Cytogenetic and molecular analyses in troglobitic and epigean species of Pimelodella (Siluriformes: Heptapteridae) from Brazil

Abstract

Samples from seven different locations of the genus Pimelodella were genetically examined, two caves (exclusively subterranean, upper Tocantins River and São Francisco River) and five epigean (from upper Paraná River basin). Cytogenetic analyses revealed the same diploid number (2n=46) for all species besides similarities in both number and location of nucleolar organizer regions and C bands. FISH with 5S rDNA probes and CMA 3 staining indicated significant differences among the studied species. Application of PCR-RFLP in ATPase 6 and 8 mitochondrial genes allowed building a minimum evolution phenogram identifying the close evolutionary relationship among groups. Both chromosomal and molecular data were useful to infer the relationships among studied Pimelodella species.Amostras de sete diferentes localidades do gênero Pimelodella foram geneticamente analisadas, duas cavernícolas (exclusivamente subterrâneas, alto rio Tocantins e rio São Francisco) e cinco epígeas (provenientes da bacia do alto Paraná). Análises citogenéticas revelaram o mesmo número diploide (2n=46) para todas as espécies, além de similaridades no número e localização das regiões organizadoras de nucléolo e bandas C. FISH com sondas de rDNA 5S e marcação com CMA 3 indicaram diferenças significativas entre as espécies estudadas. A aplicação da técnica de PCR-RFLP nos genes mitocondriais ATPase 6 e 8 permitiu a construção de um fenograma de evolução mínima identificando uma estreita relação evolutiva entre as espécies estudadas.

Enzymatic distance in two species of the genus Pimelodella (Siluriformes, Heptateridae) from the Upper Paraná River basin, Paraná State, Brazil

“…Many are the difficulties remaining to identify the genus Pimelodella by means of morphological characters once it possesses the largest number of species of the Heptapteridae family, around 82 valid ones (Terra et al, 2022). There are also the voucher species that were not filed yet (Dazzani, Garcia, Peixoto, Trajano, & Almeida-Toledo, 2012). The traditional classification based on morphology needs to be revised (Slobodian et al, 2017;Conde-Saldaña, Albornoz-Galzón, García-Melo, & Villa-Navarro, 2019;Alves, Chambrier, Luque, & Scholz, 2020).…”

Spinitectus aguapeiensis n. sp. (Nematoda: Cystidicolidae) from Pimelodella avanhandavae Eigenmann (Siluriformes: Heptapteridae) in the River Aguapeí, Upper Paraná River Basin, Brazil

“…Pimelodella is the most species-rich genus within the family Heptapteridae, with 71 valid species largely distributed in South America (Bockmann & Guazzelli, 2003;Froese & Pauly, 2016). Its representatives are small to medium-sized catfishes (less than 15 to 20 cm in length), dwelling in several habitats, like streams, large rivers and surface or subterranean environments (Dazzani et al, 2012). Pimelodella avanhandavae Eigenmann is an endemic species to South America, distributed mostly in Brazil, along the Upper River Paraná, and is popularly known as ''mandizinho'' and/ or ''mandi-chorão''.…”