Bilateral genital asymmetry in livebearer fishes of the genus Phalloceros Eigenmann, 1907, with description of a new species from coastal drainages of southern Brazil (Cyprinodontiformes: Poeciliidae)

A new species of Phalloceros is described from the Tijucas, Maruim, Aririú, Cubatão do Sul, Rio da Madre, D'Una and Tubarão river basins in southern Brazil. The new species is diagnosed among congeners by the bilateral asymmetry of a hood-like structure located immediately anterior to the urogenital papilla of females. The hood is fused with the urogenital papilla on the right side, but free from the papilla on the left side. This hood is reported for the first time in the genus and is present in six of the 21 valid species of Phalloceros, but its bilateral asymmetry is an exclusive condition of the new species. These species do not constitute a monophyletic group. The new species is likely to be phylogenetically related to P. caudimaculatus, whose females have a symmetrical hood.

Poor taxonomic sampling undermines nomenclatural stability: A reply to Roxo <em>et al. (2019)</strong>

A recent study based on genomic data by Roxo et al. (2019) provided a phylogeny of the Loricariidae, the largest catfish family and second largest Neotropical fish family with approximately 1,000 species. The study represents a valuable and innovative contribution for understanding higher-level relationships within the family. The phylogenetic tree inferred by Roxo et al. (2019) thoroughly corroborates the monophyly and relationships of most currently accepted subfamilies of Loricariidae, based on a fair taxon sampling (nearly 14% of the species in the family) representing most genera of each but one of the subfamilies, the Lithogeninae, the sister-group of the remaining members of the family (Pereira & Reis, 2017; Reis et al., 2017). In addition to a hypothesis of relationships, Roxo et al. (2019) also proposed a series of lower-level taxonomic changes, which are deemed premature considering that the taxonomic sampling of the study targeted higher-level clades, and go against one of the pillars of biological classification: nomenclatural stability (e.g., Heterick & Majer, 2018; Beninger & Backeljau, 2019). Here we (1) discuss implications of inadequate taxonomic sampling as a basis for changes in classification of species; (2) explain why the taxonomic sampling design of Roxo et al. (2019) is inadequate for the proposed nomenclatural changes; and (3) advocate that changes to classifications must be grounded on phylogenies with dense sampling of taxa at the relevant level.

A new species of Bryconops (Ostariophysi: Characiformes: Characidae) from the upper rio Tocantins drainage, Brazil

ABSTRACT A new species of the genus Bryconops , subgenus Bryconops , is described from the rio Conceição, a tributary to the rio Palma, upper rio Tocantins drainage, Tocantins State, Brazil. The new species is distinguished from all its congeners, except B. humeralis and B. vibex by the color pattern in vivo (dorsal, adipose, and caudal fins entirely orange). The new species is easily distinguished from B. humeralis and B. vibex by the absence of a humeral spot and by the lack of maxillary teeth (vs . presence of a single humeral spot and presence of 1-3 maxillary teeth on both sides). Furthermore, the new species is distinguished from B. vibex by the number of perforated lateral line scales (38-41 vs. 44-46).

Description of males of Phallotorynus pankalos Lucinda, Rosa & Reis, 2005 and reappraisal of Phallotorynus species relationships (Teleostei: Cyprinodontiformes: Poeciliidae)

Recently discovered male specimens of Phallotorynus pankalos are described and diagnosed from males of congener species on the basis of gonopodial morphology, color pattern and number of dorsal and anal-fin rays. The phylogenetic hypothesis of relationships among Phallotorynus species is reappraised with the inclusion of P. pankalos. Phallotorynus pankalos is hypothesized as sister to P. jucundus, a clade sister to P. victoriae or to a clade composed of P. dispilos and P. psittakos. Biogeography of Phallotorynus species is discussed, and it is suggested: (1) an early basal split between the rio Paraíba do Sul drainage and the Paraná-Paraguay system, separating P. fasciolatus from the ancestor of the remaining Phallotorynus species followed by a dispersal to rio Paraíba do Sul; (2) that the formation of the Sete Quedas falls may have isolated the ancestors of P. psittakos and P. dispilos. However, the sequence of events associated with the evolutionary history of Phallotorynus remains unclear and unsatisfactory.

