Antron quercusnubila (Bassett, 1881)

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 : 24-28

Antron quercusnubila (Bassett, 1881) , sexual generation

Figs 61–78 , 80–81

Synonyms: Cynips quercusnubila Bassett (1881b: 56) , females and galls. Dryophanta nubila combination and corrected spelling by Mayr (1881); Dryophanta nubila combination by Ashmead (1885: 296); Diplolepis quercus-nubila combination by Dalla Torre and Kieffer (1910); Cynips nubila combination by Cresson (1923); Diplolepis nubila combination by Weld (1926); Cynips (Acraspis) nubila var. nubila combination by Kinsey (1930); Antron nubila combination by Weld (1951); Antron quercusnubila corrected spelling by Burks (1979). Kinsey (1930, 1936, 1938) included 10 additional species in his “ nubila ” complex, found on a range of Mexican oaks: Cynips (Acraspis) chica Kinsey 1936 ; Cynips (Acraspis) incompta ( Kinsey, 1920) ; Cynips (Acraspis) nigricula Kinsey, 1936 ; Cynips (Acraspis) radialis Kinsey, 1936 ; Cynips (Acraspis) rufula Kinsey, 1936 ; Cynips (Acraspis) russa Kinsey, 1930 ; Cynips (Acraspis) subtincta Kinsey, 1936 ; Cynips (Acraspis) tincta Kinsey, 1936 , Cynips ( nubila ) lanaris Kinsey, 1938 and Cynips ( nubila ) molucrum Kinsey, 1938.

Cynips (Acraspis) russa Kinsey, 1930 , syn. nov.. Kinsey (1930) originally used the species name Cynips nubila russa and mentioned that he found the female to be indistinguishable from the female of C. nubila . The galls are also identical to those of A. quercusnubila and the two taxa share the same host oaks ( Q. arizonica , Q. oblongifolia ) and geographic distribution (Arizona, Santa Catalina Mnt., from Tucson to Globe). Later, Kinsey (1936) put Cynips nubila russa into the genus Cynips subgenus Acraspis , nubila complex, named as Cynips (nubila) russa . Weld (1952a) treated it as Cynips nubila russa Kinsey. Weld (1960) in his Cynipid Galls of the Southwest listed only Antron nubila , and did not even mention A. russa . In Burks (1979) it is a valid species, Antron russum ( Kinsey, 1930) . The other nine species of Kinsey’s Cynips nubila complex, all occurring in Mexico, are considered valid species by Pujade-Villar & Ferrer-Suay (2015).

Material examined: 1 female and 2 males “ USA, Arizona, Molino Basin campground, Santa Catalina Mtns. leg. J. Nicholls, 2008.04.09. Code AZ1875 , spAZb9; ex Quercus oblongifolia ”. Specimens have been deposited at the USNM .

Diagnosis. Two species of Antron Kinsey, 1930 , A. douglasii ( Ashmead, 1896) and A. quercusechinus ( Osten Sacken, 1870) , are known from a sexual generation in California; both induce succulent green bud galls on Q. douglasii , Q. dumosa , and Q. lobata . One other species, Antron pileus Weld, 1952 , is known from Arizona from its sexual generation; this species induces bud galls on Q. turbinella ( Weld 1952b) . Galls of A. pileus are mushroomlike and without hairs while the bud galls of A. quercusnubila are oblong with long hairs. In A. pileus the female head is coriaceous, antenna with 13 flagellomeres, the disk of mesoscutellum finely rugose, and the male antenna has 14 flagellomeres while in A. quercusnubila , the sexual female head is alutaceous, antenna with 12 flagellomeres, the disk of mesoscutellum uniformly smooth, glabrous, with net of strong irregular rugae and the male antenna has 13 flagellomeres.

Description. Sexual female ( Figs 61–65 , 70–72 , 76–77 ). Head, mesosoma, metasoma, maxillary and labial palpi, legs uniformly yellow; antenna darker than head.

Head alutaceous, with sparse white setae, 1.3× as broad as high and slightly broader than mesosoma in frontal view, 2.2× as broad as long in dorsal view. Gena alutaceous, not broadened behind eye, invisible in frontal view, narrower than transverse diameter of eye in lateral view. Malar space smooth, glabrous, without striae; eye 4.1× as high as length of malar space. Inner margins of eyes parallel. POL 3.9× as long as OOL, OOL slightly shorter than diameter of lateral ocellus, 2.0× shorter than LOL, all ocelli ovate, of same size. Transfacial distance slightly shorter than height of eye, diameter of antennal torulus 2.0× as long as distance between them, distance between torulus and eye slightly shorter than diameter of torulus; lower face smooth, glabrous, with a few short white setae, without striae; slightly elevated median area smooth, glabrous, without striae, with some short setae; small area under torulus, between toruli and area between torulus and eye delicately alutaceous. Clypeus trapezoid, slightly broader than high, smooth, glabrous; ventrally rounded, not emarginate, without median incision, with a few long setae; anterior tentorial pit large, deep, rounded, epistomal sulcus and clypeo-pleurostomal line distinct. Frons and slightly elevated interocellar area alutaceous, with short white setae. Vertex alutaceous; occiput, postocciput, postgena smooth, glabrous, with a few setae; posterior tentorial pit large, elongated, area below impressed; occipital foramen as high as height of postgenal bridge; hypostomal carina emarginate, continuing into postgenal sulci which do not unite, diverging until postgenal bridge which is as broad as occipital foramen.Antenna longer than head+mesosoma, with 12 flagellomeres, scape, pedicel and F1 lighter than rest of flagellomeres, pedicel subglobular; F1 2.7× as long as pedicel and 1.3x as long as F2, F2=F3=F4, F4 slightly longer than F5; F7 to F11 equal in length; placodeal sensilla on F5–F12, absent on F1–F4.

