Laccobius (Microlaccobius) formosus Gentili, 1979 台灣flǿ牙ḃ

(Figs 11, 15, 19, 23)

Laccobius (Microlaccobius) formosus Gentili, 1979: 48 .

Material examined. TAIWAN: TAITUNG: 1 male, 3 females, (NMNS): Lanyu [ae嶼], Yonghsing, 17-19.VIII.1998. H.T.Shih & K.W.Huang. L.I.T, [specimens NMNS ENT 3209-1094, 3209-1690, 3209-1141, 3209-1403] ; 1 male, (NMNS): Donghe [東河], Jindonglai Forest Road, 4.VIII.2012, Y. T. Wang leg , Light . KAOHSIUNG: 1 male, 6 spec., (NMNS): Liukuei, Shanping [Oi平], 22-23.IV.2004. C.S.Lin & W.T.Yang, UV light trap, [specimens NMNS ENT 4409-723, 4409-737, 4409-712, 4409-919, 4409-734, 4409-709, 4409-711] ; 1 male, (HCLC): Liouguei District [六 AE區], Laonong River [Ž濃ë], 22.996017°N 120.638178°E, 229m, 24.VI.2020. Hsing-Che Liu & Uitsiann Ong leg. HSINCHU: 1 male, 1 female, (HCLC): Hengshan Township [DZ山ė], Youluo Stream [油ǎë], 24.714584°N 121.141335°E, 172 m, 14.II.2019. Hsing-Che Liu leg. NANTOU: 1 males, 5 spec., (NMNS): Puli Township [埔¶ D], Meixi [眉ë], 23.988475°N 121.017601°E, 536m, 12.II.2020. Hsing-Che Liu leg. ; 9 spec., (NMPC) 4.4 km W of Puli Township start of the Shikeng Road, 530 m 23.988000, 121.017833 15.II.2020. Fikáček, Hu, Liang & Liu lgt. (2020-TW003) . PINGTUNG: 1 spec., (TARI): Neipu [內埔], 26.II.2020. Y.-T. Chung leg. ; 1 male, 2 spec., (HCLC) Ligang Township [¶ffiė], Erchong River [二AEë], 22.7982°N 120.5011°E, 32m, 26.IV.2020. Hsing- Che Liu leg. TAINAN: 1 male, (HCLC): Zuozhen District [左D區], Jiaotan [m潭], 23.V.2020. by light trap, Kunta Ho & Wei-Chai Wang leg. TAICHUNG: 8 spec. (NMPC): Heping distr,, Bashianshan Mts., Dajiaxi River at Songhe village, 24.17996°N 120.98233°E, 665 m, 5.i.2018, stony river partly with gravel banks: in fine gravel below stones and in green algae mats at the side of the river, Fikáček, Liang & Hsiao lgt. (2018-TW01) ; 1 spec. (NMPC): Heping distr., Xueshankengxi River E of Taoshan village, 24.32684°N 120.95377°E, 743 m, 6.i.2018, in gravel and among algae at side of a large stony river, Fikáček, Liang, Hsiao lgt. (2018-TW06) .

Published records. Taihoku [= Taipei] (Gentili 1979). Chipon [= Taitung County]; Kaohsiung; Heito [= Pintung County]; Hualien; Ilan [= Yilan] (Gentili 1989, 1995); New Taipei (Gentili 2003).

Diagnosis. Body size 2.2–2.7 mm, body width 1.6–1.9 mm. Body oval (Fig. 11). head black with preocular yellowish spots, Antennae with 8 antennomeres. Pronotum pale, with a large slightly metallic central dark spot (Fig. 19). Elytra surface pale, with dense slightly irregular series of dark spots. Male genitalia (Fig. 15): Aedeagus 0.7 mm long. Median lobe slender, rounded and membranous at apex; parameres much longer than median lobe, apex widely rounded and membranous, truncate inwards.

Differential diagnosis. Laccobius formosus Gentili, 1979 is very similar to L. fragilis Nakane, 1966, from which it only differs in the median lobe broadly rounded at apex.

Distribution. China (Gansu, Guandong, Guangxi, Hainan, Hubei, Hunan, Jiangxi, Liaoning, Sichuan, Shaanxi, Shandong), Russia (Far East), Taiwan (Fig. 27) (Przewoźny 2020, this paper). In Taiwan, L. formosus is distributed throughout the main island.

Bionomics. All specimens were collected from stony streams (Fig. 23).