Grahamstoneia Melika & Nicholls, 2021

Melika, George & Nicholls, James A., 2021, A new genus of Nearctic oak gall wasp, Grahamstoneia Melika & Nicholls, gen nov. (Hymenoptera: Cynipidae, Cynipini), Zootaxa 4999 (5), pp. 456-468 : 458-462

Grahamstoneia Melika & Nicholls , gen. nov.

Figs 1–12

urn:lsid:zoobank.org:act:15FE9256-ADA6-4618-835F-3096DD1A52FE

Type species. Grahamstoneia humboldti Melika & Nicholls. Designated herein.

Etymology. In recognition of the continuous contribution of Prof. Graham N. Stone (Institute of Evolutionary Biology, University of Edinburgh, UK) to related studies on oak gall wasps.

Gender. Masculine.

Diagnosis. Grahamstoneia , gen. nov. is closely related phylogenetically (see Fig 13 ) and morphologically to Heteroecus , but differs in multiple morphological characters as listed below:

Grahamstoneia , gen. nov. Heteroecus spp.

Head nearly as wide as high in frontal view Head transverse in frontal view

Head reticulate Head delicately coriaceous, never reticulate

Head and mesosoma dark brown to black Head and mesosoma lighter, chestnut brown or rusty brown

Antenna with 12 flagellomeres; suture between F12 Antenna with 12–13 flagellomeres; all distinct and F11 indistinct, F12 shorter than F11

Pronotum laterally, mesoscutum, mesopleuron uni- Pronotum laterally, mesoscutum, mesopleuron deliformly reticulate cately coriaceous, never reticulate

Pronotum along anterolateral edge with few setae Pronotum along anterolateral edge always with dense white setae

Notauli posteriorly extremely broad Notauli posteriorly of usual width

Lateral propodeal area with dense white setae hiding Lateral propodeal area with less dense white setae, the surface sculpture surface sculpture clearly visible

Second metasomal tergite with short, dense felt-like Second metasomal tergite with numerous setae anterosetae anterolaterally laterally, without dense felt-like setae

Prominent part of ventral spine of hypopygium as Prominent part of ventral spine of hypopygium always long as broad distinctly longer than broad, at least 3.0–4.0x as long as broad

In all Dryocosmus species the head is alutaceous and the mesopleuron and mesoscutum are smooth and shining, while in Grahamstoneia all these structures are reticulate. Similarly, no Andricus Hartig, 1840 or Callirhytis Foerster, 1869 species are known in which the mesoscutum, mesopleuron and pronotum are all reticulate, with at least one of the mentioned structures (usually the lateral side of the pronotum and/or the mesopleuron) with nonreticulate sculpture. Additional characters also differentiate Grahamstoneia gen. nov. from these genera.

Grahamstoneia gen. nov. also partially resembles Zapatella . However, in Zapatella the ventral edge of the mesopleuron is always smooth, glabrous, not reticulate; notauli are narrower posteriorly; the median mesoscutal line always present; second metasomal tergite with felt-like dense ring of white setae, interrupted dorsally; narrow posterior band on second metasomal tergite and all subsequent tergites with delicate micropunctures; the prominent part of the ventral spine of the hypopygium 6.0–8.5x as long as broad in ventral view.

Description. Asexual female ( Figs 1–11 ). Head and mesosoma dark brown to black. Antennae, mouthparts, tegulae, metasoma brown, legs dark brown, with black coxae.

Head reticulate, with sparse white setae, denser on lower face, as broad as high and broader than mesosoma in frontal view, 2.0x as broad as long in dorsal view. Gena alutaceous, not broadened behind eye in frontal view, 1.5x as wide as transverse diameter of eye in lateral view. Malar space reticulate, with delicate striae radiating from clypeus but not reaching eye, malar sulcus absent; height of eye equal to length of malar space. Inner margins of eyes parallel. POL 1.8x as long as OOL, OOL 1.8x as long as diameter of lateral ocellus and as long as LOL; lateral ocelli of equal size, slightly larger than central ocellus. Transfacial distance 1.2x as long as height of eye; diameter of antennal torulus 2.2x as long as distance between them, distance between torulus and eye 1.2x as long as diameter of torulus; lower face reticulate with dense white setae, with a few delicate striae radiating from clypeus and extending slightly above ventral edge of eyes; slightly elevated median area reticulate, with setae. Clypeus quadrangular, nearly as broad as high, smooth, glabrous, with a few long setae; ventrally rounded, not emarginate and without median incision; anterior tentorial pit large, rounded, epistomal sulcus and clypeo-pleurostomal line broad, well impressed. Frons and interocellar area uniformly reticulate, without striae and setae. Vertex, occiput, postocciput, postgena uniformly reticulate, with sparse white setae; posterior tentorial pit small, rounded, area below impressed; occipital foramen 2.5x as high as height of postgenal bridge; hypostomal carina emarginate, postgenal bridge very narrow, delimited by parallel postgenal sulci. Antenna slightly longer than head+mesosoma, with 12 flagellomeres (suture between F12 and F11 indistinct but traceable), pedicel slightly longer than broad; F1 1.7x as long as pedicel and equal in length to F2; F2 1.2x as long as F3; F3=F4, F5–F6 shorter and equal in length; subsequent flagellomeres shorter, nearly equal in length; F12 shorter than F11; placodeal sensilla on F3–F12.

