Diagnosis. Both this and the next species, ischyra Prout, have a triarcuate forewing postmedial that separates a paler distal half from a darker basal half as discussed under the previous species. Males of H. mandatalis are smaller, with the forewing a darker, less ochreous brown. There is a mauve tinge along the costa and on each side of the medial zone. The anterior discal spot of the forewing is more evident usually than in ischyra, and there is a conspicuous dark brown band that runs from just distal to the discal spots almost to the margin. The marginal zone posterior to this is relatively more uniform than in ischyra where it is more variegated. Also in ischyra the submarginal is usually conspicuous, with darker, irregular blocks giving way abruptly to narrower pale areas in each space. The male genitalia are typical of the genus but have a distinctively developed ventral margin to the pleat of the valve.
Taxonomic note. No definite females have been located for mandatalis. The taxon isogona Meyrick (= hedychroa Bethune-Baker; Edwards in Nielsen et al. (1996)) from N. Australia, New Guinea and Rennell I. (Fletcher, 1957) has similar males, and the females of this species are much paler, with the postmedial straight. The medial area basal to this is darker as in the male, and the darker bar posterior to the apical lens persists and is conspicuous. However, this provides no guide to potential females for mandatalis because isogona has male genitalia that place it in Dichromiacomb. n. Edwards suggested that isogona might be a species complex, but this needs investigation. The type material of New Guinea taxa appears to be all conspecific, but the females from Rennell I. identified as hedychroa by Fletcher (1957) are smaller and lack a conspicuous dark bar at the forewing margin. The record of mandatalis from Australia in Nielsen et al. (1996) also needs investigation in this general context.
Geographical range. Indian Subregion, Sumatra (Lödl, 1999e), Borneo, Sulawesi, Australia (Nielsen et al., 1996).
Habitat preference. This species is much rarer than ischyra, represented by three males only, two from upper montane forest at 1790m on G. Mulu and one from an Acacia mangium plantation near Brumas in the lowlands of Sabah.
Biology. The species identified as mandatalis when reared by Bell (MS) in India (Robinson, et al. 2001) is in fact H. robustalis Snellen (vouchers examined in BMNH: no. 918), and the life history is described under that species above.