Escola Paulista de Enfermagem: um pouco da sua história Escuela Paulista de Enfermería: un poco de su historia Paulista School of Nursing: a little bit of history

Universidade Federal de São Paulo (UNIFESP)UNIFESPSciEL

Evolutionary Divergence Among Oligosarcus

The Doce River, in southeastern Brazil, is a coastal drainage, configured since the Late Cretaceous, when South America separated from Africa. Of the 77 native fish species of the Doce River Basin, 37 are potentially endangered - Oligosarcus solitarius, Menezes 1987, is the only endemic species of the quaternary lakes in the middle portion of this drainage and Oligosarcus argenteus, Günther 1864, is distributed in the Doce River channel and headwaters. This study characterizes the morphological, cytogenetic, and mitochondrial DNA variation in the Oligosarcus spp. populations from the Doce and São Francisco River Basins. The principal component analysis indicates three morphological groups. Cytogenetic data corroborate existence of the O. solitarius and O. argenteus fish species in the Doce River Basin, with high levels of population cytogenetic polymorphism. Taking into consideration the Pleistocene-Holocene formation of the lacustrine system in the middle Doce River, with low molecular differentiation and high levels of chromosomal variation among the O. solitarius populations, we concluded that O. solitarius has the highest rate of chromosomal evolution observed in Neotropical freshwater fishes. The morphological and cytogenetic patterns of the Oligosarcus sp. population collected at the Das Velhas River headwaters suggest that it may represent an undescribed species. © Copyright 2015, Mary Ann Liebert, Inc. 2015

The first cytogenetic data on Strumigenys louisianae Roger, 1863 (Formicidae: Myrmicinae: Dacetini): the lowest chromosome number in the Hymenoptera of the neotropical region.

In the present study, the first cytogenetic data was obtained for the ant species Strumigenys louisianae, from a genus possessing no previous cytogenetic data for the Neotropical region. The chromosome number observed was 2n = 4, all possessing metacentric morphology. Blocks rich in GC base pairs were observed in the interstitial region of the short arm of the largest chromosome pair, which may indicate that this region corresponds to the NORs. The referred species presented the lowest chromosome number observed for the subfamily Myrmicinae and for the Hymenoptera found in the Neotropical region. Observation of a low chromosome number karyotype has been described in Myrmecia croslandi, in which the occurrence of tandem fusions accounts for the most probable rearrangement for its formation. The accumulation of cytogenetic data may carry crucial information to ensure deeper understanding of the systematics of the tribe Dacetini