Copelatus tenebrosus Régimbart, 1880

(Figs 22, 61–62)

Copelatus tenebrosus Régimbart, 1880: 210 . For full list of synonyms, see Nilsson & Hájek (2022a: 61); Zimmermann 1927: 32 (Yunnan); Feng 1933: 326 (Fujian: Amoy); Jäch & Easton 1998: 44 (Macao: Friendship Monument).

Type locality. “Solok, district of Rawas and Soeroelangoen” [Indonesia, Sumatra Island] .

Type material. Syntypes deposited in Naturalis Biodiversity Center [former Rijksmuseum van Natuurlijke Historie], Leiden, Netherlands (not studied) .

Material examined. CHINA: Guangdong: 3 ♂, 1 ♀, Zhuhai, Hengqin Island, 10.vii.2006, F. Jia leg. (SYSU) ; 3 ♂, Zhuhai, Qi’ao Island, 13.-15.vii.2005, Y. Jia leg. (SYSU) . Macao: 1 ♂, Cotai Ecological Zone, 4.-5.iv.2013, F. Jia & W. Xie leg. (SYSU) ; 4 ♂, 3 ♀, Cotai Ecological Zone, 10.x.2020, F. Jia & W. Xie leg. (SYSU) . Yunnan: 7 ♂, 8 ♀, Jinghong, xii.1984 (SYSU) ; 4 ♂, 7 ♀, Xishuangbanna Agricultural Science Institute, xii.1985 (SYSU) ; 1 ♂, 2 ♀, Xishuangbanna, xii.1985 (SYSU) ; 2 ♂, 3 ♀, Xishuangbanna, Jinghong, eastern city, 500m, 12.xi.1999, M. Jäch et al. leg. (NHMW, NMPC) ; 1 ♀, Mengla County, Shangyong Town, 2.viii.2007, L. Shi leg. (SYSU) ; 1 ♂, Mengla County, Shangyong Town, 1.-3.viii.2007, J. Li leg. (SYSU) ; 1 ♀, Mengla Nature Reserve, 4.-5.viii.2007, J. Li leg. (SYSU) .

Diagnosis. Smaller (TL: 4.0– 4.9 mm), oblong-oval species. Head dark brown, clypeus and anterior part of frons usually paler, reddish; pronotum dark brown, laterally broadly reddish, anterior and posterior margin sometimes reddish translucent; elytra dark brown to black, with paler, reddish brown sides laterally from stria 6. Pronotum with short longitudinal strioles laterally. Each elytron with six complete discal striae and one submarginal stria: striae 1 and 5 beginning slightly posteriorly from base, stria 6 more distinctly so; even striae ending close to apex, odd striae usually shorter, ending more subapically; stria 6 shortest, ending at apical fourth; submarginal stria long, beginning at elytral mid-length and ending at apical fourth (Fig. 22). Median lobe of aedeagus in lateral view sickle-shaped, simple, regularly turned in apical half to obtusely pointed apex (Fig. 61). Parameres broad, ‘D’-shaped; apex short and broad; apical lobes long, club-shaped (Fig. 62). Female identical to male.

Collection details. Copelatus tenebrosus inhabits various kinds of stagnant water bodies, especially puddles and small pools with at least some vegetation; abundant in paddy fields; frequently attracted at light traps.

Distribution. One of the most widespread Copelatus species, occurring in the Oriental and Australian Regions, from the Indian subcontinent to Australia (Sheth et al. 2018, Hendrich et al. 2019). Its northernmost distribution is confined to southern China (Fujian, Macao, Taiwan, Yunnan) and Ryukyus (Satô 1985, Nilsson 1995); first record from Guangdong (Fig. 83).