Dryocosmus juliae Melika, Nicholls & Stone, 2018

Nicholls, James A., Melika, George & Stone, Graham N., 2018, New species of Dryocosmus Giraud gallwasps from California (Hymenoptera: Cynipidae: Cynipini) galling Chrysolepis Hjelmq. (Fagaceae), Zootaxa 4532 (3), pp. 407-433 : 414-417

publication ID

https://doi.org/ 10.11646/zootaxa.4532.3.6

publication LSID




persistent identifier


treatment provided by


scientific name

Dryocosmus juliae Melika, Nicholls & Stone

sp. nov.

Dryocosmus juliae Melika, Nicholls & Stone , new species

Figs 18–45 View FIGURES 18–27 View FIGURES 28–35 View FIGURES 36–45


Type material. HOLOTYPE female: “ USA, CA, 30 km E of Arcata ( CA1232 ), ex buds of Chrysolepis chrysophylla , leg. J. Nicholls, 2009.07.13”; 10 female and 4 male paratypes: 3 females and 1 male with the same labels as the holotype; 1 female “ USA, CA, 30 km E of Arcata ( CA1253 ), ex leaves of Chrysolepis chrysophylla , leg. J. Nicholls, 2009.07.13”; 1 male as “ USA, CA, 30 km E of Arcata ( CA1214 ), ex leaves of Chrysolepis chrysophylla , leg. J. Nicholls, 2009.07.13”; 3 females and 2 males as “ USA, California, 30 km E of Arcata, leg. J. Nicholls, 2012.07.0 1 ex leaves of Chrysolepis chrysophylla ( CA1313 , spCAl13_5)”; 1 female as “ USA, California, 30 km E of Arcata, leg. J. Nicholls, 2009.07.26 ex leaves of Chrysolepis chrysophylla ( CA1243 , spCAl14_2)”; 1 female as “ USA, California, 30 km E of Arcata, leg. J. Nicholls, 2012.07.23, adult emerge 2012.08.0 4, ex stems of Chrysolepis chrysophylla ( CA1310 , spCAs5_9)”; 1 female as “ USA, California, 30 km E of Arcata, leg. J. Nicholls, 2012.08.0 7 ex stems of Chrysolepis chrysophylla ( CA1312 , spCAs5_15)” . Holotype female, 2 female and 1 male paratypes are deposited in the USNM, 8 female and 3 male paratypes in the PHMB .

Etymology. Named in honour of Mrs. Julia DeMartini, wife of Prof. J. DeMartini, who provided extensive assistance looking for galls on Chrysolepis and other oak taxa.

Diagnosis. Most closely resembles sexual D. rileypokei . In D. rileypokei the malar space, in both females and males, has striae radiating from clypeus and reaching eye margin ( Figs 46, 50 View FIGURES 46–56 ), females are reddish brown, the occiput with numerous delicate striae ( Figs 48, 52 View FIGURES 46–56 ); the mesoscutellum delicately coriaceous ( Figs 60, 64 View FIGURES 57–64 ), lateral propodeal carinae subparallel ( Fig. 61 View FIGURES 57–64 ) while in D. juliae , new species, striae on the malar space are indistinct, short and not reaching the eye ( Figs 18, 22 View FIGURES 18–27 ), females are blackish, the occiput without striae ( Figs 20, 24 View FIGURES 18–27 ); the mesoscutellum uniformly rugose ( Fig. 30 View FIGURES 28–35 ), lateral propodeal carinae bent outwards at mid height ( Fig. 31 View FIGURES 28–35 ). The two species induce very different galls ( Figs 36–45 View FIGURES 36–45 , 80–85 View FIGURES 80–85 ). Also resembles D. demartinii , see the key and the Diagnosis to D. demartinii .

Description. Sexual female. Head dark brown to black; mandibles, labial and maxillar palps light brown; antenna brown; mesosoma and metasoma dark brown to black; legs uniformly yellow.

