The Odonata of Bioko, Republic of Equatorial Guinea, with the description of fan-shaped setae on early instar Libellulidae larvae

A checklist of 48 spp. recorded from the island of Bioko (3°30’N 8°40’E), based on historical records compiled by Dr Elliot Pinhey and augmented by a collection made in March-April 1999, is presented, together with notes on the distribution of the spp. on the island. The Odonata fauna apparently comprises 2 elements, an upland fauna which includes 6 spp. that only occur above 500 m, and a lowland fauna of 17 spp., none of which occurs above 500 m. A further 13 spp. have been found in both lowland and upland sites. There are insufficient published data on the remaining 13 spp. to assign them to either of these faunistic elements. In addition, unique fan-shaped setae on the dorsum of the head, thorax and abdomen of early instar libellulid larvae are described. These setae are thought to be mechano-receptors that are held above the sediment to detect the presence of prey and current flow while the larva remains buried.