Two new species of the banjo catfish Bunocephalus Kner ( Siluriformes : Aspredinidae ) from the upper and middle rio São Francisco basins , Brazil

Two new species of banjo catfish of the genus Bunocephalus are described from the upper and middle rio São Francisco basins of Brazil. Bunocephalus hartti is distinguished from all its congeners by the absence of serrations along the anterior margin of pectoral-fin spine in adults (vs. presence of serrations along the anterior margin of the spine). Bunocephalus minerim can be diagnosed from all congeners, except B. larai, by the absence of an epiphyseal bar between the paired frontals (vs. presence of the epiphyseal bar at least in adults). Bunocephalus minerim is distinguished from B. larai and other congeners, except B. chamaizelus, by having nine principal caudal-fin rays (vs. 10 principal caudal-fin rays).


Introduction
Bunocephalus Kner, 1855 belongs to Aspredinidae, a group of Siluriformes known as banjo catfishes, recognized by their distinctively depressed head and body, followed by a slender caudal peduncle, resembling a banjo (Myers, 1960;Friel, 2003).As currently recognized, the Bunocephalus contains 11 valid species, distributed through most tropical river systems in South America, such as the Orinoco, Amazon, Paraná-Paraguay and rivers in the northwestern slope of the Andes (Friel, 2003;Cardoso, 2010;Eschmeyer, 2014).Bunocephalus species are benthic, usually found within leaf litter or buried in the substrate of slowflowing backwaters of creeks and rivers (Leal et al., 2011).The species of Bunocephalus appear to be generalized omnivores, feeding on terrestrial insects, larvae of aquatic insects, small fishes, leaves and flowers (Mérigoux & Ponton, 1998;Melo et al., 2004).Bunocephalus species are of no commercial interest for food, but several of them appear regularly in the ornamental fish trade (Friel, 2003).
In an attempt to improve aspredinid classification, some species previously included in Bunocephalus (e.g., Friel, 2003;Ferraris, 2007) were placed in a new genus, Pseudobunocephalus Friel, 2008.However, hitherto there is not an unambiguous diagnosis for Bunocephalus, and there is no evidence that the remaining species still included in this genus do form a monophyletic group.Therefore, species that are included and were recently described in Bunocephalus lack the synapomorphic characters of other genera of Aspredinidae (Friel, 1994;Cardoso, 2010).
Furthermore, the genus Amaralia Fowler, 1954 may be closely related to some species of Bunocephalus (Friel, 1994) and at this moment the monophyly of the genus is uncertain.There is also a debate as to whether the type species of Bunocephalus designated by Kner (1855) is Silurus verrucosus Walbaum, 1792 or Bunocephalus hypsiurus Kner, 1855 (Ferraris, 1991;2007;Friel, 2003contra Mees, 1988;1996).Final resolution of these issues may only be possible following future taxonomical changes as result of phylogenetic analyses within the group, an ongoing research being performed by the authors.
The rio São Francisco basin has about 181 species of freshwater fishes with a high level of endemism, about 60% (106 spp.) of the total number of species (Albert et al., 2011).The first record of a banjo catfish from rio São Francisco basin was made by Mees (1989) who tentatively identified a single specimen from a tributary of the rio das Velhas as B. larai.As indicated by several authors (Alves & Pompeu, 2001, 2005;Barbosa & Soares, 2009) the known populations of Bunocephalus in the São Francisco basin represent two undescribed species.Here we describe these two new species as endemics of the upper and middle portions of the rio São Francisco basin and we comment about their diagnostic characters.