Mesosoma distinctly longer than high, without setae. Pronotum smooth, glabrous, without striae along posterior margin, with a few setae; invaginated anterior margin of pronotum smooth, glabrous. Propleuron smooth, glabrous, without setae. Mesoscutum smooth, longer than broad (greatest width measured across mesoscutum level with base of tegulae). Notaulus complete, deep, with smooth, glabrous bottom, converging posteriorly; anterior parallel line invisible; parapsidal line and median mesoscutal line absent; circumscutellar carina narrow, reaching notaulus. Mesoscutellum slightly longer than broad, with nearly parallel sides, uniformly smooth, glabrous, with net of strong irregular rugae, overhanging metanotum. Mesoscutellar foveae in the form of a transverse anterior impression, not separated medially, with smooth, glabrous bottom. Mesopleuron smooth, glabrous, without setae; mesopleural triangle smooth, glabrous, with white setae, without striae; dorsal and lateral axillar areas smooth, glabrous, with white setae; subaxillular bar smooth, glabrous, narrow, at posterior end higher than height of metanotal trough; metapleural sulcus delimiting very narrow area, reaching mesopleuron at its mid height, upper part of sulcus distinct. Metascutellum smooth, glabrous, slightly higher than smooth, glabrous ventral impressed area; metanotal trough smooth, glabrous, without setae; central propodeal area smooth, glabrous, without setae, with a few delicate short striae in anterocentral part; lateral propodeal carinae nearly parallel, bent outwards at most posterior end; lateral propodeal area smooth, glabrous, with long setae. Nucha without sulci. Tarsal claws with distinct basal lobe.

Forewing longer than body, hyaline, with dark brown veins, margin without cilia; radial cell open, 2.0× as long as broad, R1 and Rs nearly reaching wing margin, areolet triangular, well-delimited, Rs+M distinct along entire length, reaching basalis in lower 1/3.

Metasoma slightly longer than head+mesosoma, slightly longer than high in lateral view; 2nd metasomal tergum extending to 2/3 of metasoma length in dorsal view, without setae anterolaterally, without micropunctures; subsequent terga smooth, glabrous, without micropunctures. Hypopygium without micropunctures, prominent part of ventral spine of hypopygium as broad as long in ventral view, with long setae that extend far beyond apex of spine and form a tuft. Body length 2.6–2.9 mm (n = 4).

Male ( Figs 66–69 , 73–75 , 78 ). Similar to female but head, mesosoma, metasoma dark brown to black, legs yellow. Head slightly broader than high in frontal view; malar space shorter; eyes larger, ocelli larger, ovate, POL 4.6× as long as OOL, OOL 2.0× shorter than length of ocellus and shorter than LOL; interocellar area elevated. Antenna with 13 flagellomeres, F1 straight; placodeal sensilla on all flagellomeres.

Gall ( Figs 80–81 ). The sexual generation develops in a small oblong bud gall, 5 mm long, 3 mm in diameter, pale green with white or pink pubescence, hairs several mm long. The gall develops on lenticel buds on stems or on the bark of larger branches.

Biology. Asexual galls ( Fig. 79 ) develop on leaves, sexual galls in lenticel buds; both generations on Q. arizonica , Q. rugosa and Q. oblongifolia .

Distribution. USA: Arizona ( Burks 1979).

Molecular taxonomy. Alternating generations were matched using DNA data, with four individuals (two asexual females, two sexual males) sequenced for both cytb and ITS2. Two cytb haplotypes were found across the four individuals, differing by 0.92% (GenBank accessions OM321623 – OM321626 ); two ITS2 alleles were also observed, differing by 0.19% (with a single base indel within a polyT repeat region; OM331816 – OM331819 ).

Figures

FIGURES 61–69. Antron quercusnubila (Bassett), sexual generation. 61–64, head, female: 61, frontal view, 62, dorsal view, 63, posterior view, 64, lateral view. 65, antenna, female. 66–68, head, male: 66, frontal view, 67, dorsal view, 68, posterior view. 69, antenna, male.

FIGURES 70–75. Antron quercusnubila (Bassett), sexual generation. 70–72, female: 70, mesosoma, lateral view, 71, mesoscutum and mesoscutellum, dorsal view, 72, forewing, part. 73–75, male: 73, mesosoma, lateral view, 74, mesoscutum and mesoscutellum, dorsal view, 75, metascutellum and propodeum, posterodorsal view.

FIGURES 76–78. Antron quercusnubila (Bassett), sexual generation, metasoma. 76–77, female: 76, lateral view, 77, ventral view. 78, male, lateral view.

FIGURES 79–81. Antron quercusnubila (Bassett). 79, asexual gall. 80–81, sexual gall.