Ctenostegus hansoni sp. nov., a new species of spider wasp endemic to Lord Howe Island (Hymenoptera: Pompilidae)

Abstract

Lord Howe Island is a UNESCO World Heritage Site with a highly endemic biota and a history of recent species extinction. During the 2017 and 2018 Australian Geographic Society expeditions to Lord Howe Island, spider wasps in the genus Ctenostegus Haupt, 1930 were collected from various sites. A new species – C. hansoni sp. nov. – is described based on this material. The external morphology and male genitalic features are illustrated for all constituents of the C. immitis species-group, for which an identification key is provided. New distribution data for the Hymenoptera of Lord Howe Island include an additional genus of Pompilidae (Fabriogenia sp.) and the first record for the family Mutillidae (Ephutomorpha sp.). Ctenostegus hansoni sp. nov. is one of the few spider wasps restricted to an oceanic island and constitutes an intriguing new record of long-distance dispersal from mainland Australia followed by speciation.