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Berta digitijuxta sp.n  

Berta digitijuxta
(holotype, Java)

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. comm.).

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