Taxonomia de Hyalella Smith, 1874 (Amphipoda: Hyalellidae) da parte alta do Parque Nacional do Itatiaia, RJ e MG

Abstract

Hyalella Smith, 1874 is a genus of freshwater amphipod endemic to the American continent. In South America, this is the only epigeal freshwater genus and, despite this, its diversity is little explored. Considering the different degrees of sensitivity to environmental pollution of hyalellids and the rapid depredation of lake ecosystems, it is urgent to expand knowledge about the group and its different species. In view of this, this dissertation aims to carry out a taxonomic analysis of species of the genus Hyalella belonging to an area of conservation priority, the Itatiaia National Park. The material was collected in 2012 and 2013, in the regions of 22°21'22"S – 44°44'07"O, 22°24'S – 44°41'O e 22º22′13,3″S – 44º42′32,6″O, with the species present in the first two localities being new species (Hyalella sp. nov. 1 and Hyalella sp. nov. 2), while the latter were specimens of H. montana Rodrigues, Senna, Quadra & Bueno, 2017. Each new species was dissected, illustrated and digitalized. Hyalella sp. nov. 1 has as its main characteristics paposerrate setae on the inner plate of maxilla 2; gnathopod 1 with serrate setae at the base, ischium, merus, carpus and propodus, inner surface of the carpus and propodus with serrate setae with accessory seta, carpal lobe with scales and postero-distal margin of the propodus with scales and polygonal pattern; gnathopod 2 with serrate setae at the base, ischium, merus and anterior margin of the carpus, merus and carpus also with serrate setae with accessory seta; uropod 1 of the male with a curved setae on the inner ramus; epimeral plate 2 acuminate and larger than the others. Hyalella sp. nov. 2 differs from the others in that it has an apical setae on the palp of maxilla 1; maxillipod with a serrate distal nail; gnathopod 1 with serrate setae at the base, ischium, merus, carpus and propodus, serrate setae with accessory seta on the inner surface of the carpal lobe and propodus and the presence of a polygonal pattern on the ischium, merus, propodus and dactyl; gnathopod 2 with a serrate setae at the base, ischium, merus and carpus, base, merus and carpus also with serrate setae with accessory seta; the male's uropod 1 has, as a variation, a curved seta on the inner ramus and, when present, it has an accessory seta. The UERJ crustacean collection was strengthened with 1,556 specimens of the three species distributed in 110 new lots. A dichotomous key was also developed for the male of epigeal species from southeastern Brazil, in which the species H. montana appears twice due to the fact that its specimens may or may not have eyes present. At the end of this work, the total number of officially valid Brazilian species rises to 44, of which 19 belong to the southeast region (seven in Minas Gerais, seven in São Paulo, in addition to H. warmingi Stebbing, 1899, described for both states and four in Rio de Janeiro), 15 of which are epigeal