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Risoba
Moore
Type
species: repugnans
Walker, N. India.
Synonyms: Lycoselene
Möschler (type species
lunata
Möschler, Ghana);
Pitrasa
Moore (type species
variegata
Moore, India).
The thorax
and anterior of the abdomen are characterised by erect tufts of scales, longest
on the patagia and tegulae. The antennae are long, filiform, but strongly
ciliate in males. The venation is of the groundplan type. The facies is
distinctive, the forewings strongly variegated in shades of straw, green, brown
and black, usually involving a distinct disc-like patch at the apex and often
also a paler basal patch defined by a straight or arcuate line running from the
base of the costa to about one-third along the dorsum. The hindwings are usually
straw colour with a broad, dull brown border.
The male genitalia have several diagnostic features. The uncus is long, slender,
sigmoid, flexed initially ventrally from its junction with the tegumen. The tegumen terminates ventrally on each side in a structure rather like the head of
a spanner. The saccus is long. The valves are elongate, ovate, with a basally
directed marginal fringe of hairs. The subbasal process of the valve costa is
very long, usually as long as the valve itself, slender, and bears numerous
setae. The sacculus may have a harpe, or there may be distinctive ridges or
folds in the lamina just ventral to the costal process. The aedeagus often has
fields of spines and the vesica usually has cornuti in a diversity of
configurations.
The male genitalia and, in some cases, facies features can be used to define
groups of species as follows:
The repugnans Walker group. There is marked sexual dimorphism of the
forewing as discussed in more detail under repugnans. The male genitalia
are symmetric with one additional costal and two ventral processes to the valve.
The aedeagus vesica is large with many large triangular cornuti. The group
ranges throughout the Indo-Australian tropics.
The jucunda
Walker group has more irregular forewing facies with sexual dimorphism weak or
absent. The male genitalia have the valve saccular process absent or
occasionally present but weak. There is a more prominent structure just distal
to the subbasal process of the valve costa, usually a ridge or flange that
extends into the valve lamina and has a central crimp or triangular process,
though a similar feature is seen also in the next group. The aedeagus vesica is
usually narrow with a single long lobe that bears spines or spicules, these
always narrow even when large; the aedeagus itself may also have spines. The
group is restricted to Sundaland where it is diverse. In addition to the species
treated below (calaina
Zerny to harmani
sp. n.), the group includes the Sumatran endemics
R.
calainodes
Prout and
R.
diehli
Kobes,
R.
glauca
Hampson (Peninsular Malaysia) and an undescribed species in Sumatra (slide
16700) and Peninsular Malaysia (16701).
The diversipennis
Walker group. The two species in this group have a flange in the valve costal
area similar to that of the jucunda group but also have a very long,
slender saccular process characterised by a subbasal lateral spur. The aedeagus
vesica is slender to moderate, lined with numerous slender spicules on one side.
Both species are wide-ranging.
The obstructa
Moore group is monobasic, the species extending throughout the Indo-Australian
tropics. The male genitalia have a long, slender process on the valve sacculus
but that in the costal area is weak, slightly bilobed. The aedeagus vesica is
small, globular, unornamented, the aedeagus apex with three longitudinal ridges
of spines.
The vialis
Moore group is moderately sexually dimorphic, males often having a more
prominent oblique white postmedial band on the forewing. The group is
characterised by asymmetry in the male genitalia, the left saccular process
being shorter and more erect than that on the right, often apically expanded and
bifid. Ornamentation of the costal area is reduced to a slight angle on the very
margin. The vesica is very narrow and bears spines of varying size, usually
small and fine. The group ranges throughout the Indo-Australian tropics.
The female genitalia have a ductus of variable length and an elongate bursa that
is generally scobinate, sometimes with corrugations but in the species examined,
without a signum.
The genus is found throughout the Old World tropics, being most diverse in Sundaland (Table 3) because of the jucunda group. Species in other groups
are more widespread, but only one (obstructa
Moore = grisea
Bethune-Baker syn. n.; Nielsen et al., 1996) of the species in New
Guinea extends to Australia.
The larvae of several species are described below. Host records are frequently
from the Combretaceae and Melastomataceae, but there are also a few from
Juglandaceae, Leguminosae, Lythraceae, Myricaceae and Sterculiaceae (Robinson
et al., 2001).
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