate and central portion of base of caudal fin. Upper lateral row extend-
ing along dorsal part of flanks, with three well-defined, bilaterally-aligned anterior spots (third one at transverse line
through origin of dorsal fin), plus three or four poorly-defined and bilaterly misaligned ones. Middorsal series with
three spots evenly spaced between occiput and origin of dorsal fin (with third one right at fin origin), plus fourth one
at middle of dorsal-fin base. Anterior two middorsal spots intercalated with those of upper lateral row. Isolated final
middorsal spot on terminus of edge of caudal peduncle. Midventral row with three spots, aligned respectively with
distal portion of pelvic fins, middle of anal-fin base and middle of caudal peduncle. Faint files of dark chromato-
118 · Zootaxa 4895 (1) © 2020 Magnolia Press
phores along limits of myotomes, more pronouncedly on epaxial series. Head with large dark field extending over
middle of posterior part of neurocranium, from slightly anteriorly to eyes to limit of epaxial musculature, forming
two dark arms at that limit. Cephalic color pattern poorly-defined. Eyes and iris black. Narrow dark field extending
laterally between anterior and posterior nostrils. Remainder of dorsal surface of head with light uniform covering of
dark chromatophores. Nostrils outlined in abrupt white, in stark contrast with remainder of dorsal surface of head.
Dark concentration on opercular patch of odontodes. Ventral part of head entirely white. Maxillary and nasal bar-
bels with dark chromatophores concentrated at base. Rictal barbel white. Dark concentrations on proximal third of
pectoral fin. Remaining fins hyaline. Pale-gray vertical bar on caudal-fin base.
Etymology. The specific epithet is derived from the second-largest meteorite discovered in Brazil, the Bend-
egó. Found in 1794 in Northeastern Brazil, it was transported to the Museu Nacional in 1888, where it became part
of its exhibit ever since. In 2018, a fire of huge proportions destroyed part of the Museu Nacional, Universidade
Federal do Rio de Janeiro (MNRJ) including some of its bicentennial collections. Even though part of the building
collapsed, the Bendegó remained intact at the main entrance of the museum, where it was seen by the crowd that
gathered the day after the fire, becoming a symbol of the resistance of the institution. This is not only an homage
to the MNRJ, its employees and students, but also an allusion to the resilience of the species herein described in
Atlantic Forest basin severely impacted by anthropic actions. A noun in apposition.
FIGURE 5. Caudal skeleton of Microcambeva bendego, new species, holotype, MNRJ 52042, 28.1 mm SL. Left lateral view.
Abbreviations: HES: Hemal spine; HYP 1–2: Hypural plate 1–2 plus parhypural, fused; HYP 3–5: Hypural plate 3–5 fused;
NES: Neural spine; URO: Uroneural. Scale bar: 1.0mm.
FIGURE 6. Geographic distribution Microcambeva catfishes in the Atlantic Forest costal basins of southeastern Brazil. White
star: type locality new species M. bendego; Black square: type locality of M. barbata; Blue hexagon: M. filamentosa; Gray
diamond: M. ribeirae; Red triangle: M. jucuensis; Yellow circle: M. mucuriensis; Pentagon orange: M. draco. White line: Gua-
nabara Bay region; Black line: River basin limits.
MICROCAMBEVA BENDEGO, NEW TRICHOMYCTERID CATFISH Zootaxa 4895 (1) © 2020 Magnolia Press · 119
Distribution. Known only from its type locality, in the middle section of the rio Guapiaçu, in the Guapi-Ma-
cacu system, a basin that drains directly into the northeastern portion of Guanabara Bay (Fig. 6).
Habitat and ecological notes. Microcambeva bendego was found in the middle course of rio Guapiaçu, in
a stream approximately 10 m wide and 1 m deep, with sandy bottom and riparian vegetation composed most-
ly of grass-like Cyperaceae. The new species was collected along with Hypostomus affinis (Steindachner 1877),
Parotocinclus maculicauda (Steindachner 1877) and Rineloricaria sp., plus two introduced aquarium species, the
three-spot gourami Trichopodus trichopterus (Pallas 1770) and the jewel tetra Hyphessobrycon eques (Steindachner
1882). A recent visit to the type locality did not secure any Microcambeva specimens. According to local fishermen,
the African catfish Clarias gariepinus (Burchell 1822) is also found in the stream.