Material and Methods
Measurements were taken point to point with a digital caliper.Measurements are expressed as percent of the standard length (SL), except subunits of head, expressed as percent of the head length (HL).The measurements follow those proposed by Friel (1994) and Cardoso (2010), except for cleithral process length, which was taken from the anterior margin of the cleithrum on its lateral portion to the posterior tip of the cleithral process.Vertebral counts include all preural vertebrae, including the five vertebrae modified into the Weberian Apparatus, plus the PU1+U1 and U2 elements on the caudal skeleton counted as a single vertebrae, according to Lundberg & Baskin, (1969) and de Pinna & Ng (2004).Cleared and stained specimens (c&s) were prepared according to the method described by Taylor & Van Dyke (1985).Sex was determined by direct inspection of gonads on dissected specimens.Anatomical illustrations were made under a stereomicroscope using a camera lucida.Drawings were digitized and edited using Adobe Photoshop CC and Adobe Illustrator CC.Photos of pectoral-fin spines were taken using an AxioCam ERc5s camera attached to a Zeiss Stemi 2000 C steromicroscope.Osteological descriptions focused on aspects and characters used in previous phylogenetic studies of the family Aspredinidae (Friel, 1994;de Pinna, 1996;Cardoso, 2008).Osteological terminology follows de Pinna (1996), except for the lacrimal, here treated as antorbital.Institutional abbreviations follow Sabaj Pérez (2014).Pictures were taken in a photo-tank following the techniques described by Sabaj Pérez (2009) with a Nikon D90 and a Nikon D7100 digital SLR.
Description.Morphometric data summarized in Table 1.Maximum body size moderate to small compared to congeners (maximum observed size 57.7 mm SL).Dorsal, left lateral and ventral views of body in Fig. 1.Head and body depressed, lateral profile ascending from tip of snout to dorsal-fin origin, with bony skull ornamentations in between.Posterodorsal profile of body straight and descending from dorsal-fin origin to near base of caudal fin, becoming slightly convex anterior to caudal-fin base.Ventral body profile convex from mouth to insertion of pelvic fin; concave from this point to anal-fin origin, straight and ascending from anal-fin origin to base of caudal fin, slightly concave at caudal-fin base.Caudal peduncle slender, somewhat rounded in cross section, but flattened dorsally and ventrally, shallowest at midpoint between end of anal fin and caudal-fin origin.
Skull ornamentation weakly developed.Eye small and positioned dorsolaterally.Skin covering eye dense and pale.Anterior nostril located terminally at tip of snout, associated with fleshy tube projecting beyond upper lip.
Posterior nostril without flap, opening anteromedially near eye.Mouth subterminal, upper lip more prominent relative to lower lip.All barbels simple, unbranched; maxillary barbel reaching or slightly surpassing insertion of pectoralfin spine, posterolateral mental barbel twice as long as anteromedial one.Opercular opening reduced to small valvular slit located just anterior and medially to insertion of pectoral-fin spine.Axial slit pore present, dorsoventrally inclined underneath posterior cleithral process.Adult males with digitiform testes.Integument covered with large unculiferous tubercles, forming series of aligned longitudinal rows on posterior portion of body.Large and well-defined rows of tubercles on caudal peduncle, one on middorsum, and three on lateral of body.Other rows poorly defined.Dorsal fin with five or six rays (modally five), without spinelet.First ray unbranched followed by four or five branched rays.Membrane of last dorsal-fin ray adnate to dorsum.Anterior nuchal plate absent, middle nuchal plate contacting posterior nuchal plate laterally.Posterior nuchal plate not developed laterally, lateral limit not extending beyond contact with middle nuchal plate.Pectoral fin with one rigid spine and five branched soft rays.Pectoral spine curved, feeble serrations present in anterior portion in juveniles, but absent in adults (Figs.2a,b).Serrations along