Synopsis of the endemic New Zealand genera of the beetle subfamily Sphaeridiinae (Coleoptera: Hydrophilidae)

The type material of the endemic New Zealand Sphaeridiinae (tribes Rygmodini, Tormissini, Coelostomatini) is revised. Keys are given to known species of all genera. Rygmodus pedinoides White, 1846, previously considered a synonym of R. modestus White, 1846, and Adolopus altulus (Broun, 1880), previously considered a synonym of A. badius (Broun, 1880), are reinstated as valid species. The following new synonyms are established (junior synonyms in parentheses): Saphydrus suffusus Sharp, 1884 (= Saphydrus collaris Broun, 1921, Saphydrus consonus Broun, 1921, synn. n.); Rygmodus cyaneus Broun, 1881 (= Rygmodus ovalis Sharp, 1884, Rygmodus puncticeps Broun, 1886, Rygmodus nigripennis Broun, 1903, synn. n.); Rygmodus tibialis Broun, 1893 (= Rygmodus limbatus Broun, 1893, syn. n.); Tormus helmsi Sharp, 1884 (= Stygnohydrus posticalis Broun, 1917, syn. n.); Tormus ["Stygnohydrus"] nitidus (Broun, 1893) (= Tormus nitidus Broun, 1893, Stygnohydrus basalis Orchymont, 1937, synn. n.); Exydrus ["Cyclonotum"] gibbosus (Broun, 1880) ( = Cyclonotum flavicorne Broun, 1880, Exydrus thomasbrouni Hansen, 1991, synn. n.); Hydrostygnus ["Cyclonotum"] frontalis (Broun, 1880) (= Hydrostygnus minor Broun, 1893, Hydrostygnus bifoveatus Broun, 1893, synn. n.); Tormissus ["Hydrostygnus"] linsi (Sharp, 1884) (= Tormissus marginatus Broun, 1893, Tormissus magnulus Broun, 1893, synn. n.); Cyloma guttulatus Sharp, 1884 (= Psephoboragus dispar Broun, 1910, syn. n.); Cyloma ["Psephoboragus"] lineatus (Broun, 1893) (= Psephoboragus signatus Broun, 1893, syn. n.); and Adolopus helmsi Sharp, 1884 (= Adolopus vicinus Broun, 1886; Adolopus montanus Broun, 1893, Adolopus australis Broun, 1909, Adolopus tibialis Broun, 1909, synn. n.). The following new combinations are made: Saphydrus antennatus Sharp, 1884 = Rygmodus antennatus (Sharp) comb. n., Saphydrus longulus Sharp, 1884 = Rygmodus longulus (Sharp) comb. n., Stygnohydrus femoralis Broun, 1910 = Tormus femoralis (Broun) comb. n., Hydrostygnus linsi Sharp, 1884 = Tormissus linsi (Sharp) comb. n., and Namostygnus flemingi Ordish, 1974 = Cyloma flemingi (Ordish) comb. n. Lectotypes are designated for Saphydrus longulus Sharp, 1884, Saphydrus obesus Sharp, 1884, Saphydrus suffusus Sharp, 1884, Rygmodus cyaneus Broun, 1881, Rygmodus femoratus Sharp, 1884, Rygmodus modestus White, 1846, Rygmodus ovalis Sharp, 1884, Rygmodus pedinoides White, 1846, Rygmodus puncticeps Broun, 1886, Rygmodus tibialis Broun, 1893, Rygmodus unguicularis Sharp, 1884, Tormus nitidus Broun, 1893, Stygnohydrus posticalis Broun, 1917, Hydrostygnus frontalis Broun, 1880, Hydrostygnus linsi Sharp, 1884, Thomosis guanicola Broun, 1904, Tormissus magnulus Broun, 1893, Cyloma altulum Broun, 1880, Cyloma badium Broun, 1880, Cyloma lawsonus Sharp, 1872, Cyloma stewarti Broun, 1894, Cyloma thomsonus Sharp, 1884, Psephoboragus lineatus Broun, 1893, Psephoboragus signatus Broun, 1893, Gitocyloma nigratus Broun, 1915, Adolopus helmsi Sharp, 1884, and Adolopus rugipennis Broun, 1886. Lectotype designations of Adolopus vicinus Broun, 1886 and Adolopus australis Broun, 1909, made by D. Miller (but never published), are here confirmed and validated.