TRIBE CISTHENINI
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Byrsia Walker

Type species: dotata Walker, Indonesia (Timor, Batjan).

The remaining genera in this complex represented in Borneo belong to a quartet related to Scaptesyle Walker, the most distinctly Oriental member of the four, and have somewhat similar facies of black borders to both fore- and hindwings on a ground colour of bright cadmium yellow or pure white. The forewing border is broadly red over the central part. The inner boundary of the forewing apical border is often indented, and the basal area may also be black.

This pattern is reproduced on the underside. Males of these genera lack secondary sexual modification of the wings (Fig 6a), and definitive features are found more in the genitalia. The dorsal part of the valve in all four tends to be somewhat extensile, sometimes almost corematous. The complex was reviewed by Holloway (1984b). Many species currently attributed to the four genera he recognised, particularly from the New Guinea area, are probably misplaced.


Fig 6a: Byrsia dotata Walker

Byrsia species have the red and black margin to the forewing roughly triangular, the lobes to the ventral part of the vinculum are reduced, and the valves have coremata basally. The dorsal part of the valve is invested with a mass of swollen, club like scales, and the saccular process is strongly hooked. The aedeagus vesica bears a single massive cornutus.

The genus is represented more or less allopatrically by about six species from Sundaland to the Solomons, excluding Australia. It may be mainly day-flying.

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