Zapatella quercusphellos
(Osten Sacken) comb. n.
Cynips quercusphellos Osten Sacken, 1861. Callirhytis quercusphellos (Osten Sacken ) (Burks 1979).
Cynips quercussimilis Bassett, 1864, syn. n. Callirhytis quercussimilis (Bassett) (Burks 1979).
Callirhytis (Cynips) quercussimilis (sexual form) was known, inducing stem swelling galls on Quercus incana, Quercus falcata, Quercus ilicifolia Wangenh., Quercus imbricaria Michx., and Quercus myrtifolia along the Atlantic coast, from Florida to New York state (Burks 1979). The galls are club-shaped swellings if they form on terminal twigs, with 1–4 cells (Weld 1959). Green and fleshy galls develop in May, and later turn woody (become lignified). Adults emerge in June to the beginning of July (Bassett 1864, Weld 1959).
The author of Callirhytis quercusphellos (Osten Sacken 1861) collected greenish rounded woody swellings at the tip of the twigs of Quercus phellos (L.) in Virginia, near Potomac river in June; four sexual females emerged by the end of June Osten Sacken (1865) mentioned that his species somehow resembles Callirhytis quercussimilis (Bassett), however, differs from it. Dalla Torre and Kieffer (1910) treated them as different species. Weld (1922b) erroneously synonymised Cynips similis Bassett to Callirhytis quercusphellos (O.S.). Later, the two species were treated as different species (Weld 1926, 1928, 1951, 1959; Burks 1979). Weld (1922b) observed galls absolutely similar to those of Zapatella quercusphellos on Quercus falcata, Quercus incana, Quercus texana Buckley, Quercus laurifolia Michx. and Quercus myrtifolia.
Zapatella quercusphellos was collected also at Rosslyn, Virginia from Quercus imbricaria in June and Quercus phellos in May, adults emerged in late June. In both cases the greenish fresh galls were similar terminal enlargements on new growths, inconspicuous, only 5 mm long; after maturation galls were 8–10 mm in diameter (Weld 1926).
A detail examination of specimens of Callirhytis quercusphellos and Callirhytis quercussimilis, mentioned above, showed no appreciable morphological differences and thus, Callirhytis quercussimilis is a syn. n. of Callirhytis quercusphellos and here in the species transferred to the Zapatella genus, Zapatella quercusphellos, comb. n.
Only the sexual generation is known. It induces stem swelling galls on Quercus incana, Quercus falcata, Quercus ilicifolia Wangenh., Quercus imbricaria, Quercus myrtifolia and Quercus phellos along the Atlantic coast, from Florida to New York state (Burks 1979).
