José L. O. Birindelli

Morphology of the Gas Bladder in Thorny Catfishes (Siluriformes: Doradidae)

ABSTRACT. The gross morphology of the gas bladder is described, illustrated, compared and categorized among 86 of 88 nominal valid and six undescribed species representing all 31 genera of Doradidae with comments on ontogenetic and taxonomic variation when observed. The putatively basal-most doradids exhibit an unmodified cordiform gas bladder. Derived taxa exhibit an impressive suite of modifications including the addition of a secondary bladder, pronounced reduction of the posterolateral chambers, internal trabeculae, associations with bony capsule-like expansions of the anterior (Weberian) vertebrae, and accessory diverticula varying widely in size, shape, abundance, and distribution, Intra-specific differences are minor, most often reflective of ontogenetic changes especially in large-size species, whereas inter-specific and inter-generic differences are significant, in many cases diagnostic, and suggestive of phylogenetic signal excepting instances of evident convergence such as gas bladder reduction in Rhynchodoras and all but one species of Leptodoras.

New species of the genus Leporinus Agassiz (Characiformes: Anostomidae) from the rio Curuá, rio Xingu basin, Serra do Cachimbo, Brazil, with comments on Leporinus reticulatus

A new species of Leporinus Agassiz is described from the rio Curua, a tributary of the rio Iriri, rio Xingu basin, Serra do Cachimbo, Para State, Brazil. The new species is diagnosed by the color pattern, which consists of eight to ten midlateral round dark blotches plus 20 to 40 smaller ones scattered over the body, dental formula 3/4, subinferior to inferior mouth, 37 to 38 lateral line scales, 4/3-4 transversal series of scales, and 12 circumpeduncular scale series. The new species most closely resembles L. octomaculatus and L. reticulatus from the upper Tapajos basin, and L. marcgravii and L. microphthalmus from the rio Sao Francisco and the rio Paranaiba, respectively. Based on recently collected specimens, L. reticulatus is re-diagnosed as having an allometric elongation of the snout.

Taxonomic revision of extant Doras Lacepède, 1803 (Siluriformes: Doradidae) with descriptions of three new species

ABSTRACT Extant Doras are newly diagnosed among Doradidae by the unique combination of maxillary barbels long and fimbriate; mesethmoid with anterior lateral margins converging towards narrow tip; single anterior cranial fontanel contained largely within frontals and anteriorly by mesethmoid (posterior cranial fontanel occluded); anterior nuchal plate wide, pentaganol or roughly hexagonal, sharing distinct lateral suture with epioccipital and isolating supraoccipital from middle nuchal plate; nuchal foramina absent; coracoid process short, posterior tip falling well short of that of postcleithral process; dentary with acicular teeth; and skin immediately ventral to postcleithral process perforated with conspicuous pores. One fossil species, †D. dioneae, and two nominal extant species, D. carinatus and D. micropoeus, are recognized as valid and the latter two redescribed. Three additional extant species, D. phlyzakion, D. higuchii and D. zuanoni, are newly described from the middle Amazon and tributaries, lower Amazon tributaries and rio Araguaia (Tocantins drainage), respectively. Doras phlyzakion and D. zuanoni form a monophyletic group that is found in lowland, lentic habitats, and is characterized by multiple conspicuous pores in skin on breast and abdomen, a trait unique among doradids and rare if not unique among all catfishes. The remaining extant species, D. carinatus, D. higuchii and D. micropoeus, with uncertain relationships, are found in upland, lotic habitats. The occurrence of D. carinatus in the Orinoco basin suggests a historical link between right-bank tributaries of the lower Orinoco (e.g., Caroní) draining the western Guiana Shield and more eastern rivers (e.g., Cuyuní-Essequibo) that drain the Shield directly into the Atlantic Ocean. A key to extant species is provided, a neotype is designated for Silurus carinatus Linnaeus 1766, and Mormyropsis Miranda Ribeiro, 1911, is placed in the synonymy of Doras Lacepède, 1803. New taxa: Doras higuchii Sabaj Pérez and Birindelli, Doras phlyzakion Sabaj Pérez and Birindelli, Doras zuanoni Sabaj Pérez and Birindelli

