Cat. Lep. Ph. Brit. Mus. Vol. 1:

515. Cosmosoma xanthostictum, hn. sp. (Plate IX. fig 21.)
Cosmosoma metallescens, Druce, Biol. Centr.-Am., Het. i. p. 58 (nee Mén.).
male . Black ; vertex of head, thorax above and at sides, and legs
with patches of metallic blue scales; tarsi white at extremity ;
abdomen with lateral blue spots at base, followed by orange-yellow
spots on Znd and 3rd segments, a dorsal series of yellow and blue
spots ; wings hyaline, the veins and margins black. Fore wing
with basal black patch with metallic blue spots on it ; a discocellular
band; the terminal band very wide on apical area and expanding
at torpus. Hind wing with the terminal band expanding towards
apex and tornus.

AZ NOTE: Cat. Lep. Ph. Brit. Mus. uses a non-standard definition of "tegulae" and "patagia".
From Vol. 1:
"The thorax consists of three segments-the prothorax, bearing the
tegulm or collar-lappets, the patagia or shoulder-lappets, and the
fore legs ..."