Neptosternus hydaticoides (Régimbart, 1877), Regimbart, 1877

Zhao, Shuang, Hájek, Jiří, Jia, Fenglong & Pang, Hong, 2012, A taxonomic review of the genus Neptosternus Sharp of China with the description of a new species (Coleoptera: Dytiscidae: Laccophilinae), Zootaxa 3478, pp. 205-212 : 207-210

Neptosternus hydaticoides (Régimbart, 1877)

(Figs. 5, 11)

Laccophilus hydaticoides Régimbart, 1877 : LXXIX (original description, Philippines: Luzon). Neptosternus hydaticoides: Régimbart 1899: 270 (new combination); Hendrich & Balke 1997: 58 (redescription). Neptosternus tenasserimus Guignot, 1956: 452 (original description; Myanmar: Tenasserim); Hendrich & Balke 1997: 57 (new

synonymy).

Neptosternus yanbini Bian & Ji, 2009: 36 (original description; China: Hainan), syn. nov.

Type material studied. Neptosternus yanbini Bian & Ji, 2009 : Holotype 3 ( CASS), labelled: “ China: Hainan Province, Changjiang County, Bawangling Natural Reserve, 609 m, 13. iii. 2007, Yanbin Liu leg.”, “ Holotype Neptosternus yanbini Bian et Ji ”. Paratypes: 6 exs., same label data as the holotype, but “ Paratype Neptosternus yanbini Bian et Ji ” ( CASS).

FIGURES 3–9. Habitus of Neptosternus . 3–4. N. wewalkai ; 5. N. hydaticoides ; 6. N. coomani ; 7. N. strnadi ; 8. N. maculatus . Scale bar = 1 mm.

Additional material examined. 1Ƥ, China, Guangdong Province, Dinghu Mountain, 9. vii. 1964, Entian. Wu leg.; 1Ƥ, same data, but BangFa Lin leg.; 2ƤƤ, China, Guangdong Province, Qujiang County, Guitou, autumn 1942, Mengyi Mo leg. [identified as Neptosternus coomani by H. Zeng]; 13 exs., Guangdong Province, Zhuhai, Zhuhai Campus of Sun Yat-sen University, 5-8. vii. 2011, Fenglong Jia leg. (all SYSU).

Remark. Bian & Ji (2009) described a new species Neptosternus yanbini from Hainan, China. Based on the original description, the species was only compared with N. pocsi , a species occurring in Vietnam and Thailand, from which N. yanbini differs in its narrower habitus and the male genitalia. However, examination of the type series of N. yanbini by the senior author revealed no significant difference between N. yanbini and the widely distributed Oriental species N. hydaticoides .

Bian & Ji (2009) reported a rather small body size for their specimens of N. yanbini (TL: 2.6–2.9 mm) while Balke & Hendrich (1997) gave 3.25–3.30 mm for their material of N. hydaticoides . We can report a TL of 2.7–3.3 mm in the extensive material of N. hydaticoides available to us, from the whole area of its distribution. Thus, we attribute the slightly smaller body size of N. yanbini to intraspecific variability.

This opinion has been confirmed by a recent study by D. Bian (personal communication). Therefore we consider N. yanbini as a junior subjective synonym of N. hydaticoides .

Distribution. Neptosternus hydaticoides is recorded from China (Guangdong, Guangxi, Hainan, Hong Kong), through Myanmar, Thailand, Vietnam and peninsular Malaysia to Indonesia and the Philippines.