Tolumnia antennata Distant

Kaur, Harbhajan & Sharma, Kanu, 2015, First report on meiotic behavior of chromosomes in three species of subfamily Pentatominae (Pentatomidae: Heteroptera), Zootaxa 3920 (2), pp. 393-400 : 394

Tolumnia antennata Distant

Tolumnia antennata has diploid chromosome complement of 2n=14=12A+XY. Two pairs of autosomes are distinctly large while rest of the four pairs show slight gradation in size. X is smaller than the two largest pairs of autosomes while Y is the smallest element of the complement (fig.1). At diffuse stage, X and Y chromosomes remain fused together forming a single darkly stained heteropycnotic body while the autosomes appear as diffused chromatin (fig. 2). At diplotene, autosomal bivalents become distinct but X and Y still remain fused. One (68.48% of 36 cells analyzed) or two (31.52%) autosomal bivalents show more than one chiasma while the rest show one terminal chiasma each (figs. 3, 4). By diakinesis, two chiasmata in one of the bivalent are seen in 13% of 26 cells analyzed. X and Y become distinct and well separated ( Fig 5 ). At metaphase I, all autosomal bivalents form a ring and sex chromosomes lie within the ring (fig. 6). At metaphase II, too, autosomes form a ring, while X and Y that associate terminally to form a pseudobivalent, lie within the ring (fig. 7). Two types of telophase II plates are seen, one with 6A+X and the other with 6A+ Y (fig. 8).

Figures

FIGURES 1 – 8. Tolumnia antennata; fig. 1 spermatogonial metaphase, fig. 2 diffuse stage showing fused XY, fig. 3 early diplotene, fig. 4 late diplotene, fig. 5 diakinesis, fig. 6 metaphase I, fig. 7 metaphase II showing XY pseudobivalent, fig. 8 telophase II. Arrowhead shows fused XY. Bigger arrow points to X. Smaller arrow points to Y.