Atrusca quercuscentricola (Osten Sacken, 1861)

Atrusca quercuscentricola (Osten Sacken, 1861)

Figs 447–460 View FIGURES 447–452 View FIGURES 453–456 View FIGURES 457–460

Cynips quercus centricola Osten Sacken, 1861: 53 , 58, female, gall.

Cynips centricola Osten Sacken, 1865: 339 .

Loxaulis [sic!] centricola : Ashmead 1885: 296.

Holcaspis centricola Ashmead 1885: 304 .

Dryophanta centricola : Mayr 1902: 290.

Diplolepis quercus-centricola : Dalla Torre & Kieffer 1910: 369.

Disholcaspis centricola : Kinsey 1920: 398.

Cynips (Atrusca) centricola Osten Sacken : Kinsey 1930: 295, female, gall.

Cynips centricola variety centricola Osten Sacken : Kinsey 1930: 297, female, gall. Diplolepis quercus-rubrae Karsch, 1880: 293 , female, gall. Synonym in Weld 1951: 638. Cynips centricola variety rubrae (Karsch) : Kinsey 1930: 301, female, gall.

Atrusca centricola (Osten Sacken) : Weld 1951: 638.

Type examined. We did not find where the type is deposited, probably lost.

Material examined. Two non-paratype females “Hopk. US, 10774E”, “reared nov. 27-18”, “ Quercus minor ”, “ SA Rohwer coll.”, “Ironton Mo”.

Diagnosis. Atrusca quercuscentricola is characterized by a brown body, the transversely ovate head with the interocellar area strongly elevated above the head in frontal view, and prominent lateral ocelli. The fore wing presents complete venation and Rs almost straight in the radial cell. The mesopleuron is setose, displaying transverse parallel striae. The median line of mesoscutum is present, while the mesoscutellum shows distinct sculpturing. The ventral spine of the hypopygium is short, approximately 2.5–3.0× as long as broad. These character states are shared by the species A. strians . Atrusca quercuscentricola differs from A. strians by a uniformly alutaceous-reticulate pronotum, without setae; the median mesoscutal line superficial, and alutaceous-reticulate mesopleuron without setae, while A. strians displays a rugose pronotum with prominent lateral rugae, the long median mesoscutal line extends for one-fourth of the mesoscutum, and the mesopleuron is setose, displaying transverse parallel striae.

Re-description. Asexual female ( Figs 447–459 View FIGURES 447–452 View FIGURES 453–456 View FIGURES 457–460 ). Head black, except dark brown malar space; antenna dark brown; mesosoma black with some lighter areas, legs dark brown to black, metasoma dark brown; second metasomal tergum dark brown, subsequent terga lighter.

Head transversally quadrangular in frontal view, alutaceous, with sparse white setae, 1.3× as broad as high and narrower than mesosoma in frontal view, 2.0× as broad as long in dorsal view. Gena alutaceous-reticulate, not broadened behind eye in frontal view, narrower than transverse diameter of eye in lateral view. Malar space alutaceous-reticulate, without striae; malar sulcus absent; eye 2.3× as high as height of malar space. Inner margins of eyes slightly diverging ventrally. POL 2.0× as long as OOL; OOL 1.3× as long as diameter of lateral ocellus and 1.2× as long as LOL; all ocelli ovate, of same size. Transfacial distance 1.3× as long as height of eye and 1.6× as long as height of lower face; diameter of antennal torulus equal to distance between them, distance between torulus and eye 1.25× as long as diameter of torulus; lower face alutaceous-reticulate along eye, coriaceous centrally, below toruli, with few setae; slightly elevated median area coriaceous, with few setae. Interocellar area elevated above head in frontal view, lateral ocelli prominent. Clypeus impressed, uniformly rugose, rectangular, slightly broader than high, with few long setae; ventrally rounded, emarginate, without median incision; anterior tentorial pit large, rounded, epistomal sulcus and clypeo-pleurostomal line broad, well impressed. Frons and interocellar area alutaceous-reticulate, without striae, with few short setae. Vertex, occiput, postgena uniformly alutaceous-reticulate, with sparse white setae; postocciput smooth, shining; posterior tentorial pit large, ovate, area below impressed; occipital foramen slightly higher than height of postgenal bridge; hypostomal carina emarginate, continuing into postgenal sulci which bent outwards towards occipital foramen, postgenal bridge dorsally as broad as width of occipital foramen. Antenna longer than head+mesosoma, with 12 flagellomeres, pedicel 1.6× as long as broad, F1 1.2× as long as scape+pedicel and 1.1× as long as F2; F2 1.3× as long as F3; F3=F4, F5=F6, subsequent flagellomeres progressively shorter, F12 1.6× as long as F11; placodeal sensilla on F5–F12.

