Genus Hyalella (Amphipoda: Hyalellidae) in Humid Pampas: molecular diversity and a provisional new species

Abstract

Hyalella is a genus of epigean freshwater amphipods endemic to the Americas. The study of morphological characters alone has traditionally dominated the description of new species. Recently, molecular systematics tools have contributed to identifying many cryptic species and a high level of convergent evolution in species complexes from North America and the South American highlands. In this study, we evaluate for the first time the molecular diversity in Hyalella spp. in Uruguay, a country located in the humid pampa ecoregion, based on four molecular markers. Thus, we investigate the systematic position of H. curvispina in the context of the available phylogenetic hypothesis for the genus. Phylogenetic and morphological analyses confirm that there is a “curvispina complex”. This complex includes H. curvispina and several similar morphological forms but is paraphyletic in relation to some altiplano species. In addition, we found one provisional new species. The results obtained are contrasted with previous studies to help understand the mechanisms of genetic differentiation and speciation of the genus, which seems to have a strong tendency towards morphological convergence.

Two new species of Hyalella (Amphipoda, Dogielinotidae) from the Humid Chaco ecoregion of Paraguay

“…nov. and H. julia sp. nov. can be recognised as distinct species based on the taxonomic keys by Damborenea et al (2020) and morphological differences from other recently described South American species ( Reis et al 2020 ; Jaume et al 2021 ; Limberger et al 2021 ; Rocha Penoni et al 2021 ; Talhaferro et al 2021a , b ; Vernica et al 2022; Waller et al 2022 ; Peralta and Verónica 2023 ; Reis et al 2023 ). Both H. mboitui and H. julia show a smooth body without dorsal or lateral processes or mucronations, have pigmented eyes, and lack setae on the dorsal margin of uropod 3.…”

“…The two new Paraguayan taxa are also readily distinguishable from recently described Hyalella species from nearby Argentina ( Peralta and Miranda 2019 ; Vernica and Alejandra 2022 ) and southern Brazil ( Reis et al 2020 ; Limberger et al 2021 ; Rocha Penoni et al 2021 ; Talhaferro et al 2021a , b ) by the number and type of setae on the telson and uropods 1 and 3 (Figs 5B, D , 11B, D ). Their level of morphological differentiation also indicates that the new Paraguayan species cannot be subsumed under the South American H. curvispina Shoemaker, 1942 species complex, which appears to comprise significant cryptic diversity based on recent molecular marker analyses ( Waller et al 2022 ). Despite similarities in telson shape and the morphology and setal cover of maxillae and maxillipeds (Figs 2H–J , 8H–J ; Shoemaker 1942 ; Grosso and Peralta 1999 ), H. mboitui and H. julia are distinguished from H. curvispina by their diagnostic mandibular dentition, the absence of a plumose seta on the dactyli of male gnathopods, the number of setae on the telson, and the shape and number of setae of the uropod 3 peduncle, which is wider than long in H. curvispina ( Shoemaker 1942 ; Grosso and Peralta 1999 ; Damborenea et al 2020 ) but not in H. mboitui and H. julia (Figs 5D , 11C ).…”

“…However, occurrences of this genus have not been systematically documented in their neighbouring country, Paraguay. Recent taxonomic and genetic studies of Hyalella suggest that the full extent of its diversity and distribution is vastly underestimated ( Limberger et al 2021 ; Talhaferro et al 2021a ; Waller et al 2022 ). Therefore, reported discrepancies in regional taxonomic richness may be largely due to limited sampling ( Reis et al 2020 , 2023 ).…”

Description of a new thermal species of the genus Hyalella from Peru with molecular phylogeny of the family Hyalellidae (Crustacea, Amphipoda)

“…Recent molecular phylogenetic analyses have revealed the presence of many cryptic species in this genus (Witt et al . 2006; Waller et al . 2022) and further research is expected to increase the number of Hyalella species to 500 (Väinölä et al .…”

“…Hyalella occurs in freshwater; most are surface species but a few groundwater species are also known (Cardoso et al 2014;Rodrigues et al 2014). Recent molecular phylogenetic analyses have revealed the presence of many cryptic species in this genus (Witt et al 2006;Waller et al 2022) and further research is expected to increase the number of Hyalella species to 500 (Väinölä et al 2008). Molecular phylogenetic analyses also reveal an interesting evolutionary history, including a Gondwanan origin of Hyalellidae and Chiltoniidae, (Cannizzaro and Berg 2022) and multiple origins of species in Lake Titicaca, South America (Adamowicz et al 2018;Zapelloni et al 2021).…”