posterior margin of spine increasing in number with larger body sizes, maximum of 10 serrations on posterior margin.Two ossified plus one cartilaginous pectoral-fin radial.Postcoracoid process of pectoral girdle extending slightly posterior to postcleithral process in lateral view.Pelvic fin with six soft rays, second and third rays longest, not reaching anal-fin origin, first ray unbranched.Posterior margin of basipterygium jagged.Lateral cartilage of basipterygium extending from its anteriormost portion to contact with last pelvic-fin ray.Anal fin with seven to nine rays (modally eight), first two or three unbranched, third of length of last anal-fin ray extension adnate by membrane to body.Caudal fin with ten principal rays, five associated with upper lobe and five with ventral lobe, posterior margin of caudal fin convex.Lowermost and uppermost caudal-fin rays unbranched, with proximal expansion and slightly shorter than branched middle rays.Caudal fin with two procurrent rays on upper and lower lobes, anterior procurrent ray small, triangular in shape, posterior procurrent ray longer and spine like.Posterior margin of upper hypural plate extending posteriorly further than lower hypural plate (hypurals one and two fused with parhypural).Second ural half-centrum well developed.Adipose fin absent.Two new species of Bunocephalus 504 Nasal canal ossified and positioned laterally to mesethmoid, one or two separate tubular ossifications around canal.Antorbital present, with anterior limb pointed, extending anterior to anterior margin of premaxilla.Antorbital mesial limb rounded and associated with laterosensory canal.Infraorbital canal present with three tubular ossifications, canal exiting antorbital, passing below eye margin and entering neurocranium through sphenotic.Mandibular canal interrupted, with two tubular ossifications lateral to posterior portion of dentary, and two tubular ossifications near to contact with preopercle.Extrascapular present.Lateral line not associated with fourth parapophyses, anterior portion running just aside margin of parapophyses.Lateral line complete, extending variably to caudal peduncle, formed by simple tubes, median portion presenting small inconspicuous hooks.
Color in alcohol.Head and body light brown dorsally, ventral portions lighter brown to yellowish pale.Four saddles of dark coloration on dorsal surface of body.First dark saddle at level of dorsal fin, second at anal fin vertical, third at middle caudal peduncle and fourth at origin of caudal fin.Second, third and fourth saddles sometimes not connected at middorsal line.Dorsal fin mostly dark brown with light distal margin; pectoral fin whitish cream to hyaline with small light brown spots, pelvic and anal fins mostly hyaline, without conspicuous dark spots.Caudal fin hyaline with dark blotch at proximal portion and scattered black spots on distal third sometimes forming band.
Distribution.Known from several tributaries of the upper and middle rio São Francisco basins including the das Velhas, Paraopeba and Formoso rivers in Minas Gerais State, Brazil (Fig. 4).
Etymology.The epithet hartti is a patronym honoring Charles Frederick Hartt, a Canadian-American geologist, and first professor of Geology at Cornell University.Hartt worked extensively in Brazil, and a few of his notable accomplishments include the publication of "Geology and physical geography of Brazil" (Hartt, 1870), and serving as the founder and director of the section of geology at the Museu Nacional of Brazil from 1866 to 1867.
Conservation status.Bunocephalus hartti is known from an Extent of Occurrence (EOO) of approximately 34,000 km 2 , and despite some areas within its range suffer continuing decline in habitat quality because of contamination from the city of Belo Horizonte and also mining and agriculture, there is no evidence of its habitat being severely fragmented or occurring extreme fluctuations in range or number of individuals.Considering that no specific threats to the species were detected, B. hartti is categorized as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions subcommittee, 2014).

