Ophiogomphus (Ophionurus) sinicus (Chao, 1954)

(Figs 12, 13, 26, 27, 34, 35)

Examined specimens. 1 ♂, Nam Toong bridge (22.7853 N, 105.8512 E, altitude 1373 m), Pia Oac National Park, Cao Bang Province, northern Vietnam, 18.v.2015, Q. T. Phan leg.

Notes. This species was described from Guangxi, China (Chao 1954) and subsequently recorded in Jiangxi, Fujian, Guangdong, and Hong Kong (Zhang 2019) and northern Vietnam on an internet blog (Kompier 2014). Ophiogomphus sinicus is the largest representative of the genus in Vietnam (measurements: Abdomen including appendages: 46 mm; Hw 37 mm).

It should be noted here that, Karube (2014: p. 80) stated that the apical 2/3 of male cerci of Ophiogomphus sinicus from Cao Bang Province, North Vietnam are yellowish. However Wilson (per. comm.) has informed us that some specimens of O. sinicus from Hong Kong have entirely blackish-brown cerci. This may represent onto genetic or geographic variability.

Distribution. Vietnam: Cao Bang Province (Pia Oac National Park) (Fig. 36); China: Jiangxi, Fujian, Guangdong and Guangxi Provinces and Hong Kong (Zhang 2019).