Dryocosmus demartinii 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 : 410-413

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

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Dryocosmus demartinii Melika, Nicholls & Stone

sp. nov.

Dryocosmus demartinii Melika, Nicholls & Stone , new species

Figs 1 View FIGURES 1–8 –17


Type material. Holotype female: “ USA, CA, 30 km E of Arcata, leg. J. Nicholls, 2011.10.27, ex Chrysolepis chrysophylla (spCAb7_4, CA1308 )”, and 12 female paratypes: 1 female as “ USA, CA, 30 km E of Arcata, leg. J. Nicholls, 2011.09.28, adult emerge 2012.10.0 5, ex Chrysolepis chrysophylla (spCAb7_14, CA1314 )”; 1 female (without metasoma) as “ USA, CA, 30 km E of Arcata, leg. J. Nicholls, 2011.10.27, ex Chrysolepis chrysophylla (spCAb7_3, CA1308 )”; 5 females as “ USA, CA, 30 km E of Arcata, leg. J. Nicholls, 2011.10.27, ex Chrysolepis chrysophylla ”, however, with different field collection codes: spCAb7_5 ( CA1308 ), spCAb7_6 ( CA1308 ), spCAb7_7 ( CA1308 ), spCAb7_9 ( CA1308 ), spCAb7_10 ( CA1308 ); 1 female as “ USA, CA, 30 km E of Arcata, leg. J. Nicholls, 2011.09.28, adult emerge 2012.08.25, ex Chrysolepis chrysophylla (spCAb7_12, CA1314 )”; 1 female as “ USA, CA, 30 km E of Arcata, leg. J. Nicholls, 2011.09.28, adult emerge 2012.08.25, ex Chrysolepis chrysophylla (spCAb7_17, CA1314 )”; 3 females as “ USA, CA, 30 km E of Arcata , leg. J. Nicholls, 2011.09.28, adult emerge 2012.10.0 5, ex Chrysolepis chrysophylla ”, with three different field codes: spCAb7_18 ( CA1314 ), spCAb7_20 ( CA1314 ), spCAb7_21 ( CA1314 ) . Holotype female and 2 female paratypes are deposited in the USNM, 10 female paratypes in the PHMB .

Etymology. Named in honour of Prof. John DeMartini, who searched extensively to discover new gall types on Chrysolepis and other oak species.

