Andricus balanaspis (Weld, 1922) Nicholls & Melika & Digweed & Stone, 2022

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 : 20-24

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Andricus balanaspis (Weld, 1922)

comb. nov.

Andricus balanaspis (Weld, 1922) , comb. nov., sexual generation

Figs 44–57 View FIGURES 44–50 View FIGURES 51–55 View FIGURES 56–60

Synonyms: Callirhytis balanaspis Weld, 1922b: 22 , female, gall.

Material examined: 5 females and 5 males “ USA, Florida, Archbold BioStation, leg. J. Nicholls, 2008.04.15. Code FL1073 , spFLc1a; ex Quercus inopina ”. Specimens have been deposited at the USNM and PHDNRL .

Diagnosis. The sexual generation of A. balanaspis most closely resembles three species from Florida that also gall catkins, Callirhytis myrtifoliae ( Beutenmueller, 1917) on Q. myrtifolia , Callirhytis quercusturnerii (Ashmead, 1881) on Q. nigra and Andricus cooki Melika, Nicholls & Stone, 2021 on Q. myrtifolia and Q. laurifolia . In C. myrtifoliae the clusters of catkin galls are smooth and shiny, without pubescence, while in A. balanaspis the catkin galls are covered with sparse white setae. In A. cooki , clusters of galls are dark green to purple with dense short pubescence, contain 10-20 individual galls tightly grouped together that cause shortening of the catkin axis; in A. balanaspis the galls are pale green with longer pubescence, and are scattered along a normal-length catkin. In A. cooki the head, antennae, mouthparts, mesosoma and legs reddish brown, metasoma brown, with darker brown areas, OOL 1.7× as long as LOL, antenna with 12 flagellomeres, the mesopleuron and speculum uniformly reticulate, lateral propodeal carinae bent slightly outwards in posterior 1/3 of propodeum, the prominent part of the ventral spine of hypopygium 8.3× as long as broad in ventral view. In the sexual generation of A. balanaspis the head, mesosoma, metasoma, antenna, mouthparts and legs are uniformly light brown to reddish, OOL 1.2× as long as LOL, female antenna with 11 flagellomeres, the mesopleuron with delicate transverse subparallel striae and only the speculum is uniformly reticulate, lateral propodeal carinae bent slightly outwards at the mid-height of propodeum, the prominent part of the ventral spine of hypopygium short, slightly longer than broad in ventral view. In C. quercusturnerii the head of male entirely reddish brown; in females the mesoscutellar disk uniformly covered with strong rugae; the mesopleuron uniformly reticulate, the mesosoma and metasoma reddish brown. In the sexual generation of A. balanaspis the head of male is black; in females the center of the mesoscutellar disk is coriaceous, with strong irregular rugae laterally and posteriorly, the mesopleuron with delicate transverse subparallel striae, the mesosoma and metasoma light brown to reddish.

Description. Sexual female ( Figs 44–47 View FIGURES 44–50 , 51–55 View FIGURES 51–55 ). Head, mesosoma, metasoma, antenna, mouthparts, legs uniformly light brown to reddish.

Head alutaceous, with sparse white setae on lower face, 1.2× as broad as high and slightly broader than mesosoma in frontal view, 2.0× as broad as long in dorsal view. Gena alutaceous, not broadened behind eye in frontal view, narrower than transverse diameter of eye in lateral view. Malar space alutaceous, glabrous, with delicate striae radiating from clypeus and reaching eye, malar sulcus absent; eye 1.7× as high as length of malar space. Eyes slightly converging ventrally. POL 1.6× as long as OOL, OOL 2.3× as long as diameter of lateral ocellus and 1.2× as long as LOL, all ocelli ovate, of same size. Transfacial distance 1.7× as long as height of eye; diameter of antennal torulus as great as distance between them, distance between torulus and eye 1.3× as long as diameter of torulus; lower face alutaceous, glabrous, with white setae, without striae radiating from clypeus; slightly elevated median area alutaceous, glabrous, without setae. Clypeus rectangular, nearly 2.0x as broad as high, smooth, glabrous, with long setae; ventrally rounded, not emarginate and without median incision; anterior tentorial pit large, rounded, indistinct, epistomal sulcus distinct, clypeo-pleurostomal line inconspicuous. Frons uniformly reticulate, without striae or setae, interocellar area reticulate. Vertex and occiput reticulate, with sparse white setae; postocciput smooth, glabrous; postgena mainly reticulate, smooth and glabrous along occipital foramen, postgenal bridge and hypostomata; posterior tentorial pit large, ovate, area below impressed; occipital foramen higher than height of postgenal bridge; hypostomal carina emarginate, continuing into postgenal sulci which diverge strongly toward occipital foramen, postgenal bridge anteriorly as broad as occipital foramen. Antenna longer than head+mesosoma, with 11 flagellomeres, pedicel slightly longer than broad, flagellomeres slightly broader towards apex; F1 2.0× as long as pedicel and slightly longer than F2; F2 1.2× as long as F3; F3=F4, F5=F6=F7, subsequent flagellomeres nearly equal in length; placodeal sensilla indistinct on all flagellomeres.

