SUBFAMILY RISOBINAE
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Risoba repugnans Walker
Thyatira repugnans Walker, 1856, List Specimens lepid. Insects Colln Br. Mus., 9: 9.
Risoba
literata Moore, 1881, Proc. zool. Soc. Lond., 1881: 329.
Heliothis albistriata Pagenstecher, 1888, Jb. nassau. Ver. Naturk., 41: 132.

 


Risoba repugnans


Diagnosis.
This and the next two species have males with uniform green forewings crossed by oblique white lines: an arcuate oblique one dividing off a paler basal patch and a straight oblique one postmedially, distal to which is a browner apical patch and a finer, fainter, irregular white submarginal. The females also have a green ground colour and have a similar but more conspicuously paler basal zone to the males, but distally the postmedial and submarginals are indistinct, dark, rather crenate, rather than white, and there are conspicuous brown patches apically and along the dorsum, the former circular, divided by a white arcuate line nearer the more basal part of the circumference, and the latter consisting of two semicircles based on the dorsum. The species differ markedly in features of the male genitalia as described below; distinction on facies is less reliable and assignation of females to males of the new species is tentative. All the species have a large aedeagus vesica ornamented with several triangular cornuti, perhaps the most characteristic feature of the species group. The valves have a slender process from the sacculus that extends to a more distal subventral position on the valve where there is usually a small, spur-like structure, and there is also a process, usually a distally directed spine, on the valve costa; there is no bilateral asymmetry. In repugnans the aedeagus vesica cornuti are separated into basal and distal groups, the latter with fewer members (only one in the Bornean specimen dissected); the valve costal process is slender and the more distal ventral one is small, acute. A specimen from Rook I. off New Guinea (slide 16690) has this distal process blunt and has a more angled aedeagus vesica with the distal group of cornuti on the angle with about a dozen members as distinct from two large ones basally. There is therefore some variation in these features that requires further investigation; the name albistriata (t. loc. Ambon) is available for more easterly populations. In addition to the next species, there is a further member of the complex in Sulawesi (slide 16691); the aedeagus is short, the vesica large, the cornuti relatively massive, and the valve has a shorter saccular process and a squarish subbasal flange directed basally from the valve costa.

Geographical range. Indo-Australian tropics east to the Solomons but not recorded from Australia (Nielsen et al., 1996).

Habitat preference. All four specimens seen are from the lowlands up to 450m, three from forested localities.

Biology. Bell (MS) reared typical repugnans in India. The larva is similar to that of R. basalis Moore (see below), light grass green, usually with a broadish pale pink lateral to subspiracular band. Primary setae are set on small black bases on a small white spot. The dorsum tends to be glaucous, with a pulsating purple dorsal line.

The pupa is more cylindrical than in basalis but with a similar anal segment, and with the proboscis projecting 4mm beyond the end of the pupa. The cocoon is also similar.

The host-plant was Melastoma (Melastomataceae).

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