Thosea
borneensis Hering
Thosea sinensis borneensis Hering,
1931: 712.
Thosea borneensis Hering; Holloway, 1982a: 184.
Diagnosis. The facies is as illustrated; the female is similar but larger. This is
the only grey Bornean species to lack a strong medial shade and to have a
uniform marginal zones. In the male genitalia the valve shape is definitive. In
the female genitalia the eighth segment is very large.
Taxonomic notes. The species is allied to loesa Moore (Java, Bali), which is
possibly a junior synonym of unifascia Walker, the type species. In loesa
the furca arms are only equal in length to the valves, curved rather than
straight; the valves are produced ventrally at the apex rather than rounded with
a small costal spur; the valve costa is centrally folded and the sacculus
ventral margin is more angular; the gnathus is somewhat broadened, triangular
over the basal half. In Peninsular Malaysia and Singapore is another very
similar species to which the name mediostrigata Hering (based on a
female, possibly aberrant) may be referable. In this species the valve is much
as in loesa though broader apically but the furca arms are long as in borneensis
with distinctive curvature over the apical third; The uncus and gnathus are
very much broader than in the other two species. In all three species there is a
small lobe at the aedeagus apex but this is weak only in loesa. A
specimen from Palawan (in Zoologisk Museum, Copenhagen) is probably referable to
borneensis but has a blunter spur at the valve apex and shorter furca
arms.
Geographical
range. Borneo;
Palawan.
Habitat preference. The species has been taken in areas of lowland
forest, but is never common.
Biology. Piepers & Snellen (1900) described and illustrated the larva of loesa.
It is of typical shape, a light greyish green with a yellow or white dorsal
band that is occasionally indistinct. In the dorsal band (which also has blue
or lilac variants if these do not belong to a different species) there are
sometimes two little yellow patches circled with reddish brown. There are two
rows of red or lilac subdorsal spots. The tubercles are usually green but
occasionally partially or wholly red or reddish brown with black and green dots.
The two posterior tubercles and sometimes the anterior ones are somewhat longer
than the others. Horsfield & Moore (1959) also described and illustrated the
larva.
It has been reared from a wide range of host-plants: Musa (Musaceae);
Camellia (tea; Theaceae); Citrus (Rutaceae); Phaseolus,
Erythrina (Leguminosae); Psidium (Myrtaceae); Cinchona (Rubiaceae)
Mangifera (Anacardiaceae); Shorea (Dipterocarpaceae); Punica (Punicaceae);
Cordia (Ehretiaceae).
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