Abstract. Phylogenetic relationships among species groups of Trichadenotecnum were inferred based on morphology and the partial sequences of five gene regions (mitochondrial 12S rDNA, 16S rDNA, cytochrome oxidase I, NADH dehydrogenase subunit 5 and nuclear 18S rDNA). All analyses supported the monophyly of Trichadenotecnum and all previously proposed species groups, except that T. circularoides was excluded from the spiniserrulum group. To examine the phylogenetic usefulness of morphological data, the morphological characters used in the construction of an earlier taxonomic system for Trichadenotecnum were mapped parsimoniously on the molecular tree. As a result: (1) commonly used forewing marking features (sparsely or extensively spotted) are considered to be very homoplastic and less informative of higher-level phylogenetic relationships; (2) a broadly expanded epiproct lobe is considered to be independently evolved at least two or three times, and a detailed morphological re-examination allows recognition of these convergent structures; (3) the short ventral valve of gonapophyses independently evolved at least three or four times, although this character was used initially to diagnose the spiniserrulum group.