Bunocephalus minerim, new species
u r n:lsid:zooban k.org:act:41D3FB3D -FA F6 -4894 -A8C9-5EC56878B8FB Figs. 5, 6 Posterior nostril without flap, opening anteromedially near eye.Mouth subterminal, upper lip more prominent relative to lower lip.All barbels simple, unbranched, maxillary barbel slightly surpassing insertion of pectoral-fin spine, posterolateral mental barbel twice as long as anteromedial one.Opercular opening reduced to small valvular slit located just anterior and medially to insertion of pectoral-fin spine.Axial slit pore present, dorsoventrally inclined underneath posterior cleithral process.Some female specimens with eggs attached to lateral and ventral surface of the body and pectoral, pelvic and anal fins (Fig. 6).Adult males with digitiform testes.Integument covered with small unculiferous tubercles, those on posterior portion of body larger and forming series of aligned longitudinal rows.Large and well-defined rows of tubercles on caudal peduncle, especially in juveniles, one on middorsum and three on lateral of body.Other rows poorly defined.interdigitated suture.Posterior ceratohyal with foramen on midventral portion.Interhyal present.Typically five branchiostegal rays (four on one side in few specimens).Urohyal present, pointed anteriorly, without foramen.Lateral wings and dorsal keel of urohyal reduced or absent.First and second pharyngobranchials absent, third present and ossified, fourth present and variably ossified.First hypobranchial ossified, second variably ossified and third cartilaginous.Second basibranchial ossified, third variably ossified.Third epibranchial bearing uncinated process.Gill rakers absent on first and second branchial arches, small and scattered on third and fourth arches.Pharyngeal teeth well developed on upper tooth plate; about two rows of teeth on fifth ceratobranchial.Dorsal lamina of Weberian complex reaching dorsal surface of body, lateral profile of lamina ascending posteriorly with anterior concavity and bony knob at middle portion (Fig. 3b).Parapophysis of fourth vertebra forming broad lamina over swim bladder presenting hookshaped process at posterior lateral margin.Parapophysis of fourth vertebra contacting parapophysis of fifth vertebrae extensively.Parapophysis of fifth vertebra long, extending to lateral body surface transverse to main body axis.Distal portion of fifth parapophysis expanded in adult specimens.Total vertebrae 34-37 (modally 34).Vertebrae bearing horizontal transverse processes from 7 th to penultimate centrum.Hemal spines simple, those contacting anal-fin pterygiophores not bifid.Four pairs of ribs, on vertebrae six to nine.Abdominal vertebrae foramina (hemal arches) for hemal canal on 6 th or 7 th and posteriorly on 11 th vertebrae.
Dorsal fin with four or five rays (modally five), without spinelet.First ray unbranched followed by three or four branched rays.About half length of last dorsal-fin ray adnate to dorsum by membrane.Anterior nuchal plate absent, middle nuchal plate contacting posterior nuchal plate laterally.Posterior nuchal plate not developed laterally, lateral extension passing slightly beyond contact with middle nuchal plate.Pectoral fin with one rigid spine and five branched soft rays, last one variably branched.Pectoral spine curved, bearing recurved serrations along ¾ of its anterior and posterior margins.Serrations increasing in number with larger body sizes, to maximum of 10 serrations on anterior and posterior margin of pectoral spines.A single ossified plus one cartilaginous pectoral-fin radial, one specimen with two ossified and one cartilaginous radial.Postcoracoid process of pectoral girdle extending slightly posterior to postcleithral process in lateral view.Pelvic fin with six soft rays, second and third rays longest, just reaching to anal-fin origin, first ray unbranched.Basipterygium with reniform shape, its posterior margin jagged and not bearing cartilaginous tip in adults.Lateral cartilage of basipterygium extending from anteriormost portion of bone to contact with last pelvic-fin ray.Anal fin with seven to nine rays (modally nine), first three to five unbranched.Caudal fin with nine principal rays, five associated with upper lobe and four with ventral lobe, posterior margin of caudal fin convex.Lowermost and uppermost principal caudal-fin rays unbranched with proximal expansion and slightly shorter than branched middle rays.Caudal fin with two procurrent rays on upper and lower lobes, anterior procurrent circular to rectangular in shape, posterior procurrent ray longer and spine-like.Posterior margin of upper hypural plate extending posteriorly further than lower hypural plate.Second ural half-centrum well-developed.Adipose fin absent.
Nasal canal ossified positioned laterally to mesethmoid, variably one or two tubular ossifications around canal.Antorbital present, with anterior limb pointed, extending anterior to anterior margin of premaxilla.Antorbital mesial limb rounded and associated with laterosensory canal.Infraorbital canal present with three tubular ossifications, canal exiting antorbital, passing below eye margin and entering neurocranium through sphenotic.Mandibular canal interrupted, with one tubular ossification lateral to posterior portion of dentary, and one or two tubular ossification near to contact with preopercle.Extrascapular present.Lateral line not associated with fourth parapophysis, anterior portion running just ventrally to margin of parapophysis.Lateral line complete; extending variably to caudal peduncle, with simple ossified tubes presenting variably few inconspicuous hooks on anterior portion.