Discussion. Microcambeva bendego has all four putative synapomorphies so far proposed for the genus, viz.,
a reduction in the quadrate process, a rectangular ventral hypural plate; and a reduced number of opercular and in-
teropercular odontodes (Costa & Bockmann 1994; Costa et al. 2020a; 2020b), although polarity of those characters
are debatable. The new species has the largest number of opercular odontodes (19) in the genus (6–7 in M. barbata,
9–14 in M. mucuriensis, M. ribeirae, M. draco and M. filamentosa, and 13–15 in M. jucuensis) (Costa & Bockmann
1994; Costa et al. 2004; 2019a; 2020b).
An additional putative synapomorphy of the genus is the presence of a distinct pair of finger-like projections,
similar in position to a mentonian barbel. This barbel of unknown function occurs in all species of the genus, except
M. filamentosa (Costa et al. 2020b), and at least five unrelated trichomycterid species, Pseudostegophilus macula-
tus (Steindachner 1879), Malacoglanis gelatinosus Myers & Weitzman 1966, Stenolicmus sarmientoi de Pinna &
Starnes 1990, Ammoglanis pulex de Pinna & Winemiller 2000, and A. obliquus Henschel, Bragança, Rangel-Pereira
& Costa 2019 (de Pinna & Winemiller, 2000; Henschel et al. 2020). The structure in M. bendego is the largest so far
recorded for the genus, in stark contrast to the minute barbels seen in M. draco, M. jucuensis, and M. mucuriensis
and the medium-sized ones in M. barbata and M. ribeirae.
Microcambeva ribeirae, M. filamentosa and M. bendego share three character-states not observed in other
congeners: median fusion of the third pore (s6) of the supraorbital canal, absence of the anterior autopalatine os-
sification, and a deep concavity between the base of the ascending process of opercle and the patch of odontodes.
Among Microcambeva, the new species additionally shares exclusively with M. ribeirae two distinct features: a
non-filamentous first pectoral-fin ray and conspicuous series of dark spots along the body. In other congeners, the
first pectoral-fin ray is modified as a filament, as the long filament in M. filamentosa (70–80% pectoral-fin length
without filament), medium sized in M. barbata (40%) and M. draco (50%), and short in M. jucuensis and M. mu-
curiensis (5% to 10%). In the sarcoglanidines Sarcoglanis simplex Myers & Weitzman 1966 and Malacoglanis ge-
latinosus, the trichomycterine Scleronema Eigenmann 1917, and in the stegophiline Ochmacanthus batrachostoma
(Miranda Ribeiro 1912) a small reduction in the size of the first pectoral filament is observed (Myers & Weitzman
1966; Neto & de Pinna 2016; Ferrer & Malabarba 2020); however this reduction is not comparable to that observed
in M. ribeirae and M. bendego.
Several psammophilic species display a reduction in integumentary pigmentation, as observed in the sarcoglan-
idines S. sarmientoi, Stauroglanis gouldingi de Pinna 1989, Microcambeva and Ammoglanis Costa 1994 species.
Species of Scleronema, have a yellowish background and patterns composed of rounded brown blotches (de Pinna,
1989; de Pinna & Winemiller 2000; Ferrer & Malabarba 2020). A unique pattern of color of the body, composed of
a yellowish background with larger dark spaced spots is observed in Stenolicmus ix Wosiacki, Coutinho & Montang
2011, M. ribeirae and M. bendego, however in the Amazon species, the spots are distributed irregularly along the
middle of the body, while in Atlantic forest species, the spots form a series along the middle of the body. These
shared characteristics suggest that M. bendego is more closely related to M. ribeirae from the Ribeira de Iguape
ecoregion than to species in its own Fluminense ecoregion.
