First report on the chromosomal analysis of three species of tribe Eristalini (Diptera: Syrphidae) from outer Himalayas, India

In the present study, the chromosomes of three species of tribe Eristalini (family Syrphidae) were studied for karyotypic details, morphometric data, C-banding and meiosis. Two species Eristalinus laetus and E. obscuritarsis showed 2n = 10 diploid chromosome number and the remaining third species E. obliquus revealed 2n = 12 chromosomes as diploid number. All the three species exhibited XY sex mechanism in males. The morphology of Y chromosome was similar in all the three species studied. C-banding revealed the presence of constitutive heterochromatin at pericentromeric locations and established the euchromatic or heterochromatic nature of sex chromosomes. Meiotic observations included leptotene, pachytene, diplotene, metaphase-II and anaphase-II. The study is useful in chromosomal evolution and in the solution of taxonomic problems within the family Syrphidae.