Berta digitijuxta sp.n
12-14mm. This species is closely related to B.
subrectistriga Prout, described from the Philippines, but also occurring in
Sulawesi (slide 17294) and Seram (slide 12562). Both taxa are distinguished in
facies from chrysolineata by a more regular, curvilinear arrangement of
the postmedial white patches on the forewing, often fused into a single dentate
band. The forewing discal mark is a more definite figure eight. The male
genitalia of both species have a sclerotised distal lobe or special process to
the oblique structure of the valve: small, elliptical in subrectistriga (more
digitate in Sulawesi and Seram); more extensive, rugose, downcurved in digitijuxta,
particularly in the single Bornean specimen. The eighth sternite has a
circular notch flanked by tapering processes in subrectistriga and Javan digitijuxta,
but this is more angular and obtuse, slightly rugose in the Bornean male.
The definitive feature of digitijuxta is a long calcar-like, digitate
process from the juxta. In mainland Asia (N.E. Himalaya (slide 17295) to S.
China, Taiwan (slide 17298) and Peninsular Malaysia (slide 17303) flies a
further species with a more punctate facies like chrysolineata, but
sharing some of the features of the valve of digitijuxta and subrectistriga,
though it is much more rugose and right-angled in form: the cleft in the
eighth sternite is an obtuse angle, strongly and densely spinose, yielding a
chevron-like structure as in B. anteplaga Prout, described below.
The Bornean species is a rather discoloured male, so the species is here
typified by Javan material. Male genitalia from both localities are illustrated.
Holotype . JAVA occident, Mons Tjikorai, 4000-1892
(H. Fruhstorfer). BM geometrid slide 17285.
Paratypes: 1 4
Nongkodjadjar, E. Java, 4000ft.,
December 1933 / January 1934 (A.M.R. Wegner).
Geographical range. Java, Bali; Borneo..
Habitat preference. The single specimen was taken at 1930m on
G. Kinabalu on (part of the series referred to B. chrysolineata Walker
by Holloway (1976)).
Biology. The mainland Asian species has been reared in Hong
Kong by a Miss Choong from Castanopsis (Fagaceae) (A. Galsworthy, pers.
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