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Rhesala Walker
Type
species: imparata Walker,
Sri Lanka.
Synonyms: Hingula
Moore
(type species albolunata Moore,
India); Magulaba Walker
(type species moestalis Walker,
Sierra Leone); Rimulia Saalmüller
(type species malgassica Heyden,
Madagascar, = moestalis).
The
genus consists of small, dark, dark brown species that are distinguished
externally by white marks centrally on the forewings that arise to a mark shaped
like and ‘X’ or an inverted ‘V’ between the reniform and orbicular.
There may be a smaller mark basal to the orbicular and also one associated with
the discal spot on the hindwing. The strongest fasciation on all wings is the
darker brown postmedial that, on the forewing, flexes round the reniform, and in
some species is broadened at the costa. The male antennae are ciliate. The
labial palps are typically catocaline.
The male
abdomen has the eighth segment of the framed corematous type, but the sternite
may be strongly modified in some species (e.g. Fig. 903). The genitalia have the
tegumen very much longer than the vinculum. The shape of the uncus is highly
variable, from broad and short through elongate, narrow, to crested with hairs
and peaked, sometimes with lateral processes. The tegumen is much longer than
the vinculum. The valves are simple, elongate and ovate, with the basal saccular
portion semi-detached and terminating in a slight distally directed spur on the
ventral margin. There may be small coremata associated with this basal structure
of the valve. The aedeagus vesica is broad, often with lobes or diverticula, and
usually with some scobination.
The
female genitalia have the ostium bursae between the seventh and eighth segments.
Posterior and adjacent to the eighth segment on the intersegmental membrane is a
distinctive zone of dense spining. The ductus is usually unsclerotised, narrow.
The corpus bursae is ovate to pyriform and usually contains much coarse spining
though may be sclerotised over the basal part (imparata).
The biology of the type species is described below. All host records are from
the Leguminosae, the exception being one from Mangifera (Anacardiaceae)
(Robinson et al., 2001).
The
genus is found throughout the Old World tropics to as far east as New Caledonia
and Fiji (Holloway, 1979). R.
moestalis Walker
is widespread in Africa and the Indian Subregion, and extends to Peninsular
Malaysia and Singapore, where it and the type species can seriously defoliate
rain trees (Samanea saman) grown for shade and decorative purposes
in urban situations. The male genitalia of moestalis
are
characterised by asymmetry: the species may prove to occur in Borneo, and it is
small like R. nigricans Snellen.
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