Cytogenetics and molecular differentiation in the African armoured ground bushcrickets (Orthoptera: Tettigoniidae: Hetrodinae)
2015
Grzywacz, Beata | Hemp, Claudia | Heller, Klaus-Gerhard | Hemp, Andreas | Chobanov, Dragan P. | Warchałowska-Śliwa, Elżbieta
Spalacomimus, Enyaliopsis, Eugaster, and Eugasteroides are tettigoniid genera belonging to the African subfamily Hetrodinae. In order to understand its diversification and unravel relationships between the species, we performed molecular analysis based on a combined set of nuclear genes (18S, ITS1, ITS2). The monophyly of Hetrodinae was supported by Bayesian inference and maximum likelihood analysis. Tree topology and cytogenetic data revealed two main lineages: (1) Eugaster and Eugasteroides and (2) Enyaliopsis and Spalacomimus. The molecular results were compared with previous and new cytogenetic and morphological data. Species of the North African genus Eugaster and the East African species Eugasteroides loricatus showed the same chromosome number (29), but differed in the number of rDNA signals, whereas the East African Enyaliopsis ephippiatus exhibited a reduced chromosome number (27) and only one rDNA-bearing chromosome pair. Both genera have the same X0 (plesiomorphic) sex chromosome system. The greatest chromosome reduction (to 24) was observed in two species of the East African genus Spalacomimus, both having neo-XY sex chromosome systems. However, the morphology of the sex chromosomes differed between these species, indicating different origins of their neo-XY systems. More molecular and cytotaxonomic analyses are necessary to further elucidate relationships within Hetrodinae. The present work sets the stage for future experimental investigations of the phylogeny and systematics of this group.
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