Melittia eurytion formosana Matsumura, 1911 (stat. nov.)

= Melittia eurytion nagaii Arita & Gorbunov, 1997 (syn. nov.)

Material examined. 1 ♂, Guangdong Prov., Shaoguang, Nanling, 900 m, 10.vii.2003 (NSMT) ; 1 ♂, Guangxi Prov., Guilin, Maoershan, 500–1500 m, 6.–10.viii.2009 (NSMT) ; 1 ♂, Guandong Prov., Shaoguang, Nanling, 600 m, 23.vii.2014 (NSMT) ; 2 ♂, same locality, 600 m, 19.vii.2014 (NSMT); 2 ♀, same locality, 2.–6.vii.2012 (CAK) .

Melittia eurytion is widespread and relatively common, occurring from India and Nepal throughout mainland south-east Asia to southern China and Vietnam. Melittia formosana was originally recorded from Taiwan, while Melittia nagaii was originally described from southern Japan and later considered a subspecies of M. eurytion (compare to Špatenka et al. 1999). Examination of multiple specimens representing this group of taxa and covering most of this range did not support the separation of distinct species. Specimens from Taiwan and the southern islands of Japan on average display somewhat smaller transparent areas than specimens from the mainland. However, no clear differences in the morphology of the genitalia were found. We consider M. formosana a subspecies of M. eurytion (stat. nov.), with M. nagaii a junior subjective synonym of Melittia eurytion formosana (syn. nov.). Several specimens were collected in the Nanling region when visiting flowering vines ( Vitis sp.).