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.
Armadillidium vulgare (Latreille, 1884) and Armadillidium nasatum (Schultz, 1961) are among the most common species of terrestrial isopods in Uruguay. The reproductive pattern of these species was studied, for first time, on a natural population at Department of San Jose (Uruguay) from June 2010 to July 2011. A total of 9136 individuals were sampled, of these 7010 were A. vulgare and 2126 were A.nasatum. Adults of A. vulgare were present throughout the year and juveniles appeared from February to November. Juveniles and adults of A. nasatum appeared from January to October, and practically disappeared from November to December. For both species ovigerous females were collected from spring to summer (October to March), this would indicate a seasonal reproduction followed by a sexual rest. In A. vulgare reproductive females cephalothorax width that varied between 1.7 to 3 mm, average fecundity was equal to 39 ± 5 eggs and average fertility was equal to 27 ± 4. In A. nasatum cephalothorax width of reproductive females oscillated between 1.5 to 2.9 mm and the average fecundity was 44 ± 5 eggs. For both species, fecundity and fertility were positively correlated with the size of the females. The incubation period ( ̅ = 13 days) and the mancas born ( ̅ = 21) were similar for both species.
Voucher specimens are the physical representatives of a species, being an elementary tool for specimenbased research. In this work, we revisit a recent record of Sibynomorphus mikanii for Santa Catarina, providing arguments for its invalidation, while reinforcing the need for a cautious review of new records based on incomplete or doubtful data.
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