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Eois Hübner

Type species: russearia Hübner, Surinam.

Synonyms: Amaurinia Guenée (type species hyperythraria Guenée, S. America); Amphibatodes Warren (type species unilineata Warren = snellenaria Möschler, Jamaica); Anthyria Swinhoe (type species grataria Walker); Bardanes Moore (type species plicata Moore, India); Cambogia Guenée (type species heliadaria Guenée, S. America); Cretheis Meyrick (type species cymatodes Meyrick, Vanuatu, Australia); Phrudoplaga (type species argentifilata Felder & Rogenhofer = adimaria Snellen, S. America); Prasinoscia Warren (type species insolens Warren, S. America); Pseudasthena Moore (type species lunulosa Moore); Psilocambogia Hampson (type species memorata Walker).

The S. American type species of Eois prompted the suspicion that Old World species might not be congeneric, despite similarities of facies: fine reddish or greyish fasciae on a yellow or whitish ground. Indeed, Nielsen, Edwards & Rangsi (1996) referred Australian species to Cretheis. The genus includes many variations on this facies theme, though Indo-Australian representatives are more uniform in character than Neotropical ones. Examination of the female genitalia of all type species led to the recognition of a synapomorphy that justifies retention of Eois for Indo-Australian species, but indicated that Synthalia Warren (type species innocens Warren, Kenya) Gen. rev. was distinct.

The common feature is the presence of a robust, multispined signum, the base of which is usually set in an evagination of the bursa wall. In addition there may be patches of sclerotisation and fields of spines adjacent to this signum. Some variations on this theme occur in Indo-Australian species that serve to define subgeneric groupings; in the Neotropical fauna the bursa is more uniform but there is considerable variation in the shape of the ovipositor lobes. In Synthalia the bursa is globular with general spining, and the male genitalia also differ markedly from those of Eois, with smaller valves that have dorsally directed hair-setae, and elongate, well developed labides, lacking in Eois.

In Eois males the valves are large, rounded or paddle-shaped, with long, hairlike setae arising in the marginal zones and directed towards the base of the valves as in Poeilasthena, Carbia and some other eupitheciines. The uncus is absent, the scaphium well developed as in the eupitheciines, but the lack of labides is inconsistent with placement of Eois in that tribe. Nielsen et al. (1996) placed Cretheis in Asthenini, but these were defined by Pierce (1914) on features such as an extended male sacculus and a long, evenly spined signum: also the uncus is weak, attached to the anal tube which has the subscaphium thickened. Labides are present in some Palaearctic Asthenini. The signum of the female in Palaearctic Asthenini is similar to that seen in Parasthena and Poecilasthena.

The male antennae in Eois are often bipectinate, and sometimes those of the female. This characterises subgenus Pseudasthena (= Anthyria) in the Indo-Australian fauna: in other groups the antennae are filiform in both sexes. The Pseudasthena group has the female signum with the spines radiating from the base which is barely evaginated, rather than in a bundle. Fusion of the signum spines into a single, rather spatulate process characterises subgenus Psilocambogia. In subgenus Bardanes the signum is reduced relative to the development of the other fields of spines in the bursa in the type species, but in other Oriental species it is more evident and closest to that seen in most Neotropical species. Cretheis is unusual in having a signum resembling a hank of hair.

In the treatment following, the first six species are referable to Psilocambogia, the next three to Bardanes and the last three to Pseudasthena. Psilocambogia is the most wide-ranging in the Indo-Australian tropics, extending as far east as New Caledonia. The rather small African fauna appears to be mainly referable to Pseudasthena. A biogeographic parallel for Eois, in terms of richness and general distribution at least, may be found in the pierid butterfly genus Eurema Hübner.

Information on early stages has only been located for E. grataria Walker. Most Bornean species are found in the lowlands.

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