Andricus balanaspis (Weld, 1922), comb. nov., sexual generation

Synonyms: Callirhytis balanaspis Weld, 1922b: 22, female, gall.

Diagnosis. The sexual generation of A. balanaspis most closely resembles three species from Florida that also gall catkins, Callirhytis myrtifoliae (Beutenmueller, 1917) on Q. myrtifolia, Callirhytis quercusturnerii (Ashmead, 1881) on Q. nigra and Andricus cooki Melika, Nicholls & Stone, 2021 on Q. myrtifolia and Q. laurifolia. In C. myrtifoliae the clusters of catkin galls are smooth and shiny, without pubescence, while in A. balanaspis the catkin galls are covered with sparse white setae. In A. cooki, clusters of galls are dark green to purple with dense short pubescence, contain 10-20 individual galls tightly grouped together that cause shortening of the catkin axis; in A. balanaspis the galls are pale green with longer pubescence, and are scattered along a normal-length catkin.

Gall (Figs 56–57). Sexual galls are aggregated on catkins, each rounded, to 3 mm in diameter, pale green with white pubescence. In sparse clusters, rarely singly, along axis of catkin; sometimes causing the catkin to curl but never stunting its development.

Biology. Alternate asexual and sexual generations are known, inducing galls on red oaks in (Quercus section Lobatae). The asexual generation galls (Figs 58–60) have been found on acorns of Q. marilandica and Q. myrtifolia, mature in October, adults emerge in spring of the following year. To date, sexual catkin galls have only been recognised on Q. inopina and Q. myrtifolia, mature in April, adults emerge soon afterwards.

Distribution. USA: Washington DC, Missouri, Arkansas, Texas, Virginia, Florida.

The authors’ unpublished sequence data show that A. balanaspis is part of a clade of species galling red oaks whose sexual generations, where known, are on catkins and asexual generations, where known, are acorn galls. This clade includes species such as Callirhytis carmelensis Weld, 1922, A. cooki, C. myrtifoliae, A. fitpatricki Melika & Abrahamson, 2021 and C. balanacea Weld, 1944