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 Georissus ( Georissus ) canalifer Sharp, 1888 [Japanese name: Marudoromushi] Figs 2A , 4A, D, G, J, M , 5A , 6A , 7A , 8A , 9A , 10A , 12A ; Table 1 Georyssus canalifer Sharp, 1888: 244 . Georyssus canalifer – Miwa 1937: 163 . Georissus ( Georissus ) canalifer – Satô 1972: 209 ; 1981: 3 ; 1985: 205 . — Hansen 1999: 50 . Diagnosis This species resembles palearctic species G . crenulatus , and is distinguished from the latter by the presence of shallow longitudinal groove on posterior portion of pronotum (lacking in G . crenulatus ). Material examined JAPAN – Hokkaido • 10 ex. ; Atsuma-cho , Yufutsu ; 12 Jun. 1995 ; S. Hori leg.; EUMJ • 9 ex. ; Kamikawagun , Shintoku-cho , Tomuraushi ; 7 Jul. 2006 ; M. Hanatsuka and Y. Hirano leg.; EUMJ • 12 ex. ; Rumoishi , Togeshita ; 4 Jun. 2004 ; H. Yoshitomi leg.; EUMJ • 10 ex. ; Hamanaka-cho , Esashito ; 1 Aug. 2004 ; K. Takahashi leg.; EUMJ • 2 ex. ; Hamanaka-cho , Biwase ; 18 Jun. 1995 ; I. Matoba leg.; EUMJ • 2 ex. ; Kaminokuni-cho , Yunotani ; 26 Jun. 1994 ; S. Hori leg.; EUMJ • 5 ex. ; Kamikawa , Ishikari-gawa : 14 Jun. 1986 ; H. Matsumoto leg.; EUMJ • 2 ex. ; Tokachi , Ashoro ; 24–31 Jul. 1959 ; K. Morimoto leg.; EUMJ • 2 ex. ; Sapporo-shi , Jozankei ; 27 Jul. 2002 ; H. Yoshitomi leg.; EUMJ • 1 ex. ; Akan-cho , Shunkushitakaragawa ; 16 Jun. 1995 ; I. Matoba leg.; EUMJ • 1 ex. ; Toyokoro-cho , Toyokita-kaigan ; 23 Jul. 1993 ; S. Hori leg.; EUMJ • 1 ex. ; Taiki-cho , Rekifune-kawa ; 23 Jul. 1993 ; S. Hori leg.; EUMJ . Redescription COLORATION ( Fig. 2A ). Black, weakly shining. HEAD ( Fig. 6A ). Clypeus uneven, provided with large granules on anterior portion; slr consisted of carinae and granules, granulation of anterior portion distinct, in contrast to posterior portion indistinct. Frons provided with scattered granules. Longitudinal groove distinct, wide, and surrounded by granules; lsa narrow, linear. PRONOTUM ( Fig. 7A ). Relatively small, widest at posterior ⅓; anterior portion sparsely provided with short grooves and small foveae; anterior margin smooth; s mlg deep, with short longitudinal grooves; posterior portion with small granules and shallow longitudinal grooves; lateral margin except anterior portion regularly bearing granules; slb indistinct, densely covered with large granules; pg short, subobsolete. ELYTRA ( Fig. 5A ). Humeral bulges distinct. All intervals slightly elevated and provided regularly with punctures. Lateral ridges indistinct, but with row of small granules. Hind wings well developed. ABDOMEN ( Fig. 8A ). Lateral margin of ventrites gradually narrowing posteriorly, especially ventrites 1–2 strongly narrowing. Granules of ventrite 1 large, relatively dense; vt large. Granulation of ventrites 2–4 indistinct, 5 distinct and dense. MALE GENITALIA ( Fig. 9A ). Aedeagus 0.40 mm long. Parameres slightly shorter than phallobase; basal portions combined as wide as anterior portion of phallobase; lateral margins slightly bulbous at anterior portion; internal margins asymmetrical; anterior portion with short setae densely. Median lobe shorter than parameres, gradually narrowing apically; basal struts short. Phallobase about 1.8 times as long as wide, widening posteriorly; posterior portion with large basal foramen. FEMALE GENITALIA ( Fig. 10A ). Latero-tergites 8 forming acute angle; apex strongly incurved. Spines of gonostylus long. Biological notes This species is common in Hokkaido and inhabits wet sandy river beds in summer ( Sharp 1888 ; Miwa 1937 ). Distribution Japan : Hokkaido ( Fig. 13 ); Russia : Sakhalin , Kunashir ( Ryndevich et al . 2021 ).