Risoba basalis Moore
Moore, 1881, Descr. new Indian lepid. Insects Colln W.S. Atkinson: 91.
Risola [sic.] basalis ab.
Warren, 1913, Gross-Schmett. Erde, 3: 293.
Walker sensu Martini & Thöny, 1993: 7.
Diagnosis. See R. martinii sp. n. above. The facies is also
similar to diversipennis and distinguished under that species. Some
specimens of basalis have a diffuse, curved dark line facing concavely
and obliquely to the angled postmedial.
Geographical range. Indian Subregion, Taiwan, Vietnam (Zilli, 1999),
Sundaland, Philippines, Sulawesi.
Habitat preference. Mostly old material has been seen: without altitude data
from G. Kinabalu; inland from Pontianak. Martini & Thöny (1993) recorded a
specimen as diversipennis from 950m on G. Trus Madi, Sabah.
Biology. Bell (MS) reared the species in India. The larva is cylindrical
with all prolegs fully developed. The head is as broad as the body, and segments
have one to many transverse depressed lines. Primary setae only are set on
small, white, often inconspicuous tubercles. The colour is violet brown, bluish
dorsally on T1, with a broad, spiracular to lateral white band made up of
transverse white lines interspersed by thin greenish ones. An alternative colour
is whitish grey tinged with olive green dorsally and ventrally. Sevastopulo
(1947) described the larva as pale green with white markings, becoming tinged
with pink in the final instar, so it is probably quite variable.
The pupa is claviform, the anterior nearly squarely truncate. The proboscis is
produced to twice the length of the whole pupa. The posterior segment is short,
pointed, flattened dorsolaterally, roughened dorsally but without hooklets or
hairs. Pupation is in a long, spindle-shaped cocoon incorporating bark particles
and woven along a twig or branch. The proboscis length dictates the length of
the cocoon and is variable, although significantly shorter in the female than
the male. Pupal segments A9-10 are wrinkled, reticulated dorsally where they
join. Pupae of all species ‘shiver’ inside the cocoon if it is touched.
The larva lies stretched out along a branch or twig when at rest. More or less
mature leaves of the host-plant, Quisqualis (Combretaceae), are eaten as
a rule according to Bell. Mell (1943) and Sevastopulo (1947) noted Melastoma
(Melastomataceae) as a host-plant, and Sevastopulo recorded Osbeckia in
the same family.
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