Andricus williami Melika, Nicholls & Stone, 2021

Melika, George, Nicholls, James A., Abrahamson, Warren G., Buss, Eileen A. & Stone, Graham N., 2021, New species of Nearctic oak gall wasps (Hymenoptera: Cynipidae, Cynipini), Zootaxa 5084 (1), pp. 1-131 : 70-74

Andricus williami Melika, Nicholls & Stone , sp. nov.

Figs. 256–274

urn:lsid:zoobank.org:act:122D3049-1D0A-4527-807C-B89DBFA47209

Type material: HOLOTYPE female “ USA, Arizona, Chiricahua Mtns. summit, leg. J. Nicholls, 2008.04.07. Code AZ1976, spAZa3; ex Quercus arizonica ” . PARATYPES: 8 females and 3 males with the same labels as the holotype. The holotype is deposited at the USNM , 8 females and 3 males at the PHDNRL .

Etymology. Named after William L. Nicholls, son of J.A. Nicholls (Institute of Evolutionary Biology, University of Edinburgh, UK and Australian National Insect Collection, CSIRO, Canberra).

Diagnosis. Andricus (Callirhytis) species, known to induce acorn galls in the USA southwest are A. costatus Weld, 1944 , A. prescotti Weld, 1952 , C. balanella Weld, 1957 , C. cistella Weld, 1952 , and C. petrina Weld, 1922 . However, in A. williami the tarsal claws have a basal lobe, while in C. balanella , C. cistella , C. petrina the tarsal claws are simple, without a basal lobe. In A. williami the anterior end of notaulus with rounded deep impression, the mesoscutum uniformly reticulate, while in A. costatus and A. prescotti the anterior end of the notaulus without rounded impression, the mesoscutum entirely glabrous, without any surface sculpture.

Description. Sexual female ( Figs. 256–258, 261, 263–269 , 271 ). Head and mesosoma black, antennae dark brown, metasoma reddish brown; mandibles, maxillary and labial palpi, legs light brown.

Head coriaceous to reticulate, with dense white setae, denser on lower face and postgena; 1.3× as broad as high and slightly broader than mesosoma in frontal view, 2.0× as broad as long in dorsal view. Gena reticulate, broadened behind eye in frontal view, broader than transverse diameter of eye in lateral view. Malar space reticulate, with striae radiating from clypeus and reaching eye; eye 2.6× as high as length of malar space. Inner margins of eyes parallel. POL 1.8× as long as OOL, OOL 1.2× as long as diameter of lateral ocellus and shorter than LOL, all ocelli ovate, of same size. Transfacial distance nearly equal to height of eye; diameter of antennal torulus 2.0× as long as distance between them, distance between torulus and eye equal to diameter of torulus; lower face delicately coriaceous, with dense short white setae, without striae; slightly elevated median area coriaceous, without striae, with setae. Clypeus quadrangular as high as broad, smooth, glabrous; ventrally rounded, emarginate, without median incision, with a few long setae; anterior tentorial pit large, rounded; epistomal sulcus and clypeo-pleurostomal line indistinct. Frons and slightly elevated interocellar area reticulate, with short white setae. Vertex reticulate; occiput with delicately transverse parallel striae, with dense white setae; postocciput smooth, glabrous; postgena smooth, glabrous, with dense setae; posterior tentorial pit large, ovate, area below impressed; occipital foramen 3.0× as high as height of postgenal bridge; hypostomal carina emarginate, continuing into postgenal sulci which are not united, running parallel and slightly diverging in anterior 1/3, postgenal bridge anteriorly as broad as occipital foramen. Antenna longer than head+mesosoma, with 12 flagellomeres, scape, pedicel and F1 lighter than all subsequent flagellomeres, pedicel slightly longer than broad; F1 2.0× as long as pedicel; F1=F2; F2 1.3× as long as F3, F3=F4; subsequent flagellomeres shorter, nearly equal in length; F12 slightly longer than F11; placodeal sensilla on F3–F12.

Mesosoma longer than high, with dense white setae. Pronotum glabrous, with delicate striae laterally and dense setae; propleuron coriaceous, with dense setae. Mesoscutum reticulate, with dense setae; slightly longer than broad (greatest width measured across mesoscutum at level of base of tegulae). Notaulus complete, with smooth, glabrous bottom, broadened in posterior 1/3, posteriorly converging; anterior parallel and parapsidal lines marked by smooth glabrous areas; median mesoscutal line absent; circumscutellar carina narrow, reaching notaulus. Anterior end of notaulus with rounded deep impression. Mesoscutellum slightly longer than broad, trapezoid, broadened in posterior 1/3; uniformly rugose, with long white setae, posteriorly rounded, overhanging metanotum. Mesoscutellar foveae ovate, broader than high, with smooth, glabrous bottom, separated by narrow triangular elevated coriaceous central carina. Mesopleuron and speculum smooth, glabrous, with setae in posteroventral quarter, along anterior and ventral margins; mesopleural triangle smooth, glabrous, with dense white setae; dorsal and lateral axillar areas smooth, glabrous, with white setae; subaxillular bar smooth, glabrous, triangular, posterior end higher than height of metanotal trough; metapleural sulcus reaching mesopleuron in upper 1/3 of height, upper part of sulcus indistinct. Metascutellum coriaceous, 2.0× as high as height of smooth, glabrous ventral impressed area; metanotal trough smooth, glabrous, with few setae; central propodeal area smooth, glabrous, with few rugae and dense setae along subparallel lateral propodeal carinae; lateral propodeal area smooth, glabrous, with long white dense setae. Nucha with numerous delicate sulci dorsally and laterally. Tarsal claws toothed, with basal lobe.

Forewing longer than body, hyaline, margin with long dense cilia, veins dark brown, radial cell open, 3.4× as long as broad; R1 and Rs nearly reaching wing margin; areolet triangular, well-delimited, Rs+M distinct for 1/2 of the distance to basalis, its projection reaching basalis in mid height.

Metasoma slightly longer than head+mesosoma, longer than high in lateral view; second metasomal tergite extending to half the length of metasoma in dorsal view, with a few white setae anterolaterally, without micropunctures posteriorly, subsequent tergites smooth, glabrous, without micropunctures. Hypopygium without micropunctures, prominent part of ventral spine of hypopygium 2.5× as long as broad in ventral view, with long setae ventrally which not extend beyond apex of spine. Body length 2.7–3.1 mm (n = 8).

Male ( Figs. 259–260, 262 , 270, 272 ). Similar to female but hind coxae black; transfacial distance as long as height of eye; malar space with numerous striae radiating from clypeus and reaching eye; eye 3.0× as high as length of malar space; POL 1.8× as long as OOL, OOL 1.3× as long as diameter of lateral ocellus and 1.6× as long as LOL; ocelli larger; interocellar area elevated; antenna with 13 flagellomeres, F1 slightly curved, apical 2/3 broader than basal 1/3; F13 slightly longer than F12; placodeal sensilla on all flagellomeres; mesopleuron without white setae anteriorly. Body length 2.6–2.9 mm (n = 3).

Gall. ( Figs. 273–274 ). An acorn gall, developing as a swelling external to the cotyledons around the base of the acorn inside the acorn cup (see also Weld 1960, Fig. 18 ). The larval cell intrudes into the body of the acorn; adults emerge through holes they create along the rim of the acorn cup. The gall is unilocular and consists only of the larval chamber ca 3 mm long and 1.5–2 mm in diameter, surrounded by a hard woody wall. Several galls may develop around the same acorn.

Biology. Only a sexual generation is known, which induces acorn galls on Q. arizonica . Weld (1960) also records this gall type from Q. gambelii , Q. rugosa and Q. turbinella . Galls mature in April, adults emerge soon afterwards.

Distribution. USA, Arizona, Chiricahua Mountains.

Comments. All known Callirhytis and Andricus species that induce acorn galls, whether pip galls (external to the acorn cup) or stone galls (within the acorn cup and/or also inside the cotyledons of the acorn), have their asexual generations making such galls. The only exception, other than A. williami , is the sexual generation of Andricus chrysobalani Weld, 1926 which develops on Q. chrysolepis and is known only from California.

Figures

FIGURES 256–264. Andricus williami Melika, Nicholls & Stone, sp. nov., sexual generation. 256–258, head, female: 256, frontal view, 257, dorsal view, 258, posterior view. 259–260, head, male: 259, frontal view, 260, dorsal view. 261–262, antenna: 261, female, 262, male. 263, tarsal claw, female. 264, forewing, part, female.

FIGURES 265–269. Andricus williami Melika, Nicholls & Stone, sp. nov., sexual generation, female. 265, mesosoma and propleura, frontal view, 266, mesosoma, lateral view, 267, mesoscutum, dorsal view, 268, mesoscutellum, dorsal view, 269, metascutellum and propodeum, posterodorsal view.

FIGURES 270–274. Andricus williami Melika, Nicholls & Stone, sp. nov., sexual generation. 270, mesosoma, male, lateral view. 271–272, metasoma, lateral view: 271, female, 272, male. 273–274, galls: 273, general view, infested acorns, 274, dissected acorns with larval chambers inside.

FIGURES 18–23. Andricus archboldi Melika & Abrahamson, sp. nov., asexual generation, female. 18–21, head: 18, frontal view, 19, dorsal view, 20, posterior view, 21, lateral view. 22, antenna. 23, forewing, part.