Descrição Morfológica robusta e primeiros traços ecológicos para a população de Hyalella Smith, 1874 (Amphipoda: Hyalellidae) do Guareí

Abstract

The present dissertation describes a new species of the genus Hyalella Smith, 1874, and investigates its ecological traits related to population structure and reproductive parameters in a freshwater ecosystem in southeastern Brazil. Variables such as sex ratio, body size, fecundity, and egg volume of females were analyzed. Significant results were observed for the analyzed variables, indicating that environmental factors directly influence life-history strategies. The morphological data collected supported the preparation of a taxonomic article, which resulted in the formal description of the new species. Distinguishing traits from the other 22 species reported for southeastern Brazil include: absence of a curved seta on the inner ramus of uropod 1 in males; sternal gills present on segments 3–7; presence of comb-scales on both gnathopods; gnathopod 2 with two distal plumose setae on the dactylus; uropod 3 with peduncle bearing three cuspidate setae with an accessory seta, and ramus with eight setae; maxilla 1 with seven serrate setae on the outer plate; and telson with four distal cuspidate setae and four lateral plumose setae on each side. Therefore, the results obtained reinforce the importance of environmental conditions in determining population and reproductive characteristics, contributing to the ecological understanding of the genus Hyalella and providing a basis for future conservation efforts.