Georissus Latreille 1809
Creators: name: Yasuda, Kohei
name: Yoshitomi, Hiroyuki
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Georissidae
Georissus

description: Genus Georissus Latreille, 1809
Georissus Latreille, 1809: 377.
Type species: Pimelia pygmaea Fabricius, 1798 (= Byrrhus crenulatus Rossi, 1794) [monotypy].
Cathammistes Illiger, 1807a: 297; 1807b: 322 [suppressed, cf. ICZN 1998: 58]. Gender: masculine.
Georyssus [unjustified emendation] – Stephens 1828: 105.
Supplementary description
BODY. Black to reddish brown, oval, strongly convex dorsally.
CLYPEUS. Uneven, with granules or carinae on its surface; articulated carinae arising at antero-lateral portion of clypeus and reaching anterior portion of frons (slr in Fig. 1A); a pair of distinct bulges (smb in Fig. 1A) on antero-median portion of frons (in Nipponogeorissus and Neogeorissus); sides of frons smooth, lacking granules (lsa in Fig. 1A). Eyes developed, not protuberant. Antennae (Fig. 4M–O) short, 9-segmented, with 3-segmented pubescent club (7-segmented with one-segmented club in Australian species: Fikáček 2019). Mandibles (Fig. 4J–L) large and well sclerotized, partly concealed beneath clypeus and labrum; antero-lateral margin forming obtuse angle; apex pointed; internal margin with microtrichia except apex. Maxillary palpi (Fig. 4A–C) 4-segmented; palpomere 4 longest and nearly same length as palpomeres 1–3 combined. Labrum (Fig. 4D–F) semicircular, widest at base; lateral margins fringed with spines. Mentum subtriangular, strongly narrowed anteriorly, with long setae on disc. Labial palpi (Fig. 4G–I) as long as mentum; apical palpomere oval to oblong oval, densely bearing spines in interior margin.
PRONOTUM. Half oval to trapezoidal, divided into anterior and posterior portions; anterior portion irregularly arranged with granules or short grooves and pits, with shallow median longitudinal groove (smlg in Fig. 1B); posterior portion more convex than anterior portion, with large fovea on anteromedian portion (cd in Fig. 1B); posterior sides of cd with a pair of distinct foveae (sdp in Fig. 1B) (only in Neogeorissus); sublateral potion of posterior portion with distinct bulge (slb in Fig. 1B); behind of slb with deep groove (pg in Fig. 1B); sides somewhat protruding laterally, having dentation (sdn in Fig. 1B) in Neogeorissus.
LEGS. Protrochantins concealed. Procoxae large, plate-like, concealing prosternum. Femora somewhat flattened. Tibiae slender, especially protibiae rather flattened. Tarsal formula 5-5-5 (5-4- 4 in Australian species: Fikáček 2019).
ELYTRA. Provided with ten punctate rows. All or alternate intervals slightly to highly raised. Hind wings well developed or absent in some species.
VENTRITES. Ventrites 1 and 2 connate; ventrite 1 large, with distinct granules; posterior margin of ventrite 1 and anterior margin of ventrite 2 with a pair of ventral teeth (vt in Fig. 8A).
MALE GENITALIA (Fig. 9). Aedeagus trilobate type, almost symmetrical.
FEMALE GENITALIA. Gonocoxite (Fig. 10) long, almost cross each other posteriorly. Gonostylus short, provided with two long setae at apex. Median sclerite unilobed, densely bearing long setae. Spermatheca (Fig. 11E–H) slightly sclerotized, elongated oval. Bursal sclerite (Fig. 11A–D) somewhat developed in subgenus Neogeorissus, slightly asymmetrical.
Key to the species of the genus Georissus from Japan
1. Posterior portion of pronotum with a shallow median longitudinal groove, lacking granules or cd and sdp. Elytra bearing seriate large punctures. Elytral interstices smooth. Aedeagus broad, median lobe short (Fig. 9A–B). Subgenus Georissus Latreille, 1809 ............................................................ 2
– Posterior portion of pronotum provided with granules or foveae. Elytra bearing distinct granules. Elytral interstices raised. Aedeagus narrow, median lobe short or long (Fig. 9C–H) ...................... 3
2. Granules of clypeus distinct, large and dense (Fig. 6B). Posterior portion of pronotum lacking a longitudinal groove (Fig. 7B). Internal margins of parameres covered with long setae (Fig. 9B) ..... ...................................................................................................................... G. (G.) babai Satô, 1970
– Granules of clypeus indistinct, small and sparse (Fig. 6A). Posterior portion of pronotum having a shallow longitudinal groove (Fig. 7A). Internal margins of parameres covered with short setae (Fig. 9A) .............................................................................................. G. (G.) canalifer Sharp, 1888
3. Posterior portion of pronotum densely bearing granules, lacking cd and sdp. Pronotum lacking sdn (Fig. 7C). Aedeagus extremely narrow, phallobase posteriorly widening (Fig. 9C). Subgenus Nipponogeorissus Satô, 1972 ........................................................... G. (Ni.) granulosus Satô, 1972
– Posterior portion of pronotum provided with granules, present cd and sdp. Pronotum having sdn (Fig. 1B). Aedeagus narrow, phallobase subparallel-sided (Fig. 9D–H). Subgenus Neogeorissus Satô, 1972 ......................................................................................................................................... 4
4. Elytral interstices 2, 4, 6 highly raised (Fig. 5G–H) ............................... G. (Ne.) takahashii sp. nov.
– All elytral interstices equally raised (Fig. 5D–F, I) .......................................................................... 5
5. Coloration of body black. Elytral granules indistinct (Fig. 5E–F) ..................................................... ....................................................................................................... G. (Ne.) kurosawai Nakane, 1963
– Coloration of body dark reddish brown. Elytral granules distinct (Fig. 5D, I) ................................ 6
6. Coloration of body black to dark brown. Granulation of pronotum distinct (Fig. 7D). Median lobe shorter than parameres (Fig. 9D) ........................................................ G. (Ne.) japonicus Satô, 1972
– Coloration of dark reddish brown. Granulation of pronotum indistinct (Fig. 7I). Median lobe longer than parameres (Fig. 9H) ................................................................................. G. (Ne.) satoi sp. nov.
description: Published as part of Yasuda, Kohei & Yoshitomi, Hiroyuki, 2022, Revision of the genus Georissus (Coleoptera, Hydrophiloidea, Georissidae) of Japan, pp. 111-142 in European Journal of Taxonomy 817 (1) on pages 113-115, DOI: 10.5852/ejt.2022.817.1767, http://zenodo.org/record/6517928