Re-discovery and detailed description of the gall of Andricus mendocinensis Weld, 1957 (Hymenoptera: Cynipidae: Cynipini) on the tanoak Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh (Fagaceae)

The oak gall wasps (Hymenoptera: Cynipidae: Cynipini) consist of about 1000 species primarily found in Holarctic temperate regions and extending into sub-tropical and tropical Asia and central America (Ronquist et al. 2015). All species in this tribe induce galls on host plants in the family Fagaceae, with the vast majority associated with genus Quercus L. (Stone et al. 2002). However, in Asia there are three genera of non-Quercus Fagaceae that are hosts for 18 described and many more undescribed Cynipini species: Castanea Mill., Lithocarpus Blume, and Castanopsis (D.Don) Spach (Lobato-Vila et al. 2022, GNS & JAN, unpublished data). In North America, all but six of the approximately 700 known Cynipini species are associated with Quercus host plants. Four Cynipini species from the genus Dryocosmus Giraud, 1859 (discussed in detail by Nicholls et al. 2018b) induce galls on the plant genus Chrysolepis Hjelmq.: D. castanopsidis described by Beutenmuller (1917), D. rileypokei described more recently in Buffington & Morita (2009), and D. juliae and D. demartinii described in Nicholls et al. (2018b). Only two Cynipini species are known to attack the tanoak, Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh — the recently described Andricus notholithocarpi Melika, Nicholls & Stone, 2018 and A. mendocinensis Weld, 1957. Description of the adults, galls and biology of the former of these two species is provided by Nicholls et al. (2018a), while the latter is the focus of this study.