Bryothinusa sakishimana Sawada, 1991

Liu, Tian-tian, Ono, Hiroki & Maruyama, Munetoshi, 2021, Revision of the intertidal rove beetle genus Bryothinusa from Japan (Coleoptera: Staphylinidae: Aleocharinae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 61 (1), pp. 163-201 : 176-179

publication ID	https://doi.org/ 10.37520/aemnp.2021.009
publication LSID	lsid:zoobank.org:pub:27EA8466-6B29-40F4-8236-DD49061C523B
persistent identifier	https://treatment.plazi.org/id/03CB023B-AC07-FF92-4CC6-FA321502F9B8
treatment provided by	Carolina
scientific name	Bryothinusa sakishimana Sawada, 1991
status

Treatment

Bryothinusa sakishimana Sawada, 1991 View in CoL

( Figs 1G View Fig ; 2G View Fig ; 9 View Fig ; 21B, D View Fig ; 22 View Fig )

(Japanese name: Sakishima-nagisa-hanekakushi)

Bryothinusa sakishimana Sawada, 1991: 144 View in CoL (original description; type locality: Japan, Nansei-shotô, Iriomote-jima), 145 (compared with B. nakanei Sawada View in CoL );Aඌ*üൾ (2004): 594 (in annotated catalogue of world species); Sආൾඍൺඇൺ (2004): 464 (in catalogue of Palearctic species); F*©ൺඇκ &A*üඇ (2011): 27 (in checklist); Sർ*ü*“අκൾ & Sආൾඍൺඇൺ (2015): 676 (in catalogue of Palearctic species); Lංඎ et al. (2020): 589 (in key of Japanese species), 592 (in checklist).

Type material. Not examined.

Material examined. JAPAN: Nൺඇඌൾං-ඌΗඈඍත: 3 JJ 2 ♀♀, 11 unsexed spec., Ôgomori, Takara-jima, Tokara-rettô, Kagoshima-ken, 3.vii.2019, T. Liu, N. Tsuji & H. Ono; 1 unsexed spec., Mouth of Honera-gawa, Takana, Taketomi-chô, Iriomote-jima, Okinawa-ken, 2.iv.2019, T. Nozaki. Deposited at KUM but some will be distributed to NMPC and BMNH.

Redescription. Body ( Fig. 1G View Fig ) small, about 1.6–1.9 mm in length, covered with minute setae. Abdomen almost black and darker than head and pronotum; elytra lighter than pronotum; antenna and legs yellowish brown.

Head evenly rounded, more or less produced anteriorly, wider than long, shorter than pronotum and elytra; eyes ( Fig. 2G View Fig ) large, setae present between about 21–23 facets, slightly longer than tempora length; antenna yellowish brown, longer than total length of head and pronotum; segment I 1.4 times longer than II, almost 3.8 times longer than III, and longer than XI; antennal segments V–X almost as long as wide.

Mouthparts ( Figs 9A–E View Fig ) with distribution of labral setae as in Fig. 9A View Fig , with large and thick spiniform seta antero-laterally; mandibles ( Fig. 9B View Fig ) elongate triangle, asymmetrical, right mandible with median tooth; median tooth shorter than 1/4 of mandibles; left without tooth, blunt at apex; maxilla with apical margin of lacinia ( Fig. 9C View Fig ) with second spine very small, not obvious; 3 setae on inner margin of lacinia; labial palpus ( Fig. 9D View Fig ) with most setae located basally; mentum ( Fig. 9E View Fig ) with antero-lateral angles prolonged into spinose processes; anterior margin deeply truncate; small “v seta” far away from apical setae.

Pronotum shorter than elytra, wider than head.

Elytra subquadrate, narrower than pronotum; almost unicolour and hind wings present but small, apparently flightless.

Male abdominal sternite VIII ( Fig. 9F View Fig ) with posterior margin slightly serrate. Median lobe of aedeagus as in Figures 9H, I View Fig ; paramere ( Fig. 9J View Fig ) elongate.

Female abdominal sternite VIII ( Fig. 9G View Fig ) slightly serrate alike male on posterior margin. Spermatheca ( Fig. 9K View Fig ) about 1.5 times coiled near base, apical part elongate.

Measurements. BL 1.60–1.90, FBL 0.70–1.00, HL 0.28– 0.33, HW 0.35–0.40, PL 0.33–0.38, PW 0.40–0.45, EL 0.35–0.40, EW 0.38–0.40, HTL 0.33–0.35, AL 0.70–0.83, AS-I 0.12–0.15, AS-II 0.09–0.10, AS-III 0.03–0.04.

Differential diagnosis. In Nansei-shotô, this species is especially similar to B. nakanei , but easily distinguished from it by the paler elytral colour, the number of facets, the spermathecal shape and the posterior margin of the tergite X rounded medially. This species is also similar to B. constricta sp. nov. in general appearance but differentiated from it by the elytral shape not being almost square and the shape of the spermatheca.

Distribution. Japan (Nansei-shotô: Kagoshima-ken: Takara-jima; Okinawa-ken: Iriomote-jima).

Remarks. This species is distributed in Nansei-shotô of Japan. A distribution map of examined specimens of this species in Japan is illustrated in Figure 22 View Fig .