Bryothinusa minuta ( Sawada, 1955 )

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 : 169-173

Bryothinusa minuta ( Sawada, 1955)

( Figs 1B ; 2B ; 4 ; 20B–D ; 21G ; 22 )

(Japanese name: Hoso-nagisa-hanekakushi)

Halesthenus minutus Sawada, 1955:83–84 , plate 16 (original description, illustrated, type locality:Yoriki, Nakano-shima, 4.vi.1953, S. Uéno). Bryothinusa minuta : Sൺඐൺൽൺ (1971): 82 (transferred from Halesthenus ; redescription;new distribution records); Sൺඐൺൽൺ (1972):unnumbered table at end of article (characters); Mඈඈ*©ൾ et al. (1973): 74in (key to species of Bryothinusa ), 77 (nomenclatorial history; diagnosis); Mඈඈ*©ൾ & Lൾ*ûඇൾ*© (1975):109–110 (in key to species Bryothinusa of), 111 (in tabular key to known species of Bryothinusa ); A*üඇ & Aඌ*üൾ (2004): 123–138 (phylogeny of Myllaenini and related taxa);A*üඇ& Jൾඈඇ (2004): 34 (new record of Korea);Aඌ*üൾ (2004):592 (in annotated catalogue of world species); F*©ൺඇκ & A*üඇ (2011): 27 (in checklist); Sർ*ü*“අκൾ & Sආൾඍൺඇൺ (2015):676 (in catalogue of Palearctic species); A*üඇ et al. (2017): 307 (in checklist of Staphylinidae in Korea); Lංඎ et al. (2020): 589 (in key of Japanese species), 591 (in checklist).

Type material. Not examined.