The apparent sister-group relationship between M. bendego and M. ribeirae is surprising given that the new
species is geographically closer to M. barbata, with the two type localities separated by mere 35 km in straight
line. Geomorphological data, however, lend support to this biogeographic pattern. The Guapi-Macacu and São João
drainages are separated by the Serra do Sembê, which extends from the Serra dos Órgãos Mountains to the Cabo
Frio Magmatic Lineament (CFML) (Riccomini et al. 2005). These high and ancient rocky escarpments act as a geo-
graphical barrier, which has influenced the vicariant patterns and the high diversity of freshwater fish species in the
Fluminense ecoregion (Lima et al. 2017). This is reflected in some taxa with different species on each side of this
divide, such as the Atlantirivulus Costa 2008 rivulids, and Parotocinclus Eigenmann & Eigenmann 1889 loricari-
120 · Zootaxa 4895 (1) © 2020 Magnolia Press
ids, and Listrura and Homodiaetus Eigenmann & Ward 1907 trichomycterids (Koch 2002; Villa-Verde et al. 2012;
Roxo et al. 2017; Lima et al. 2017). In addition, Santos et al. (2009) and Pereira et al. (2013) also demonstrated that
Hoplias malabaricus (Bloch 1794) lineages’ from Guanabara Bay drainages are more closely related to those from
the distant Paranaguá Bay, in Paraná State, than to the rio São João basin, corroborating the effectiveness of this bar-
rier for the freshwater aquatic biota (Riccomini et al. 2005; Lima et al. 2017). Thus, the apparently geographically
counter-intuitive relationships of M. bendego actually fits a broader biogeographical pattern.
It is not ideal to describe a species based on few specimens, because obviously there is not enough material to
address such basic questions as ontogenetic or intraspecific variation (de Pinna et al. 2020). Still, some important re-
cent discoveries on trichomycterid diversity were based on few individuals, e.g: M. barbata (n=4), M. draco (n=2),
Listrura boticario de Pinna & Wosiacki 2002 (n=1), L. depinnai Villa-Verde, Ferrer & Malabarba 2014 (n=2), and
Trichogenes beagle de Pinna, Reis & Britski 2020 (n=3) (Costa & Bockmann, 1994; de Pinna & Wosiacki 2002;
Mattos & Lima 2010; Villa-Verde et al. 2014; de Pinna et al. 2020). The realities of this kind of research sometimes
make it imperative to release new taxonomic knowledge on elements of biodiversity even with limited material.
Species must be made available for phylogenetic, biogeographic, ecological and conservation strategies (Silva et
al. 2019; de Pinna et al. 2020), especially for those occurring in highly impacted areas, such as the Guanabara Bay
area in the present case.
Conservation status. The Guanabara Bay is composed of approximately 40 rivers and streams, and the region
has been sampled by many naturalists since the 19th century. The type locality of the new species is near large urban
conglomerates and rural properties concentrating approximately 70% of the metropolitan region of Rio de Janeiro
State, including a major industrial center (Bizerril & Primo 2001). The rio Guapi-Macacu basin has an area of
ca. 1.600 km², making it the largest drainage flowing into the Guanabara bay. Inserted in the inner portion of the
basin, with its headwaters in the Serra dos Órgãos mountain range, it is considered as a biodiversity pocket of the
Guanabara Bay region. It has been heavily impacted by unrestrained urban occupation, intensified in the mid-1930,
deforestation of riparian forests, fires, diversion of river courses and water pollution (Bizerril & Primo 2001).
The intense degradation of the Guanabara’s Bay aquatic environments is evidenced by its numerous threatened
freshwater fish species, such as the ‘endangered’ Brycon insignis Steindachner 1877, Hyphessobrycon flammeus
Myers 1924, and Spintherobolus broccae Myers 1925, and the ‘critically endangered’ Characidium grajahuense
Travassos 1944, Listrura nematopteryx de Pinna 1988, Kryptolebias brasiliensis (Valenciennes 1821), Leptolebias
marmoratus (Ladiges 1934), Leptopanchax splendens (Myers 1942), and L. opalescens (Myers, 1942) (ICMBio,
2018). While species previously considered extinct such as L. splendens, were later rediscovered in remnant natural
areas of the Guanabara Bay region (Costa et al. 2019b), others like Leptopanchax sanguineus Costa 2019, may
already be extinct (Costa 2019). Considering that Microcambeva bendego was only collected in a single locality
consisting in a highly degraded habitat of well-sampled drainage, that recent efforts failed in the obtaining ad-
ditional specimens, and its area is occupation of less than 20 km2, the B2ab(iii) critically endangered category is
recommended as an obvious preventive measure (IUCN 2012).
