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Ischyja Hübner
Type
species: manlia Cramer, India.
Synonym:
Potamophora
Guenée
(type species manlia).
The
species are all large with strikingly patterned but cryptic forewings and with
pale blue or white flash coloration on the more uniform hindwings. There is
some sexual dimorphism, the males tending to have
more variegated and clearly marked forewings. The male hindwing venation is
strongly modified with disruption and shortening of the cell, separation of M2
from the rest of the quadrifid system, the remaining three branches remaining
closely associated before diverging relatively distally, almost as a trident in
one species (inferna Swinhoe) but with the CuA branches stalked to beyond
this point of divergence in the rest. The two anal veins are closely associated
near the base, and the dorsum is thickly scaled. The wider spaces within this
modified system are relatively thinly scaled and slightly translucent. The
underside is more uniform, though the forewings as well as the hindwings have an
irregular blue postmedial fascia; the hindwings are more extensively blue below
in several species.
The male
antennae are somewhat flattened in the vertical plane and broader towards the
base; they are fasciculate. The antennae extend well beyond the centre of the
forewing costa. The labial palps of both sexes are directed forwards, the third
segment very slender but equal in length to the robust second.
In the
male abdomen the eighth segment is only slightly modified, with the tergite
narrowing distally slightly from a broad anterior margin and being slightly less
sclerotised in a circular lacuna, and with the sternite being slightly broader,
with its posterior margin broadly notched. The genitalia have a balland-claw
apex to the uncus, and a scaphium is present. The juxta, possibly modified from
the inverted ‘V’ type, is diamond- or flask-shaped with, ventrally, a
vertical, central, narrow, less sclerotised strip between two shallow flanges.
The valves are robust, broadly based, narrowed distally beyond an angle in the
ventral margin, and without accessory processes. The aedeagus has a transversely
oriented, somewhat convolute vesica that bears three or so small sclerotisations
with spines as well as more general scobination. The male genitalia are very
uniform in structure throughout the genus, and species are usually more clearly
identified from facies features.
The
female genitalia (hagenii Snellen, paraplesius Rothschild)
have the seventh sternite reduced, its posterior margin slightly cleft and
associated with the ostium. The ductus is very short, sclerotised, laterally
scrolled. The ductus seminalis arises at the very base of a corrugated and
scobinate basal section of the corpus bursae. This section is swollen centrally
and twice as long as the distal, ovate section, from which it is separated by a
constriction. The ovate section is more weakly scobinate and without
corrugation.
The
genus extends throughout the Indo-Australian tropics to as far east as the
Solomons, but is possibly most diverse in Sundaland.
There are 11 species in Borneo.
A number
of authors (Moore, 1884-1887 (with illustration); Gardner, 1947; Tanahara &
Tanahara, 2000; Bell (MS)) have described larvae attributed to I.
manlia,
and one was illustrated by Kuroko & Lewvanich (1993). Confusion of the
identity of manlia,
and the presence of I. marapok sp. n. with it in the Indian Subregion
make it difficult to ascertain which species may have been involved, so these
descriptions and the host plants recorded are treated here in a generic context.
Bell (MS) suspected, from the variety of larval forms in India, that more than
one species was involved (see below); material from his collection in BMNH
included specimens of marapok and hemiphaea Hampson.
The
larva illustrated by Kuroko & Lewvanich is a semi-looper, though the prolegs
on A3 appear to be only slightly reduced. Gardner (1947) noted numerous external
setae on the prolegs, an unusual feature in the quadrifine Noctuidae. The body
tapers forward through the thorax to the head, and segments A1 and A2 have pairs
of tubercles dorsally, and there are dorsal humps on A7 and A8, the latter large
and bearing a pair of tubercles. The body is a variegated golden brown with a
fine, paler reticulation. There are transverse violet grey bands anterior to the
tubercles on A2 and A3.
Moore
(1884-1887) and Gardner (1947) referred to dark speckling, purplish variegation,
and irregular marking with black streaks. Bell (MS) described various colour
forms: light pinkish brown, suffused and reticulated with pale chocolate brown
above a blackish dorsal line, this suffusion fading dorsally and with the
ventral surface black and green; with a white subdorsal spot at anterior of A3
but generally more blackish and variegated; similar to the previous but greyish.
The pupa
has a bluish-white bloom (Gardner, 1947), noted also in other species by H.S.
Barlow (pers.
comm.
and see below).
The host
plants recorded (Bell, MS; Robinson et al.,
2001) are: Achyranthes
(Amaranthaceae);
Mangifera
(Anacardiaceae);
Ananas
(Bromeliaceae);
Canarium
(Burseraceae);
Terminalia
(Combretaceae);
Shorea
(Dipterocarpaceae);
Castanopsis,
Quercus
(Fagaceae);
Cinnamomum
(Lauraceae);
Bauhinia,
Dalbergia,
Xylia
(Leguminosae);
Aglaia
(Meliaceae);
Malus
(Rosaceae);
Cupania,
Cupaniopsis,
Litchi,
Nephelium
(Sapindaceae);
Vitis
(Vitaceae).
Tanahara & Tanahara, 2000 noted Cinnamomum and
Stauntonia
(Lardizabalaceae)
as natural hosts on Okinawa I., but found the larvae would accept Rosa,
Eriobotrya
(Rosaceae),
Diospyros
(Ebenaceae)
and Mussaenda
(Rubiaceae)
in captivity.
Adults
of a species identified as manlia were recorded as piercing fruit in
Thailand (Bänziger, 1982; Kuroko & Lewvanich, 1993). The species may come
more readily to fruit bait than to a light-trap, hence comments on rarity that
follow are relative within the genus but possibly not comparative outside it.
S.J. Willott (unpublished data) recorded several species in moderate frequency
in lowland forest near the Danum Valley Field Centre; such records were all from
samples made in the understorey.
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