Revision of the intertidal rove beetle genus Bryothinusa from Japan (Coleoptera: Staphylinidae: Aleocharinae) Author Liu, Tian-tian Entomological Laboratory, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819 - 0395, Japan & The Kyushu University Museum, Hakozaki Author Ono, Hiroki Sounan, Minami-ku, Sagamihara-shi, Kanagawa, 252 - 0312, Japan Author Maruyama, Munetoshi The Kyushu University Museum, Hakozaki dendrolasius@gmail.com text Acta Entomologica Musei Nationalis Pragae 2021 Acta. Ent. Mus. Natl. Pragae 2021-05-07 61 1 163 201 http://dx.doi.org/10.37520/aemnp.2021.009 journal article 10.37520/aemnp.2021.009 1804-6487 5037330 27EA8466-6B29-40F4-8236-DD49061C523B Bryothinusa moriguchii sp. nov. ( Figs 1P ; 2P ; 18 ; 22 ) (Japanese name: Moriguchi-nagisa-hanekakushi) Type material. Hඈඅඈඍඒඉൾ: J, JAPAN : Nൺඇඌൾං-ඌΗඈඍත: Yagaji-jima, Nago-shi, Okinawa-ken, 21.iii.2005 , M. Moriguchi ( KUM ). Pൺ*©ൺඍඒඉൾඌ: 3 JJ 3 ♀♀ , 4 unsexed spec., same data as holotype ( KUM , NMPC , BNMH ); 2 ♀♀ , 4 unsexed spec., Uehara, Iriomote-jima, 2.iv.2004 , M. Moriguchi ( KUM ). Description. Body ( Fig. 1P ) small, about 1.9–2.2 mm in length, covered with minute setae. Basically, dark brown, elytra brown palest, head and pronotum similarly coloured, paler than abdomen; antenna, mouthparts and legs similarly coloured, lightly paler than head colour and paler toward apex. Head oval, wider than long, almost as long as pronotum, shorter than elytra; eyes ( Fig. 2P ) small, reniform, longer than 2/3 of head length, with 32–34 facets; antennal length slightly longer than distance from anterior margin of head to posterior margin of pronotum; segment I as long as II, almost 2.5 times longer than III, and as long as XI; antennal segments I–III and XI longer than wide, antennal segments IV–X almost as long as wide. Mouthparts ( Figs 18 A-E) with distribution of labral setae as in Figure 18A , with large and thick spiniform seta antero-laterally; mandibles ( Fig. 18B ) elongate triangle, asymmetrical, right with median tooth; median tooth shorter than 1/4 of mandibles; left mandible without tooth, blunt at apex; maxilla with apical margin of lacinia ( Fig. 18C ) with second spines very small and not obvious, at tip with two spines not closely interdigitating; 3 setae on inner margin of lacinia; labial palpus ( Fig. 18D ) with most setae located basally; mentum ( Fig. 18E ) with antero-lateral angles prolonged into spinose processes; anterior margin deeply truncate; small “v seta” of mentum lower than level of anterior margin. Pronotum shorter than elytra, almost as wide as head. Elytra subquadrate but wider than long, wider than pronotum; hind wings fully developed. Male abdominal sternite VIII ( Fig. 18F ) with posterior margin slightly serrate. Medial posterior margin not protruded, sharp in form on tergite X of male ( Fig. 18H ). Median lobe of aedeagus ( Fig. 18J ) and dorsal view in Figure 18K ; paramere ( Fig. 18L ) elongate. Female abdominal sternite VIII ( Fig. 18G ) with posterior margin slightly sunken but smoother than in male. Medial posterior margin protruded sharp in form on tergite X of female ( Fig. 18I ). Spermatheca ( Fig. 18M ) of complicated shape, about 2.5 times coiled near base. Measurements. BL 1.90–2.20, FBL 1.00–1.10, HL 0.35– 0.40, HW 0.43–0.45, PL 0.38–0.40, PW 0.45–0.46, EL 0.45–0.48, EW 0.50–0.55, HTL 0.33–0.38, AL 0.75–0.85, AS-I 0.10–0.13, AS-II 0.10–0.13, AS-III 0.04–0.05. Differential diagnosis. In general appearance the species is very similar to B. okinawana sp. nov. , but easily distinguished from it by having large, thick spiniform seta at the antero-lateral part of the labrum, and the coil number of the spermathecal basal part and of the posterior margin of the tergite X being protruded. Etymology. This new species is named after Mr. Mitsuru Moriguchi, the collector of the type series. Fig. 18. Bryothinusa moriguchii sp. nov. A – labrum; B – mandible, dorsal view; C – lacinia, dorsal view; D – labium; E – mentum; F – male sternite VIII; G – female sternite VIII; H – male tergite X; I – female tergite X; J – median lobe, ventral view; K – median lobe, lateral view; L – paramere; M – spermatheca. Scale bars: 0.1 mm. Fig. 19. Bryothinusa gangjinensis Ahn & Jeon, 2004 .A – labrum; B – mandible, dorsal view; C – lacinia, dorsal view; D – labium; E – mentum; F – male sternite VIII; G – female sternite VIII; H – median lobe, ventral view; I – median lobe, lateral view; J – paramere; K – spermatheca. Scale bars: 0.1 mm. Distribution. Japan ( Nansei-shotô: Okinawa-ken:Yagajijima, Iriomote-jima). Remarks. This species may occur in other areas, especially the coastline of western Japan . A distribution map of examined specimens of this species in Japan is illustrated in Figure 22 .