Bassettia pallida Ashmead, 1896

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 : 34-38

Bassettia pallida Ashmead, 1896 , sexual generation

Figs 95–111 , 113

Synonyms: Bassettia archboldi Melika & Abrahamson, 2007 , syn. nov. This species was initially described based only on males, without knowledge of the females or the galls they induce; a male was obtained in a Malaise trap in November in Florida, at the Archbold Biological Station ( Melika & Abrahamson 2007).

Material examined: Two females and one male “Skinners nursery, Crescent City., FL, gall coll. 04/03/24. Tree 20C, Bassettia gall.”. Four males “ USA, FL, Highlands Co., Lake Placid, Archbold Bio Sta, 1995.10.11. MT. leg. G. Melika ” (in the collection of the Archbold Biological Station , Highlands Co. , Florida). Two males have been deposited at the USNM , two female and three males at the PHDNRL .

Diagnosis. Both females and males most closely resemble B. ligni Kinsey, 1922 . In B. pallida the mesoscutum is longer than broad in dorsal view, the mesoscutellar foveae in the form of a narrow transverse semi-lunar impression, without a median carina, while in B. ligni the mesoscutum nearly as long as broad, mesoscutellar foveae broad, separated by a distinct median carina. For species identification the key to Bassettia can also be used ( Melika & Abrahamson 2007).

Description. Sexual female ( Figs 95–98 , 103–104 , 109–111 ). Head and mesosoma black, antenna brown, metasoma dark brown; legs light brown with dark brown coxae, trochanter and tibia.

Head alutaceous without setae; rounded, 1.2× as broad as high and broader than mesosoma in frontal view, 1.9× as broad as long in dorsal view. Gena alutaceous, slightly broadened behind eye in frontal view, narrower than transverse diameter of eye in lateral view. Malar space alutaceous, without sulcus or striae; eye 4.8× as high as height of malar space. Eyes slightly converging ventrally. POL 5.4× as long as OOL; OOL nearly 2.0× as long as diameter of lateral ocellus and 2.0× as long as LOL; all ocelli ovate, of same size. Transfacial distance 1.3× as long as height of eye; diameter of antennal torulus 2.0× as long as distance between them, distance between torulus and eye 1.2× as long as diameter of torulus. Lower face alutaceous, 2.0x as long as frons in dorsal view, without setae or striae; sculpture of lower face rougher than frons; median area alutaceous, not elevated; lower face with two impressed smooth glabrous sulci starting from lateral edges of clypeus and extending to 1/3 of lower face height. Clypeus rectangular, 1.4× as high as broad, uniformly alutaceous, ventrally emarginate, without median incision, reaches beyond ventral edge of lower face; anterior tentorial pit small, rounded, inconspicuous; smooth, glabrous epistomal sulcus and smooth, glabrous clypeo-pleurostomal line distinct, strongly impressed. Frons and interocellar area uniformly alutaceous, without setae. Vertex, occiput, postocciput, postgena uniformly alutaceous, without parallel striae, with white setae; posterior tentorial pit large, ovate, area below impressed; occipital foramen 1.6× as long as height of postgenal bridge; hypostomal carina emarginate, continuing into united postgenal sulci which strongly diverge toward occipital foramen, postgenal bridge anteriorly broader than high. Antenna longer than head+ mesosoma; with 11 flagellomeres; scape, pedicel, F1 and F2 much lighter than F3–F11; pedicel slightly longer than broad, F1 1.7× as long as pedicel and 1.4× as long as F2, F2 to F6 nearly equal in length, subsequent flagellomeres slightly shorter but equal in length; placodeal sensilla on F2–F11.

