124. Parnara cf. ganga (The Continental Swift)

Number: 124

Family: Hesperiidae
Sub-Family: Hesperiinae

Species: Parnara cf. ganga (Evans, 1937)

Common name(s): The Continental Swift

Photography location: Huu Lien Nature Reserve (Lang Son Prov.)

Five Parnara species are listed by Monastyrskii & Devyatkin (2016) from Vietnam viz P. apostata, P. bada, P. ganga, P. batta and P. guttata. The latter flies from China, Korea and Japan to Himalaya and central Asia. 

Parnara species show a great similarity of the external features and it is very difficult to determine with certainty the species only from a photograph. For proper identification, it is better to voucher the specimen to have a complete view of the FW and HW pattern (often incomplete in a shot) and, ideally, to confirm the ID by examination of the genitalia - a matter for specialists.
In the females, the size and spotting pattern are highly variable, this making most of the species almost indistinguishable by the external features. 

Photographed in open agricultural land

A close-up view of the forewing (FW) upperside, illustrating post-discal spots in spaces 2-4, 6-7, no cell spots. Hindwing (HW) discal spots in spaces 2-5 large, spot 6 absent.
FW 13 mm in this specimen

P. guttata is larger (FW 15-19 mm),with both FW cell spots present.
P. apostata is much darker.

In P. bada, HW spots in spaces 2-5 small and irregular and may be absent.

Another supposed Parnara ganga from Mt. Tam Dao (foothills, open area).
Note the position of wings : usually for a Hesperiine, the adults commonly bask with the forewings held at a 45° angle, and the hindwings held flat.

   
References : A revision of the genus Parnara Moore (Lepidoptera, Hesperiidae), with special reference to the Asian species (Chiba & Eliot, 1991) PDF here.