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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 |
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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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