The coastal basins of Atlantic Forest harbor many endemic and restricted-range freshwater fish species. How-
ever, the habitat loss along five centuries of colonization has left its mark, with several of those species currently
threatened (Abilhoa et al. 2011). To some of these ‘endangered’ species, the creation or expansion of conservation
units encompassing small hydrographic basins and associated riparian zones in southeastern Brazil are important
measures (Menezes et al. 2007). In the estuarine portion of rio Guapi-Macacu basin, there are two conservation
units, the Guanabara Ecological Station (GES) between the municipalities of Itaboraí, Guapimirim, São Gonçalo
and Magé, covering an area of 1,420km², and the Guapi-Mirim Environmental Protection Area (GMEPA), cover-
ing an area of 138.25 km². Outside the protected areas this region is severely impacted, with the riparian zone de-
forested, diversion of river courses to agriculture, and the introduction of exotic species (Bizerril & Primo 2001).
Although the type locality of M. bendego is close to the buffer zone of the GES inside in GMEPA, its geographic
distribution is limited to the middle section of the rio Guapiaçu. A measure that will contribute to the conservation,
not only of the new species, but also of other aquatic species, is the expansion of the GES area to the middle portions
of the rio Guapi-Macacu river basin to protect most freshwater habitats and their associated biota (Azevedo-Santos
et al. 2019).
Comparative material. Rio de Janeiro: Microcambeva barbata: MZUSP 43678, 24.7 mm SL, holotype, rio
São João. MZUSP 43679, 1, 18.7 mm SL, paratype. DZSJRP-Pisces 13861, 25.1 mm SL, affluent rio São João.
MNRJ 49371, 22.7 mm SL, rio Aldeia Velha. MNRJ 47108, 19.6 mm SL, rio Aldeia Velha. MNRJ 37572, 26.3 mm
MICROCAMBEVA BENDEGO, NEW TRICHOMYCTERID CATFISH Zootaxa 4895 (1) © 2020 Magnolia Press · 121
SL, rio São João. São Paulo: Microcambeva ribeirae: MZUSP 84301, 47.8 mm SL, holotype, rio São Lourencinho.
MZUSP 79953, 7, 25.9–36.6 mm SL, paratypes, rio Espraiado. MZUSP 74699, 10, 35.0–47.5 mm SL, paratypes, rio
Faú. MNRJ14304, 3, 29.5–32.4 mm SL, paratypes, tributary of rio São Lourencinho. MNRJ 37165, 35.1 mm SL, rio
Jacupiranga. Paraná: Microcambeva ribeirae: UFRGS 24759, 37.7 mm SL, tributary of rio Guaraqueçaba. Bahia:
Microcambeva draco: MCP 17796, 2, 24.6–22.6 mm, holotype, rio Jucuruçu. Microcambeva jucuensis: MZUSP
91641, 11, 19.5–24.6 mm SL, rio Formate.
This study is part of the master’s thesis of the first author in the Programa de Pós Graduação em Sistemática e
Evolução (PPGSE) of the Universidade Federal do Rio Grande do Norte (UFRN). We thank M. Britto, M. Targino,
S. Santos, I. Souto-Santos and D. Moraes from Museu Nacional do Rio de Janeiro. To V. Reis, G. Vita, O. Oyakawa,
M. Gianeti and A. Carvalho from Museu de Zoologia da Universidade de São Paulo. We are grateful for the valuable
comments of reviewers. We thank A. Carvalho for expert technical support with the CT-scan facilities at MZUSP
and image editing. LSM is grateful to CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) for
a Master’s scholarship (#1798425). CRM received financial support from FAPERJ (#200.095/2019–E_15/2018).
