Andricus coriarius (Hartig, 1843)

Host plants. Israel: Q. ithaburensis, Q. libani, Q. cerris (sexual generation), Q. boissieri (asexual generation). Elsewhere: numerous oak species from sections Cerris (sexual generation) and Quercus (asexual generation).

Life history. Both the sexual and asexual generations were previously recorded (Stone et al. 2008), but a detailed description of the sexual-generation galls was not given and is provided here for the first time. Galls of the sexual generation develop on oaks from section Cerris. They usually form a cluster of 15 or more conical, single- chambered, 2.0– 2.5 mm long and 1.5 mm wide units that are tapered apically, smooth, greenish-brown and thinwalled (Fig. 52). Galls of the asexual generation are found on oaks from section Quercus, and are morphologically diverse. The typical galls are composed of several tapering, curved lobes up to 30 mm long, which form a big, irregular sphere and are multi-chambered (Fig. 15). Other galls in the population have shorter, thicker lobes (Fig. 16). Young galls are pale green with flexible spiny lobes, sometimes with soft brown hair at their center. Mature galls are brown and woody.

Phenology. Adults of the sexual generation emerge in May in most locations in Israel, but at higher elevations and cooler habitats (e.g. Mt. Hermon) galls become apparent only in April and adults emerge in June. Galls of the asexual generation begin to develop in August and adults emerge from them in late December to January, after which galls may remain on the tree for several years.

Distribution. Israel: Mt. Hermon, 1500 and 1780 m.a.s.l., Mt. Kahal, En Zivan, Allone HaBashan, Tel Hazeqa. Elsewhere: common and widespread in Europe, from Great Britain to the Iberian Peninsula and Greece, Morocco, Turkey, Transcaucasia and Iran (Melika 2006b).

Comments. Galls of the sexual generation (Fig. 52) are very similar to galls of the A. burgundus species complex. Stone et al. (2008) showed that the sexual generation of several Andricus species, including A. caputmedusae, A. coriarius and A. hystrix, develops in small, aggregated bud galls similar to those of the A. burgundus species complex or A. atkinsonae. Our unpublished molecular results corroborate that observation, hence the galls and adults of both generations of A. coriarius are now known. Adults of the sexual generation will be described elsewhere.

The typical galls of the asexual generation are superficially similar to those of A. grossulariae (Fig. 9) but differ in the more delicate and pointed lobes. The less common morphologies of this gall (Fig. 16) resemble the galls of A. coriariformis (Fig. 17) but lobes of the latter are shorter and widely splayed.