First Note on Chromosomes and Male Meiosis Division of Collembola in China

Chromosomes of two Collembola species,Hypogastrura adexilis (Stach,1964) (Hypogastruridae) and Sinella curviseta Brook 1889 (Entomobryidae),were investigated for the first time by squashing whole mount. The results indicated:in H.adexilis,haploid chromosome number was n=7,and 2n=13 in male and 2n=14 in female,so sex chromosome system should be XO;in S.curviseta,n=6,2n=11 in male and 2n=12 in female,also XO sex determination.The male meiosis of H.adexilis was observed:at prophase Ⅰ,homologous chromosomes pairing occurred,and chiasma presented in some bivalents;in the others,homologue were just end-to-end associations;at early anaphase Ⅰ,sex chromosome typically was left behind when autosome half bivalents moved to the poles, and it moved to one of the poles in late telophase Ⅰ.