Volume 81, Issue 1
January 1975, pages 1-60
pp 1-6 January 1975
The diploid chromosome number in spermatogonial metaphase, the meiotic cycle, the haploid number with the chromosome formula and sex chromosome mechanism at primary spermatocyte division have been studied for the first time in five species of tenebrionid beetles,Platynotus exavatus F.,Gonocephalum depressum Fabr.,Pachycera arta Hbst.,Himatismus fasciculatus Fabr., andHiperops coromendelensis Sol. The first, second and the last three species belong to the subfamilies Pedininae, Opatrinae and Epitraginae respectively. The Karyotypes are uniformly viewed as 2n=20 orn (1st div.)=10 with sex mechanism Xyp having the chromosome formula 9AA+Xyp. Against the background of the previous study the modal chromosome number and the sex mechanism are discussed.
pp 7-19 January 1975
This paper incorporates observations on the ecology of sixteen species of black flies occurring in the Darjeeling area of India. Of the species ofSimulium, himalayense was most abundant;rufibasis andgrisescens moderately abundant; anddentatum, ramosum, nigrifacies andbiforaminiferum confined to certain pockets of the area. Of the species ofEusimulium, praelargum was very abundant;gracilis moderately abundant; andpurii, aureohirtum, nemorivagum anddasguptai almost rare. Of the species ofGomphostilbia, tenuistylum was moderately abundant, whiledarjeelingense andmetatarsale were localized. The species ofSimulium exceptnigrifacies andbiforaminiferum selected rapid water; the species ofEusimulium, andbiforaminiferum andnigrifacies, preferred very slow or sometimes quiet water, while the species ofGomphostilbia were often adapted to medium current for oviposition. Oviposition was exhibited by (i) freely dropping eggs from the air; (ii) tapping the abdomen through the water while hovering or (iii) while alighting; and by (iv) crawling under the water. The peak period of oviposition was normally in the evening before sunset. Hibernation was observed in the egg-stage inhimalayense, rufibasis, grisescens (in a lowland river) andtenuistylum; and in the larval stage inpraelargum, gracilis and probablygrisescens (in upland streams). One generation per year was observed intenuistylum; two generations inpraelargum, gracilis andgrisescens (in upland streams); three generations inrufibasis andgrisescens (in a lowland river) and at least three generations inhimalayense. Larvae of some species were found to remain in association with those of others, depending upon environmental conditions. Larvae ofEusimulium especially, almost always hid themselves under the substrata to get constant supply of sufficient oxygen from trickles of water they were found to inhabit.
pp 20-28 January 1975
Loligo duvauceli which contributes to the cephalopod fishery in India is a carnivorous like other cephalopod species. Its stomach contents are mainly the crustaceans, fish and squid. Mysiids, euphausiids and ostracods from bulk of the crustacean intake in the squid diet. Major items of food differ significantly from month to month. Fish always occurs in the diet of the squids of all sizes. The preference to crustacean meal declines with the increase in size and the squids above 80 mm in size are cannibals. Crustaceans are present in the squid stomach during four month period, October to January. The data indicate that the occurrence of empty stomachs is more common in female than in male squids. Normal feeding was noticed during the period January to May 1970, but the slackness in the feeding was evident in October–November 1969 during spawning period.
pp 29-60 January 1975