Description of two new species of Physopyxis and redescription of P. lyra (Siluriformes: Doradidae)

Abstract

The genus and species Physopyxis lyra was originally described based on only one very distinctive specimen. Analysis of a larger number of specimens provided a more precise characterization of the genus and the type species. Additionally, two new species are described based on material already available in museums and new collections. Physopyxis lyra is characterized by having a well developed coracoid process with divergent tips, and only one series of spines on the lateral plates. Physopyxis ananas, new species, has a thin coracoid process, convergent, and more than one series of spines on the lateral plates. Physopyxis cristata, new species, is a slender species, characterized by an incomplete series of lateral plates and the presence of a middorsal series of spines formed by the tips of the vertebral neural spines. The poorly known geographic distribution of the genus Physopyxis is vastly enlarged to include various drainages of the Amazon and Essequibo basins.<br>Physopyxis lyra foi originalmente descrita com base em apenas um exemplar de características muito peculiares. Análises de um grande número de exemplares possibilitou uma caracterização mais precisa do gênero e da espécie tipo. Adicionalmente, duas novas espécies são descritas com base em material disponível em museus e em exemplares coletados recentemente. Physopyxis lyra é caracterizado por possuir um processo coracóide muito desenvolvido com as extremidades voltadas para fora, e por apresentar placas laterais com apenas uma fileira de espinhos. Physopyxis ananas, espécie nova, possui processo coracóide estreito e ligeiramente convergente, com mais de uma fileira de espinhos ao longo das placas laterais. Physopyxis cristata, espécie nova, é uma espécie menos robusta, caracterizada por possuir linha lateral incompleta com placas pouco desenvolvidas e presença de uma fileira mediana dorsal de espinhos, formada pela extremidade dos espinhos neurais das vértebras. A distribuição geográfica do gênero Physopyxis, muito pouco conhecida até então, é bastante ampliada, incluindo agora diferentes drenagens da bacia Amazônica e do Essequibo

Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units

“…Instead, in most topologies those two rivers are, respectively, more closely related to the Essequibo and Orinoco. Interestingly, the Negro and Branco share a miniscule number of exclusive species, with only three such cases, Physopyxis cristata Sousa, Rapp Py-Daniel (see Sousa, Py-Daniel, 2005), Apistogramma gibbiceps Meinken (see Kullander, 1980) and Crenicichla virgatula Ploeg (see Ito, 2013). This is remarkable in view of the massive physical connections between those basins.…”

Trichomycterus anhanga, a new species of miniature catfish related to T. hasemani and T. johnsoni (Siluriformes: Trichomycteridae) from the Amazon basin, Brazil

“…These catfish live interstitially on the sandy bottom and amongst the leaf litter and debris of riverbeds (Wosiacki, 2002). Recently, field work focusing on unusual microhabitats like leaf litter and sand banks has resulted in an increase in the number of records of miniature species (Sousa & Rapp Py-Daniel, 2005;Wosiacki et al, 2011), included the form reported herein.…”

Phylogenetic relationships of the South American Doradoidea (Ostariophysi: Siluriformes)

“…Since then, the taxonomic knowledge of the family has greatly increased. Sousa & Rapp Py-Daniel (2005) revised Physopyxis, describing two new species. Sabaj (2005) revised Leptodoras, describing three species as new.…”

“…However, in the Aspredinidae, auchenipterids Auchenipterichthys thoracatus, Centromochlus, and Trachelyopterus coriaceus (Soares-Porto, 1998: #35), and doradids Acanthodoras, Agamyxis, Anadoras, Astrodoras, Hemidoras, Megalodoras, Ossancora, Scorpiodoras, Trachydoras paraguayensis, and T. steindachneri (Higuchi, 1992: #105;Sousa, 2010: #67), the ventroposterior border of the coracoid is thick and visually exposed in alcohol-preserved specimens. In some species of Astrodoradinae, this feature is further developed, and the entire ventral face of the pectoral girdle is visually exposed in some cases (Sousa & Rapp Py-Daniel, 2005;Higuchi et al, 2007;Sousa, 2010).…”