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Beana
Walker
Type species:
polychroma
Walker (= terminigera Walker), Borneo.
Synonym:
Pitacota
Moore (type species
terminigera
Walker, India).
This genus was considered as possibly a basal branch to the Nolinae by Holloway
(1998) on the basis of reduction of the first pair of larval prolegs and
possession of a lateral pair of setose sclerotisations in the scaphial region.
However, the larvae lack verrucae, the adult has ocelli and the pupa has a row
of carinae on the abdomen. The hindwing venation is quadrifine, with M3 and CuA1
connate but not stalked.
The build and facies are reminiscent of some of the amphipyrine noctuids. There
is strong sexual dimorphism, the male having a uniformly mottled brown forewing
apart from a pale apical patch, and the female having a triangular whitish area
filling most of the basal half of the wing.
In the male abdomen there are large but narrow and well separated apodemes on
the eighth tergite but none on the sternite. In the genitalia the uncus has
dorsal and ventral opposed processes that both terminate in a rake-like
structure, with a heart-shaped plate in between. There is a prominent pair of
angled processes, somewhat foot-shaped, flanking the anal tube. The valves are
long, narrow, with a central, asymmetrically bifid process distal to a
longitudinal brush of setae on the sacculus of each. The saccular shield is
present but small and associated with a narrow anellar ring. The aedeagus vesica
is large, multidigitate.
The female has a moderate, narrow, sclerotised ductus bursae that leads into a
large, ovate corpus bursae that is very finely scobinate but lacks a signum.
Characters of the larva have
already been noted, though Gardner (1947) mentioned additionally an unusual
horn-like protrusion to the suranal plate (pygidium); there is a more detailed
description of the biology below. The genus consists of the type species, B.
umbrina
Hampson from the Philippines, and B. inconspicua
Bethune-Baker and B.
opala
Pagenstecher from New Guinea. B. nitida
Tams from Thailand may be misplaced, resembling more a species of
Zigera
Walker.
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