Systematic revision of the Neotropical catfish genus Scleronema (Siluriformes: Trichomycteridae), with descriptions of six new species from Pampa grasslands

Abstract

<jats:p>ABSTRACT The Neotropical genus Scleronema is revised based on the re-examination of the type specimens and 1,713 newly collected specimens. Scleronema is diagnosed from other trichomycterids by the following unambiguous derived characters: fleshy flap at the base of the maxillary barbell; skin flap in the posterior margin of the opercle; articulation between the autopalatine and the vomer ventrally located, with the medial margins of the autopalatines very close to each other; and autopalatine with an interrupted or not interrupted ossified arch-shaped process on its dorsal surface forming a canal. Scleronema minutum and S. operculatum are redescribed, S. angustirostre is considered a junior synonym of S. minutum, and six new species are described. A lectotype is designated for Trichomycterus minutus. The type localities of S. angustirostre, S. minutum, and S. operculatum are reviewed in order to correct erroneous information cited in articles and catalogs subsequent to the original descriptions. Species of Scleronema are geographically distributed in the La Plata basin and Atlantic coastal drainages from Southern Brazil, Southern Paraguay, Northeastern Argentina and Uruguay. They inhabit rivers or streams with sand- or gravel-bottoms across the Pampa grasslands. We provide evidences to recognize two putative monophyletic units within the genus, namely the S. minutum species group and the S. operculatum species group, and discuss the distribution patterns of their species.</jats:p>

A new species from subtropical Brazil and evidence of multiple pelvic fin losses in catfishes of the genus Cambeva (Siluriformes, Trichomycteridae)

“…As discussed above, this study indicates that the pelvic fin and pelvic-fin support have been lost independently in three lineages of the genus Cambeva, corresponding to three species in a total of 27 (11.1%). This result highly contrasts with the closely-related trichomycterine genus Trichomycterus, in which only one species, T. candidus, does not have pelvic fin and girdle, amongst a total of 50 valid species (0.2%), as well as Scleronema, the sister group of Cambeva (Katz et al, 2018), with all the nine included species having well-developed pelvic fin and girdle (Ferrer and Malabarba 2020). These data suggest a stronger tendency to losing pelvic fin in Cambeva than in these closely-related genera, but factors favouring this evolutionary event are still unknown.…”

Comparative Osteology, Phylogeny and Classification of the Eastern South American Catfish Genus Trichomycterus (Siluriformes: Trichomycteridae)

“…The nomenclatural solution found by Katz et al [9] was to restrict Trichomycterus to the molecularly well-supported subclade including T. nigricans and to describe a new genus Cambeva Katz, Barbosa, Mattos and Costa 2018 for the subclade sister to Scleronema. Presently, Cambeva comprises 29 species [23], Scleronema, eight species [24] and Trichomycterus sensu Katz et al [9] (hereafter Trichomycterus s.s. [sensu stricto]), 60 species [25]. Trichomycterus s.s. occurs in a broad area between the Rio de Contas basin, north-eastern Brazil, at about 13 • 30 S [26] and the rivers draining the Baía de Paranaguá basin, in southern Brazil, at about 48 • 15 S [27].…”

Peces endémicos de sistemas fluviales de la Selva Atlántica en la Argentina: Áreas prioritarias para su conservación

“…Además, se consultaron listas actualizadas de especies disponibles en Sudamérica (Reis et al 2003) (Mirande and Koerber 2020). Para determinar la distribución y el estatus de las especies de peces consideradas se consultó una amplia serie de trabajos publicados en las últimas dos décadas (López et al , 2008Casciotta and Almirón 2008;Araya et al , 2012Piálek et al 2011Piálek et al , 2015Piálek et al , 2019Říčan et al 2011, 2017Baumgarter et al 2012;Almirón et al 2014a,b;Azpelicueta and Koerber 2015;Casciotta et al 2015Casciotta et al , 2016Casciotta et al , 2017Liotta 2016;Aguilera et al 2017;Terán et al 2017;Alonso et al 2019;Ferrer and Malabarba 2020;Flores et al 2020;Mirande and Koerber 2020). Se seleccionaron las especies endémicas de cursos fluviales de la Selva Atlántica por su importancia reconocida en la conservación (Burlakova et al 2011).…”