Faunis indistincta subsp. luctus Monastyrskii & Vu 2021, subspec. nov.

Faunis indistincta luctus Monastyrskii & Vu subspec. nov.

(Figure 13, 14)

Description: Male: length of forewing: HT: 45.0 mm; PTs: 46.0; 45.0; 46.0 mm; antennae dark brown (22.0 mm).

Forewing upperside (Figure 13A): ground colour uniformly grey; area from termen and apex to postmedian and subcostal penetrating into discal cell uniformly blackish brown; there is a smooth transition from greyish black to bright grey in the postmedian area; series of small whitish subterminal spots is lined from cell R 4 to Cu 1a; cilia dark brown.

Hindwing upperside (Figure 13A): ground colour uniformly grey with blackish brown bordering from termen to subterminal area and smooth transition to greyish colour; there is a series of small and subtle whitish subterminal spots from cell Rs to Cu 1a; cilia dark brown. At base of cubitus there is hair tuft touching a small spot of specialised scent scales on underside of forewing base.

Forewing underside (Figure 13B): Ground colour dark brown with three darker brown fasciae located within discal cell (submedian) and at postmedian and subterminal areas; series of subterminal small whitish spots located in a row from cell R 4 to Cu 1a.

Hindwing underside (Figure 13B): ground colour is similar to the forewing; the hindwing pattern includes submedian straight fascia extending from Sc+R 1 to Cu 1b; postmedian fascia extending from Sc+R 1 to Cu 1b and subterminal fascia from Rs to Cu1b; series of small whitish subterminal spots extending from cell Rs to Cu 1a

Female: unknown

Diagnosis. The new taxon collected in Lao Cai Province resembles members of the Faunis aerope speciesgroup distributed in southern China and northern Vietnam. The most distinctive character of F. indistincta Mell is the male genitalia structure which vaguely resembles that of F. aerope: relatively short and curved valvae with apex covered by dense spines (Figure 14A, C–E). Faunis indistincta luctus is similar to recently the described species Faunis caelestis Monastyrskii & Lang, 2016 (Figure 13C–D). Both species have similar wing patterns on the undersides of both wings, though in F. caelestis the ground colour is paler. The upperside of F. indistincta luctus is similar to F. aerope yunnanensis Brooks and F. caelestis, though the new taxon has broad black borders on both wings (Figure 13A) and distinctive male genitalia (Figure 14A, C–E). The female genitalia structures in species of F. aerope group are also distinctive; however, this character cannot be used in the current study because the female of F. indistincta luctus has not yet been discovered.

Type material. Holotype: NORTHERN VIETNAM, ♂, Lao Cai province, Hoang Lien N.P., Cong Troi pass (Tram Ton ranger station), 20.V.2011; evergreen mountain forest at ~ 1,900 m; VVL leg.; Paratypes: 3♂: same data as holotype. The holotype and two paratypes will be deposited in the VNMN (Hanoi); one paratype will be deposited in the NHM (London).

Distribution and habitats. The new taxon has been recorded only at Hoang Lien National Park in the vicinity of Fan Si Pan peak and the forest ranger station at elevations around 2,000 m.