Colobopsis explodens sp. n., model species for studies on “exploding ants” (Hymenoptera, Formicidae), with biological notes and first illustrations of males of the Colobopsis cylindrica group

A taxonomic description of all castes ofColobopsisexplodensLaciny & Zettel,sp. n.from Borneo, Thailand, and Malaysia is provided, which serves as a model species for biological studies on “exploding ants” in Southeast Asia. The new species is a member of theColobopsiscylindrica(COCY) group and falls into a species complex that has been repeatedly summarized under the nameColobopsissaundersi(Emery, 1889) (formerlyCamponotussaundersi). The COCY species group is known under its vernacular name “exploding ants” for a unique behaviour: during territorial combat, workers of some species sacrifice themselves by rupturing their gaster and releasing sticky and irritant contents of their hypertrophied mandibular gland reservoirs to kill or repel rivals. This study includes first illustrations and morphometric characterizations of males of the COCY group:ColobopsisexplodensLaciny & Zettel,sp. n.andColobopsisbadia(Smith, 1857). Characters of male genitalia and external morphology are compared with other selected taxa of Camponotini. Preliminary notes on the biology ofC.explodensLaciny & Zettel,sp. n.are provided. To fix the species identity of the closely relatedC.badia, a lectotype from Singapore is designated. The following taxonomic changes within theC.saundersicomplex are proposed:Colobopsissolenobia(Menozzi, 1926),syn. n.andColobopsistrieterica(Menozzi, 1926),syn. n.are synonymized withColobopsiscorallinaRoger, 1863, a common endemic species of the Philippines.ColobopsissaginataStitz, 1925,stat. n., hitherto a subspecies ofC.badia, is raised to species level.