MdP and SMQL received financial support from CNPq (#310688/2019-1 and #313644/2018-7, respectively).
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... 7). The presence of jaw teeth with bifid cusps is considered a putative synapomorphy for Loricarioidei (de Pinna, 1998), distinctly present in astroblepids, loricariids, and scoloplacids (Schaefer, 1990), as well as in Nematogenys Girard, 1855 and in the basal trichomycterid subfamilies Copionodontinae and Trichogeninae (de Pinna, 1998;de Pinna et al., 2010de Pinna et al., , 2018de Pinna et al., , 2020. Therefore, the presence of spatulate teeth with expanded cusps, sometimes bifid, may be an ancestral loricarioid condition present in the basal trichomycterids Copionodontinae and Trichogeninae and retained by the trichomycterines Bullockia, Scleronema, and a few species of trichomycterus. ...
... Among trichomycterids, strict psammophily has also been recorded for: all eight valid species of the microcambevine genus Microcambeva (Costa & Bockmann, 1994;Costa et al., 2004Costa et al., , 2019Mattos & Lima, 2010;Costa et al., 2020c;Medeiros et al., 2020Medeiros et al., , 2021; all four valid species of the glanapterygine genus Pygidianops (Schaefer et al., 2005;de Pinna & Kirovsky, 2011;Carvalho et al., 2014); all five valid species of the glanapterygine genus typhlobelus (Schaefer et al., 2005;de Pinna & Zuanon, 2013); all six valid species of the sarcoglanidine genus Ammoglanis (Costa, 1994;de Pinna & Winemiller, 2000;Mattos et al., 2008;Costa et al., 2020d;Henschel et al., 2020a, b;Canto et al., 2022); the single species of the sarcoglanidine genus Sarcoglanis (Myers & Weitzman, 1944); and the single species of the sarcoglanidine genus Stauroglanis (de Pinna, 1989;Zuanon & Sazima, 2004;Zuanon et al., 2006). However, all these genera are distantly related to Scleronema (Ochoa et al., 2017(Ochoa et al., , 2020Katz et al., 2018), so it is reasonable to assume that the psammophily in this genus originated independently from these other groups. ...
A new species of Scleronema (Trichomycteridae) is described from the lowlands of three coastal river basins in the Atlantic Forest of the Santa Catarina state, Southern Brazil. Aspects of the anatomy, reproduction, diet, feeding behavior and habitat of the new species are described and discussed in comparison with related taxa. The conservation status of the new species, which currently faces several threats due to environmental impacts on its region of occurrence, is established. Based on characteristics observed in the new species, as well as in most of its congeners, the phylogenetic position and monophyly of Scleronema are discussed and traits considered synapomorphic for the subgenera Plesioscleronema and Scleronema are reviewed. The monophyly of the genus Scleronema is supported by a new synapomorphy. In addition, two new synapomorphies, one of which based on behavior, are suggested for the subgenus Scleronema, justifying the inclusion of the new species. Within the subgenus Scleronema, the new species is assigned to the S. minutum group, which currently includes the majority of species of the genus, due to the presence of synapomorphic traits related to the body shape, maxillary barbel, skin flap of the opercle, caudal and pectoral fins, as well as osteological features of the lower jaw, hyoid arch, and postcranial axial skeleton. The species herein described differs from all its congeners by a combination of characters from various morphological complexes, which are described in detail using different methodologies, including radiography, whole-specimen clearing and double-staining procedures, and tridimensional computer nanotomography (3D nano-CT).
