Phylogenetic relationships and description of two new species of Diapoma (Characidae: Stevardiinae) from the La Plata River basin

Abstract

Herein we describe two new species of Diapoma, one from the Negro River, a tributary of the Uruguay River in Brazil and Uruguay, and one from the Iguaçu River, in Brazil and Argentina. The new species from the Negro River basin is distinguished from its congeners by the following combination of characters: a black narrow and conspicuous line restricted to the body horizontal septum, incomplete lateral line, tricuspid teeth in the inner series of the premaxilla, and a lower body depth at vertical through the dorsal-fin origin (29.3–32.8% SL in males and 27.7–33.3% SL in females). The new species from the Iguaçu River basin is distinguished from its congeners by the following combination of characters: a discontinuous lateral line, adipose fin hyaline, longer anal-fin base (26.5–32.4% SL), and a longitudinal black stripe along the median region of caudal-fin rays. Additionally, we updated the molecular phylogeny of the genus, including new sequences from these two new species and Diapoma thauma. An identification key for species of Diapoma is presented, modified from previous study.

On the lectotype designation of Bryconamericus rubropictus (Berg) (Characiformes, Characidae, Stevardiinae)

“…The genus Bryconamericus Eigenmann 1907 with c. 50 valid species is currently classified within the family Characidae (1255 valid species), as a member of the tribe Diapomini in Stevardiinae (364 spp.) (Ferreira et al, 2021;Fricke et al, 2023;Ito et al, 2022;Mirande, 2019;Thomaz et al, 2015).…”

Here comes the large catfish “jaú” Zungaro jahu (Ihering 1898) (Teleostei, Pimelodidae): a new alarming case of fish introduction in a high-endemism Neotropical ecoregion

“…non-native catfish "jaú" Zungaro jahu (55 cm standard length) took place. Ito et al, 2022). In addition, it is a migratory species (Agostinho et al, 2003;Alves et al, 2007) usually found in fast-flowing waters, rocky bottoms, and deep waters in stretches of rivers wherein the natural flow is preserved (Agostinho et al, 2003;Suzuki et al, 2004).…”