Discovery of a new host plant of Pseudasphondylia tominagai Elsayed amp; Tokuda, 2019 (Diptera, Cecidomyiidae)

Barely visible flower bud galls of Deutzia floribunda Nakai (Hydrangeaceae) were found in Kumamoto Prefecture, Kyushu, Japan. Morphological and molecular analyses indicated that the gall inducer is Pseudasphondylia tominagai Elsayed & Tokuda, 2019 (Diptera, Cecidomyiidae), previously known only to form galls on Eleutherococcus spinosus (L.f.) S.Y.Hu (Araliaceae) in Honshu, Japan. This study marks the first report of a species of Pseudasphondylia Monzen, 1955 on Hydrangeaceae, having host plants from different families and establishing D. floribunda as a new host record for P. tominagai.