Bonvicino C R, de Menezes A R E A N, Oliveira J A
Genetics Division, Diretoria de Pesquisa, Instituto Nacional de Câncer, Rio de Janeiro, Brazil.
Hereditas. 2003;139(3):206-11. doi: 10.1111/j.1601-5223.2003.01807.x.
Phylogenetic relationships among available samples of the genus Isothrix using mitocondrial gene cytochrome b were carried out and a new karyotype of Isothrix specimens referred to Isothrix negrensis from the mid course of Rio Negro, in the Brazilian Amazon, was described. Molecular, karyological and morphological data of Isothrix negrensis was compared to that of I. bistriata and I. pagurus. Cytochrome b DNA sequence analyses clearly separate I. negrensis from I. bistriata and genetic distances estimates between then are greater than between species of the related genus Mesomys. The median-joining analysis postulated the presence of two median vectors between I. bistriata haplotypes from adjacent localities, suggesting that genetic isolation between them is unrelated to geographic distance. These results confirm previous molecular differences suggesting that I.bistriata is a composite of several taxa. The karyotype of Isothrix negrensis also differs from those reported for I. bistriata and I. pagurus. In relation to the external morphology I. negrensis differs from I. bistriata by the overall darker dorsal coloration, head darker than dorsum, presence of a longitudinal line of blackish hairs in the proximal part of the tail extending until near to its base, dorsal surface of hind feet covered with yellowish hairs and stripe of light hairs in the head reduced to a small patch.
利用线粒体细胞色素b基因对伊斯索鼠属现有样本进行了系统发育关系研究，并描述了来自巴西亚马逊地区内格罗河中游的被称为黑腹伊斯索鼠的伊斯索鼠标本的一种新核型。将黑腹伊斯索鼠的分子、核型和形态学数据与双色伊斯索鼠和巴氏伊斯索鼠的数据进行了比较。细胞色素b DNA序列分析清楚地将黑腹伊斯索鼠与双色伊斯索鼠区分开来，两者之间的遗传距离估计大于相关的中鼠属物种之间的遗传距离。中位数连接分析推测，相邻地区的双色伊斯索鼠单倍型之间存在两个中位数向量，这表明它们之间的遗传隔离与地理距离无关。这些结果证实了先前的分子差异，表明双色伊斯索鼠是几个分类单元的复合体。黑腹伊斯索鼠的核型也与报道的双色伊斯索鼠和巴氏伊斯索鼠的核型不同。在外部形态方面，黑腹伊斯索鼠与双色伊斯索鼠的不同之处在于，其背部整体颜色较深，头部比背部颜色深，尾巴近端有一条黑色毛发纵线，一直延伸到接近基部，后足背面覆盖着淡黄色毛发，头部的浅色毛发条纹缩小为一个小斑块。
