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About 40 species of membracids have been cytologically studied so far by other workers (vide infra) to which the chromosome number of ten species has been added by us (Bhattacharya and Manna 1967). Besides these ten species, only eight were reported from India (Banerjee 1958, Menon 1958, Rao 1956and Sharma et al. 1964). The present study deals with the morphology of gonial meta phase chromosomes of both sexes, the behaviour and measurement of spermatocyte chromosomes and the cytotaxonomical evaluation of the family. Nine out of the ten species have been cytologically investigated for the first time. Further, no species belonging to Cocosterphus and Tricentrus was studied previously. Material and methodsSeveral adult male and female individuals of ten species were collected locally from different host plants (Table 1) and their testes and ovaries were fixed in acetic alcohol for squash preparations. Testes of some individuals were also fixed in Sanfelice for sectioning. Iron-alum haematoxylin and Fuelgen stain were used for the testes while the oogonial complements were studied from temporary acetic carmine preparations. A metrical study of first spermatocyte metaphase chro mosomes was done following the method described elsewhere (Bhattacharya and Manna 1970 andManna 1951). ObservationsThe pattern of male meiosis was more or less the same in different species, but they differed to some extent when the morphology and the behaviour of gonial and meiotic chromosomes were critically analysed. For this reason some accounts of them has been presented one by one.Oxyrachis tarandus had 22 chromosomes in the oogonial (Fig. 1) and 21 in the spermatogonial metaphase complements (Fig. 2). Chromosomes were gradually seriated bean shaped structures and inter-connected, likepenta tomid bugs in both types of gonial complements. The difference of one chromosome suggested XX: XO sex mechanism but X chromosome was not demarcable by its size or staining

The karyomorphometrical analysis of somatic chromosomes of females of three species (vide infra) presented in this paper seemed not to have been carried out prior to our preliminary report (Khuda-Bukhsh and Manna 1974 a , b). Materials and methodsThree living specimens each of Mystus gulio (Fam: Bagridae), Eutropiichthys vacha (Fam: Schilbeidae) and Mastacembelus armatus (Fam: Mastacembelidae) were intramuscularly injected with 0.1% colchicine solution at the rate of 2ml/100 gm of body weight. After 5 hours their kidneys were separately removed into 1 sodium citrate solution, minced and flushed repeatedly to bring the cells into suspen sion. Cytological preparations were made according to the acetic alcohol-flame drying-Giemsa technique.The arm ratio and centromeric indices of metaphase chromosomes were determined following Levan et al. (1964) on which the morpho logical types and the chromosome formulae were assigned.Results

Some 1240 odd species of Heteroptera are estimated to be cytologically in vestigated (see Ueshima 1979, Manna 1982, 1984 of which the family Largidae after it was raised from the subfamily of Pyrrhocoridae comprised only 10 species , viz., 2 each Euryopthalmus (Piza 1946(Piza , 1953 and Largus (Wilson 1909), 1 of Lohita (as Macroceroea) (Banerjee 1958, Manna and Deb-Mallick 1981a) belonged to the subfamily Larginae and 5 species of Physopelta (vide infra) under the subfamily Physopeltinae. Largids have characteristically one pair of m-chromosomes and the general absence of the Y except in some species of Physopelta while pyrrhocorids have both, the absence of the Y and the m-pair except Iphita limbata which possesses a pair of m-chromosomes (Manna and Deb-Mallick 1981b). The present paper on the chromosomes of 4 species of Physopelta so far investigated accounts for the highly interesting difference in sex chromosome mechanism in species studied from Japan by Ueshima while all the three species studied from India by us had the com mon occurrence of the X1X2Y type of sex chromosomes in males indicating in 3 species very abrupt deviation from the pyrrhocorid-largid sex chromosome com plex and also showing more evolutionary dynamism of the sex chromosomes than autosomes in these two allied families. Materials and methodsTestes from males of 4 species of Physopelta constituted materials for the pre sent study. Thus 4 species of Physopelta cytologically known so far are as follows: 1. P. schlanbuschi (Fabr.) reinvestigated freshly from a different population at Kalyani separated by 50km from the previous place of collection (Manna 1951) agreeable to that of the earlier cytological findings (Ray-Chaudhuri and Manna 1955). 2. P. quadrigutta Bergs. were collected from Darjeeling, hill station, West Bengal at an altitude of 6,800ft. 3. P. gutta Burm. were also collected from Darjeeling in the above area. 4. P. gutta Burm. were collected from Mie, Japan and studied by Ueshima. 5. P. cincticollis Stal reinvestigated from a different population (at Mie) from the previous one (at Fukuoka) in Japan and studied by Ueshima agreeable to that

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