Morphology, behaviour and metrical studies of the germinal chromosomes of ten species of membracidae (Homoptera)

Abstract

The karyotype analysis of ten species of Membracidae (Homoptera) showed the oogonial and spermatogonial chromosomes as bean shaped and gradually seriated elements. Sex chromosomes were two in the female and only one in the male but these did not exhibit any staining difference compared to the auto somes. The diploid number in female and male complements were 22 and 21 respectively in Oxyrachis tarandus, Oxyrachis sp., Leptocentrus substitutus, Otinotus elongatus, Otinotus sp. and 20 and 19 in Tricentrus albomaculatus, Tricentrus sp., Gargara contraria, G. flavolineatus, Cocosterphus decoloratus. The pattern of meiosis in males of the species investigated was very conservative type. There was a faint "bouquet" at the early primary prophase. The first division was reductional while the second equational. The sex determining mechanism was XX: XO in all of them. The 19 chromosome species were character-ised by a huge autosomal bivalent. The relative percentage volumes of the chro-mosomes was determined from primary spermatocyte metaphase plates. In the light of the data published by earlier workers and the results obtained in this investi-gation, the probable mode of evolution in the group has been discussed.