Jumping across Wallace's line:: Allodessus Guignot and Limbodessus Guignot revisited (Coleoptera: Dytiscidae, Bidessini) based on molecular-phylogenetic and morphological data

The monotypic genus Allodessus (Coleoptera: Dytiscidae: Bidessini) has previously been considered to be strictly Australian, with A. bistrigatus (Clark) having a wide range on that continent and in Tonga. Based on data gathered from extensive museum collections and a molecular phylogeny of the group, this concept is revised. The following species of the Bidessini are now assigned to Allodessus: Bidessus megacephalus Gschwendtner (East Palearctic), Liodessus oliveri Ordish (New Zealand), Bidessus skottsbergi Zimmermann (Chile: Easter Island) and Bidessus thienemanni Csiki (Indonesia: Java). The latter, as well as L. oliveri, are morphologically extremely similar to A. bistrigatus and are, perhaps, the same species. As currently delimited, Allodessus has a wide range, spanning parts of the Australian, Oriental, Palearctic and Oceanian regions. Based on a cladistic analysis of mtDNA sequence data, we synonymize Boongurrus Larson and Tjirtudessus Watts & Humphreys with Limbodessus Guignot. Australian species of Liodessus Guignot are transferred to Limbodessus, which is the sister group of Allodessus. The following 33 species are transferred to Limbodessus: Oceania -Liodessus cheesmanae (Balfour-Browne 1939) [Vanuatu], Bidessus curviplicatus Zimmermann 1927 [Samoa]; Australian epigean-Bidessus dispar Sharp 1882, B. praelargus Lea 1899, Hydroporus amabilis Clark 1862, H. gemellus Clark 1862, B. inornatus Sharp 1882, B. Shuckardii Clark 1862; Australian hyporheic -Boongurrus rivulus Larson 1994; Australian stygobiont -Nirridessus bigbellensis Watts & Humphreys 2000, N. challaensis Watts & Humphreys 2001, N. cueensis Watts & Humphreys 2000, N. fridaywellensis Watts & Humphreys 2001, N. hinkleri Watts & Humphreys 2000, N. lapostaae Watts & Humphreys 1999, N. masonensis Watts & Humphreys 2001, N. morgani Watts & Humphreys 2000, N. pinnaclesensis Watts & Humphreys 2001, N. pulpa Watts & Humphreys 1999, N. windarraensis Watts & Humphreys 1999, Tjirtudessus bialveus Watts & Humphreys 2003, T. cunyuensis Watts & Humphreys 2003, T. eberhardi Watts & Humphreys 1999, T. hahni Watts & Humphreys 2000, T. jundeeensis Watts & Humphreys 2003, T. karalundiensis Watts & Humphreys 2003, T. macrotarsus Watts & Humphreys 2003, T. magnificus Watts & Humphreys 2000, T. raesidensis Watts & Humphreys 2001, T. silus Watts & Humphreys 2003, T. sweetwatersensis Watts & Humphreys 2003, T. wilunaensis Watts & Humphreys 2003, T. yuinmeryensis Watts & Humphreys 2003. Limbodessus compactus (Clark) has a wide Asian/Australian range, while all other Limbodessus spp. are endemic to the Australian region and represent an adaptive radiation of epigean, hyporheic and subterranean species, as well as numerous undescribed New Guinea high-altitude specialists. Another species of Bidessini, Papuadessus pakdjoko Balke, is newly recorded from Papua New Guinea here.