Herein, Austrelatus gen. nov. (type species: Copelatus irregularis W.J. Macleay, 1871) is described for a distinctive lineage of predominantly Australasian species previously assigned to Copelatus Erichson, 1832. The new genus was retrieved as well supported, monophyletic clade in phylogenetic analysis of DNA sequences data using Bayesian and parsimony approaches. The main morphological diagnostic character of Austrela-tus is a complex median lobe of the aedeagus, with evident dorsal and ventral sclerites usually divided in apical half into two lobes of different shape or otherwise modified. Morphological comparison of the new genus with other Copelatinae genera, especially with Copelatus and Exocelina Broun, 1886, and a generic key to the New Guinean Co- pelatinae are provided. New combinations are established for 31 already described spe- cies mainly from the Australian Region (all from Copelatus): Austrelatus adelbert (Meg -na, Atthakor, Manaono, Hendrich & Balke, 2017), comb. nov.; A. badeni (Sharp, 1882), comb. nov.; A. bakewelli (J. Balfour-Browne, 1939), comb. nov.; A. baranensis (Hajek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A. bougainvillensis (Hajek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A. boukali (Hendrich & Balke, 1998), comb. nov.; A. clarki (Sharp, 1882), comb. nov.; A. daemeli (Sharp, 1882), comb. nov.; A. davidi (Wewal-ka, 2017), comb. nov.; A. deccanensis (Sheth, Ghate & Hajek, 2018), comb. nov.; A. fid- schiensis (Zimmermann, 1928), comb. nov.; A. gestroi (Regimbart, 1892), comb. nov.; A. irregularis (W.J. Macleay, 1871), comb. nov.; A. kaszabi (Guignot, 1956), comb. nov.; A. kietensis (Hajek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A. laevipennis (Ha- jek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A. luteomaculatus (Guignot, 1956), comb. nov.; A. maushomi (Sheth, Ghate & Hajek, 2018), comb. nov.; A. neoguineensis (Zimmermann, 1919), comb. nov.; A. nigrolineatus (Sharp, 1882), comb. nov.; A. papu-ensis (J. Balfour-Browne, 1939), comb. nov.; A. parallelus (Zimmermann, 1920a), comb. nov.; A. schuhi (Hendrich & Balke, 1998), comb. nov.; A. sibelaemontis (Hajek, Hendrich, Hawlitschek & Balke, 2010), comb. nov.; A. strigosulus (Fairmaire, 1878), comb. nov.; A. ternatensis (Regimbart, 1899), comb. nov.; A. uludanuensis (Hendrich & Balke, 1995), comb. nov.; A. urceolus (Hajek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A. va-riistriatus (Hajek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A. wallacei (J. Bal - four-Browne, 1939), comb. nov. and A. xanthocephalus (Regimbart, 1899), comb. nov. Austrelatus species from New Guinea are divided into two informal species groups, the A. neoguineesis group and A. papuensis group, and A. fumato sp. nov. and A. setiphallus sp. nov. standing aside of them. The A. neoguineensis group is introduced with three previously known species and 29 new species described here based on the morphologi- cal characters and Cox1 data: Austrelatus baliem sp. nov., A. bormensis sp. nov., A. braz-za sp. nov., A. debulensis sp. nov., A. fakfak sp. nov., A. febrisauri sp. nov., A. fojaensis sp. nov., A. garainensis sp. nov., A. innominatus sp. nov., A. lembenensis sp. nov., A. lisae sp. nov., A. manokwariensis sp. nov., A. mimika sp. nov., A. mirificus sp. nov., A. more-guinensis sp. nov., A. nadjae sp. nov., A. oksibilensis sp. nov., A. pseudoneoguineensis sp. nov., A. pseudoksibilensis sp. nov., A. rajaampatensis sp. nov., A. rouaffer sp. nov., A. rugosus sp. nov., A. sandaunensis sp. nov., A. sarmiensis sp. nov., A. securiformis sp. nov., A. testegensis sp. nov., A. toricelli sp. nov., A. vagauensis sp. nov., and A. wangga-rensis sp. nov. Copelatus vagestriatus Zimmermann, 1919, syn. nov. is recognised as a junior subjective synonym of A. clarki (Sharp, 1882). The lectotypes of Copelatus gestroi Regimbart, 1892, C. neoguineensis Zimmermann, 1919 and C. xanthocephalus Regim- bart, 1899 are designated. All species are (re)described, and their important species characters (genitalia, habitus, and colour patterns) are illustrated. Keys to all species are provided. The known distribution and habitat preferences of each species are out- lined briefly. New Guinean Austrelatus occupy a variety of stagnant water habitats, either lentic sensu stricto, or standing water associated with lotic habitats (e.g., backflows, rockpools, intermittent / ephemeral stream pools).
