Revision of the genus Georissus (Coleoptera, Hydrophiloidea, Georissidae) of Japan Author Yasuda, Kohei C660A24E-D4D7-4985-951F-A4093FFBEE57 Entomological Laboratory, Faculty of Agriculture, Ehime University, Tarumi 3 - 5 - 7, Matsuyama, 790 - 8566 Japan. koheizari303@gmail.com Author Yoshitomi, Hiroyuki 744FA6FC-2D84-41B7-8A6C-C1611CC68EE1 Entomological Laboratory, Faculty of Agriculture, Ehime University, Tarumi 3 - 5 - 7, Matsuyama, 790 - 8566 Japan. hymushi@agr.ehime-u.ac.jp text European Journal of Taxonomy 2022 2022-05-03 817 1 111 142 http://dx.doi.org/10.5852/ejt.2022.817.1767 journal article 55730 10.5852/ejt.2022.817.1767 529dc516-47b9-424e-93ac-3787e407e100 2118-9773 6517928 FFB05CE7-3712-4FD0-91B4-FD84863CF9D7 Subgenus Nipponogeorissus Satô, 1972 Nipponogeorissus Satô, 1972: 212 . Type species: Georissus granulosus Satô, 1972 (by original designation). Redescription HEAD. Both clypeus and frons uneven, provided extensively with foveae, with distinct carinae; slr reaching anterior margin of frons; lsa connecting each other, forming U-shape. Granulation of clypeus indistinct. Mandibles ( Fig. 4K ) relatively large; lateral margin linear, apex unidentate; mola not developed. Antennae ( Fig. 4N ) relatively short; antennomere 4 as wide as antennomere 3, about twice as long as antennomere 3; pubescence of club short. Labrum ( Fig. 4E ) protruding anteriorly; spines on anterior margin indistinct. Apical labial palpomere ( Fig. 4H ) elongated oval, densely bearing short spines. Galea ( Fig. 4B ) densely bearing short setae. PRONOTUM. Half oval; lateral portion slightly projecting laterally; disc densely provided with granules; smlg distinct; without sdn . ELYTRA. Bearing four longitudinal costae consisting of granules. Humeral bulges distinct. Lateral ridges indistinct. ABDOMEN. Ventrites densely bearing granules; ventrites 1–2 without vt and excavation. MALE GENITALIA. Aedeagus elongated. Parameres as long as phallobase. Median lobe little shorter than parameres. Basal struts short. Phallobase bulbous at basal portion. Remarks This subgenus is distinguished by the combination of the following characters: pronotum provided with large granules extensively (not extensively in subgenera Georissus and Neogeorissus ); disc of clypeus and frons provided with many carinae, granulation indistinct (in other subgenera, granulation distinct). This subgenus comprises only two species from Japan and Papua New Guinea : the Japanese species is G . ( Ni .) granulosus Satô, 1972 , and the other species is G . ( Ni .) biroi Delève, 1969 . Georissus ( Neogeorissus ) maritimus Fikáček et al ., 2012 described from Socotra Island ( Yemen ) is similar to Nipponogeorissus species in the entirely granulated pronotum, and narrow, elongated aedeagus ( Fikáček et al . 2012 ).