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The Microcambevinae are a catfish subfamily endemic to the Brazilian Atlantic Forest, comprising rare species with interstitial habits. Microcambevines have been classified in two genera, Listrura and Microcambeva, but the relationships among included intrageneric lineages are still poorly understood. The objectives of this study are to conduct a phylogenetic analysis integrating morphological characters and a multigene dataset, and to propose a classification better reflecting morphological diversity and phylogenetic relationships. Phylogenetic analyses combining 57 morphological characters and a 2563 bp molecular dataset generated similar phylogenetic trees with high support values for most clades, including the two genera and some intrageneric groups. Six morphologically distinctive infrageneric lineages, three in Listrura and three in Microcambeva, are classified as subgenera, as well as two new species are described. The morphological diversity here recorded integrated to available information about habitat indicate high level of divergent specialisation among lineages. The analyses indicate a series of convergent morphological traits between Listrura and other teleosts sharing a fossorial lifestyle, as well as specialised traits independently occurring within Listrura lineages. Similarly, a great diversity of morphological traits occurs convergently in Microcambeva lineages and other teleosts sharing psammophilic habits. This study shows that combining molecular and morphological data yields well-supported phylogenies, making possible to unambiguously diagnose clades and to establish evolutionary hypothesis on morphological evolution.
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The Neotropical genus Scleronema is revised based on the re-examination of the type specimens and 1,713 newly collected specimens. Scleronema is diagnosed from other trichomycterids by the following unambiguous derived characters: fleshy flap at the base of the maxillary barbell; skin flap in the posterior margin of the opercle; articulation between the autopalatine and the vomer ventrally located, with the medial margins of the autopalatines very close to each other; and autopalatine with an interrupted or not interrupted ossified arch-shaped process on its dorsal surface forming a canal. Scleronema minutum and S. operculatum are redescribed, S. angustirostre is considered a junior synonym of S. minutum, and six new species are described. A lectotype is designated for Trichomycterus minutus. The type localities of S. angustirostre, S. minutum, and S. operculatum are reviewed in order to correct erroneous information cited in articles and catalogs subsequent to the original descriptions. Species of Scleronema are geographically distributed in the La Plata basin and Atlantic coastal drainages from Southern Brazil, Southern Paraguay, Northeastern Argentina and Uruguay. They inhabit rivers or streams with sand- or gravel-bottoms across the Pampa grasslands. We provide evidences to recognize two putative monophyletic units within the genus, namely the S. minutum species group and the S. operculatum species group, and discuss the distribution patterns of their species.
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A new species of the rare genus Trichogenes is reported on the basis of specimens without locality and other associated data. The obvious distinctiveness, taxonomic relevance, and phylogenetic importance of the new taxon justify its description with material at hand. Trichogenes beagle, new species, differs from all congeners by the presence of tricuspidate teeth on its jaws; by the distribution of opercular odontodes along a wide area of the margin of the opercle; by the pale integumentary pigmentation, composed of few scattered small spots on dorsum and flanks, but lacking large spots near the base of the anal fin; and by the absence of differential concentration of dark chromatophores along the base of the dorsal fin. The new species differs further from each of its two congeners, T. longipinnis and T. claviger, by various additional traits of internal and external morphology and pigmentation. Trichogenes beagle seems to be the closest relative of T. claviger, the two species sharing a number of putatively derived traits not present in T. longipinnis, such as the presence of a large anterodorsal clawlike process on the neural arches of the anterior four free vertebrae. The three species now included in Trichogenes share all synapomorphies previously proposed for the genus, thus strongly supporting generic monophyly. The enigmatic disc-shaped orbital bone in T. beagle and congeners is homologous to a topologically equivalent rodlike structure in other trichomycterids. New comparative information corroborates the hypothesis that the bone is a neomorphic structure, here called the barbular bone. Previous proposals of its homology with the antorbital or supraorbital are refuted. Ontogenetic data demonstrate that the anterior element of the infraorbital series in trichomycterids is a fusion between the lacrimal and antorbital, as postulated—but previously poorly demonstrated—for other catfishes. The structure of the opercle in the new species is intermediate between the highly derived morphology in most trichomycterids and the plesiomorphic condition in other loricarioids, helping to understand the evolution of the opercle of trichomycterids. New information on T. claviger is reported on the basis of additional material.