Diagnosis. Cynipini host-plant associations are extremely conserved phylogenetically ( Stone et al. 2009), with monophyletic lineages typically galling only a single subgenus of oaks or genus of other non-oak Fagaceae ( Castanea , Castanopsis , Lithocarpus , and Notholithocarpus ; Tang et al. 2011, 2016). Hence, we provide diagnostic characters to distinguish only those Dryocosmus species which are trophically associated with Chrysolepis . In D. demartinii , new species the gena in anterior view are slightly broadened behind the eye ( Fig. 1 View FIGURES 1–8 ), which is a character state typical for asexual females; the timing of gall development and emergence of adults also indicate the described samples represent an asexual generation. Both D. castanopsidis and D. rileypokei are also known from their asexual generations. Dryocosmus demartinii , new species most closely resembles D. castanopsidis . However, D. demartinii is smaller in size, body dark brown to black, setae less dense, female F1 longer than F2 ( Fig. 5 View FIGURES 1–8 ), the radial cell 4.1x longer than broad ( Fig. 6 View FIGURES 1–8 ) while D. castanopsidis is larger in size, body reddish brown, setae denser, length of female F1 equal F2 ( Fig. 90 View FIGURES 86–91 ), the radial cell 3.6x longer than broad ( Fig. 91 View FIGURES 86–91 ). Since the galls of asexual D. demartinii are hard to tell apart from the asexual galls of D. rileypokei , diagnostic characters for separating the asexual females of these two species are as follows. In D. rileypokei the head, mesosoma and metasoma are reddish brown, the gena measured along the ventral margin of eye are as broad as the diameter of eye ( Fig. 72 View FIGURES 69–74 ), F1=F2 ( Fig. 73 View FIGURES 69–74 ), the prominent part of the ventral spine of the hypopygium is greater than 3.0x longer than broad from the ventral view ( Fig. 79 View FIGURES 75–79 ), while in D. demartinii the head, mesosoma and metasoma are dark brown to black, the gena measured along the ventral margin of eye are broader than the diameter of eye ( Fig. 4 View FIGURES 1–8 ), F1 1.2x longer than F2 ( Fig. 5 View FIGURES 1–8 ), the prominent part of the ventral spine of the hypopygium is as long as broad in ventral view ( Fig. 12 View FIGURES 9–13 ). This species also resembles D. juliae , new species. In D. demartinii F1 longer than F2 ( Fig. 5 View FIGURES 1–8 ), genae are very slightly broadened behind eyes ( Figs 1–2 View FIGURES 1–8 ), the median mesoscutal line is distinct, broad, reaching to 1/10 of the mesoscutum length ( Fig. 9 View FIGURES 9–13 ), the mesopleuron has rugae along the mesopleural triangle ( Fig. 8 View FIGURES 1–8 ), while in D. juliae F1 equal F2 ( Fig. 25 View FIGURES 18–27 ), the gena is not broadened behind the eye ( Figs 18–19 View FIGURES 18–27 ), the median mesoscutal line is in the form of a short indistinct triangle ( Fig. 29 View FIGURES 28–35 ), the mesopleuron is smooth and without rugae along the mesopleural triangle ( Fig. 28 View FIGURES 28–35 ).

Description. Asexual female ( Figs 1–13 View FIGURES 1–8 View FIGURES 9–13 ). Head uniformly black; mandibles brown, labial and maxillar palps yellow; antenna brown, flagellomeres progressively darker; mesosoma dark brown to black; coxae in basal third black, the rest brown, legs uniformly brown; metasoma dark brown, dorsally darker than lateroventrally and ventrally; each tergite in posterior third always lighter than in anterior two thirds; ventral spine of hypopygium light brown to yellow.

Head alutaceous, with sparse white setae, denser on lower face, 2.5x broader than long in dorsal view; 1.3x broader than high in anterior view and slightly broader than mesosoma. Gena alutaceous, slightly broadened behind eye in dorsal view; as broad as cross diameter of eye in lateral view. Malar space alutaceous, without striae radiating from clypeus; eye 2.5x higher than length of malar space. Inner margins of eyes parallel. POL 1.4x longer than OOL; OOL 2.1x longer than diameter of lateral ocellus, 1.5x longer than LOL; ocelli ovate, all three equal in size. Transfacial distance 1.3x longer than height of eye and 1.5x longer than height of lower face (distance between antennal rim and ventral margin of clypeus); diameter of antennal torulus 1.5x longer than distance between them, distance between torulus and eye margin 1.4x longer than diameter of torulus. Lower face delicately coriaceous, with white setae, without striae radiating from clypeus, median area not elevated. Clypeus trapezoid, flat, broader than high, alutaceous, with deep anterior tentorial pits, distinct epistomal sulcus and clypeopleurostomal line; ventrally straight, not emarginate, not incised medially, with dense long setae reaching far beyond ventral margin of clypeus. Frons alutaceous, with rare short setae; vertex, interocellar area, occiput alutaceous with rare short white setae. Postgena smooth, glabrous, postocciput around occipital foramen impressed, smooth, glabrous, with some delicate interrupted striae along occiput; posterior tentorial pits large, deep, elongate; postgenal bridge narrowed to a strip, at least 2.0x higher than broad; occipital foramen higher than height of postgenal bridge, 2.0x shorter than height of oral foramen. Antenna with 12 flagellomeres, longer than head+mesosoma; pedicel 1.5x longer than broad, F1 slightly longer than length of scape+pedicel, 1.2x longer than F2, F2 slightly longer than F3, F3 slightly longer than F4, F5=F6, subsequent flagellomeres equal in length, except F12 which 1.6x longer than F11; placodeal sensilla on F5–F12, in numerous rows.