A new pale-spotted species of Hypostomus Lacépède (Siluriformes: Loricariidae) from the rio Tocantins and rio Xingu basins in central Brazil

A new species of the genus Hypostomus Lacepede (Siluriformes, Loricariidae) from rio Tocantins and rio Xingu basins in central Brazil, is described. The new species is distinguished from its congeners by a unique combination of pale blotches over a darker background on head, body and fins, and conspicuous keels on head, predorsal region and lateral plates. Comments on the pale-spotted species of Hypostomus are provided.

Ossancora, New Genus of Thorny Catfish (Teleostei: Siluriformes: Doradidae) with Description of One New Species

ABSTRACT. Ossancora, new genus, is diagnosed within Doradidae by having the unique combination of posterior coracoid process approximately as long as posterior cleithral process in adults, posterior cranial fontanel occluded, long maxillary barbel with smooth elongate fimbriae, and teeth present on dentary and premaxilla. A similarly long posterior coracoid process is found in only one other doradid species, Trachydoras paraguayensis, which is distinguished, as are its congeners, from Ossancora by having a small posterior cranial fontanel retained in adults, a relatively short maxillary barbel with stout fimbriae, and edentulous jaws. Three nominal species are recognized as valid and redescribed in Ossancora: Doras punctatus Kner 1853, in both the Amazonas and Paraná-Paraguay basins, Oxydoras eigenmanni Boulenger 1895, in the Paraguay basin, and Doras fimbriatus Kner 1855 in the Amazonas basin. The younger name Doras fimbriatus Kner 1855 is considered valid as a nomen protectum according to Article 23.9 of the ICZN, and its older synonym, D. loricatus Kner 1853 qualifies as a nomen oblitum. A fourth new species, Ossancora asterophysa, is described and diagnosed in part by a gas bladder morphology that is distinctive among congeners. Three species, O. eigenmanni, O. fimbriata and O. asterophysa, form a monophyletic group based on three shared characteristics: smooth elongate fimbriae inserted in more than one row, one dorsally and one ventrally, along anterior margin of maxillary barbel (uniquely derived among Doradidae), elongate fimbriae on mental barbels, and anterior nuchal plate reduced, not sutured to epioccipital (latter two features uniquely derived among Ossancora). Ossancora is typical of lowland floodplain lakes and river channels, and its occurrence in the both the Amazonas and Paraná-Paraguay supports a historical link between these two basins. A key to species and detailed anatomical descriptions are provided. Type specimens are discussed and lectotypes are newly designated for Oxydoras eigenmanni Boulenger 1895, D. fimbriatus Kner 1855, and Doras (Corydoras) punctatus Kner 1853, respectively.

Morphology of the gas bladder in bumblebee catfishes (Siluriformes, Pseudopimelodidae)

The gross morphology of the gas bladder is described and compared for representatives of all valid genera of Pseudopimelodidae (Siluriformes). Cephalosilurus albomarginatus and species of Batrochoglanis, and Microglanis have the most basic form: a large, cordiform gas bladder with a simple internal T‐shaped septum. Cephalosilurus apurensis, C. fowleri, and C. nigricauda also have a large, cordiform gas bladder, but they have well‐developed trabeculae associated with the internal T‐shaped septum, and a pair of well‐developed constrictor muscles inserted on the external wall; the latter feature is present in most species of Pimelodidae, but absent in all other catfishes. The monotypic Lophiosilurus alexandri also has well‐developed constrictor muscles, and its gas bladder is moderately sized. The species of Pseudopimelodus and Cruciglanis have a diminutive gas bladder partially divided into two lateral sacs without internal communication, and lack constrictor muscles. The parapophysis of the fourth vertebra is a wide and long shelf connected to the dorsal surface of the gas bladder in most pseudopimelodid genera. However, in the species of Pseudopimelodus and Cruciglanis the parapophysis of the fourth vertebra is shorter and has its anterior ramus folded back, partially covering the gas bladder anteroventrally; and the tympanic opening is smaller than in species of the other genera. Five phylogenetic characters are proposed based on the morphology of the gas bladder and associated structures in species of Pseudopimelodidae, and the evolution of those characters in the family is discussed. J. Morphol., 2011.

