Andricus notholithocarpi, n. sp.

Gall: Four different gall types induced by this species were found (Figs. 10–16). Three are very similar, differing only by the plant organ on which they occur. The fourth probably represents an early developmental stage of the typical gall induced on a leaf; perhaps with development stopped due to parasitism.

1. Galls in buds (authors' field code spCAb4) (Figs. 10–12) — small (∼3–5 mm long) pip gall in an axillary bud, with longitudinal ridges along the gall surface. Pale green when developing, rusty-brown when mature. Collected in October, December, April and May.

2. Galls on catkins (authors' field code spCAc?) (Fig. 13) — small conical gall on staminate catkins, with delicate longitudinal ridges along gall, several mm long, pale green when developing. Collected in August, September and December. The gall is very similar to spCAb4 and spCA115, just on a different plant organ.

3. Galls on leaves (authors' field code spCA115) (Fig. 14) — small conical leaf gall, on edge of leaf, causing infolding of leaf edge and bending of midrib, small longitudinal ridges on outside of gall. Collected in June, August, October, December, January and March. The gall is very similar to spCAc? and spCAb4, just on a different plant organ.

4. Galls in swollen leaf midribs (authors' field code spCA18) (Figs. 15–16) — swollen leaf midrib or petiole, green or yellowish-green; usually causes midrib of leaf to bend. Collected in June, September, October, January and April. No adult gall-inducers were reared from this gall type; only unidentified cynipid inquilines (Synergini) and parasitoids from the superfamily Chalcidoidea were reared. However, remains of larval gall inducers were dissected from this gall type.

Biology : Galls start to develop in June–August at the same time as new leaf and flower development. Gall and larval development continues during September-December, larvae overwinter in galls and adults emerge in early spring of the following year. Currently known only from Notholithocarpus densiflorus.

Distribution: Currently known only from California, USA.

Tanoak-Pip-Gall Wasp
Andricus notholithocarpi
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Galls measure 3-5 mm long, are relatively smooth and glabrous, and are marked by longitudinal ridges on the gall surface terminating in a rounded point. When fresh in late spring, the galls are light green; they age to light brown by winter.