Identification of cryptic species in allopatric populations of Hypostomus tietensis (Siluriformes: Loricariidae) through cytogenetics analyses

Abstract

Hypostomus is the most specious genus of Hypostominae, composed of several species with high intraspecific morphological and color pattern variation, making their identification a complex issue. One of the species with problematic identification is Hypostomus tietensis that was described from a single specimen, resulting in uncertainties about its color pattern and correct identification. To assist in this context, cytogenetic analyzes were carried out in three putative populations of H. tietensis from the Upper Paraná River basin, one of them from the type locality. The three populations showed considerable cytogenetic differences, with 2n = 72 chromosomes for the population from the type locality and 2n = 76 chromosomes for the others. Terminal NORs were detected (Ag- and 18S rDNA-FISH), being simple for the type locality population (acrocentric pair 23, long arm) and the Pirapó River (subtelocentric pair 11, short arm), and multiple for Do Campo River (subtelocentric pairs 11 and 12, short and long arm, respectively). C-banding was efficient in differentiating the type locality population from the others. Cytogenetic data revealed that populations from Pirapó and Do Campo rivers, although treated until now as Hypostomus aff. tietensis, represent a cryptic species, and those morphological analyses are necessary to differentiate and for describing this new species.

Karyotype of the Mormyrid Baby Whale Fish (Osteoglossiformes: Mormyridae): Brienomyrus Brachyistius in Oluwa River, Nigeria

“…Therefore, a better comprehension of the diversity, taxonomy and phylogeny of the Mormyridae requires additional tools to complement the use of morphometric, osteological and analysis of mormyrids' electric organ discharge systems (Boden et al, 1997;Hopkins et al, 2007;Hilton, 2003;Kramer et al, 2013;Hilton. & Lavoué, 2018) The advent of molecular cytogenetic methods has paved the way for the discovery of many cryptic species, species complexes, and hybrid characterization and provided data for taxonomic, evolutionary, biogeographical, and phylogenetic studies of many fish taxa (Nakayama et al, 2001;Milhomem et al, 2008;Poletto et al, 2010;Cioffi et al, 2018;Barby et al, 2018;Toma et al, 2019;da Costa et al, 2019;Borges et al, 2019;Goes et al, 2020;Kretschmer et al, 2021;Paula et al, 2022Machado et al, 2022. However, the conventional cytogenetic approach is still valuable and can provide insight into the species diversity of some fish groups (Reviewed in Cioffi et al, 2019;Jegede et al, 2018).…”

Turnover of multiple sex chromosomes in Harttia catfish (Siluriformes, Loricariidae): a glimpse from whole chromosome painting

“…Despite their great diversity in morphology, ecology, and habitats, Loricariidae is recovered as a monophyletic group in both morphological and molecular phylogenetic reconstructions, though the relationships between the tribes and genera have not been fully resolved so far (Covain et al, 2016;Londoño-Burbano and Reis, 2021). In this context, cytogenetic research provides important landmarks for solving issues related to taxonomy, phylogeny, and biodiversity in loricariids (e.g., Rocha-Reis et al, 2018;Glugoski et al, 2020;Takagui et al, 2020;Takagui et al, 2023;de Paula et al, 2022) as well as in other teleosts (Bellafronte et al, 2005;Cioffi et al, 2018;Gavazzoni et al, 2023). Moreover, particularly in the Neotropical region, with the richest freshwater biodiversity on the planet (Albert et al, 2020), cytogenetic investigation has abundant opportunities to deeply scrutinize the relationship between karyotype and sex chromosome evolution and reproductive isolation/diversification (Cioffi et al, 2017;Cioffi et al, 2018;de Souza et al, 2022).…”