Ischyja inferna Swinhoe

Ischyja inferna Swinhoe, 1902, Ann. Mag. nat. Hist. (7), 10: 498.

Ischyja inferna achysis Prout, 1928, Bull. Hill Mus. Witley, 2: 258.

Diagnosis

In males, the species is distinguished by the oblique shape of the forewing reniform, together with the shape of the loop mark on the dorsum, with its investiture of black at and beyond its interior end and the creamy highlights within this and near the dorsum. These last are faintly seen on the much more uniform female. The hindwing blue band is relatively broad; the underside in the typical race is pale blue to well distal to the postmedial fascia in the male, but the female often has a pale blue band medially that is divided by a fine brown fascia, though this band can be only weakly developed. The species is unusual in the modification of the male hindwing venation (noted by Prout in describing achysis) in that veins M3 to CuA2 diverge more or less at the same point, rather than having CuA1 and CuA2 diverging more distally from each other after divergence from M3. See also Ischyja manlioides Prout.

Geographical range

Borneo, Peninsular Malaysia, Sumatra, Java, Lombok, Palawan, Sulawesi. Thailand (VK); (ssp. achysis).

Habitat preference

The species is commoner in the lowlands, but has been recorded up to 1930m.

Biology

The species was reared in Peninsular Malaysia from Saurauia (Actinidiaceae), but pupated before a description could be made (H.S. Barlow, pers. comm.). The pupa was formed in spun-up leaves of the host plant and covered by a bloom of grey-blue powder. The adult emerged just over two weeks after pupation. See also under G. marapok sp. n. below.

Taxonomic Note

A larva of I. inferna was discovered fully grown on a sapling of Shorea curtisii (Dipterocarpaceae) in Peninsular Malaysia, but was not actually observed to feed on this (S.K.L. Hok & H.S. Barlow, pers. comm.). It was a dark vinous brown with a delicate tracery of pale lines as illustrated in Plate 9. The prolegs on A3 are somewhat reduced and there are protuberances dorsally on A2 and A3. A prominent transverse ridge occurs on A8, with a slighter one on A7, and one barely evident on A6; the pale tracery is more evident running obliquely into the ridge on A7. It is not clear whether the coloration represents prepupal darkening.

Genitalia: