TRIBE STERRHINI
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Idaea Treitschke

Type species: aversata Linnaeus, Europe.

Synonyms: currently over fifty genus-group names are placed in synonymy with Idaea. They are listed by Nielsen, Edwards & Rangsi (1996). No comprehensive attempt has been made to assess whether their type species share the characters discussed below in definition of the genus but a selection that have already been dissected in the BMNH collection or are illustrated in the literature such as Pierce (1914) do conform (e.g. all those based in European species, plus Cacorista Warren, Carphoxera Riley, Mnesterodes Meyrick and Pythodora Meyrick).

The genus has male genitalia typical of the tribe, with the valves simple, strap-like, tapering to the apex where a few slightly more robust setae or an apical spine may occur. Many species have only a single cornutus in the aedeagus vesica, though others have more. Coremata have only been noted at the valve bases in a trio of species from New Caledonia (Holloway, 1979) and where indicated in the species descriptions following. I. themeropis West has strong rugosity on the second abdominal sternite and some species have pouches, though others lack any modification.

The females have the general spining in the bursa discussed in the tribal description but its extent is highly variable, apparently correlating to some extent with the size and number of cornuti in the aedeagus vesica of the respective male.

The generality of this definition is not entirely satisfactory, but a global review of the genus as currently constituted would be necessary to establish whether any useful subdivisions can be clearly characterised. However, one fairly obvious separation of a natural group, that of Lophophleps Hampson, is made later. The structure of the female genitalia, more so than the male, may provide a basis for recognising further natural groupings with Idaea: brief comments on genitalic features of both sexes will be made as taxonomic notes for each species. Indeed there seems to be a grade towards the characteristics of Lophophleps in the number of cornuti in the aedeagus, spining and reversed back flexure of the bursa, presence of coremata on the male genitalia and elsewhere in the abdomen, loss of a structure on the male second sternite and projection of its posterior margin and the lateral, elongate, strutted lacunae into the centre of the third sternite. Species from I. craspedota Prout onwards show these bands progressively. Genus-group names such as Janarda Moore (species like I. protensa Butler ) and Andragrupos Hampson (see I. violacea Hampson) are involved.

A number of unidentified species are represented by limited material, and correlation of the sexes is very difficult. Hence these are listed at the end, but not formally described as new. Also, three species described from Sumatra, I. afflata Fuchs, I. infantilaria Fuchs and I. salebrosa Fuchs, need to be examined, but the type material has yet to be located. The original descriptions, particularly with reference to hindwing shape, suggest these may be more referable to Lophophleps than to Idaea.

General comments on early stages and biology are made in the tribal introduction, but all too little is known of the life histories of South-east Asian species.

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