SUBFAMILY RIVULINAE
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Rivula leucosticta Swinhoe
     Rivula leucosticta Swinhoe, 1895, Trans. ent. Soc. Lond., 1895: 49.

 

Rivula leucosticta
Figure 8
Figure 19


Diagnosis.
This and the next three species are dark brown, the forewings a richer tone and marked with white spots. In leucosticta, the largest species, there is an oblique, straight antemedial row of such spots, a large subcostal medial one with smaller ones immediately in front of and behind it, and a series of small ones marking the postmedial. This postmedial is very irregular in course, with a bidentate bulge distad just outside the discal area.

Taxonomic note. Naarda albopunctalis Rothschild (New Guinea) is probably also a member of this species group, but has not been dissected.

Geographical range. India, Borneo.

Habitat preference. The species is infrequent, taken in recent surveys in forest up to an elevation of 300m: near the Danum Valley Field Centre in Sabah; on G. Mulu and in heath forest near the Melinau Gorge in Sarawak; in the Ulu Temburong and Ulu Belait in Brunei.

Biology. The species was reared by T.R.D. Bell (MS) in India. The larva has a large, heart-shaped, shining head and well defined, somewhat constricted body segments. The prolegs are fully developed, all large and straggling, the anal claspers especially stout, widely divergent behind. The primary setae are longer than the width of the body, plumose and set on small white chalazae. The setae of the head are also plumose. The head is a light watery yellow, clouded with a red-brown band extending up from the ocelli. The body is grass-green with broken white dorsolateral lines (two elongate spots per segment) that end on T1 in a shining black patch. The spiracles are small and white, and the setae are reddish brown.

The larvae live on the undersides of leaves of the host plant (see below), generally gregariously, making triangular notches in the edges. Bell also described pupae found in a silken cell at the tip of a large sedge (Cyperaceae) leaf, where the edges were pulled round in an open pyramid, the opening traversed by strands of silk. The larval skins with these pupae were ringed by a black band through the chalazae, which were also black, including the plumose setae. The head was shining black. The host plant from which the larvae were described was Phrynium (Marantaceae), but both these and the pupae from the sedge gave rise to identical adults. It was not possible to locate the voucher material from these rearings (no. 511).

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