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Historical information on the probable type-locality of Pimelodus quelen and of its four junior synonyms that share the same neotype, Pimelodus namdia, Pimelodus sebae, Heterobranchus sextentaculatus, and Silurus rivularis, is presented and discussed. The neotype designation for those four species is deemed invalid for not complying with the provisions of the International Code of Zoological Nomenclature, making it technically possible to revalidate any of the four taxa from the synonymy of Rhamdia quelen without having to address the International Commission of Zoological Nomenclature. The type-locality of both Curimata gilbert and Callichthys asper are also restricted to rio Macacu at the village of Japuíba, State of Rio de Janeiro, Brazil.
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Ammoglanis obliquussp. nov. , a minute catfish species reaching a maximum adult size of 15.5 mm, is described from the Rio Preto da Eva drainage in the central Brazilian Amazon. It is distinguished from all of its congeners in possessing an exclusive combination of character states, including the presence and number of premaxillary and dentary teeth, number of interopercular and opercular odontodes, presence of cranial fontanel, number of dorsal-fin rays, number of anal-fin rays, number of caudal-fin rays, number of pelvic-fin rays, number of pectoral-fin rays, absence of pelvic splint, antorbital morphology, and absence of supraorbital and autopalatine morphology. It is considered to be a member of a clade also including A. pulex and A. amapaensis due to the unique oral, antorbital, and autopalatine morphology. Ammoglanis obliquus is regarded as more closely related to A. pulex than to any other congener, as both species exhibit a similar colour pattern, an absence of the metapterygoid, and the presence of two finger-like projections on the chin region.
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Sarcoglanidinae and Glanapteryginae catfishes are among the most unusual elements of the Neotropical freshwater fish fauna. Microcambeva ribeirae, M. barbata and M. draco are miniaturized Sarcoglanidinae known to occur in sandy microhabitats in drainages of the Brazilian Atlantic Forest. Due to their specific habitats, specimens of Microcambeva are rare in fish collections, and new records are considered noteworthy to warrant report. Recently, specimens of this genus were newly found in the Rio Doce basin in Minas Gerais and Espírito Santo States. Such new records expand the known geographic distribution of Microcambeva. Further records of Microcambeva for Rio Peruípe in south Bahia State are also reported. Comments on the distribution of Microcambeva species along the Atlantic Forest coastal basins and suggestions on its conservation status are also offered.
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Specimens found between 1985 and 1988 in the Magé River Basin, south-eastern Brazil were misidentified as L. splendens. The recent rediscovery of other specimens in the Estrela River Basin near the type locality of L. splendens has clarified the species' concept, making it possible to recognise the Magé River Basin specimens as a new species. The new species is herein described as Leptopanchax sanguineussp. nov. and is distinguished from all other cynopoecilines by a unique colour pattern in males, including red bars with sinuous margins. It was collected in a well-preserved, temporary shallow swampy area within dense moist forest, but since 1990 the species has not been found again. Leptopanchax sanguineussp. nov. is one of three species of cynopoeciline killifishes living in lowland moist forests of the coastal plains of Rio de Janeiro State, where the greatest diversity of endemic cynopoecilines is concentrated. Each of these species has been recorded a single time in the last 30 years, a surprisingly low record attributable to intense deforestation during the last several decades resulting in small fragmented lowland moist forests of today. This study indicates that seasonal killifishes adapted to uniquely live in this kind of habitat should be regarded with special concern in studies evaluating conservation priorities.
A second species of Microcambeva, M. ribeirae, is described from the Rio Ribeira do Iguape basin, S o Paulo, southeastern Brazil, which constitutes the southernmost record for sarcoglanidine catfishes. It is distinguished from M. barbata by a series of morphological features, including nasal barbel extent, position of the eye, first pectoral-fin ray extent, position of the anal fin, position of the posterior pore of the supraorbital canal, frontal shape, cranial fontanel extent, lateral process of the sphenotic, absence of the anterior ossification of palatine, and size of the posterior process of the palatine and supraorbital bone.
