Description of the karyotype of Sphyracephala detrahens (Diptera, Diopsidae)

Abstract

The eye stalks in Diopsidae (Bilberg, 1820) have been widely examined, but the evolutionary origin of this unique trait remains unclear. Thus, further studies ofSphiracephala(Say, 1828), the extant genus forming a basal branch of Diopsinae, are needed. The present study aimed to identify the karyotype ofSphyracephala detrahens(Walker, 1860) with conventional Giemsa staining. Cytogenetic analysis revealed a diploid number of 2n = 10 including two pairs of metacentric chromosomes, a pair of telocentric chromosomes, a pair of dot-like chromosomes, and a pair of sex chromosomes inS. detrahens. The congenerSphyracephala brevicornis(Say, 1817) has been reported to have the same diploid number, 2n = 10, but different chromosome formula. These results demonstrate that chromosome rearrangements often occur in the genusSphyracephala.