Material examined. JAPAN: Hඈκκൺංൽô: 2 ♀♀, Usu-chô, Date-shi, Hokkaidô, 12.iv.2020, Y.Tasaku. HඈඇඌΗǕ: 44 unsexed spec., Sunosakikaigan, Sunosaki, Tateyama-shi, Chiba-ken, 6.ii.2007, H.Ono; 1 unsexed spec., Kanaya, Futtsu-shi, Chiba-ken, 9.iv.2007, H. Ono; 2 unsexed spec., Shibasaki-bashi, Kanaya, Futtsu-shi, Chiba-ken, 14.vi.2009, H. Ono; 2 unsexed spec., Nagasakibana, Chôshi-shi,Chiba-ken, 16.ix.2009, H.Ono; 2 unsexed spec., same locality, 13.x.2009, H. Ono; 1 unsexed spec., Kuruwa-kaigan,Akiya, Yokosuka-shi, Kanagawa-ken, 14.ix.2013, H. Ono; 3 JJ 5 unsexed spec., Mouth of Kô-gawa, Numazu-shi, Shizuoka-ken, 1.x.2000, T.Kurihara; 3 ♀♀, 5 unsexed spec., Tsumeki-zaki, Shimoda-shi, Shizuoka-ken, 21.iv.2003, M.Maruyama; 1 J, Wakamatsu-zaki, Numazu -shi, Shizuoka-ken, 1.x.2000, T.Kurihara; 2 unsexed spec., Kusumibana, Ôbatake, Kojima, Kurashiki-shi, Okayama-ken, 21.iii.2009, O. Yamaji; 3 unsexed spec., Ta-no-ura, Naga-shima, Kaminoseki-chô, Yamaguchiken, 15.x.2005, Y. Nakase. SΗංκඈκඎ: 1 J, Kaigan-ji, Nishishirakata, Tadotsu-chô, Kagawa-ken, 31.iii.2008, H. Fujimoto; 2 JJ 2 ♀♀, 3 unsexed spec., Ôyatomi-machi, Sakaide-shi, Kagawa-ken, 29.iii.2008, H. Fujimoto; 1 J 2 ♀♀, 10 unsexed spec., Mouth of Umayado-gawa, Umayado, Higashi-kagawa-shi, Kagawa-ken, 11.v.2014, T. Taki; 7 unsexed spec., Ado-ike, Hiketa, Higashi-kagawa-shi, Kagawa-ken, 28.vii.2013, T. Taki; 17 unsexed spec., same locality, 11.v.2014, T. Taki; 2 unsexed spec., Koura-kaigan, Koiso, Higashi-kagawa-shi, Kagawa-ken, 29.iv.2014, T. Taki; 1 unsexed spec., same locality, 21.iv.2014, T. Taki. KඒǕඌΗǕ: 1 J, Suno-saki, Imazu, Nishi-ku, Fukuoka-shi, Fukuoka-ken, 26.vi.2020,Y.Hisasue; 31 unsexed spec., same locality, 16.x.2020, T. Liu & T. Nozaki; 1 unsexed spec., Miyaga-hama, Ibusuki-shi, Kagoshimaken, 19.iv.2008, M. Maruyama; 2 unsexed spec., Ko-ura, Kasasa-machi, Minamisatsuma-shi, Kagoshima-ken, 20.iv.2008, M. Maruyama; 3 unsexed spec., Aiboshi-gawa, Aiboshi, Minamisatsuma-shi, Kagoshima-ken, 20.iv.2008, M. Maruyama. Nൺඇඌൾං-ඌΗඈඍත: 6 unsexed spec., Ôgomori, Takara-jima, Tokara-rettô, Kagoshima-ken, 6.vii.2019, T. Liu, N. Tsuji & H. Ono; 3 JJ 1 ♀, 27 unsexed spec., Yoriki (a gravel beach), Nakano-shima, Tokara-rettô, Kagoshima-ken, 7.vii.2019, T.Liu, N.Tsuji & H. Ono; 15 unsexed spec., same locality, 8.vii.2019, T. Liu, N. Tsuji & H. Ono; 1 unsexed spec., You, Kasari-chô, Amami-Ôshima, Ôshima- gun, Kagoshima-ken, 27.ii.2004, H. Kamezawa; 2 ♀♀, 2 unsexed spec., Kasari-wan, Kasari-chô, Amami-Ôshima, Kagoshima-ken, 4.vi.2008, M. Maruyama; 4 unsexed spec., Yuwan, Uken-son, Amami-Ôshima, Kagoshima-ken, 5.vi.2008, M. Maruyama; 1 J 1 ♀, 3 unsexed spec., Shokazu, Setouchi-chô, Kakeroma-jima, Kagoshima-ken, 6.vi.2008, M. Maruyama; 1 ♀, Onna-son, Inbu-gun, Okinawa-ken, 11–13.v.2005, M. Sugimoto;3 JJ, Teruma,Yonagusuku-son,Okinawa-ken, 14.ix.2003, M. Moriguchi; 2 unsexed spec., Fûne,Ishigaki-shi, Okinawa-ken, 7.iii.2000, T. Kurihara; 6 JJ 8 unsexed spec., same locality, 8.iii.2000, T. Kurihara; 3 unsexed spec., same locality, 12.iii.2000, T. Kurihara; 10 unsexed spec., Nagura-Anparu, Nagura, Ishigaki-shi, Okinawa-ken, 4.ii.2009, H. Ono; 2 JJ 2 ♀♀, 42 unsexed spec., Mouth of Honera-gawa, Iriomote-jima, Takana, Taketomi-chô, Okinawa-ken, 2.iv.2019, T. Nozaki; 3 unsexed spec., Mouth of Honera-gawa, Takana, Taketomi-chô, Iriomote-jima, Okinawa-ken, 24.vi.2019, T. Liu & N. Tsuji. OǤൺඌൺඐൺඋൺ-ඌΗඈඍත: 2JJ 1 ♀, 6 unsexed spec., Ô-mura, Chichi-jima, Ogasawara-shotô, Tôkyô-to, 1.x.1977, Y. Watanabe. Deposited at KUM but some will be distributed to NMPC and BMNH.

