Abstract
The family Pyrrhocoridae (Hemiptera: Heteroptera) is characterized by a modal diploid chromosome number of 16 (♂) rang- ing from 12 to 33 and simple (X0), multiple (X 1 X 2 0) and neo-sex chromosome systems (neoX-neoY). Out of about 340 known species, only 22 species belonging to 7 genera have to date been cytogenetically analysed. In the present study, the chromosome complement and meiotic details of one species, Odontopus nigricornis Stal has been revised, whilst that of another species, Antilochus russus Stal has been cytogenetically analyzed for the first time. The diploid chromosome complement of O. nigricornis is 2n (♂) = 25 = 22A + X 1 X 2 X 3 0; the first time this particular multiple sex chromosome system has been reported in the Pyrrhocoridae. Three sex chromosomes mostly remain intimately associated during male meiosis and their number was confirmed at diplotene and anaphase II, where they dissociate slightly to become distinct. Meiosis is post-reductional for sex chromosomes. However, unlike other pyrrhocorids with mul- tiple X chromosomes, the X 1 , X 2 and X 3 lie outside the autosomal ring on the metaphase plate during both divisions. The male diploid chromosome complement of A. russus was found to be 2n = 27 = 26A + X0. Apart from the typical meiotic features of heteropterans, the latter species shows inter- and intra-population variations in frequency of ring bivalents.
Highlights
The family Pyrrhocoridae (Hemiptera: Heteroptera), which occurs throughout the tropical and subtropical regions of the world with a few species present in temperate areas, contains about 33 genera and 340 species (Schuh & Slater, 1995; Henry, 2009)
This data reveals that the family is characterized by a modal diploid chromosome number of 16 (♂), ranging from 12 to 33, with simple (X0), multiple (X1X20) and neo-sex chromosome systems, apart from the general features of heteropterans, that is, holokinetic chromosomes and post-reductional meiotic division of sex chromosomes
Adult male O. nigricornis and A. russus were collected from wild vegetation on the Forest Research Institute (FRI) campus, Dehradun, which is situated in valley at the foothills of the Himalayas, whilst the later species was collected at Ghumarwin, a hilly area, both sites lying in the northern part of India at roughly the same elevation, about 300 km apart
Summary
The family Pyrrhocoridae (Hemiptera: Heteroptera), which occurs throughout the tropical and subtropical regions of the world with a few species present in temperate areas, contains about 33 genera and 340 species (Schuh & Slater, 1995; Henry, 2009). Only 22 species belonging to 7 genera of Pyrrhocoridae have to date been investigated (Papeschi & Bressa, 2006; Verma & Kurl, 2009; Bardella et al, 2014). This data reveals that the family is characterized by a modal diploid chromosome number of 16 (♂), ranging from 12 to 33, with simple (X0), multiple (X1X20) and neo-sex chromosome systems (neoX-neoY), apart from the general features of heteropterans, that is, holokinetic chromosomes and post-reductional meiotic division of sex chromosomes. A multiple sex chromosome system (X1X20) has been reported in 8 species of Dysdercus investigated (Piza, 1947a, 1951; Mendes, 1949; Manna, 1951; Sharma et al, 1957; Banerjee, 1958; Ray-Chaudhuri & Banerjee, 1959; Ruthmann & Dahlberg, 1976; Manna & Deb-Mallick, 1981; Kuznetsova, 1988; Suman, 2010), a species of Pyrrhopeplus (Parshad, 1957) and a species of Odontopus (Verma & Kurl, 2009), whereas a neo-X neo-Y sex chromosome system was described in another species of Dysdercus studied (Bressa et al, 1999; 2009)
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