A detailed morphological study of head, thorax, and abdomen is provided for three closely related species of Neotropical sun-moths. The taxonomic position of these species is controversial. Prior to the present study two of these species belonged to the genus Telchin Hübner, 1825, and one to the monotypic genus Castniomera Houlbert, 1918 (type species: Castnia atymnius Dalman, 1824). The hypothesis of some authors of placing the three species in a single genus is here supported on morphological evidences from head, thorax, and abdomen. Castniomera Houlbert is treated as synonym of Telchin Hübner comprising the following species: Telchin licus (Drury, 1773), Telchin syphax (Fabricius, 1775), and Telchin atymnius (Dalman) new combination. The three species of the T. licus complex are illustrated with line drawings and color photographs.
Castniid moth; morphological variation; Neotropical; taxonomy
