A new species of freshwater amphipod (Crustacea, Peracarida, Hyalellidae) from Southern Brazil

Abstract

The freshwater amphipod of the genus Hyalella is typical from continental American waters and shows high levels of endemicity and Brazil has the second largest diversity. A new species is described here, Hyalella longipropodus n. sp. that occurs in a spring of southern Brazil in the municipality of Palmeira das Missões, in the northwestern region of state of Rio Grande do Sul, southern Brasil. Hyalella longipropodus n. sp. shows the following character states: antenna 2 more than half body length, gnathopod 2 propodus elongated, uropod 1 inner ramus of male without apical curved setae, uropod 3 peduncle with seven strong distal setae with accessory setae, ramus of uropod 3 with ten cuspidate setae with accessory setae. Hyalella longipropodus n. sp. occurs in sympatry with H. gauchensis, but these differ especially in the size and shape of gnathopod 2, the presence of curved setae on uropod 1 in H. gauchensis and the absence in H. longipropodus n. sp., antenna length (longer in H. longipropodus n. sp.) and number of cuspidate setae on uropods 1, 2, and 3. Besides the morphological differences, H. longipropodus n. sp. presented genetic differences always above 19% for the COI gene and 29 % for the 16S rRNA gene, when compared with other species found in the northwestern region of the state of Rio Grande do Sul, showing that it is really a species not yet described by science.

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

“…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 ).…”

“…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.…”

“…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 ).…”

“…Amphipods, including Hyalella , sustain key links in matter and energy transfers in freshwater ecosystems, where they act as ecologically abundant grazers and detritivores, provide hosts for diverse micro- and macro-parasites, and serve as important prey items for both vertebrate and invertebrate predators ( Duffy and Hay 2000 ; Castiglioni and Bond-Buckup 2008 ; Giari et al 2020 ; Streck-Marx and Castiglioni 2020 ). Members of Hyalella support these critical ecosystem functions across diverse habitats, from hypogean waters to wetlands, from sea level up to above 4000 metres of elevation and inhabit both benthic sediments and a range of aquatic macrophytes ( Castiglioni and Bond-Buckup 2008 ; Limberger et al 2021 ; Zapelloni et al 2021 ).…”

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

“…There are 84 described species of Hyalella (Tuparai Talhaferro et al 2021;Limberger et al 2021), but taxonomic knowledge of the genus is incomplete. Highly complex cryptic species with very subtle interspecific and interpopulation morphological variations (Worsham et al 2017) make identifying and differentiating species challenging.…”