The Eugoa Walker group of genera
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Eugoa Walker

Type species: aequalis Walker, Borneo.

Synonym: Hectogama Meyrick (type species dissozona Meyrick, New Guinea).

This is one of the larger Indo-Australian genera. It is probably best defined on a combination of forewing venation and facies characters. All forewing veins are present, with three bifurcate systems: (R3, R4); (R5, M1); (M2, M3). This feature (Fig 7b) is also seen in Euconosia and the next two genera. R1 anastomoses with Sc. The forewing facies usually consists of one or two dark discal dots (if two, then quite close together and set slightly obliquely, not longitudinal and well separated as in Holocraspedon and allies) that are flanked by diffuse, often broad, oblique fasciae, usually a postmedial and frequently also an antemedial. The submarginal, when present, has a characteristic irregularity, with a short centre section displaced distad. The ground colour is usually some shade of fawn or grey, sometimes very pale, and the markings and suffusions are respectively brown or blackish. The hindwings are often more of a creamy colour. The antennae of the male are ciliate or serrate, sometimes bipectinate.

Fig 7b: Eugoa humerana Walker

The male genitalia are extremely variable in form, usually with the distal part of the valve entire, sometimes with a saccular process and frequently with a zone of costally directed setae along most of its length. In a few species the tegumen is shouldered or bears processes. The aedeagus vesica is often convolute but not elongate except for a frequently occurring tapering diverticulum, and may have cornuti. The ductus ejaculatorius may also be sclerotised.

The female usually has the ductus and corpus bursae short, the former often broad, the latter generally spined or scobinate. There may be a longer appendix bursae, and sometimes there are spines or other structures from the lamellae vaginales.

The greatest diversity is in the Oriental tropics, particularly in Sundaland, but there are one or two species groups in New Guinea, and weak representation in Australia, Japan and Africa. Some attempt has been made to identify groupings in the Bornean fauna. These will be identified in the taxonomic note for the first in a sequence. The biology of one species is discussed below.

The biology of the Japanese E. grisea Butler was described by Issiki et al (1965), with an illustration of the larva. The larva is pale grey with more rufous verrucae and mottling, the verrucae bearing whitish setae. There are dorsolateral black marks, roughly triangular and irregularly surrounded by cream, two on each side of each segment, adjacent to each other across the intersegmental membrane. The host was foliose liverwort growing on tree trunks.

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