Jacobs Dawid H
Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.
Folia Biol (Krakow). 2003;51(1-2):23-32.
The nominate subspecies of Dundocoris flavilineatus Jacobs occurs in indigenous evergreen forests over a wide area in KwaZulu-Natal and the Eastern Cape Province of South Africa. It has a chromosome number of 2n male = 28XY, which is the ancestral number for the genus. D. flavilineatus ndabeniensis, which comprises an isolated sibling population at Ndabeni forest in northern KwaZulu-Natal, possesses a multiple sex chromosome system, presumably a X1X2Y system and has a chromosome number of 2n male = 27X1X2Y. The system probably originated when an autosome and the Y-chromosome of the 28XY karyotype fused. In contrast to the situation previously described in the XY1Y2 system of D. nodulicarinus the autosomal and original Y-chromosome parts of the neo-Y chromosome seem to have a reciprocal influence on each other in terms of structure and staining intensity during prophase 1. The autosomal part of the neo-Y adopts a granulate, heteropycnotic, linear structure while the original Y part is less globular than usual in structure. The neo-X chromosome (= X2) behaves like, and stays isopycnotic with the autosomes. It is connected to the neo-Y by terminal association--probably a terminal chiasma. The sex chromosome system is post-reductional and a sex chromosome trivalent is present in all metaphase II cells. The origin and behaviour of the neo-X1X2Y sex chromosome system in D. flavilineatus ndabeniensis are described, discussed, illustrated with photomicrographs and compared to the XY1Y2 system in D. nodulicarinus. Idiograms of the karyotypes of the two subspecies of D. flavilineatus are also presented.
黄纹邓氏蝽的指名亚种分布于南非夸祖鲁-纳塔尔省和东开普省的大片原生常绿森林中。其染色体数目为2n雄性 = 28XY，这是该属的祖先数目。黄纹邓氏蝽恩达贝尼亚种在夸祖鲁-纳塔尔省北部的恩达贝尼森林中形成了一个孤立的姐妹种群，拥有一个多性染色体系统，推测为X1X2Y系统，染色体数目为2n雄性 = 27X1X2Y。该系统可能起源于28XY核型的一条常染色体与Y染色体融合之时。与先前在结节邓氏蝽的XY1Y2系统中描述的情况不同，新Y染色体的常染色体部分和原始Y染色体部分在减数分裂前期1的结构和染色强度方面似乎相互影响。新Y染色体的常染色体部分呈现颗粒状、异固缩的线性结构，而原始Y染色体部分的结构则比通常情况下的球状程度低。新X染色体（= X2）的行为与常染色体相似，并与常染色体保持等固缩状态。它通过末端联会——可能是一个末端交叉——与新Y染色体相连。性染色体系统是减数后性染色体系统，在所有中期II细胞中都存在一个性染色体三价体。本文描述、讨论并通过显微照片展示了黄纹邓氏蝽恩达贝尼亚种新X1X2Y性染色体系统的起源和行为，并将其与结节邓氏蝽的XY1Y2系统进行了比较。文中还给出了黄纹邓氏蝽两个亚种核型的模式图。
