Atrusca cava ( Weld, 1926 )

Atrusca cava ( Weld, 1926)

Figs 169–172 View FIGURES 169–172

Diplolepis cava Weld, 1926: 22 , female, gall.

Cynips (Atrusca) ( dugesi ) cava (Weld) : Kinsey 1930: 293, female, gall.

Cynips View in CoL ( dugesi ) cava (Weld) : Kinsey 1936: 103, female, gall.

Atrusca cava (Weld) : Weld 1951: 637.

Types examined. HOLOTYPE female Diplolepis cava “Austin, Tex., Dec. 4, 1917”, “ Quercus breviloba View in CoL ”, “Diploleps cava Weld ” red label ”Type No. 27189 U.S. N.M.”, deposited in USNM, examined by GM.

Diagnosis. Atrusca cava belongs to the couplet characterized by reddish-brown body coloration, the fore wings mostly of normal size (1.21–1.40× as long as body length), with complete venation, the Rs vein of the radial cell strongly curved distally; the mesoscutum with prominent dark stripes, visible piliferous points, and without median mesoscutal line, the mesoscutellum that is coriaceous, sometimes with some lateral rugae, as in A. aspera . Atrusca cava can be distinguished from A. aspera by the transversely quadrangular head in frontal view, exhibiting dense setae; the pronotum with parallel rugae posteroventrally in lateral view, the rugae extend to half-width of pronotum; the mesoscutum only displays sparse piliferous points; the fore wings are somewhat reduced; the radial cell is hyaline and the Rs vein is distally curved, while A. aspera the head is transversely ovate in frontal view, with sparse setae; the pronotum lacks any irregular rugae; the mesoscutum exhibits numerous dense distinct piliferous points; the fore wings are normally sized; the radial cell has a dark spot and the Rs vein is strongly curved distally, forming a straight angle with the anterior margin of the fore wing.

Re-description. Asexual female ( Figs 169–171 View FIGURES 169–172 ). Species description combined from Weld (1926: 22) and our observations of the type photos.

Entire body, including antennae and legs reddish brown; palpi yellowish; black stripes along parapsidal lines and between notauli in anterior 2/3 of mesoscutum length; mesopleuron and mesosoma ventrally blackish.

Head transversely quadrangular in frontal view, with sparse white setae, 1.3× as broad as high and as broad as mesosoma in frontal view. Gena alutaceous, not broadened behind eye in frontal view, narrower than transverse diameter of eye in lateral view. Malar space delicately coriaceous, without striae, malar sulcus absent; eye 1.8× as high as height of malar space. Inner margins of eyes diverging ventrally. Transfacial distance 1.4× as long as height of eye and 1.7× as long as height of lower face; diameter of antennal torulus 1.6× distance between them, distance between torulus and eye slightly longer than diameter of torulus; lower face alutaceous asides, rugose in central part below toruli, with few setae; slightly elevated median area rugose, shining, without setae. Interocellar area elevated above head in frontal view. Clypeus impressed, uniformly coriaceous, trapezoidal, 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. Antenna longer than head+mesosoma, with 12 flagellomeres, pedicel slightly longer than broad, F1 1.3× as long as scape+pedicel and 1.3× as long as F2.

Mesosoma 1.2× as long as high, with sparse short white setae. Pronotum laterally alutaceous in dorsal half, smooth, shining on rest surface, with sparse setae, with parallel rugae posteroventrally, extending to half width of pronotum. Mesoscutum uniformly alutaceous-reticulate, with sparse white setae and sparse piliferous points; slightly longer than broad (greatest width measured across mesoscutum at level of base of tegulae). Notaulus complete, deep, broad, with alutaceous bottom, posteriorly broader and converging; anterior parallel and parapsidal lines indistinct, hardly traceable, indicated by smooth dark stripes; median mesoscutal line absent; parascutal carina narrow, smooth, reaching notaulus. Mesoscutellum delicately coriaceous centrally, with rugae laterally and posteriorly coriaceous-rugose, ovate, slightly longer than broad, posteriorly rounded, overhanging metanotum; mesoscutellar foveae, transverse, broader than high, smooth, shining, separated by central carina. Mesopleuron and speculum uniformly delicately coriaceous. Central propodeal area smooth, shining, without rugae, limited by lateral propodeal carinae bent outwards. Tarsal claws toothed, with basal lobe.

Fore wing longer than body but somewhat reduced, hyaline, margin with long dense cilia, multiple slightly darker spots all over the wing, veins light brown, radial cell open, 2.4× as long as broad; second abscissa of Rs curved distally; R1 and Rs nearly reaching wing margin; areolet triangular, indistinct, Rs+M inconspicuous, traceable along entire length, reaching basalis at mid height.

Metasoma longer than head+mesosoma, higher than long in lateral view; second metasomal tergum dark brown, extending over 3/4 of metasoma length in dorsal view, with dense white setae anterolaterally, without band of micropunctures posteriorly; subsequent terga without micropunctures. Hypopygium without micropunctures, prominent part of ventral spine of hypopygium 4.0× as long as broad in ventral view, with few short setae extending beyond apex of spine.

Body length 2.9–3.9 mm ( Weld 1926).

Gall ( Fig. 172 View FIGURES 169–172 ). A bulboid gall, 14–20 mm in diameter, usually single on under side of leaf. Reddish-brown, not spotted, with thin walls, central cell supported by numerous silky fibers (gall pics from Weld, 1959).

Biology. The asexual generation is only known to induce leaf galls on Q. sinuata (= Q. breviloba ). Galls mature in late autumn; adults emerge next year in spring.

Distribution. USA: Texas.