Sphaeroteras carolina ( Ashmead, 1887 )

Nicholls, James A., Melika, George, Digweed, Scott C. & Stone, Graham N., 2022, Pairing of sexual and asexual generations of Nearctic oak gallwasps, with new synonyms and new species names (Hymenoptera: Cynipidae, Cynipini), Zootaxa 5145 (1), pp. 1-79 : 67-68

Sphaeroteras carolina ( Ashmead, 1887) , comb. rev., sexual generation

Figs 226–235, 237

Synonyms: Dryophanta carolina Ashmead (1887: 145) , asexual females, galls. Sphaeroteras carolina ( Burks 1979) . Atrusca carolina ( Melika & Abrahamson 2002) .

Material examined: 2 females as “ USA, Florida, Manatee Co., Lake Manatee SRA, leg. J. Nicholls, 2008.04.16. FL1097 , spFLb4; ex Quercus chapmanii ”. One female has been deposited at the USNM , one female at the PHDNRL .

Diagnosis. No other sexual generation Sphaeroteras species are known from Florida on Q. chapmanii , especially in spring. The sexual gall resembles those of A. kingi and A. dumosae . However, those two species are known only from California, and gall other species of oaks which are distributed only on the Pacific slope.

Description. Sexual female ( Figs 226–235 ). Head, mesosoma light brown, metasoma darker; antenna dark brown; mouthparts yellow, legs yellow, except dark brown tibiae and tarsi.

Head smooth, shiny, polished, without surface sculpture, with sparse white setae on frons and lower face; strongly transverse, 1.4× as broad as high and broader than mesosoma in frontal view, 2.4× as broad as long in dorsal view. Gena smooth, not broadened behind eye in frontal view, narrower than transverse diameter of eye in lateral view. Malar space smooth, without striae, eye 3.5× as high as height of malar space. Inner margins of eyes parallel. POL 1.7× as long as OOL; OOL 1.5× as long as diameter of lateral ocellus and 1.4× as long as LOL; all ocelli slightly ovate, of same size. Transfacial distance slightly longer than height of eye; diameter of antennal torulus 1.4× as long as distance between them, distance between torulus and eye 1.1× as long as diameter of torulus. Lower face smooth, polished, with white setae, without striae; median area smooth, not elevated. Clypeus nearly quadrangular, smooth, polished, with a few setae, ventrally not emarginate, without median incision; anterior tentorial pit small, rounded, inconspicuous; epistomal sulcus and clypeo-pleurostomal line narrow, slightly impressed. Frons smooth, with a few white setae; area under central ocellus smooth, glabrous; interocellar area smooth, with some setae. Vertex smooth; occiput smooth, without parallel striae; postocciput smooth, glabrous; postgena smooth, without setae; posterior tentorial pit large, ovate, area below impressed; occipital foramen about as high as height of postgenal bridge; hypostomal carina emarginate, continuing into postgenal sulci which diverge strongly toward occipital foramen, postgenal bridge anteriorly broader than high. Antenna longer than head+mesosoma, with 12 flagellomeres, pedicel slightly longer than broad, F1 2.8× as long as pedicel and 1.1x as long as F2, F2 slightly longer than F3, subsequent flagellomeres gradually shorter until F11, F12 slightly longer than F11; placodeal sensilla on F4–F11.