Description of a new species of the genus Leporinus Spix (Characiformes: Anostomidae) from the rio Araguaia, Brazil, with comments on the taxonomy and distribution of L. parae and L. lacustris

A new species of the genus Leporinus is described from the rio Araguaia, in Mato Grosso and Goias states, Brazil. The new species has the dental formula 4/3, a unique feature within the genus; all other species of Leporinus have dental formulae 3/3, 3/4 or 4/4. In addition, the new species can also be distinguished by the following combination of characters: 36 to 37 scales in the lateral line, 4/4.5 or 4/5 series of scales in the transversal line, 16 circumpeduncular scale series, anal fin surpassing base of lower caudal-fin rays and three blotches along the lateral line. The new species shares with L. parae and L. lacustris a rather deep body, terminal mouth, long anal fin, three small dark blotches on the lateral line, the latter two, particularly the last one, usually fading, and preference for lentic habitats. Comments on the taxonomy and distribution of the species L. parae and L. lacustris are provided.

Two new species of Moenkhausia Eigenmann (Characiformes: Characidae) from Serra do Cachimbo, Pará, Northern Brazil

Two new species of Moenkhausia, one from the rio Tapajos and the other from the rio Xingu basins are described as apparently endemics of the Serra do Cachimbo. Both species, along with M. petymbuaba, share a distinct color pattern composed of large conspicuous dark blotches on the base of the body scales. Moenkhausia chlorophthalma, from rio Treze de Maio, a tributary to rio Curua (rio Xingu basin), is distinguished by the presence of a proximal well delimited black area on the adipose fin and a green eye in life. Moenkhausia plumbea of the headwaters of tributaries of the rio Braco Norte, rio Tapajos basin is diagnosed by the presence of a dark longitudinal stripe across the eye and six branched pelvic-fin rays (vs. seven). Relationships of the new species with other Moenkhausia are discussed.

New species of Jupiaba Zanata (Characiformes: Characidae) from Serra do Cachimbo, with comments on the endemism of upper rio Curuá, rio Xingu basin, Brazil

A new species of Jupiaba is described from rio Curua, a tributary of the rio Iriri, rio Xingu basin, Para State, Brazil. The new species is distinguished from its congeners by the unique combination of teeth cusps of similar size, dentary teeth gradually decreasing in size towards posterior portion, color pattern consisting of dark markings on the base of the majority of lateral body scales, inconspicuous dark elongate humeral blotch and conspicuous dark round blotch on the caudal peduncle, and 21 to 24 branched anal-fin rays. The new species is very similar, and possibly sister taxon to J. meunieri. Comments on the endemism of the fish fauna of the upper rio Curua are given.

Hypostomus chrysostiktos, a new species of armored catfish (Siluriformes: Loricariidae) from rio Paraguaçu, Bahia State, Brazil

Hypostomus chrysostiktos, a new species of armored catfish of the family Loricariidae, is described. The most remarkable characteristic of the new species, which allows its prompt diagnosis from congeners, is the high number of branched rays in the dorsal fin (10-11). In addition, the new species can be diagnosed from the remaining Loricariidae by the combination of the following characters: slightly evertible cheek plates, four branched anal-fin rays, naked abdomen, and snout almost completely plated. The characters states shared by H. chrysostiktos and the tribe Hypostomini, which indicates it as belonging to that group, are: a hatched-shaped opercle, the anterior process of the pterotic-supracleitrum passing halfway the orbit, a pointed post-cleithral process, and slightly evertible cheek plates. The description of this armored catfish provides more evidence for the high level of endemism in the ichthyofauna of rio Paraguacu basin, a coastal river of northeastern Brazil.