Head alutaceous, with sparse white setae, denser on lower face and occiput, 2.1x broader than long in dorsal view; 1.3x broader than high in anterior view and not broader than mesosoma. Gena alutaceous, not broadened behind eye, 2.4x narrower than cross diameter of eye, invisible in anterior view. Malar space alutaceous, with delicate, hardly traceable striae radiating from clypeus and not reaching eye; height of eye 3.0x longer than length of malar space. Compound eyes converging ventrally. POL 1.8x longer than OOL; OOL 1.6x longer than diameter of lateral ocellus, slightly longer than LOL; ocelli ovate, all equal in size. Transfacial distance 1.2x longer than height of eye and 1.55x longer than height of lower face (distance between antennal rim and ventral margin of clypeus); diameter of antennal torulus 1.2x longer than distance between them, distance between torulus and eye margin 1.4x longer than diameter of torulus. Lower face alutaceous, without striae, with elevated median area. Clypeus rectangular, flat, broader than high, alutaceous, with deep anterior tentorial pits, distinct epistomal sulcus and clypeo-pleurostomal line; ventrally rounded, not incised medially. Frons, interocellar area, vertex, occiput uniformly alutaceous. Postgena smooth, glabrous, postocciput around occipital foramen impressed, smooth, glabrous, with parallel striae; posterior tentorial pits large, deep, elongate; postgenal bridge narrow, 2.3x higher than broad; occipital foramen higher than height of postgenal bridge. Antenna with 12 flagellomeres, longer than head+mesosoma; pedicel 1.8x longer than broad, F1 2.0x shorter than length of scape+pedicel, equal in length to F2, F2 slightly longer than F3, F3 slightly longer than F4, F5 longer than F6, subsequent flagellomeres equal in length, F11 shorter than F12; placodeal sensilla on F3–F12, in numerous rows.

Mesosoma longer than high in lateral view. Pronotum smooth, glabrous; with few white setae and with irregular delicate wrinkles laterally, emarginate along lateral edge. Mesoscutum smooth, glabrous; nearly as long as broad (width measured across base of tegulae); notauli complete, deeply impressed for full length; median mesoscutal line in the form of a short triangle; anterior parallel and parapsidal lines not impressed, but traceable; parascutal carina broad, deep, anteriorly reaching notauli. Transscutal articulation deep, distinct. Mesoscutellum only slightly longer than broad, nearly rectangular, anteriorly slightly narrower than posteriorly; shorter than mesoscutum, uniformly rugose, overhanging metanotum; scutellar foveae transverse ovate, with smooth, glabrous bottom, divided by central elevated carina. Mesopleuron, including speculum, smooth, glabrous, with few white setae in ventroposterior third, without wrinkles at mid height; mesopleural triangle coriaceous, with few white setae and some delicate irregular short wrinkles. Metapleural sulcus reaching mesopleuron at half its height; preaxilla delicately coriaceous, glabrous; dorsal and lateral axillar areas glabrous, smooth, with few setae; axillar carina broad, with longitudinal striae; subaxillular bar narrow, smooth, glabrous, at most posterior end shorter than height of metanotal trough. Metascutellum uniformly coriaceous, higher than height of smooth, glabrous ventral impressed area; metanotal trough smooth, glabrous, with few white setae. Lateral propodeal carinae distinct, bent outwards at mid height, central propodeal area smooth, glabrous, without wrinkles; lateral propodeal area smooth, with dense white setae; nucha short, with delicate longitudinal sulci dorsolaterally and laterally.

Forewing as long or slightly longer than body, with distinct brown veins, margin with long dense cilia; radial cell 3.3x longer than broad, R1 and Rs nearly reaching wing margin; areolet triangular, well-delimited by distinct veins; Rs+M well-pigmented, its projection reaching basalis at mid-height. Tarsal claws simple, without basal lobe.

Metasoma longer than head+mesosoma, longer than high in lateral view, smooth, glabrous; 2nd metasomal tergite basally with ring of dense white setae only laterally, interrupted dorsally; 2nd tergite extending to 1/3 length of metasoma; prominent part of ventral spine of hypopygium nearly 2.5x longer than broad in ventral view, with white setae, extending beyond apex of spine but never forming a tuft. Body length 2.2–2.5 mm (n=8).

MALE. The colour pattern of the body the same as in female. Similar to female but compound eyes bigger and thus frons and lower face narrower than in female; also ocelli bigger. Antenna longer than body, with 13 flagellomeres, F1 uniformly broad, curved and excavated. Body length 2.1–2.4 mm (n=6).

Morphological variability. In some type specimens (collection codes CA1313, spCAl13_5) the mesosoma is slightly lighter than in all others, otherwise no other differences were found.

Gall ( Figs 36–43 View FIGURES 36–45 ) 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 View FIGURES 36–45 )—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 View FIGURES 36–45 )—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 View FIGURES 36–45 )—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 View FIGURES 36–45 )—an integral stem gall, collected in July and August, causing swelling of the terminal bud and immediately adjacent new twig growth.

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 View FIGURES 36–45 ).

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.


Chicago Academy of Sciences


Smithsonian Institution, National Museum of Natural History













GBIF Dataset (for parent article) Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF