Odorous and monophyletic – systematic revision of the endemic Madagascan genus Tritonaclia with the first record of wing scent scales in Syntomini Polka Dot Moths (Noctuoidea: Erebidae: Arctiinae)

In the highly diverse, endemic Madagascan lineage of Syntomini, the “ black-and-white ” general body pattern appears to be present in a few closely unrelated clades (and in six existing genera), causing uncertainties in their systematics. Based on materials from five natural history collections, we confirm the monophyletic character of the morphologically variable and largely montane genus Tritonaclia Hampson, 1898, with six existing species, inferred from both molecular and morphological evidence.

The taxonomy of the genus is revisited, with the description of two new species: T. vonifotsy Wiorek, sp. nov. and T. ombilahy Wiorek & Przybyłowicz, sp. nov .. Naclia melania Oberthür, 1923 syn. nov. is treated as a junior subjective synonym of Glaucopis tollini Keferstein, 1870, and lectotypes of both taxa, now placed in Tritonaclia, are designated. We provide determination keys for the genus, based on adults, and their male and female genitalia.

All available data on the distribution and ecology of Tritonaclia species are presented, including new geolocalisation of some important insect collecting places in Madagascar. Additionally, we provide descriptions and illustrations of male scent scales (androconial patches) on fore- and hindwings, present in two Tritonaclia species: T. tollini and T. vonifotsy Wiorek, sp. nov. Such structures are recorded in the tribe Syntomini for the first time.