Studies on secondary male genitalia of the type species of some dragonflies (Odonata: Anisoptera: Libellulidae)

Abstract

1505 Manuscript 984; Received 13 January 2003; Revised finally accepted 31 March 2004; © Zoo Outreach Organisation Insect genitalia commonly show much interspecific variation, even between closely related species. Odonata are practically unique among winged insects in that the primary genitalia do not meet during copulation. In addition to that, the male possesses another set of copulatory apparatus, the secondary genitalia, on the ventral aspect of second and third abdominal segments, which shows the same variation and function as the primary genitalia in other group of insects. Cowley (1937) in his communication on the genitalia of family Chlorocyphidae laid stress on the point of using the genitalia along with other characters in the taxonomic studies of odonates. Though, Fraser (1936) while characterizing different species in the ‘Fauna of British India’, gave due importance to various morphological taxonomic characters on head, thorax, legs, wings and abdomen, he failed to do justice while treating the genitalic features. Among older descriptions of anisopteran genital structures, those by Thompson (1908), Schmidt (1915), Whedon (1918) and Kennedy (1922) are some of the most useful. The significance of external genitalia in the odonate taxonomy has been realized for quite some time now by some Indian workers such as Prasad and Srivastava (1960), Khan (1969, 1972, 1973, 1974, 1976), Lahiri (1987), Prasad (1988), and, Andrew and Tembhare (1993). But, as far as the Indian species are concerned, very little has been investigated so far. However, Miller (1981, 1982, 1984, 1988, 1990, 1991a, 1991b, 1995) through his valuable contributions on libellulid dragonflies highlighted the value of genital structures in the discrimination of the species and genera. His work was confined to species from foreign lands. None of the above listed workers have described the male genitalic attributes in depth and in a detailed manner. These considerations necessitated the authors to undertake more detailed observations on the structure of male genitalia in 11 type species belonging to different genera of family Libellulidae, all collected from the various far flung localities of northwestern India. The terminology for naming the various parts of the male copulatory apparatus has been followed from Chao (1953) and Miller (1991a). ABSTRACT The secondary male genitalic characters of 11 type species of family Libellulidae have been examined and studied in considerable details. The taxonomic significance of the genitalic features of these species has been highlighted.