Mesosoma 1.5× as long as high. Pronotum alutaceous, with white setae along margin, laterally broader than width of mesopleuron. Propleuron alutaceous. Mesoscutum alutaceous, with sparse white setae lateral of parapsidal line; slightly longer than broad (greatest width measured across mesoscutum level with base of tegulae). Notaulus, anterior parallel line, median mesoscutal sulcus absent; parapsidal line in the form of a smooth stripe; circumscutellar carina broad, smooth along tegula. Mesoscutellum ovate, slightly longer than broad; posteriorly rounded; anterior 2/3 with delicate net of rugae; posteriorly alutaceous, without setae, not overhanging metanotum. Mesoscutellum with narrow short transverse semilunar impression anteriorly, with smooth, glabrous bottom. Mesopleuron alutaceous, with transverse invagination in ventral part; mesopleural triangle alutaceous, without striae or setae; dorsal and lateral axillar areas alutaceous, without setae; subaxillular bar smooth, glabrous, at posterior end shorter than height of metanotal trough; metapleural sulcus reaching mesopleuron below half its height, delimiting broad alutaceous area along mesopleuron; upper part of mesopleural sulcus absent, area above sulcus uniformly alutaceous. Metascutellum smooth, slightly higher than height of smooth, glabrous ventral impressed area; metanotal trough alutaceous, glabrous, without setae; propodeum uniformly alutaceous, without propodeal carinae, without rugae or setae. Nucha very short, smooth. Tarsal claws simple, without basal lobe.

Forewing longer than body, hyaline, with dense long cilia on margin, veins brown, radial cell open, 4.8× as long as broad; R1 and Rs nearly reaching wing margin; areolet small, triangular, distinct, Rs+M distinct along 2/3 of its length, 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 1/3 of metasoma length in dorsal view, with very few setae scattered anterolaterally; all terga smooth, glabrous, without micropunctures. Hypopygium without micropunctures, prominent part of ventral spine of hypopygium short, as long as broad in ventral view, without setae ventrally. Body length 2.7–2.8 mm (n = 2).

Male ( Figs 99–102 , 105–108 ). Similar to female, body uniformly brown, lighter than female, legs uniformly light brown. Head 1.8× as broad as long in dorsal view, ocelli larger than in female, POL 2.4× as long as OOL, OOL slightly shorter than diameter of ocellus and equal to LOL. Antenna slightly longer than body, light brown, with last four flagellomeres darker, with 14 flagellomeres. F1 equal to scape+pedicel, 1.5× as long as F2, F2 slightly longer than F3, F3 slightly longer than F4, F4=F5=F6, subsequent flagellomeres nearly equal in length, F14 slightly shorter than F13, placodeal sensilla on F4–F14, absent on F1–F3. Metasoma nearly 2.0× as long as head+mesosoma, 2nd metasomal tergum extending to half the length of metasoma in dorsal view; all terga smooth, glabrous, without punctures.

Gall. Asexual galls ( Fig. 112 ) are in twigs, larval cells develop as cryptic elliptical chambers 3.2 mm long by 1.2 mm in diameter under the bark of small twigs. Sexual galls remain to be confirmed but may well be found within hypertrophied buds that occur in clusters on stems, with bud scales open, although with no obvious cavity observed within the bud ( Fig. 113 ).

Biology. Bassettia pallida , previously known only from asexual females, is now also known from its sexual generation. The asexual galls develop under the bark of twigs on Q. virginiana and Q. geminata . Galls mature in late September-October; adults emerge in November. Both sexual females and males were reared from galls within the same twig with enlarged and distorted buds on it, collected at the Archbold Biological Station (Florida) from Q. geminata in October. See Weinersmith et al. (2020) for the community ecology and natural enemy assemblage associated with galls.

Distribution. USA: Florida, Georgia, Missouri ( Burks 1979).

Figures

FIGURES 95–102. Bassettia pallida Ashmead, sexual generation. 95–97, head, female: 95, frontal view, 96, dorsal view, 97, posterior view. 98, antenna, female. 99–101, head, male: 99, frontal view, 100, dorsal view, 101, posterior view. 102, antenna, male.

FIGURES 103–108. Bassettia pallida Ashmead, sexual generation. 103–104, female: 103, head, lateral view, 104, mesosoma, lateral view. 105–108, male: 105, head, lateral view, 106, pronotum and propleuron, frontal view, 107, mesoscutum, dorsal view, 108, mesoscutellum, dorsal view.

FIGURES 109–111. Bassettia pallida Ashmead, sexual generation, female. 109, metascutellum and propodeum, posterodorsal view. 110, forewing, part. 111, metasoma, lateral view.

FIGURES 112–113. Bassettia pallida Ashmead. 112, asexual gall, 113, putative sexual gall.