A new species of the genus TetragonopterusCuvier, 1816 (Ostariophysi: Characiformes: Characidae) from the rio Tocantins drainage, Brazil

A new species of the genus Tetragonopterus is described from specimens of the upper and middle portions of the rio Tocantins drainage. The new species can be distinguished from all congeners by the possession of a very uniquely shaped maxilla.

Three new Pimelodus species (Siluriformes: Pimelodidae) from the rio Tocantins drainage, Brazil

Three new species of Siluriformes from the rio Tocantins drainage of Brazil are placed in the genus Pimelodus, P. stewarti, P. joannis, and P. halisodous. Pimelodus halisodous differs from the sympatric P. joannis and P. stewarti by the number of premaxillary tooth rows (13-16 vs. 5-9). Pimelodus joannis differs from P. stewarti by the presence of two dark blotches on the base of the caudal fin. The three new species differ from all other species of Pimelodus by the possession of a uniform gray coloration along flanks; the relatively short distance between the posterior nostril and the anterior orbital border; a short maxillary barbel, that only slightly surpasses the caudal-fin base.

Fish, Lajeado Reservoir, rio Tocantins drainage, State of Tocantins, Brazil

The Lajeado HR is the fourth hydroelectric power plant constructed in the rio Tocantins. The implementation of hydroelectric plants in the rio Tocantins basin is of high environmental concern because they may result in severe damage to the ichthyofauna. A species list of the area of influence of the Lajeado HR is provided, in the hope that it will contribute to the knowledge of this potentially threatened ichthyofauna. A few comments on the ichthyofauna of the rio Tocantins drainage are also provided.

Astyanaxelachylepis, a new characid fish from the rio Tocantins drainage, Brazil (Teleostei: Characidae)

A new characid species, Astyanax elachylepis, is described from the rio Tocantins drainage. The new species is distinguished from its congeners by possessing 48-53 perforated scales along the lateral line, a large caudal-peduncle spot, the presence of bony hooks on dorsal, anal, pelvic, and pectoral fins of males, one or two vertically-elongated humeral spots, one maxillary tooth, and 22-27 branched anal-fin rays.

Systematics and biogeography of the genus Phalloptychus Eigenmann, 1907 (Cyprinodontiformes: Poeciliidae: Poeciliinae)

The genus Phalloptychus is revised. Phalloptychus iheringii is removed from the synonym of P. januarius. Three species are recognized: P. eigenmanni, P. januarius, and P. iheringii. Phalloptychus eigenmanni can be distinguished from its congeners by the number of pelvic-fin rays in females, the number of predorsal scales, and the predorsal distance in females. Phalloptychus iheringii and P. januarius can be distinguished by the number of epipleural ribs, number of gonopodial rays, and a significantly different number of vertical bars along body side in females. Lectotypes are designated for Girardinus iheringii and G. januarius. Redescriptions and known distribution ranges are provided for each species as well as an identification key. Derived features supportting the monophyly of the genus and infrageneric clades are presented and discussed. The biogeo-graphic implications of the geographic distribution of Phalloptychus species are discussed.

Systematics of the genus Cnesterodon Garman, 1895 (Cyprinodontiformes: Poeciliidae: Poeciliinae)

A phylogenetic hypothesis of relationships is proposed for the species of Cnesterodon. A series of derived features supports the monophyly of the genus and infrageneric clades. The genus Cnesterodon is revised, with Gulapinnus considered a junior synonym. A lectotype is designated for Poecilia decemmaculata Jenyns. Nine species of Cnesterodon are recognized: C. decemmaculatus, C. carnegiei, C. brevirostratus, C. septentrionalis, C. omorgmatos, C. hypselurus, C. raddai, a new species from the rio Ribeira de Iguape, described herein, and a new species from the Rio Grande do Sul, being described by in a separate paper. Diagnoses and distribution ranges are provided for each species as well as a key to identification of the species.