Redescription. Body ( Fig. 1B ) small, about 1.6–1.7 mm long, densely covered with minute setae. Head, pronotum and elytra light yellow; abdominal tergites VI–VII almost infuscate posteriorly; antenna, mouthparts and legs similarly coloured, lightly paler than head colour and paler toward apex.

Head oval, wider than long, longer than pronotum and elytra; eyes ( Fig. 2B ) small, reniform, shorter than 1/4 head length, with 3 or 4 facets; antennal length shorter than distance from anterior margin of head to posterior margin of elytra; all antennal segments longer than wide; segment I 1.5 times longer than II, almost 2.5 times longer than III, and shorter than XI.

Mouthparts ( Figs 4A–E ) with distribution of labral setae as in Figure 4A ; mandibles ( Fig. 4B ) elongate triangle, asymmetrical, right mandible with median tooth; median tooth longer than 1/4 of mandibles; left mandible without tooth, blunt at apex; maxilla with apical margin of lacinia ( Fig. 4C ) with two spines interdigitating close; 2–3 setae on inner margin of lacinia; labial palpus ( Fig. 4D ) with most setae located basally; mentum ( Fig. 4E ) with antero- -lateral angles prolonged into spinose processes; anterior margin deeply truncate; small “v seta” of mentum distant from apical setae.

Pronotum longer than elytra, narrower than head.

Elytra widened apically, wider than long, narrower than pronotum; hind wings absent.

Male abdominal sternite VIII ( Fig. 4F ) with posterior margin slightly serrate. Medial posterior margin protruded sharp in form on tergite X of male ( Fig. 4H ). Median lobe of aedeagus as in Figs 4J, K ; paramere ( Fig. 4L ) elongate.

Female abdominal sternite VIII ( Fig. 4G ) with posterior margin slightly serrate but rounder and smoother than in male. Medial posterior margin protruded sharp in form on tergite X of female ( Fig. 4I ), and sharper than in male. Spermatheca ( Fig. 4M ) small and apical part very short; basal part complicated in shape; several times coiled near base. Measurements. BL 1.60–1.70, FBL 0.70–0.80, HL 0.25– 0.28, HW 0.25–0.34, PL 0.24–0.26, PW 0.25–0.28, EL 0.20–0.23, EW 0.24–0.25, HTL 0.23–0.26, AL 0.55–0.65, AS-I 0.08–0.09, AS-II 0.05–0.06, AS-III 0.03–0.04.

Differential diagnosis. This species is easily distinguished from the other Japanese species of Bryothinusa by the smaller body and strongly reduced eyes, each consisting of 3 or 4 facets only.

Distribution. Japan (Hokkaidô; Honshû: Chiba-ken, Tôkyô-to, Kanagawa-ken, Shizuoka-ken, Wakayama-ken, Okayama-ken, Yamaguchi-ken; Shikoku: Kagawa-ken; Kyûshû: Fukuoka-ken, Kagoshima-ken; Nansei-shotô: Kagoshima-ken: Takara-jima, Nakano-shima, Amami -Ôshima, Kakeroma-jima; Okinawa-ken: Okinawa-jima, Ishigaki-jima, Iriomote-jima; Ogasawara-shotô: Chichijima); Korea.

Remarks. This species is very small, currently the smallest species in Japan, and the specimens were collected under stones. In the Japanese species of Bryothinusa , B. minuta is most widely distributed, from Hokkaidô to Iriomote-jima. A distribution map of examined specimens of this species in Japan is illustrated in Figure 22 .

Bryothinusa tsutsuii ( Sawada, 1955)

( Figs 1C ; 2C ; 5 ; 20E–G ; 21D ; 22 )

(Japanese name: Kiiro-nagisa-hanekakushi)

Halesthenus tsutsuii Sawada,1955: 84 (original description; type locality: Japan: Nansei-shotô, Tokara-rettô, Takara-jima).

