divitalis Walker comb. n.
Gyrtona divitalis Walker, 1863, List Specimens lepid. Insects
Colln Br. Mus. 27: 91.
Diagnosis. The forewing of this species is a dark, relatively uniform grey with a
distinctively dark subbasal zone. It is best distinguished by the male genitalia
from similar species, such as the next three: S. yucca has an uncus
without a ventral lobe; in S. conglobalis the uncus is apically swollen,
the ventral lobe being short and broad, there is a lobe subbasally on the valve
costa, and the aedeagus has a distinctive lateral flange; in S. chlorograpta the
ventral lobe of the uncus is almost set at right angles, not adjacent. In the
female genitalia S. yucca has lateral coremata between segments 9 and 10
and an entire, thorn-like ridge of sclerotisation as a signum; S. conglobalis
has no signum but has a rectangular, expanded portion at the base of the
Taxonomic notes. S. divitalis occurs throughout the Indo-Australian tropics in
several distinct subspecies that vary in genitalic characters. This was
suggested by Holloway (1979), but the processes noted subapically on the dorsal
arm of the valve in typical divitalis are probably aberrant or even
artefacts. In the Indian subregion there is S. divitalis phaeozona Hampson
stat. & comb. n.: the forewings are very dark grey and, in the male
genitalia, the saccus and ventral process of the uncus are relatively short. The
typical race flies in Sundaland, the Philippines and, with the saccus slightly
shorter, in Sulawesi and New Guinea.
A smaller, dark taxon from the islands south east of New Guinea and from
the Bismarcks (BM slide 11442) has a short, rectangular ventral process to the
uncus and a distinctive, reticulate pattern to the setal scars on the ventral
arm of the valve; it is probably a distinct species.
The race from New Caledonia, Fiji, Samoa, the Cook and Society Is. has a
rather sinuous forewing costa in the male, a rather heavily sclerotised zone
containing setal scars on the ventral arm of the valve, and a relatively short
saccus and ventral process to the uncus (Holloway 1979: fig. 108:3, Plate
78:11). This race is here named S. divitalis pacifica ssp. n.; holotype NEW
CALEDONIA, Grand Lac (Holloway), BM noctuid slide 7501.
Geographical range. Indian subregion; Sundaland, Philippines, Sulawesi,
New Guinea; Fiji, New Caledonia, Samoa, Cook Is., Society Is.
Habitat preference. During the Mulu survey singletons were taken in upper
montane forest on G. Mulu, at 900m, and 1500m on the limestone G. Api. and in
lowland alluvial forest at Long Pala.
Biology. Bell (MS) reared the species in S. India (ssp. phaeozona). The
larva is spindle-shaped, a dull, livid white, tinged green all over. There are
usually no distinctive markings. Variants were described as uniform green.
The larva lives full stretched on the whitish or pinkish, young, hanging
leaves of the host-plant (Mesua in the Guttiferae). They are very
restless on disturbance. Bell later observed that the larvae form a loose cell
amongst the leaves with silk, much as in Lophoptera illucida, and
sometimes the leaves are brought together in a cylinder with silk.
The larvae turn dirty pinkish prior to pupation in
the soil surface in a silken cocoon incorporating earth articles. The pupal
stage takes about 11 days.
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