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Nygmia xanthomela Walker comb. rev.
Euproctis xanthomela Walker, 1862, J. Linn. Soc. (Zool.), 6:128.
Euproctis atomaria Walker, 1855, List Specimens lepid. Insects Colln Br. Mus., 4: 837,
          praeocc., syn. n.
Euproctis catala Swinhoe, 1902, Trans. ent. Soc. London, 1903: 416, syn. n.
Euproctis catala postlutosa Holloway, 1982: 219, syn. n.
Euproctis plana Walker sensu Schintlmeister, 1994:121.

Nygmia xanthomela

The male facies is similar to that of semifumosa Holloway and amplior Collenette, discussed later. The forewing is evenly and lightly suffused with darker scales, except where these intensify diffusely in the postmedial and antemedial. The male genitalia are diagnostic, with the valves bifid and the juxta broad, oval, undivided (in amplior the valve is undivided and the juxta is bifid). There are unusual ‘socii’ on the tegumen, or possibly these are derived from a dorsal extension of the valve.

Taxonomic note. The synonymy above brings together all Sundanian taxa with similar genitalia, but having a variable extent of grey shading on the hindwing, this being absent in ssp. catala and more extensive in ssp. postlutosa. The Indian species N. plana Walker comb. rev, is related, but has the dorsal arm of the valve (excluding the ‘socius’) longer than the ventral one, rather than vice versa (in ssp. catala they are more equal). Toxopeus (1948) suggested that xanthomela and catala (with plana) were subspecies of the type species, icilia Stoll (Indian Subregion), but this has broader arms to the valve and no ‘socii’.

Geographical range. Borneo; Java, Sumatra (ssp. catala); Peninsular Malaysia (ssp. postlutosa).

Habitat preference. The species has been taken singly or in small numbers in a range of lowland forest types. There are single records at 1000m on G. Mulu and at 1618m on Bukit Retak.

Biology. Moore (in Horsfield & Moore, 1859 [1860]) illustrated the larva of ssp. catala (as atomaria). It appears dark brownish grey with a broad grey dorsal band from A3 backwards between the most dorsal rows of verrucae. The verrucae are depicted distinctly darker. The head is yellowish. There is a conspicuous black semicircle dorsally on T3, the curved edge anteriorly, lined narrowly with white. Kalshoven (1981) illustrated the larva as having paired dorsal humps on A1, A2 and A8.

The host-plants given were Dioscorea (Dioscoreaceae), Annona (Annonaceae) and Tamarindus (Leguminosae), but Toxopeus, who also
mentioned Citrus (Rutaceae), suggested these were erroneous, and probably records of pupation sites in non-host plants. He indicated that Loranthus (Loranthaceae) was the only reliably identified host, and this was the only host listed for the species by Kalshoven (1981). Pholboon (1965) recorded plana as feeding on Loranthus in Thailand.

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