RESUMEN
A new species of freshwater amphipod belonging to genus Hyalella is described from a peatbog at high altitudes (3,650 to 4,400 m above sea level) in the Puna region (Salta province, northwestern Argentina). The new species can be distinguished from other hyalellid species by the following combination of characters: dorso-posterior flanges on pleonites I-III; palp on maxilla 1 reaching almost half of distance between base of palp and base of setae on outer plate, and two papposerrate setae on the inner margin of inner plate of maxilla 2; propodus of gnathopod 1 hammer-shaped, inner face with seven serrate setae; propodus of gnathopod 2 ovate; male uropod 1 without curved seta on inner side of inner ramus; ramus of uropod 3 shorter than peduncle; six pair of sternal gills on pereionites II-VII. A detailed morphological description and illustrations of the new species are provided. In Argentina, the new species represents the third record for the genus at altitudes greater than 2,000 m a.s.l., after H.kochi and H.fossamancinii (Dos Santos et al. 2008, González 2003), and the first record above 4,000 m a.s.l. Some comments about distributional and ecological aspects of the new species are included. With this new species, the number of Hyalella species known from Argentina and Falkland Islands (Islas Malvinas) rises to 12.
RESUMEN
The adult, larva, and pupa of Helicopsyche obscura sp. nov. from northwestern Argentina are described and illustrated. Descriptions and illustrations of adults and associated pupae and larvae of Helicopsyche turbida Navás and Leptonema boliviense boliviense Mosely are included. The associations of immature stages were made using the metamorphotype method. Helicopsyche turbida is newly recorded from Tucumán province. The adult males of H. obscura sp. nov. and H. turbida have similar structure in the genital segments, however, the most clear differences are in the general color and size of the adult, and in the color, size, and morphology of the metanota in the larval stages as well as the shapes of mandibles, hook plates, and terminal segments of the pupal stages. The larva and pupa of L. boliviense boliviense are compared with those of L. columbianum and other previously described species, providing differences in color, chaetotaxy, and morphology.
