Biogeography and classification of New Guinean Colymbetini (Coleoptera : Dytiscidae : Colymbetinae)

The systematics of New Guinean Colymbetini is revised. All of the species a re montane and/or subalpine, and include: Carabdytes upin Balke, Hendrich & Wewalka, 1992; Rhantus suturalis (MacLeay, 1825) s.l.; R. papuanus Balfour -Browne, 1939; and R. ekari Balke & Hendrich, 1992a. The following new spec ies are described: R. anggi, sp. nov.; R. bacchusi, sp. nov.; R. dani, sp. nov.; R. kakapupu, sp. nov.; R. riedeli, sp. nov.; and R. supranubicus, sp. nov. Rhantus neoguinensis Gueorguiev & Rocchi, 1993 is a junior subjective synonym of R. suturalis s.l. All New Guinean Rhantus Dejean, 1833 belong t o the monophyletic R. suturalis-group. Within that group, Rhantus simulans Regimbart, 1908 (southwest Australia), R. dani, R. suturalis, R. ekari and R. kakapupu form a monophyletic subgroup; the latter two are sister-species . The R. suturalis-group is suggested to be of Holarctic origin. Possible s cenarios that may explain the biogeographical history of this tribe in the Indo-Australian region are discussed. No evidence was found for monophyly o f New Guinean Rhantus. The biogeographical history of Carabdytes upin remai ns enigmatic. New Guinean Rhantus inhabit swamps at lakeshores, ponds and d itches, while C. upin Balke et al., 1992 is a rheobiont. A checklist of wor ld species of the R. suturalis-group is provided.