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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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