Hidden or unnoticed? Multiple lines of evidence support the recognition of a new species of Pseudocorynopoma (Characidae: Corynopomini)

Abstract

Species delimitation is a permanent issue in systematics. The increasing recognition of geographically isolated populations as independent lineages allowed by new methods of analysis has inflated the species‐populations dilemma, which involves deciding whether to consider separate lineages as different species or structured genetic populations. This is commonly observed between fishes of adjacent river basins, with some lineages being considered allopatric sister species and others considered isolated populations or variants of the same species. Pseudocorynopoma doriae is a characid diagnosed from its single congener by the number of anal‐fin rays and sexually dimorphic characters of males, including distinct fin colouration. The authors found variation in the colour pattern between isolated populations previously identified as P. doriae but no variation in scale or fin‐ray counts. They analysed molecular evidence at the population level and morphological differences related to life history (e.g., colour dimorphism related to inseminating behaviour). The results provide compelling evidence for the recognition of a new species of Pseudocorynopoma despite the lack of discrete differences in meristic data. The recognition of the new species is consistent with biogeographical evidence for the long‐term isolation of the respective river drainages and with differences between the ichthyofaunal communities of these rivers.

A new species of Geophagus (Teleostei: Cichlidae): Naming a cichlid species widely known in the aquarium hobby as ‘Geophagus sp. Tapajos red head’

“…The use of multiple lines of evidence is an increasing strategy in recovering and describing biological diversity, especially in the case of Neotropical fishes (Malabarba et al ., 2021). The new species described herein has long been classified as a different morphotype of the genus Geophagus in the aquarium hobby, based mostly on the peculiar red or orange colour pattern observed on the head and anterior portion of the body (Figure 8; López‐Fernández & Taphorn, 2004; Silvano et al ., 2020).…”

The record and threats of the invasion of palometa Serrasalmus maculatus (Characiformes: Serrasalmidae) in the Patos lagoon drainage, southern Brazil

“…The fish fauna from the Uruguay River and Patos Lagoon drainages have been historically isolated, as demonstrated by their compositions, with 275 and 200 species, respectively, of which only 86 occur in both basins (Bertaco et al ., 2016). In addition, there is a clear sister group pattern of relationships between several pairs of species of fishes from the Uruguay River and Patos Lagoon drainages, with registered divergence times ranging from 2.5 million of years before the present (MYBP) to 0.6 MYBP (Malabarba et al ., 2020). Species naturally codistributed in both drainages ( e.g ., Austrolebias quirogai Loureiro et al ., 2011, and Cnesterodon decemmaculatus [Jenyns 1842]) may represent recent fish faunal dispersal events due to drainage rearrangements, whose population divergences dated to <0.1 MYBP (Loureiro et al ., 2011; Ramos‐Fregonezi et al ., 2017).…”