Andricus crystallinus n. sp.

I have received at different times from Mrs. E. H. King, of Napa City, Cala., a singular species of gall which grows in clusters on the leaves of Q. agrifolia? usually but not invariably on the under side. Full grown galls are from .30 in length to .13 in diameter, but only a few seem to reach maturity. Some are mere points. They are often quite dense clusters and remind one of our common A. flocci Walsh, by their woolly appearance, but the bright pinkish wool is resolved by the magnifier into a beautiful mass of brittle crystalline fibres. The largest galls terminate in an elongated neck, the lower half of which is generally smooth, while the upper part branches out tree-like. So far as I can discover these galls contain neither woody fibre nor cellulose tissue. They bear no resemblance to any ordinary vegetable growth ; but the body of the gall and the crystalline frost-work that covers it have a clear, semi-transparency, more or less pinkish, like beautifully tinted glass. The galls have a strong astringent taste, and are nearly pure tannic acid. On opening two mature galls I found two dead but fully matured gall- flies. Each gall contains two chambers, one above the other, with a very thin partition between them. The larva matures in the lower chamber.

This species differs materially from A. echinus O. S., though the galls bear a close resemblance to that species as described by Baron Osten Sacken. The black body of the insect, and the entire absence of clouds or spots in the subhyaline wings seem to separate them specifically.

Andricus crystallinus (unisexual generation)

Quercus douglasii, dumosa, durata, garryana
Leaf galls, detachable
Fig 94. Dense cluster, brittle pink fibers.

Fig 94. Q dumosa, douglasii, garryana, durata. Adults emerged from dumosa galls Mar. 1,2,5,7,10, 18 and Apr. 5 (Boulevard); from douglasii galls Apr. 8–17 (Angels Camp). The brittleness of the red fibers indicates a high tannin content.

Andricus crystallinus (unisexual generation)

The unisexual generation is formed in pinkish, crystalline galls which are so characteristic of this species in the summer months.

Hosts:
Quercus douglasii
Quercus dumosa
Q. garryana

Andricus crystallinus (unisexual generation)

This cynipid wasp induces caterpillar-like masses of bristly-haired galls on the ventral side of leaves of blue, scrub, leather, and Oregon oaks in late spring and early summer.

Each gall usually has a slightly curved beak at the apex and a sparse coating of crystalline hairs.

Hosts:
Quercus douglasii
Quercus berberidifolia
Quercus durata
Quercus garryana

Feron crystallinum (Bassett, 1900) comb. nov.

Gall. Asexual galls (Fig. 135). Bristly-haired gall masses 35 mm long by 25 mm wide on the underside of leaves composed of small, individual, elliptical or spherical, monothalamous galls, 12–14 mm high, 7 mm in diameter. Each gall usually with a slightly curved beak at the apex and a sparse coating of crystalline white, rose pink, red, or brown hairs (Russo 2021).

Biology. Alternate asexual and sexual generations were matched by Doutt (1960). Alternate sexual and asexual generations are also confirmed herein using DNA data, with four individuals (three asexual females, one sexual female) sequenced for cytb and three individuals (two asexual females, one sexual female) sequenced for cytb. Cytb sequences grouped into two haplotypes that were 0.23% divergent (GenBank accessions KX683596, MZ030743, OQ446195–OQ446196) and ITS2 sequences were identical among the three individuals (GenBank accessions OQ448237–OQ448239). Asexual galls in autumn on leaves, adults emerge in January–February; sexual galls in spring, adults emerge in March. Both generations develop on oaks from section Quercus, subsection Dumosae: Q. douglasii, Q. dumosa and Q. garryana.

Distribution. USA: California.