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Thalatta Walker
Type
species: precedens Walker,
Indian Subregion.
The
forewings in this genus are variegated dark brown and grey, sometimes with a
subbasal white patch and sometimes with a postmedial straight fascia. They are
shaped as in the Scoliopterygini and genera such as Hyperlopha
Hampson,
but the species have male genitalia that distinguish the genus from both of
these. Kobes (1983, Heterocera Sumatrana 2: 9-13) treated the three Sundanian
species under Anomis, as the only described member of the trio, T.
holortha Hampson
comb.
n.,
was already assigned to that genus. However, the three species have some or all
the definitive features of Thalatta and are therefore transferred to this
genus. This misplacement of Thalatta species in Anomis
may
have led Fibiger (2003) to place the genus as a synonym of Anomis.
This is not supported here for the reasons given.
In the
male abdomen the eighth sternite and tergite usually have apodemes; the tergite
is often narrowed, and the sternite bears a slight pair of coremata in T.
argentipuncta Kobes comb. n.. The genitalia have the uncus long and hooked but
there is no scaphium. The juxta is an inverted ‘U’ shape. The valves are
elongate, parallel-sided except for a rounded apex. In most species they have
corematous structures basally that bear hair-pencils. The aedeagus is usually
straight, short, and the vesica short and broad with several diverticula that
are scobinate or bear clumps of spines.
In the
female genitalia (prapata Kobes; Peninsular Malaysia, Fig 529), the ostium is
between the seventh and eighth segments; the seventh sternite is moderately
reduced. The ductus bursae is very short, fluted, but unsclerotised. The corpus
bursae is large, ovate, scobinate and slightly corrugated.
The
genus is restricted to the Indian Subregion, South-east Asia and Sundaland;
there is an undescribed species from Sulawesi. In addition to the species above,
T. prapata Kobes
comb.
n. (Sumatra,
Peninsular Malaysia) should be transferred to the genus.
The
biology of the type species and fasciosa Moore
(India) was described by Gardner (1947), and Bell (MS) described that of the
former. The larva has the prolegs on A3 much reduced, and the developed ones
have four external setae rather than the usual three, a feature shared with Erebus, Spirama and Bamra. The ventrum of the type species
has a central black patch on each of segments A1-6. The setae are relatively
long, arising from chalazae that can form white spots. Pupation is within a
cocoon in folded leaves or in the soil, and the pupa lacks a bloom.
The few
recorded larval host plants are in the Malpighiaceae (Aspidopterys
and
Hiptage)
and Combretaceae (Combretum).
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