Polypogon
silvialis
Walker comb. n. Herminia silvialis Walker, [1859] 1858, List Specimens lepid. Insects Colln Br. Mus., 16: 115. Mixomelia digramma Prout, 1928, Sarawak Mus. J., 3: 477, syn. n.
Polypogon silvialis
Figure 321
Diagnosis. The wings are grey, relatively dark amongst congeners, particularly similar species such as producta and longisaccus (see above). The submarginals of all wings and the forewing antemedials are robustly darker as illustrated, the emphasis of the antemedials being unusual. The much finer forewing postmedial is particularly strongly angled at one third from the costa, distal to the cell. The male abdomen has the eighth segment of a moderately developed framed corematous type, with the sternal frame structure relatively small and weak, but including lateral rods. The frame contains a single corema. The valves are tongue-like with a small triangular process at the sacculus apex. The aedeagus has a moderately spined apex. The vesica is small compared with that of producta (see the original description of digramma where the facies is compared), with local weak scobination.
Taxonomic note. Poole (1989) retained digramma in Mixomelia but included silvialis in Lysimelia.
Geographical range. Borneo, Peninsular Malaysia, Sumatra, Bali.
Habitat preference. The species is uncommon in lowland forest, both primary and secondary, and has not been recorded above 200m. Chey (1994) recorded it as frequent in various softwood plantations near Brumas in the lowlands of Sabah, and it has also been recorded in small numbers in the understorey of primary and logged forest at around 170m in the vicinity of the Danum Valley Field Centre (S.J. Willott, unpublished data; as Mixomelia erecta).
