The origin of multiple sex chromosomes in tiger beetles.

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Abstract
In most holometabolous insects, sex determination involves differentiated sex chromosomes of the XY type (ZW, with heterogametic females in Lepidoptera). In Coleoptera (beetles) a general karyotype with meioformula 2n = 9 + XY is prevalent in the approximately 3,000 species studied to date (Smith and Virkki 1978 ; Petitpierre 1996 ), but the genetic system of Cicindelidae (tiger beetles) is unusually diverse, with many species exhibiting multiple sex chromosomes, XnY, where n varies between 2 and 4. During meiosis these heterosomes form a characteristic rosette-like multivalent linked by telomeric connections without forming chiasmata between the various X chromosomes (Giers 1977 ). The multiple sex chromosome system is widespread in cicindelids and is found in both the recognized subfamilies, including the Cicindelinae with a multiple system, which has been described for 55 species mostly in the species rich genus Cicindela (sensu lato), and the Collyrinae with three representatives studied to date. Other cicindelids, including two species of Megacephala (Serrano, Galián, and Ortiz 1986 ; Galián and Hudson 1999 ) and two species in the genus Cicindela, were found to have XY or X0 systems.

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