Chalcosia Hübner

Type species: pectinicornis Linnaeus, China.

Synonym: Charmona Billberg (type species pectinicornis).

A core group of Chalcosia (three subgroups recognised by Yen et al. (2005)) is recovered in Clade 17 in a subclade that also includes all of the genus Milleria, though the type species, M. adalifa Doubleday, is consistently placed as sister to Chalcosia rather than with its congeners. One of the two Bornean species, “C. zehma”, falls within Clade 16. The sister subclade is discussed under Psaphis Walker.

Clade 17 as a whole was stated by Yen et al. (2005: 254) to be one of the most diverse groups of the subfamily, but is well supported in the analysis. The anterior half of the forewing cell, as divided by the stem of vein M, extends beyond the posterior half in all except Chalcosia, though this feature is also widespread in the Agalopini, and the clade also has distinctive structure in the male eighth segment.

Species of Chalcosia typically have a ground colour from white to yellow, marked in black as in some Corma species: a broken medial band on the forewing; borders on all wings, but that of the forewing divided by a submarginal band of the ground colour.

The male abdomen and genitalia structures are typical of those of the more distal clades of Yen et al. (2005) as discussed on the subfamily account.

Only one species of the dozen or so typical of the genus occurs in Borneo; the rest are mostly found in mainland Asia or Taiwan. The other is probably more closely allied to species currently in Eterusia and two Chinese genera. Other atypical species are found in the Philippines: azurea Kishida & Endo (transferred to Psaphis by Yen et al. (2005)), highly sexually dimorphic with a male somewhat as in Eucormopsis and some Cyclosia; nyctemeroides Semper, with a pattern mimicking arctines in the genus Nyctemera Hübner.

The larva of the type species was described by Gardner (1942), and those of two others were illustrated by Yen et al. (2005). They tend to be pale to medium reddish brown, with fine dorsal and dorsolateral black lines and often a pale zone between the latter in the area of the prolegs. The tubercles are moderate in size, three rows on each side, those on T3 sometimes black. The ventral part of the body is paler and may be greenish.

All larval host plant records for the genus are from Symplocos (Symplocaceae) (Sugi, 1987; Robinson et al., 2001).