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Derambila
Walker
Type species: punctisignata Walker, W. Africa.
Synonyms: Chionopteryx Snellen (type species alucitaria
Snellen, Principe I.); Corium Prout (type species puella Butler,
Madagascar); Holostixa Swinhoe (type species manca Swinhoe) syn.
n.; Rambara Moore (type species lumenaria Geyer).
The genus consists of small, slender, delicate sometimes translucent
white species. The wing markings usually consist of black discal dots and
transverse fasciae in medium brown on the veins. Some species have small black
dashes along the margin in the spaces between the veins. These markings are
represented more weakly, if at all, on the underside.
In the male abdomen there are several features that appear to define the
genus. The pair of elongate zones of setae on the third sternite are close
together, convergent posteriorly, sometimes even totally fused into a central,
elongate patch. The valves have an angle or digitate process arising from the
valve costa; centrally, subcostally, there is a finely, densely setose lobe. The
uncus is basally slender, distally spatulate or divided and invested with
numerous fine, short setae. The aedeagus vesica often bears cornuti: in several
Bornean species, including D. manca Swinhoe comb. n., there
are one or two large ones.
In the female, the ornamentation of the bursa is extremely variable, its
shape and the localisation of its spining often diagnostic. In D. lumenaria Geyer
and D. gertraudae Sommerer the ovipositor lobes are considerably
extended, telescopic: this is not a general feature of the genus.
The genus Holostixa is brought into synonymy as, although the
hindwing venation of the male is extremely modified to accommodate an excavate
feature on the costa (Fig 2), it otherwise has features typical of the genus.
There is also a case for bringing the Australasian tropical genus Derxena Walker
into Derambila as, despite the pale blue translucent wings ornamented
only with black discal spots, the male genitalia have the features listed above
for Derambila.
The genus is found throughout the Old World tropics but shows it
greatest diversity on the Sunda Shelf.
The only host record located is that of Vitex (Verbenaceae) for D.
fragilis Butler as mentioned for that species below.
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