Nygmiini

The Nygmiini are most clearly defined by the well developed corethrogyne in the female abdomen. The seventh segment is expanded and membranous, sometimes with the basal margin stiffened as a sclerotised ring. This expanded membranous zone bears a dense tuft of scales: these scales are used by the female to protect the egg mass. Though this habit occurs in other lymantriid groups, it is not accompanied by expansion of the seventh segment.

The forewing lacks an areole except in Rhypotoses Collenette where its formation uniquely involves R1. The forewing facies is distinctive, often colourful, involving dense scaling and, in the majority of genera, rather bold, blocked patterning rather than fine fasciation. Where the latter occurs, it is often paler than the ground, rather than darker. Some genera, such as Rhypotoses, Cozola Walker and Medama Matsumura, have rather plesiomorphic patterning with finer, darker, more crenulate fasciation. The discal spot, when present, is a solid, dark dot rather than a V-mark or more typical noctuoid reniform stigma.

Male genitalia structure is diverse and provides diagnostic features for the various genus-groups recognised here, particularly within the very broad concept of Euproctis Hübner that has previously been applied within the Old World fauna (e.g. by Holloway (1976), Schintlmeister (1994) and Nielsen, Edwards & Rangsi (1996)). A number of species groups have been recognised and genus- group names applied mostly from within the old synonymy of Euproctis (e.g. as in Nielsen et al.). Genus-group names based on African type-species do not appear to be relevant to the Indo-Australian fauna, so it is likely that different generic concepts will apply in that continent (Maes, 1984b). Maes referred a number of Madagascan species to his Sphrageidus Maes, a genus based on the Palaearctic species similis Fuessly (See Sphrageidus Maes).It has not been possible to place the genera Epeuproctis Matsumura (type species tamahonis Matsumura) and Meteuproctis Matsumura (type species tomponis Matsumura) within this new scheme. Both were based on unique females with unmarked yellow forewings from Taiwan. It has been possible to examine photographs of these and their genitalia. A preliminary survey of Taiwan material of this facies type in BMNH did not yield a match.

The female genitalia are very variable in development, this tending to reflect characteristics of the aedeagus vesica in the male. The signum is often of the bicornute type, but this can be modified into a transverse flange or, in NygmiaHübner, a longitudinal one.

The larvae do not appear to offer any strongly definitive characteristics, having secondary setae on verrucae as in other groups. The postspiracular abdominal verrucae are reduced, and the subspiracular and supraventral ones are well separated as in Orgyiini (Gardner, 1938). The secondary setae on the verrucae can be highly urticaceous in some genera and, when the larvae are abundant and gregarious, can be a health hazard (See Toxoproctis Gen. n. and, for the Palaearctic type species of Euproctis, de Worms (1979) and Carter (1984)). In some genera (e.g. Sphrageidus, Arna Walker), Somena Walker, Orvasca Walker and Artaxa Walker the dorsal pairs of verrucae are particularly prominent on the first two abdominal segments and A8, where they have converged and coalesced. Some Nygmia also have the verrucae convergent and prominent on these segments.