Phylogeography of Hypomasticus copelandii (Teleostei, Anostomidae) Reveals Distinct Genetic Lineages along Atlantic Coastal Drainages of Eastern Brazil

Abstract

Hypomasticus copelandii is a Neotropical freshwater fish widely distributed across coastal drainages of southeastern Brazil, a highly impacted region of South America. The interspecific phylogenetic relationships within the genus and the taxonomic status of the species remain uncertain. Using two mitochondrial and one nuclear locus, we performed a phylogenetic, species delimitation, and time-calibrated analyses to test the hypothesis that H. copelandii is a species complex currently delimited by different Atlantic coastal systems. Results indicate that H. copelandii presents two well-delimited genetic lineages: one in the northern drainages of the Jucuruçu, Mucuri and Doce rivers, and the other in the southern region represented by the Paraíba do Sul River Basin. The time-calibrated phylogeny indicated a split between the two genetic lineages at around 2.8 million years ago (Ma), which might be related to headwater capture events during the Plio-Pleistocene. The discovery of a distinct genetic lineage for H. copelandii suggests distinct management plans for the northern and southern drainages. Such hidden diversity within the H. copelandii provides useful information for taxonomy and conservation across a severely impacted region of Brazil.

Past riverine connectivity effects in population structure and distribution of an endemic freshwater fish from northeastern Brazilian rivers: Phylogeographic, taxonomic, and conservation implications

“…In general, our results demonstrate that the existence of molecular structure of populations previously identified as C. bahiense (i.e., CB1 and CB2) is observed only in mtDNA (Figures 1 and 4), leading to a mitonuclear discordance. Mitonuclear discordance have been reported in other freshwater fish species of different families, such as Cichlidae ( Oreochromis Günther, Ford et al, 2019), Cyprinidae ( Squalius Bonaparte; Perea et al, 2016), and Anostomidae ( Hypomasticus Borodin; Mendes et al, 2022). This discordance may result in limitations in species delimitation based on molecular data, due to certain biological attributes (e.g., introgression and selection) that affect nuclear and mitochondrial markers differently (Flouri et al, 2018; Marshall et al, 2021).…”

“…The morphological results revealed that measurements displayed overlap between CB1 and CB2 populations, and while statistically significant differences were observed, the ability to reliably utilise external body shape for morphological delimitation between these populations remains elusive. Meristics and col- and Anostomidae (Hypomasticus Borodin; Mendes et al, 2022).…”

The role of Miocene-Pleistocene environmental change in diversification of the genusHypoclinemusChabanaud, 1928

“…Hypoclinemus mentalis is widely distributed throughout Greater Amazonia, which includes the Amazon, Essequibo, and Orinoco basins [31]. Its large distribution raises questions as to whether Hypoclinemus is in fact monotypic, since other widespread neotropical fishes have been recently split into multiple species (e.g., De Santana et al [32]; Garavello et al [33]) or shown to include hidden diversity represented by multiple species-level lineages (e.g., Mendes et al [34]).…”