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Ophiusa tirhacoides sp. n.

Ophiusa tirhacoides

25-26mm. The forewings are a warm fawnish brown with fine, transverse, striae. The antemedial and postmedial are not evident. The reniform is rather angular, a dark chevron being surrounded by paler then darker components. The orbicular is a dark dot, relatively closer to the reniform than in other species. The irregular submarginal is marked by darker suffusion on each side (seen also in O. triphaenoides Walker, described below, where the submarginal itself is much straighter), and is itself delineated by a narrowly paler component giving way abruptly distally to a darker one. The marginal zone is somewhat greyer than the rest of the wing, a contrast also seen in O. tirhaca, though in tirhaca the area basal to the submarginal is pale greenish yellow. Darker marks enclosed on the basal side of the submarginal are, as in tirhaca and triphaenoides, restricted to its anterior quarter. The hindwings are a pale dull yellow, with a diffusely defined black submarginal band. The male genitalia resemble those of tirhaca. The uncus is similarly divided, but more irregularly, and with a short acute process between the two lobes. The process on the left side of the tegumen is more sinuous and that on the right side less strongly flexed subbasally.

Holotype . BRUNEI: 3m, Anduki, secondary veg., 7.1.1980 (R. Fairclough), BM noctuid slide 18018.

Paratypes: 1 BRUNEI: 3m, Seria, secondary and coastal veg., 6.1.1979 (Lt. Col. M.G. Allen), reared from larva on Casuarina; 1 BORNEO: Sipitang, 9.xii.1922 (G.F.C. Woollett); 1 BRIT. N. BORNEO: Sipitang, 8.xii.1922 (G.F.C. Woollett).

Taxonomic note. A further species related to tirhaca is O. costiplaga Hulstaert (Kei, New Guinea, coast of N. Territory of Australia), half the size of tirhaca, with greyer forewings, a more diffuse dark triangle at the costal end of the postmedial and less black on the hindwings (type in RMNH, Leiden; E.D. Edwards pers. comm.) browner or greyer, more uniform.

Geographical range. Borneo.

Habitat preference. All four specimens are from the lowlands near or on the coast in areas where there has been considerable disturbance and deforestation.

Biology. One specimen was reared from Casuarina (Casuarinaceae).

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