Cryptic diversity and diversification processes in three cis-Andean Rhamdia species (Siluriformes: Heptapteridae) revealed by DNA barcoding

Abstract

The wide distribution of the Neotropical freshwater catfish Rhamdia offers an excellent opportunity to investigate the historical processes responsible for modeling South America's hydrogeological structure. We used sequences from cis-Andean and Mesoamerican Rhamdia species to reconstruct and estimate divergence times among cis-Andean lineages, correlating the results with known geological events. Species delimitation methods based on distance (DNA barcoding and BIN) and coalescence (GMYC) approaches identified nine well-supported lineages from the cis-Andean region from sequences available in the BOLD dataset. The cis-Andean Rhamdia lineages diversification process began in Eocene and represented the split between cis-Andean and Mesoamerican clades. The cis-Andean clade contains two principal groups: Northwest clade (MOTUs from Amazon, Essequibo, Paraguay, and Itapecuru basins) and Southeast clade (Eastern Brazilian shield basins (Paraná, Uruguay, Iguaçu, and São Francisco) plus eastern coastal basins). The diversification of the cis-Andean Rhamdia lineages results from vicariance and geodispersion events, which played a key role in the current intricate distribution pattern of the Rhamdia lineages. The wide geographical distribution and large size of the specimens make it attractive to cultivate in different countries of the Neotropical region. The lineages delimitation minimizes identification mistakes, unintentional crossings by aquaculture, and reduces natural stocks contamination.

Neotropical sisterhood: new species of Gyrodactylus von Nordmann, 1832 (Platyhelminthes: Monogenea) infecting Rhamdia guatemalensis and Rhamdia laticauda (Siluriformes: Heptapteridae) in Mexico

“…The distinction of these two species is supported by the studies by Perdices et al (2002), in which the mtDNA analyses place the trans-Andean ‘ Rhamdia quelen ’ of Central America in a different clade from the typical cis-Andean R. quelen of South America (Hernández et al , 2015). Rhamdia quelen found in South America is known to be a complex of cryptic species, containing at least seven allopatric molecular operational taxonomic units associated to different hydrological basins (Ribolli et al , 2021), which could become separate species if shown to be independent evolutionary lineages.…”