Mesosoma slightly longer than high, with sparse short white setae. Pronotum reticulate, without striae laterally; propleuron smooth, glabrous. Mesoscutum uniformly reticulate, with a few white short setae; slightly longer than broad (greatest width measured across mesoscutum at level of base of tegulae). Notaulus incomplete, extend to 2/3 of mesoscutum length, shallow, extremely broad in posterior half, bottom reticulate; shape of notaulus unusual, in posterior 1/3 broad, with parallel sides, gradually narrowing until anterior end. Anterior parallel line extends to half the length of mesoscutum, elevated, marked with smooth line; parapsidal line distinct, elevated, smooth, glabrous, extends to half the length of mesoscutum; median mesoscutal line absent; circumscutellar carina narrow, extending above tegula. Transscutal articulation broad, well-impressed. Mesoscutellum rectangular, with parallel sides, slightly longer than broad, flat, not convex; posteriorly rounded and slightly incised in mid part; rugose along sides; reticulate in mid part, with central longitudinal line running along full length of mesoscutellum; overhanging metanotum. Mesoscutellar foveae separated medially; not delimited posteriorly, not impressed, located in the same plane as rest of mesoscutellum; bottom with the same reticulation as disk of mesoscutellum. Mesopleuron and speculum uniformly reticulate, with more delicate sculpture in the form of a line running across whole mesopleuron and a line which separates the speculum; mesopleural triangle smooth, with dense white setae hiding the surface sculpture; dorsal and lateral axillar areas reticulate; subaxillular bar smooth, glabrous, triangular, most posterior part slightly taller than height of metanotal trough; metapleural sulcus reaching mesopleuron in upper 1/3, upper part of sulcus distinct; metapleural sulcus delimiting smooth, glabrous area with very dense white setae, hiding the sculpture. Metapectus reticulate. Metascutellum reticulate, at least 4.0x as high as height of smooth, glabrous ventral impressed area; metanotal trough smooth, glabrous, with few setae; central propodeal area smooth, glabrous, with a few setae along anterior margin, with network of irregular rugae; lateral propodeal carinae straight, subparallel; lateral propodeal area reticulate, with long dense white setae. Nucha with numerous delicate sulci dorsally and laterally. Tarsal claws simple, without basal lobes.

Forewing longer than body, hyaline, margin without cilia, veins yellow, radial cell opened, R1 and Rs reaching wing margin; areolet triangular, well-delimited, Rs+M indistinct, its projection reaching basalis in lower half.

Metasoma longer than head+mesosoma, slightly longer than high in lateral view; second metasomal tergum occupying 2/3 of metasoma length in dorsal view, with small dense white felt like setae anterolaterally, with dorsal and dorsolateral band of inconspicuous micropunctures on posterior end; all subsequent terga smooth, glabrous, with micropunctures. Hypopygium with micropunctures, prominent part of ventral spine of hypopygium as long as broad in ventral view, with some short setae ventrally, which do not extend beyond apex of spine.

Currently one species, Grahamstoneia humboldti Melika & Nicholls , sp. nov., belongs to this newly established genus.

Figures

FIGURE 13. Majority-rule consensus tree showing the phylogenetic relationships of the new genus Grahamstoneia, based on a Bayesian analysis of a concatenation of four loci (cytochrome b, the D2 region of the 28S rRNA gene, long-wavelength opsin, and wingless). Numbers above nodes indicate posterior probability support.

FIGURES 1–6. Grahamstoneia humboldti Melika & Nicholls, sp. nov., asexual generation, female: 1–4, head: 1, frontal view, 2, posterior view, 3, dorsal view, 4, lateral view. 5, antenna. 6, forewing, part.

FIGURES 7–11. Grahamstoneia humboldti Melika & Nicholls, sp. nov., asexual generation, female: 7, mesosoma, lateral view, 8–9, mesosoma, dorsal view, 10, metascutellum and propodeum, posterodorsal view, 11, metasoma, lateral view.

FIGURE 12. Grahamstoneia humboldti Melika & Nicholls, sp. nov., asexual generation, galls.