Musculature of the male genitalia in the tribe Ulidiini (Diptera, Ulidiidae)

Abstract

The musculature of the male genitalia was studied in three species of Ulidiini (Tephritoidea: Ulidiidae): Timia erythrocephala Wiedemann, 1824, Ulidia ruficeps Becker, 1913, and Physiphora alceae (Preyssler, 1791). Previously, the male genital sclerites of this tribe were studied (Galinskaya, 2011a, 2011b, 2012, 2014). The study has shown significant similarity of the set of muscles between the species. Small differences in the sites of muscle insertion on the sclerites do not affect the functions of these muscles. The lateral hypandrial lobes are always asymmetrical in all the species studied, the right lobe being always larger than the left one. This probably results from the postabdomen rotation and may be indirectly related to flight maneuverability during copulation. Clear separation of the attachment sites of the adductor of subepandrial sclerite M3 and the adductor of surstyli M4 is noteworthy. These muscles are synergistic, as in most other representatives of Cyclorrhapha widely varying in the structure of the surstyli and subepandrial sclerite and in the attachment of M3 and M4; their contraction results in the surstyli grasping and holding the female’s abdomen during copulation. Comparative analysis shows that all the studied representatives of Tephritoidea have a similar set of the male genital muscles. The correspondence of homologous muscle designations in different classifications has been analyzed. In particular, the phallapodemic muscle M2 in Ulidiidae is shown to be homologous to muscle MUS2 in Ceratitis capitata (Tephritidae). Thus, the hypandrial origin of the lateral sclerites is confirmed.