Halesthenus serpentis Sawada, 1955: 84–85 (original description); Sൺඐൺ- ൽൺ (1971): 85 (placed as a junior synonym of B. tsutsuii ); Sආൾඍൺඇൺ (2004): 464 (catalogue of Palearctic species; as a valid species); Sർ*ü*“අκൾ & Sආൾඍൺඇൺ (2015): 676 (catalogue of Palearctic species; as a valid species). Synonymized by Sൺඐൺൽൺ (1971: 85).

Bryothinusa tsutsuii : Sൺඐൺൽൺ (1971): 85–87 (transferred from Halesthenus ; redescription); Sൺඐൺൽൺ (1972): unnumbered table at end

of article (characters); Mඈඈ*©ൾ et al. (1973): 74 (in key to species

of Bryothinusa ), 77 (nomenclatorial history; diagnosis); Mඈඈ*©ൾ & Lൾ*ûඇൾ*© (1975): 109–110 (in key to species of Bryothinusa ), 111 (in tabular key to known species of Bryothinusa ); Aඌ*üൾ (2004): 595 (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 ♀♀, 9 unsexed spec., Mage-shima (near Tanega-shima), Kagoshima-ken, 14.x.2000, M. Maruyama (under stone on sandy beach, in a port); 5 JJ 3 ♀♀, 18 unsexed spec.,Ama-domari (a gravel beach), Nakano-shima,Tokara-rettô, Kagoshima-ken, 7.vii.2019, T. Liu & H. Ono; 1 J 6 ♀♀, 19 unsexed spec., Uken-son, Edateku-jima (near Amami-Ôshima), Kagoshima-ken, 5.vi.2008, M. Maruyama; 6 unsexed spec., Izena, Izena-son, Shimajirigun, Okinawa-ken, 5.v.2013, M. Asano; 4 JJ 5 ♀♀, 66 unsexed spec., Mihama (Sunset Beach), Chatan-chô, Okinawa-jima, Okinawa-ken, 27.iii.2009, H. Suenaga; 1 ♀, 7 unsexed spec., Chatan-chô, Okinawa, Okinawa-ken, Nansei-shotô, 26.v.2002, M. Moriguchi; 1 J 2 ♀♀, 7 unsexed spec., Teruma, Yonagusuku-son, Okinawa-ken, 14.ix.2003, M. Moriguchi; 1 ♀, 3 unsexed spec., Ou-jima, Nago-shi, Okinawa-ken, 30.iv.2006, M. Moriguchi; 2 JJ 1 ♀, 2 unsexed spec., Inbu-gun, Onnason, Okinawa-ken, 11–13.v.2005, M. Sugimoto; 3 JJ 1 ♀, 7 unsexed spec., Kadena-Marina, Kadena-chô, Okinawa-ken, 25.iv.2005, M. Moriguchi (under stone on sandy beach in estuary); 1 unsexed spec., Nakasuji, Ishigaki-shi, Ishigaki-jima, Okinawa-ken, 14.iii.2000, T. Kurihara; 1 J 2 ♀♀, 8 unsexed spec., Inoda, Ishigaki-jima, Okinawa-ken, 31.v.2003, M. Moriguchi;2 JJ 1♀, 13 unsexed spec., Fûne,Ishigaki-shi, Ishigaki-jima, Okinawa-ken, 8.iii.2000, T. Kurihara; 2 unsexed spec.,Akaishi, Ishigaki -shi, Ishigaki-jima, Okinawa-ken, 30–31.iii.2010, T. Hayama; 1 unsexed spec., Haemida,Taketomi-chô, Iriomote-jima, Okinawa-ken, 19.iii.2000, T. Kurihara; 2 ♀♀, 7 unsexed spec., same locality, 24.x.2020, T. Nozaki; 1 J 1 ♀, 7 unsexed spec., Mouth of Nakama-gawa, Haiminaka, Iriomote-jima, Yaeyama-gun, Okinawa-ken, 4.ix.2020, S. Inoue & Y. Hisasue. Deposited at KUM but some will be distributed to NMPC and BMNH.

