Dryocosmus juliae, new species

Gall (Figs 36–43) [see page 12 of the pdf for these color photos of each gall variant]
The sexual generation of Dryocosmus juliae, new species has four different galltypes, collected from Chrysolepis chrysophylla and C. sempervirens, and here listed under the field codes assigned to our collections. All galltypes occur at the same time (and often on the same individual plant) and probably reflect variation in the exact oviposition site within dormant buds before the buds develop into new growth/leaves with concurrent gall formation.

spCAl13 (Figs 36–37)—an integral leaf gall, typically developing in July, about 6–7 mm in diameter,
protruding mainly from lower surface of the leaf, sitting totally within the lamina of the leaf, never on the leaf edge, with a free-rolling inner larval cell. This is an undescribed galltype listed by Weld (1957).

spCAl14 (Fig. 38)—an integral leaf gall, developing in July, about 3–4 mm long and 2 mm across, on the edge
of the leaf blade, causing infolding of the lamina (sometimes all the way to the midrib), with a free-rolling inner
larval cell. Very similar to the previous galltype (spCAl13); however, located on the edge of the leaf blade.

spCAb5 (Figs 39–41)—a small green gall that appears to be induced in terminal or axillary buds, conical,
slightly pointed, up to 8 mm long, 4–5 mm diameter, with a free-rolling inner larval cell. Further investigation has
shown that this gall is actually induced on a leaf, and the apparent position on a bud is because gall development stops leaf growth. Collected primarily in June and July, although some galls (one containing a viable pupa) were collected in October, perhaps indicating some proportion of larvae undergo a period of diapause.

spCAs5 (Figs 42–43)—an integral stem gall, collected in July and August, causing swelling of the terminal
bud and immediately adjacent new twig growth.

Biology. Alternate sexual and asexual generations are known, developing on Chrysolepis sempervirens and C.
chrysophylla. Galls of the sexual generation typically develop in June-August, adults emerge during the same
period. Asexual galls on catkins starting to develop in September, adults probably emerge next spring.

Distribution. USA, California.

- James Nicholls, John DeMartini, George Melika, Graham Stone: (2018) New species of Dryocosmus Giraud gallwasps from California (Hymenoptera: Cynipidae: Cynipini) galling Chrysolepis Hjelmq.(Fagaceae)^©