Mesosoma 1.1× as long as high, with sparse short white setae. Pronotum uniformly alutaceous-reticulate, without setae; propleuron coriaceous, shining. Mesoscutum alutaceous-reticulate, with uniformly dense piliferous points, with sparse white setae; slightly longer than broad (greatest width measured across mesoscutum at level of base of tegulae). Notaulus complete, deep, broad, with smooth, glabrous bottom, posteriorly broader and slightly converging; anterior parallel lines indistinct, not impressed; parapsidal lines indistinct, hardly traceable, indicated by smooth stripes; median mesoscutal line superficial; parascutal carina narrow, smooth, reaching notaulus. Mesoscutellum uniformly dull rugose, ovate, slightly longer than broad, posteriorly rounded; overhanging metanotum; mesoscutellar foveae transverse, only slightly broader than high, with smooth, shining bottom, separated by broad elevated rugose area. Circumscutellar carina complete but obscured by sculpture. Mesopleuron and speculum uniformly alutaceous-reticulate, without setae without piliferous points; mesopleural triangle smooth, glabrous, with some irregular rugae and some setae; dorsal and lateral axillar areas delicately rugose, shining, with setae; subaxillular bar smooth, shining, most posterior part higher than height of metanotal trough; metapleural sulcus reaching mesopleuron at mid height, upper part of sulcus distinct. Metascutellum alutaceous-reticulate, 4.0× as high as height of smooth, glabrous ventral impressed area; metanotal trough smooth, shining, with few setae; central propodeal area smooth, shining, with some delicate subparallel longitudinal rugae posteriorly and irregular short rugae anteriorly; lateral propodeal carinae bent outwards in posterior half; lateral propodeal area alutaceous-reticulate, with long dense setae. Nucha with delicate parallel longitudinal sulci laterally, dorsocentrally smooth, shining. Tarsal claws toothed, with basal lobe.

Fore wing longer than body, of normal size, with darker spots and stripes, veins dark brown, wing infuscated, radial cell open, 2.5× as long as broad; second abscissa of Rs slightly curved without a different angle distally; R1 and Rs nearly reaching wing margin; areolet absent, invisible, Rs+M inconspicuous, traceable along entire length, reaching basalis slightly below half of its height.

Metasoma as long as head+mesosoma, higher than long in lateral view; second metasomal tergum extending to 1/2 of metasoma length in dorsal view, with white setae anterolaterally, without band of micropunctures posteriorly; subsequent terga without micropunctures, without setae. Hypopygium without micropunctures, prominent part of ventral spine of hypopygium 2.5× as long as broad in ventral view, with setae ventrally extending beyond apex of spine.

Body length 3.0– 4.5 mm ( Kinsey 1936).

Gall ( Fig. 460 View FIGURES 457–460 ). Large, up to 26.0 mm, in average 20 mm in diameter, strictly spherical, thin shelled monolocular spotted leaf gall, with sparse, radiating fibres, slightly flattened at the attachment point, ivory to apricot or more pinkish; some galls covered with purplish spots, shining and smooth; young galls with microscopic, stellate pubescence. Internally hollow, except for the thick-walled larval cell which is up to 4.0 mm in length. The gall is attached by a minute point to a vein, usually on the under side of a leaf. The gall is from https://www.gallformers. org/gall/583 by Lora Shadwick.

Biology. The asexual generation is only known to induce globular leaf galls on Q. stellata . Mature galls in early autumn; adults start to emerge from October–November.

Distribution. USA: from New Jersey to North Carolina, also MO, AR, TX.