Mesosoma slightly longer than high, with sparse white setae, denser on lateral propodeal area. Pronotum reticulate, with sparse dense setae, with some delicate striae anteroventrally; propleuron smooth, glabrous. Mesoscutum uniformly reticulate, with sparse white setae, slightly longer than broad (greatest width measured across mesoscutum level with base of tegulae). Notaulus complete, deep, broad, bottom smooth, posteriorly broader and slightly converging; anterior parallel line indistinct, marked with smooth line; parapsidal line distinct, marked with smooth line; median mesoscutal line absent; circumscutellar carina broad, reaching notaulus. Mesoscutellum trapezoid, slightly longer than broad, glabrous, with net of strong irregular rugae, posteriorly rounded, overhanging metanotum. Mesoscutellar foveae separated by narrow elevated coriaceous central carina, ovate, with smooth, glabrous bottom.Mesopleuron with delicate transverse subparallel striae, speculum uniformly reticulate; mesopleural triangle smooth, glabrous, with some delicate striae and sparse white setae; dorsal and lateral axillar areas delicately coriaceous, with a few white setae; subaxillular bar smooth, glabrous, with parallel sides, as high as height of metanotal trough, slightly higher at posterior end; metapleural sulcus reaching mesopleuron slightly above half of its height, delimiting coriaceous area, upper part of sulcus distinct. Metascutellum smooth, glabrous, slightly shorter than height of smooth, glabrous ventral impressed area; metanotal trough smooth, glabrous, without setae; central propodeal area smooth, glabrous, with a few irregular rugae; lateral propodeal carinae bent slightly outwards at midheight; lateral propodeal area smooth, glabrous, with dense white setae. Nucha with numerous sulci dorsally and laterally. Tarsal claws simple, without basal lobes.

Forewing longer than body, hyaline, without cilia on margin, veins light brown, hardly visible, radial cell open, 2.2× as long as broad; R1 and Rs reaching wing margin; areolet invisible. Rs+M narrow, inconspicuous, its projection reaching basalis at its mid height.

Metasoma as long as head+mesosoma, longer than high in lateral view; 2nd metasomal tergum extending to 2/3 length of metasoma in dorsal view, without setae and micropunctures; 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 a few short setae ventrally which do not extend beyond apex of spine. Body length 1.8–2.0 mm (n = 5).

Male ( Figs 48–50 View FIGURES 44–50 ). Similar to female, but head dark brown to black, with lighter lower face and malar space; mesosoma and metasoma dark brown to black; eye 2.5× as high as length of malar space; POL 1.7× as long as OOL, OOL equal LOL and 1.6× as long as diameter of lateral ocellus, ocelli ovate, larger than in female; interocellar area elevated in frontal view; antenna with 13 flagellomeres, F1 slightly curved, broadened in apical 2/3, F1 1.3× as long as F2, F13 equal F12; placodeal sensilla on F2–F13, absent on F1. Body length 1.7–1.9 mm (n = 5).

Gall ( Figs 56–57 View FIGURES 56–60 ). Sexual galls are aggregated on catkins, each rounded, to 3 mm in diameter, pale green with white pubescence. In sparse clusters, rarely singly, along axis of catkin; sometimes causing the catkin to curl but never stunting its development.

Biology. Alternate asexual and sexual generations are known, inducing galls on red oaks in ( Quercus section Lobatae ). The asexual generation galls ( Figs 58–60 View FIGURES 56–60 ) have been found on acorns of Q. marilandica and Q. myrtifolia , mature in October, adults emerge in spring of the following year. To date, sexual catkin galls have only been recognised on Q. inopina and Q. myrtifolia , mature in April, adults emerge soon afterwards.

Distribution. USA: Washington DC, Missouri, Arkansas, Texas, Virginia, Florida.

Molecular taxonomy. Alternating generations were matched using DNA data, with eight individuals (two asexual females, three sexual females, three sexual males) sequenced for cytb and two individuals (one asexual female, one sexual female) sequenced for ITS2. Cytb sequences were on average 0.28% divergent (range 0–0.69%; GenBank accessions KX683615, OM 321627 OM 321633 View Materials ) ; ITS2 sequences were identical except for a single base indel within a polyT repeat region ( OM 331821 View Materials OM 331822 View Materials ) .

The authors’ unpublished sequence data show that A. balanaspis is part of a clade of species galling red oaks whose sexual generations, where known, are on catkins and asexual generations, where known, are acorn galls. This clade includes species such as Callirhytis carmelensis Weld, 1922 , A. cooki , C. myrtifoliae , A. fitpatricki Melika & Abrahamson, 2021 and C. balanacea Weld, 1944 .

Comments. Detailed descriptions of the asexual generation females, galls and biology is given in Weld (1922b).


Smithsonian Institution, National Museum of Natural History


Otago Museum