Redescription. Body ( Fig. 1C ) small about 1.9–2.2 mm long, covered with minute setae. Head, pronotum and elytra yellowish brown; abdominal tergites IV–VII infuscate posteriorly; antenna, mouthparts and legs similarly coloured, slightly paler than head colour and paler toward apex.

Head oval, slightly wider than long, longer than pronotum and elytra; eyes ( Fig. 2C ) small, reniform, shorter than tempora length, setae present between about 15–17 facets; antennal length little shorter than distance from anterior margin of head to posterior margin of elytra; all antennal segments longer than wide; segment I 1.3 times longer than II, almost 2 times longer than III, and as long as XI.

Mouthparts ( Figs 5A–E ) with distribution of labral setae as in Figure 5A ; mandibles ( Fig. 5B ) elongate triangle, asymmetrical, right mandible with median tooth; median tooth longer than 1/4 of mandibles; left mandible without tooth, blunt at apex; maxilla with apical margin of lacinia ( Fig. 5C ) with three spines closely interdigitating and second spine very small, not obvious; 4 setae on inner margin of lacinia; labial palpus ( Fig. 5D ) with most setae located basally; mentum ( Fig. 5E ) with antero-lateral angles prolonged into spinose processes; anterior margin deeply truncate; small “v seta” of mentum lower than level of anterior margin.

Pronotum almost as long as elytra, slightly wider than head.

Elytra wider than long, almost as wide as pronotum; hind wings absent.

Male abdominal sternite VIII ( Fig. 5F ) with posterior margin slightly serrate. Median lobe of aedeagus as in Figures 5H, I ; paramere ( Fig. 5J ) elongate.

Female abdominal sternite VIII ( Fig. 5G ) with posterior margin slightly serrate but smoother than in male. Spermatheca ( Fig. 5K ) about 1.5 times coiled near base.

Measurements. BL 1.90–2.20, FBL 1.00–1.20, HL 0.33– 0.45, HW 0.43–0.45, PL 0.35–0.40, PW 0.40–0.46, EL 0.38–0.40, EW 0.45–0.46, HTL 0.33–0.38, AL 0.83–1.05, AS-I 0.11–0.14, AS-II 0.08–0.11, AS-III 0.05–0.07.

Differential diagnosis. In general appearance the species is closely allied to B. algarum , B. japonica , B. koreana and B. yoshigoui sp. nov., but easily distinguished from B. japonica , B. koreana and B. yoshigoui sp. nov. by the shape of the spermatheca and the median lobe of the aedeagus without granule-like projections and from B. algarum by the simplified shape of the spermatheca.

Distribution. Japan (Nansei-shotô: Kagoshima-ken: Tanega-shima, Takara-jima, Nakano-shima, Edateku-jima; Okinawa-ken: Izena-jima, Okinawa-jima, Ou-jima, Ishigaki-jima, Iriomote-jima).

Remarks. The number of facets is different from the original description, but other morphological characters completely coincide with it. The type specimen was not found despite the efforts of Mr. Shigehiko Shiyake of Ôsaka Museum of Natural History, to which Dr. Kohei Sawada donated the collection.

This species is mainly found in Nansei-shotô but probably found also in mainland Kyûshû. A distribution map of examined specimens of this species in Japan is illustrated in Figure 22 .

Figures

Fig. 1. Habitus of Bryothinusa spp. A – B. algarum Sawada, 1971; B – B. minuta (Sawada, 1955); C – B. tsutsuii (Sawada, 1955); D – B. koreana Ahn & Jeon, 2004; E – B. yoshigoui sp. nov.; F – B. japonica Liu, Ono & Maruyama, 2020; G – B. sakishimana Sawada, 1991; H – B. constricta sp. nov.; I – B. hokkaidensis sp. nov.; J – B. fulvipennis sp. nov.; K – B. itsuroi sp. nov.; L – B. aikoae sp. nov.; M – B. okinawana sp. nov.; N – B. nigra sp. nov.; O – B. nakanei (Sawada, 1955); P – B. moriguchii sp. nov.; Q – B. gangjinensis Ahn & Jeon, 2004. Scale bars: 1.00 mm.

