Cecinothofagus Nieves-Aldrey & Liljeblad (Hymenoptera, Cynipidae) is likely an endoparasitoid of the gall-maker genus Aditrochus Rübsaamen (Hymenoptera, Pteromalidae)

Paraulax Kieffer and Cecinothofagus Nieves-Aldrey & Liljeblad (Cynipidae: Paraulacini) were long supposed to be gall-makers on southern beeches (Nothofagus, Nothofagaceae). Dissections of galls on Nothofagus Blume, suggested that Cecinothofagus could be instead either endoparasitoid or inquiline of Aditrochus larva (Chalcidoidea). We sequenced the universal COI barcode and Ultra-Conserved Elements (UCEs) from young larvae of Aditrochus collected from galls on Nothofagus and highlighted that one of them also contained DNA from Cecinothofagus ibarrai Nieves-Aldrey & Liljeblad. So far, when galls attributed to Aditrochus were dissected in early development stages they all contained only a single larva and no remains of other larvae. Conversely, when Cecinothofagus ibarrai was reared from galls on Nothofagus, remains of the host larva were observed inside the larval chamber. Altogether, biological observations and molecular results suggest that Cecinothofagus ibarrai is likely an endoparasitoid of Adritrochus. This result confirms the tribe Paraulacini as being entomophagous and supports the hypothesis of an ancestral parasitoid lifestyle for Cynipoidea.