Color in alcohol.Pigmentation variable with two distinct color morphs of overall dark and light patterns (Figs.6a-b).Dark morph with dorsal portion of head and body dark brown with three poorly defined and variably present dark saddles, first beneath dorsal fin, second at vertical through middle of anal fin and third at end of caudal peduncle (Fig. 5).Light morph have similar pigmentation pattern but with light brown dorsal surface contrasting with clearly defined dark brown saddles; lateral portion of body with irregularly mottled dark blotches (Fig. 6a).Ventral surface of body overall light brown with dark pigment concentrated in unculiferous tubercles.Pectoral, ventral and anal fins with scattered dark pigment.Dorsal and caudal fins overall dark with light distal portions.Caudal fin sometimes bearing clear patch at proximal portion.
Distribution.Known from several tributaries of the upper and middle rio São Francisco basins including the das Velhas, Formoso, Paraopeba and Paracatu rivers in Minas Gerais State, Brazil (Fig. 4).
Etymology.The specific epithet, minerim, refers to the tipically regional manner of pronouncing the Portuguese word "mineirinho", diminutive of "mineiro", which refers to a person that comes from the State of Minas Gerais.The name is an allusion to the region where it is found and also to its relative small size in comparison with other species of Bunocephalus.A noun in apposition.
Conservation status.Bunocephalus minerim is known from an Extent of Occurrence (EOO) of approximately 75,000 km 2 , and despite some areas within its range suffer continuing decline in habitat quality because of contamination from the city of Belo Horizonte and also mining and agriculture, there is no evidence of its habitat being severely fragmented or occurring extreme fluctuations in range or number of individuals.Considering that no specific threats to the species were detected, B. minerim is categorized as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions subcommittee, 2014).

Discussion
The new species described herein in Bunocephalus share three apomorphic features proposed by Friel (1994) to a clade composed by Amaralia and Bunocephalus: middle nuchal plate ornamentation well developed; posterior margin of basipterygium jagged and lateral line ossicles with small hooks, this last feature being variable in B. minerim.The new species do not share most of the seven apomorphic features of Amaralia (Friel, 1994), except for the presence of four branchiostegal rays and absence of serration on anterior portion of pectoral-fin spine in B. hartti.With the limited information at hand, we prefer to include these new species in Bunocephalus since reviewing the composition and the monophyly of these two genera are beyond the scope of the present paper.
The two new species of Bunocephalus can be diagnosed among other species of the genus by apomorphic characters, which can be related to morphological changes during ontogeny.Bunocephalus hartti is unique within the species of the genus by the absence of serrations on the anterior margin of the pectoral-fin spine in adults (Fig. 2a).Feeble serrations are observed in the pectoral-fin spines of juveniles of Bunocephalus hartti (Fig. 2b), and during ontogeny these serrations seem to be absorbed by the growth of the anterior portion of the spine.Within Aspredinidae, serrations on the anterior margin of the spine are absent in most hoplomyzontines, Xyliphius Eigenmann, 1912, Amaralia and seem to have been lost multiple times within the family (Friel, 1994).
Most species of Bunocephalus possess the plesiomorphic condition within aspredinids of having an epiphyseal bar between the paired frontals.The only exceptions are B. larai, endemic from the upper rio Paraná basin, and the new species herein described B. minerim.The presence of the epiphyseal bar can be related to the degree of ontogenetical development of the specimens: a developmental series of B. verrucosus (INPA 4395) contains a juvenile specimen (38.4 mm SL) with incomplete medial contact between the frontals, whereas the bar is completely formed in all individuals above 68 mm SL.According to Friel (1994Friel ( , 2008) ) the absence of an epiphyseal bar is also observed in some members of the genus Pseudobunocephalus and at least in Xyliphius lepturus Orcés, 1962.Therefore the loss of the epiphyseal bar in adults seems to have evolved independently at least three times within aspredinids, perhaps as retention of a juvenile feature.Within Bunocephalus the absence of the epiphyseal bar may suggest a close relationship between B. larai and B. minerim.