An undescribed species of Microcambeva, a genus of small psammophilic catfishes from the Atlantic Forest of south-eastern Brazil, was found together the congener M. ribeirae inhabiting the same sand stretch of a stream, in the Rio Ribeira do Iguape basin. The new species and its sympatric congener exhibit highly divergent morphological features, but a multigene phylogeny support them as sister taxa. The new species, M. filamentosa sp. nov., is readily distinguished from all other congeners by the presence of long barbels, long filamentous first pectoral-fin ray and a hypertrophied predorsal adipose fold. Microcambeva filamentosa and M. ribeirae share two unique apomorphic features: a single supraorbital pore s6 situated on the centre of the dorsal surface of the head and a deep concavity between the dorsal process of the opercle and the opercular odontode patch, conditions that are independently acquired in other psammophilic trichomycterids. A comparative context, involving other trichomycterid lineages exhibiting similar morphological adaptations, highly suggests that morphological differences between M. filamentosa and M. ribeirae are related to different strategies to exploit their habitat. In M. ribeirae, the short and thickened first pectoral-fin ray is interpreted as an adaptation to the fish posing propped on the substratum while visually detecting potential preys, what is reinforced by the unique possession in this taxon of a relatively large eye positioned on the top of the head. On the other hand, the relatively small eye and long barbels of M. filamentosa highly suggest the use of a predominantly chemosensory and tactile detection of food, indicating possible nocturnal habits.
Interstitial trichomycterid catfishes of the Glanapteryginae and Sarcoglanidinae with uncommon morphology have been known for long time from taxa endemic to the Amazon. In most recent decades, two genera, Listrura and Microcambeva, respectively, placed in Glanapteryginae and Sarcoglanidinae on the basis of morphological characters, have been described from the Atlantic Forest of eastern South America, about 1,500 km from the area inhabited by those Amazon taxa. Herein, we first test the phylogenetic positioning of Listrura and Microcambeva using a multigene data set, including two nuclear and three mitochondrial genes for nine species of Listrura and Microcambeva and 11 species representing all closely related subfamilies (TSVSG‐clade), as well as five used as outgroups. The phylogenetic analyses generated a robust tree with high support values in all nodes, where monophyly of Glanapteryginae and Sarcoglanidinae is refuted. In contrast, Listrura and Microcambeva form a highly supported clade, herein formally described as a new subfamily, sister to a clade containing taxa representing the Glanapteryginae, Sarcoglanidinae, Stegophilinae, Tridentinae and Vandelliinae. This study also indicates that Microcambeva and Listrura exhibit divergent evolutionary trends in ecological and morphological attributes. Species of Microcambeva inhabit patches of loose sand and possess morphological traits that were convergently acquired by Amazon sand‐dwelling sarcoglanidines, including loss of body pigmentation and long maxilla. Species of Listrura live burrowed inside small stretches of dense leaf litter and have morphological traits that were convergently acquired by Amazon glanapterygines inhabiting leaf litter bottom rivers, including elongate body, with numerous vertebrae and loss or reduction of all fins.
Trichomycterid catfishes of the Sarcoglanidinae, which includes small-sized species living in sandy river substratum, have been poorly represented in collections. We herein describe two new species of the sarcoglanidine genus Microcambeva, endemic to river basins draining the Brazilian Atlantic Forest. The presence of a distal widening on the posterior process of the autopalatine and a rudimentary anterior autopalatine ossification shared by the two new species, M. mucuriensis sp. nov. from the Rio Mucuri and M. jucuensis sp. nov. from the Rio Jucu basin, and M. draco from the Rio Jucuruçu basin indicates that these three species are more closely related to each other than to other congeners. Microcambeva mucuriensis seems to be more closely related to M. draco than to M. jucuensis in that the first two species share the presence of a well-developed anterior process of the interopercle. The two new species are also distinguished from congeners by the number of opercular odontodes and premaxillary teeth, and the relative size of the sesamoid supraorbital. Available evidence taken from this study and previous reports indicates that different sarcoglanidine lineages have adapted to live in distinct riverine habitats, with species of Atlantic Forest Microcambeva inhabiting clearwater streams and Amazonian sarcoglanidines found in tea-stained acidic-water streams.