The Throana group of genera
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Nagadeba Walker

Type species: indecoralis Walker, Java, India, Burma, Andamans.

The type species has an external appearance like a smaller and more slender
Chrysograpta Hampson (p. 324), though in a darker, duller colour without yellow highlights. It shares with the previous genus and the next a conspicuously pale orbicular stigma on the forewing undersides and reduction of the phragma lobes of the second tergite. The male abdomen has the eighth segment unmodified. The genitalia have a well developed saccus. The valves are divided into three distally, somewhat as in Metaphoenia Hampson (p. 367). The aedeagus vesica contains one long, slender cornutus. The female genitalia have the ostium and the ventral part of the eighth segment pulled anteriorly into a deep cleft within the seventh sternite, which is considerably reduced. This appears to be the only feature that unites several rather disparate species currently within the genus and, as stated above, is shared by the Throana group as a whole.

Other species associated with the genus (Poole, 1989) appear to differ considerably, though not all have been examined here. The only Bornean species previously assigned to this genus,
celenoalis Walker, has very different, pale facies on much deeper wings that show sexual dimorphism as described below.

The male abdomen has the eighth segment modified from the framed corematous pattern, the tergite broadened and the sternite deeply cleft posteriorly, rendering the anterior lacuna vestigial. The genitalia are unusual with short valves that have rasp-like processes from the base of the costa and from the sacculus. The aedeagus is short, and the anellus is voluminous; the vesica is large, at right-angles to the aedeagus, with a large, slender cornutus.

The female genitalia show the generic and wider group feature having the ostium and ductus associated with the seventh segment, where the sternite appears to be vestigial. The ductus is short, the corpus bursae spherical, with some scobination and sclerotisation in its basal half. The position of the ostium within the seventh segment is also one feature that transfers geminipuncta Hampson from Egnasia to Nagadeba.

The type species was reared by Bell (MS) in India. The larva is a spindle-shaped, semi-looper, fattest centrally. The prolegs on A3 are absent. The head and body are green, the former with areas of brown dots, and the latter with most setae except the subdorsals arising from black spots. There is a darker dorsal line and a thin yellow or white one through the spiracles which are small, yellowish, with shining black rims. The young larvae are very active, flipping off the foliage if alarmed and dropping on a silk thread. Pupation is on the ground in a cell of silk incorporating particles of detritus.

The host plant is
Mussaenda (Rubiaceae). This host is also noted for N. cinerea Hampson in the Andamans (unpublished IIE records).

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