An interesting feature observed in Bunocephalus minerim is the presence of eggs directly attached to the skin surface of some females (e.g., MCP 45242, MCP 45156, MZUSP 73800 and UFRGS 11273).Such parental care in the form of physical attachment to developing embryos has previously been reported in some aspredinids such as Pterobunocephalus, Platystacus, Aspredo, and Aspredinichthys (Friel, 2003).In Pterobunocephalus, like in B. minerim, the eggs are directly attached to the body, whereas in Platystacus, Aspredo, and Aspredinichthys eggs are attached to fleshy stalks, called cotylephores (Wetzel et al., 1997).Within Bunocephalus this feature is rarely observed.From an extensive examination of museum specimens of Bunocephalus (Friel, 1994;Cardoso; 2008; lots listed herein) only three other specimens of a Bunocephalus cf.coracoideus from French Guiana were observed carrying adhesive eggs (CUMV 81970).However, the eggs in these specimens are more superficially attached to body in comparison with B. minerim, in which depressions on the skin surface are observed (Fig. 6b).

Fig. 2 .
Fig. 2. Right pectoral-fin spines of cleared and stained specimens, in dorsal view.a. Adult specimen of Bunocephalus hartti, MNRJ 31385, 42.2 mm SL. b.Juvenile specimen of Bunocephalus hartti, MCP 48280, 21.5 mm SL. c. Adult specimen of Bunocephalus minerim, MCP 28379, paratype, 48.4 mm SL.Scale bar 1 mm.Osteological description based on two cleared and stained specimens (21.5-42.2mm SL, see paratype list).Anterior margin of mesethmoid slightly concave, anterolateral projection slightly pronounced (Fig. 3a).Ethmoid cartilage separate from articular facet of palatine.Frontal with lateral projections forming dorsal margin of eye.Frontal posteriorly projected laterally to posterior cranial fontanel and contacting supraoccipital, epiphyseal bar present.Supratemporal fossa present at middle portion of contact between pterotic and supraoccipital bones.Pterotic with laterally expanded and pointed bony shelf.Premaxilla with somewhat rectangular shape, bearing few teeth on its posteromedial margin.Dentary slender, abutting counterpart at medial portion, symphyseal portion slightly expanded, teeth present along anterior half of dorsal margin.Ascending process of Meckel's cartilage present.Coronomeckelian bone present.Hyomandibula associated with preopercle and posterior portion of mandibular laterosensory canal, supraopercle absent.Cartilaginous contact of hyomandibula with neurocranium restricted to sphenotic bone.Anterodorsal process of hyomandibula developed, contacting ventral surface of sphenotic.Opercular condyle of hyomadibula well developed.Metapterygoid present, contacting quadrate and hyomandibula.Endopterygoid present, somewhat triangular in shape, located underneath contact of palatine and lateral ethmoid.Posterior margin of palatine cartilaginous and rounded.Opercle "L" shaped, posterior arm larger than ventral arm.Interopercle present, triangular in shape and firmly attached to ventral arm of opercle.Dorsal hypohyal absent.Anterior ceratohyal with expanded lamina on anteroventral margin, contacting posterior ceratohyal by

Fig. 4 .
Fig. 4. Distribution map of the new species of Bunocephalus in the rio São Francisco basin, Brazil.Circles represent Bunocephalus hartti and squares represent B. minerim, solid symbols indicate the type-localities.

Fig. 6 .
Fig. 6.Paratype specimens of Bunocephalus minerim.a. Dorsal view of MCP 34665, 31.5 mm SL; showing the saddled pattern of a distinct color morph.b.Left lateral view of a mature female, MCP 45242, 41.4 mm SL, showing the eggs adhered and marks of previously attached eggs on the lateral and ventral portions of body and fins.