Miscellaneous Genera VI
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Chorsia perversa Walker comb. n.
Xylina perversa Walker, 1862, J. Linn. Soc. (Zool.), 6: 195.


Chorsia perversa
(holotype, UM Oxford)

Chorsia perversa

Diagnosis. There may be some sexual dimorphism in this small species, a possible female (see below) being darker, greyer, more uniform. Both sexes have, along the costal zone of the forewing in sequence from the base: a tapering, distally directed dark wedge; a similarly oriented, elongately ovate pale mark; a darker triangle on the costa; a pale reniform mark, edged slightly darker distad; an irregular pale streak running obliquely into the apex. The female shows subtle differences in facies and has a much weaker subapical pale spot on the forewing; it may represent another species.

Taxonomic notes. The forewing has a subapical pale spot on the underside as in Chorsia, and the male abdomen has features shared with Chorsia rather than with Pseudogyrtona Bethune-Baker, its current combination (see below). The eighth segment is similar to that of the previous four species though the uncus is unmodified. The valve bases are fused over a considerable distance. The valve itself is apically bilobed and has a darkly sclerotised, notched distal part to the sacculus. The taxon stipata Walker (Sri Lanka) is not conspecific (Poole, 1989) with perversa but represents a good species, closely related to the Japanese Microxyla confusa Wileman, the type species of Microxyla Sugi, which has almost identical male genitalia and to which genus, therefore, stipata is transferred (see below). The record of perversa from Australia (Nielsen et al., 1996) therefore needs to be reviewed in the light of the occurrence of a number of externally similar species.

Geographical range. Borneo.

Habitat preference. The holotype (UM, Oxford) of perversa was taken in Sarawak by A.R. Wallace. There is one other specimen of the same provenance in BMNH from the Moore collection. The female is from lowland forest at Ulu Dusun, 30 miles west of Sandakan in Sabah. Two males have been recorded at 100m and 170m in lowland dipterocarp forest near the Danum Valley field Centre in Sabah. A male has also been taken at 1000m in a grove of giant bamboo in the valley bottom near Bundu Tuhan on the slopes of G. Kinabalu, though this was not identified for inclusion in Holloway (1976).

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