Mesosoma longer than high in lateral view. Pronotum smooth, glabrous; with white setae and without striae laterally; emarginate along lateral edge, followed by deep longitudinal invagination. Anterior rim of pronotum narrow, emarginate; propleuron alutaceous, with few setae, strongly concave in mediocentral part. Mesoscutum smooth, glabrous between notauli, alutaceous lateral to notauli; longer than broad (width measured across base of tegulae); notauli complete, deeply impressed for full length; median mesoscutal line distinct, broad, reaching to 1/ 10 of mesoscutum length; anterior parallel lines invisible; parapsidal lines broad, reaching about half the length of mesoscutum; parascutal carina broad, anteriorly reaching notaulus. Transscutal articulation deep, distinct, straight. Mesoscutellum only slightly longer than broad, rectangular, with parallel sides; shorter than mesoscutum, uniformly rugose, overhanging metanotum; scutellar foveae transversely ovate, with glabrous, smooth bottom, divided by narrow central elevated area. Mesopleuron smooth, glabrous, with few white setae along ventral margin, with some delicate interrupted striae along mesopleural triangle; speculum smooth, glabrous with few impressed wrinkles on the most dorsoposterior margin; mesopleural triangle alutaceous, glabrous, with some short interrupted wrinkles, with white setae. Metapleural sulcus reaching mesopleuron slightly above half height; preaxilla coriaceous, glabrous; dorsal and lateral axillar areas glabrous, alutaceous, with few setae; axillar carina broad, with longitudinal striae; subaxillular bar narrow, smooth, glabrous, in most posterior end as high as metanotal trough, posteriorly a smooth glabrous strip going up along lateral axillar area. Metascutellum rugose, 2.0x higher than height of smooth, glabrous ventral impressed area; metanotal trough smooth, glabrous, with white setae. Lateral propodeal carinae distinct, sub-parallel, central propodeal area smooth, glabrous, without rugae; lateral propodeal area alutaceous, with dense white setae; nucha very short, coriaceous, without longitudinal sulci dorsolaterally and laterally.

Forewing slightly longer than body, with distinct brown veins, margin with long dense cilia; radial cell 4.1x longer than broad, R1 and Rs nearly reaching wing margin; areolet large, triangular, well-delimited by distinct veins; Rs+M well-pigmented, nearly reaching basalis slightly below half its height. Tarsal claws simple, without basal lobe.

Metasoma slightly longer than head+mesosoma, slightly longer than high in lateral view, smooth, glabrous; 2nd metasomal tergite basally with dense white setae only laterally, ring of dense setae interrupted dorsally; 2nd tergite extending to one third of the length of metasoma; prominent part of ventral spine of hypopygium very short, as long as broad in ventral view, with long white setae, extending beyond apex of spine but never forming a tuft. Body length 2.8–3.1 mm (n = 7).

Gall (Figs 14–17). A roughly spherical axillary bud gall found on shoots of the same year, approximately 6–7 mm in diameter. Superficially similar to asexual gall of D. rileypokei , but typically smaller and rounder with smooth surface. Gall surface is smooth; purple in colour in growing galls turning yellow-brown in mature galls. The gall remains solid as it matures, with no air space between the larval cell and surrounding parenchyma tissue.

Biology. Only asexual females are known, inducing bud galls on Chrysolepis chrysophylla which develop from late summer. Galls are mature by September/October and fall to the ground to overwinter. Under laboratory conditions adults emerge the following year in summer.

Distribution. USA, California.


Chicago Academy of Sciences


Smithsonian Institution, National Museum of Natural History













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