Dryocosmus juliae, new species

Gall. The asexual generation of this species induces catkin galls, which were collected from Chrysolepis sempervirens at the two sites near Manzanita Lake (USA, California) on 2008.09.11 and 2012.09.24. However, at the time galls were collected only small larvae were inside the galls and no adults were subsequently reared. DNA sequences from these larvae matched those obtained from the sexual generation described above, confirming that this catkin gall is the alternate asexual generation of D. juliae, new species. These asexual generation galls (galltype code spCAc4) develop on staminate catkins, are around 4 mm in diameter, with a fluffy buff coloured surface. The internal structure shows an inner larval cell located at the bottom of the gall with a "dummy" cell above that contains a small opening on the upper surface (Figs 44–45). [See page 12 of the pdf for color photos of this gall].

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.

Description of a New Genus for Chrysolepis-Associated Dryocosmus Species

Four species of Dryocosmus induce galls on the host plant genus Chrysolepis on the Pacific slope of North America. These form a clearly distinct clade in both StarBEAST and ML analyses (node 8; Fig. 4 and Supplementary Fig. S3), consistent with other studies that show this set of species to be allied to Heteroecus Kinsey and Grahamstoneia Melika and Nicholls, and not with other Dryocosmus taxa (Nicholls et al. 2018, Melika and Nicholls 2021).

Here we establish the new genus, Chrysolepicynips Stone, Nicholls, Melika and Tang, gen. nov. to circumscribe the four Chrysolepis-associated Dryocosmus species, with four new combinations: Chrysolepicynips castanopsidis (Beutenmuller 1917), comb. nov., C. demartinii (Melika, Nicholls and Stone 2018), comb. nov., C. juliae (Melika, Nicholls and Stone 2018), comb. nov., C. rileypokei (Morita and Buffington 2009), comb. nov. 

Distribution and biology. All Chrysolepicynips species are known only from California, and both generations induce galls on Chrysolepis (Fig. 3). Asexual generation galls are induced on buds (C. demartinii and C. rileypokei) or catkins (C. castanopsidis and C. juliae); known sexual generation galls are induced in fruit cupules (C. rileypokei) and buds, leaves, and young shoots (C. juliae) (Nicholls et al. 2018).

Dryocosmus juliae

Hosts: Chrysolepis chrysophylla, sempervirens

The asexual generation induces nondescript round galls on the staminate flowers of chinquapin in early spring.