Diagnosis. , 17-18mm. This is a consistently larger species than silenusalis (14-16mm) but with similarly long antennae. Its wings are brownish rather than blackish, with the forewing white discal patch of silenusalis mostly obscured on both upper- and underside. The features of the male abdomen are indistinguishable, however. The species is also similar to B. umbrina Tams 107 (Thailand, N.E. Himalaya), but that species is smaller, a richer, slightly paler brown, somewhat more variegated, particularly on either side of the forewing submarginal subapically (darker on the basal side) and in a paler zone distal to the hindwing postmedial.
Holotype. Kina Balu, N. BORNEO, BM noctuid slide 19513.
Paratypes: 4, 2 Kina Balu; 1, Kina Balu, ex Staudinger, 1890; 4 NORD BORNEO: Mont Kina Balu, 5-8.1903 (John Waterstradt); 1 SARAWAK: Gunong Mulu Nat. Park, R.G.S. Exped. 1977-8 (J.D. Holloway etal.), G. Mulu, 500m, 401464, to camp [2] lights, 20.2.1978.
Geographical range. Borneo.
Habitat preference. Most material is from the vicinity of G. Kinabalu but without precise data. A female was taken at a pressure lamp in a camp at 500m in hill dipterocarp forest on G. Mulu.
