Two Rare Cases of Bi-Abdomen and a Polar Gynandromorphismin ‎Culicoides (Biting Midges) from Makurdi, Nigeria

Three developmental abnormalities were found out of a total sample of eight hundred and twenty two within the genus Culicoides. These are two rare cases of double abdomen in females of the Schultzei and Imicola groups and a polar gynandromorphism, all in the genus Culicoides (biting midges) from Makurdi, Benue State, Nigeria. These females show double symmetrical abdomens equally attached to the meta-thorax and are related both on dorsal and ventral relative positions as well as larger and smaller relative capacities. The bi-abdomens in the Culicoides oxystoma (Schultzei group) were also separated by a speculated third rudimentary abdomen similarly attached to the meta-thorax; both abdomens possess three spermathecae (receptacula seminis) each but two spermathecae in the Culicoides imicola (Imicola group). The dorsal abdomen possesses eleven spiracles while the ventral sac, ten in the Culicoides oxystoma and revealed evidence of functionality; the dorsal abdomen was observed filled while the ventral only shows a smaller content volume. Both bi-abdominal specimens demonstrated no other apparent morphological dysfunction of other parts. On the other hand, the polar gynandromorphic specimen on stereomicroscopy revealed a typical female anterior portion and a posterior portion characteristic of male adult Culicoides. Further examination of the specimen showed absence of spermatheca. These abnormalities are the first reports of any type in invertebrates in Nigeria.