Karyotypes and meiosis of the Australian Tettigoniidae (Orthoptera) II. The genus Nanodectes Rentz (Tettigoniinae)*

Abstract

The karyotypes and meioses from males of the species in the shield-backed katydid genus Nanodectes Rentz (Tettigoniinae) have been studied. The chromosome number of these species ranges from 2n = 15 to 2n =23 in the male. The male karyotypes were all X – 0 and the X was always the largest telocentric chromosome. Four types of chromosome systems are found in different populations of N. triodiae Rentz: 2n = 15 (6 metacentric + 8 telocentric autosomes + X), 2n = 15 (4 metacentric + 10 telocentric autosomes + X), 2n = 17 (4 metacentric+ 12 telocentric autosomes + X) and 2n = 19 (2 metacentric + 16 telocentric autosomes + X).

Chromosome rearrangements, such as centric fusion and tandem fusion, appear to have played an important role in chromosome evolution at the inter- and intra-specific levels in Nanodectes. Possible pathways of karyotypic evolution and speciation are discussed.

* Part I: pp. 303-51 in: 'The Tettigoniidae: Biology, Ecology, Systematics'. Eds W. J. Bailey and D. C. F. Rentz. (Crawford House: Bathurst.)