Mesosoma slightly longer than high, with sparse short white setae.Pronotum smooth,with white setae; propleuron smooth, glabrous. Mesoscutum smooth, with sparse white setae; slightly longer than broad (greatest width measured across mesoscutum level with base of tegulae). Notaulus complete, reaches pronotum, deep, broad, with smooth, glabrous bottom, posteriorly broader and strongly converging; anterior parallel line invisible; median mesoscutal line and parapsidal line absent; circumscutellar carina broad, smooth along tegula. Mesoscutellum broader than long, posteriorly rounded, uniformly rugose, overhanging metanotum, with strong, uniformly distributed white setae. Mesoscutellar foveae separated by narrow elevated smooth central carina, transverse, 1.8× as broad as high, with smooth, glabrous bottom. Mesopleuron and speculum smooth, with white setae; mesopleural triangle delicately coriaceous, without striae, with dense white setae; dorsal and lateral axillar areas smooth, with white setae; subaxillular bar smooth, glabrous, at posterior end as high as height of metanotal trough; metapleural sulcus reaching mesopleuron at half of its height, delimiting broad area along mesopleuron. Metascutellum coriaceous, as high as height of smooth, glabrous ventral impressed area; metanotal trough smooth, glabrous, with dense setae; central propodeal area smooth, glabrous, without striae; lateral propodeal carinae bent outwards at mid-height of propodeum; lateral propodeal area smooth, glabrous, with dense white setae. Nucha short, with delicate sulci dorsally and laterally. Tarsal claws simple, without basal lobe.

Forewing longer than body, hyaline, margin with short cilia, veins dark brown, with dark stripes along all veins, radial cell open, 1.8× as long as broad; R1 and Rs nearly reaching wing margin; areolet small, triangular, distinct, Rs+M projection reaching basalis slightly below its mid height.

Metasoma as long as head+mesosoma, nearly as long as high in lateral view; 2nd metasomal tergum extending to more than half the length of metasoma in dorsal view, with white setae scattered all over the tergum; all terga smooth, glabrous, without micropunctures. Hypopygium without micropunctures, prominent part of ventral spine of hypopygium short, slightly longer than broad in ventral view, with long setae ventrally which extend beyond apex of spine. Body length 3.8–3.9 mm (n = 2).

Males unknown.

Gall. Sexual galls ( Fig. 237 ) on small twigs. Initially red/yellow, becoming darker as they mature, with pale pubescence, pear-shaped, tip bent to one side, 6–7 mm long, 3 mm diameter at widest point.

Biology. Asexual detachable rounded galls ( Fig. 236 ) on leaves on Q. alba , Q. chapmanii and Q. stellata ( Burks 1979) . Sexual galls mature in April; adults emerge soon afterwards; to date found only on Q. chapmanii .

Distribution. USA: North Carolina, Florida, Missouri, Arkansas, Texas ( Burks 1979).

Molecular taxonomy. Alternating generations were matched using DNA data, with four individuals (three asexual females, one sexual female) sequenced for both cytb and ITS2. Cytb sequences were on average 1.12% divergent (range 0–2.08%; GenBank accessions OM321661 – OM321664 ); ITS2 sequences identical ( OM331851 – OM331854 ).

Comments. The genus Sphaeroteras was described by Ashmead (1897). Later, Mayr (1902), Beutenmueller (1909), Dalla Torre & Kieffer (1910) treated Sphaeroteras as a synonym of Biorhiza Westwood, 1840 . Weld (1951) re-established the validity of this genus and transferred in S. carolina from Diplolepis Geoffroy, 1762 . Melika & Abrahamson (2002) again synonymized Sphaeroteras with Biorhiza . This species was erroneously transferred to Atrusca Kinsey, 1930 , by Melika & Abrahamson (2002). Pujade-Villar et al. (2018) re-established Sphaeroteras ; however, they did not mention S. carolina in the list of taxa returned to that genus. Phylogenetic reconstruction puts this species in the same clade as some species of Antron (Nicholls unpubl. data), but this clade does not contain all current Sphaeroteras species nor all current Antron species, so delimitation of both genera requires further work.

Figures

FIGURES 226–233. Sphaeroteras carolina (Ashmead), sexual generation, female. 226–229, head: 226, frontal view, 227, dorsal view, 228, posterior view, 229, lateral view. 230, antenna. 231, forewing (not scaled to bar). 232–233, mesosoma: 232, dorsal view, 233, lateral view.

FIGURES 234–237. Sphaeroteras carolina (Ashmead). 234–235, sexual generation, female: 234, metascutellum and propodeum, posterodorsal view, 235, metasoma, lateral view. 236, asexual gall. 237, sexual gall.