Zapatella quercusmedullae

(Ashmead) comb. n.

Cynips quercusmedullae Ashmead, 1885 (females, galls). Andricus (Andricus) medullae Ashmead, 1885. Callirhytis quercusmedullae (Ashmead) (Burks 1979). Andricus cryptus Ashmead, 1887 (synonym in Dailey and Menke 1980).

Only the asexual generation is known. It induces stem swelling galls, in spring, on Quercus incana Bartram (= Quercus cinerea Raf.), Quercus marilandica (L.) Münchn. and Quercus myrtifolia in the USA (Florida, Alabama, Georgia, Missisipi, Texas) (Burks 1979). The adults emerge the following year in February and March (Ashmead 1885a, b; Weld 1959).

Callirhytis medullae (Ashm.)

Quercus catesbaei [laevis], cinerea [incana], laurifolia, phellos
Stem galls, stem swellings
Gradual swelling on one side of twig in spring. "Adults the next Feb. and Mar." Have never reared it.

Quercus falcata, myrtifolia
Stem galls, stem swellings
Not distinguished in field from [Zapatella quercusphellos]. "Adults the next Feb. and Mar." Have never reared it.

[Photo caption] On Q falcata. Also on Q coccinea, phellos, laurifolia, catesbaei [laevis], myrtifolia. "Adults the next Feb. and Mar." The writer has never reared it.

Callirhytis quercusmedullae

Cynips quercus medullae
Andricus cryptus

Weld noted this synonymy in his unpublished manuscript key to the species of Callirhytis, but it has not been established in print. We have examined the types of both species and confirm Weld’s synonymy. Two of Ashmead’s four syntypes of quercusmedullae and one of his two syntypes of crypta are extant in the USNM. Lectotype labels have been applied to one of the former and the single specimen of the latter.

The conspicuously swollen twigs from which the types of quercusmedullae emerged are quite different from the slender twig which produced the types of crypta (see figures 134 and 162 in Weld, 1959). This difference may have been caused by the presence of the inquiline, Synergus medullae Ashmead, in the galls of C. quercusmedullae. It is known that inquilines can cause modification of the host gall, as happens for example in galls of the bisexual generation of an undescribed Californian species of Callirhytis inhabited by Synergus digressus McCracken & Egbert.

Callirhytis quercusmedullae (Ashmead 1885)

Hosts: Quercus laevis, inopina, myrtifolia

[Asexual generation stem swelling galls found in Florida in the spring.]