1892, Annls Soc. ent. Belg., 36: 9.
orgyioides van Eecke, 1928, Zool. Meded. Leiden, 11: 113.
Diagnosis. The sexual dimorphism is extreme, the female being uniform pale grey
with a black discal spot on the forewing, and the male having a distinctive
rather Orgyia-like, brown forewing facies with the medial zone
distinctly paler and containing a white discal spot.
Taxonomic note. This rather incredible sexual dimorphism needs confirmation from a
reared series that yields both sexes; the records in Yunus & Ho (1980) may
represent this, but no further details have been located. However, the course of
the pale postmedial and submarginal, the shading between them is the same in
both sexes. B. nucula Swinhoe comb. n. (N.E. Himalaya) has males
with similar forewings to isabellina but brown hindwings; females are
unknown. These species and the next two are included tentatively in Bembina. The
male abdomen lacks tymbals, the uncus is relatively broad, and the aedeagus has
a few large cornuti in the vesica rather than patches of small spines. The
valves are divided as in many Nygmia, however.
Geographical range. Sumatra, Peninsular Malaysia, Borneo.
Habitat preference. This is a rare species of lowland forest, with most
specimens in recent surveys taken in heath or swamp forest.
Biology. The species has been reared from Cinnamomum zeylanicum (Lauraceae)
in Peninsular Malaysia under both synonyms and (as isabellina) from Zea
mays (Gramineae) (Yunus & Ho, 1980)
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