Fig. 2. Compound eyes of Bryothinusa spp.A – B. algarum Sawada, 1971; B – B. minuta (Sawada, 1955); C – B. tsutsuii (Sawada, 1955); D – B. koreana Ahn & Jeon, 2004; E – B. yoshigoui sp. nov.; F – B. japonica Liu, Ono & Maruyama, 2020; G – B. sakishimana Sawada, 1991; H – B. constricta sp. nov.; I – B. hokkaidensis sp. nov.; J – B. fulvipennis sp. nov.; K – B. itsuroi sp. nov.; L – B. aikoae sp. nov.; M – B. okinawana sp. nov.; N – B. nigra sp. nov.; O – B. nakanei (Sawada, 1955); P – B. moriguchii sp. nov.; Q – B. gangjinensis Ahn & Jeon, 2004. Scale bars: 0.05 mm.

Fig. 4. Bryothinusa minuta (Sawada, 1955).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 – medin lobe, ventral view; K – medin lobe, lateral view; L – paramere; M – spermatheca. Scale bars: 0.1 mm.

Fig. 20. Collection localities of Bryothinusa species in Japan:A – B. algarum Sawada, 1971 in Nemoto, Chiba; B – B. minuta (Sawada, 1955), B. nakanei (Sawada, 1955) and B. sakishimana Sawada, 1991 in Takara-jima (Ôgomori beach), Tokara-rettô; C – B. minuta in Nakano-shima (Yoriki), Tokara-rettô; D – B. minuta, B. nakanei and B. sakishimana in Iriomote-jima (mouth of Honera-gawa); E – B. tsutsuii (Sawada, 1955) in Nakano-shima (Amadomari), Tokara-rettô; F – B. nakanei and B. tsutsuii in Iriomote-jima (Haemida); G – B. tsutsuii in Iriomote-jima (mouth of Nakama-gawa); H – B. itsuroi sp. nov. and B. koreana Ahn & Jeon, 2004 in Kakise, Taka-shima, Nagasaki.

Fig. 21. Collection localities of Bryothinusa species in Japan: A – B. koreana Ahn & Jeon, 2004 and B. japonica Liu, Ono & Maruyama, 2020 in Shima-nogita, Fukuoka; B – B. aikoae sp. nov., B. fulvipennis sp. nov., B. japonica and B. nigra sp. nov. in Kuroto, Chiba; C – B. hokkaidensis sp. nov. in Shunkunitai, Hokkaidô; D – B. nigra sp. nov. and B. tsutsuii (Sawada, 1955) in Edateku-jima; E – B. nakanei (Sawada, 1955) in Nagura-anparu, Ishigaki-jima; F – B. gangjinensis Ahn & Jeon, 2004 in Iki-no-matsubara, Fukuoka; G – B. algarum Sawada, 1971, B. japonica and B. minuta (Sawada, 1955) in Sunosaki, Fukuoka.

Fig. 22. Map of examined specimens of Bryothinusa spp. from Japan: white inverted triangle – B. algarum Sawada, 1971; black inverted triangle – B. minuta (Sawada, 1955); white star – B. tsutsuii (Sawada, 1955); black star – B. koreana Ahn & Jeon, 2004; black square – B. yoshigoui sp. nov.; white triangle – B. japonica Liu, Ono & Maruyama, 2020; black diamond – B. sakishimana Sawada, 1991; white diamond – B. constricta sp. nov.; white square – B. hokkaidensis sp. nov.; black triangle – B. fulvipennis sp. nov.; double circle – B. itsuroi sp. nov.; arrow – B. aikoae sp. nov.; black hart – B. okinawana sp. nov.; circled dot – B. nigra sp. nov.; white circle – B. nakanei (Sawada, 1955); white hart – B. moriguchii sp. nov.; black circle – B. gangjinensis Ahn & Jeon, 2004.

Fig. 5. Bryothinusa tsutsuii (Sawada, 1955).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.