Atrusca aggregata ( Weld, 1926 )

Atrusca aggregata ( Weld, 1926)

Figs 15–32 View FIGURES 15–20 View FIGURES 21–24 View FIGURES 25–28 View FIGURES 29–32

Diplolepis aggregata Weld 1926: 15 , female, gall.

Atrusca aggregata : Weld 1951: 637.

Types examined. HOLOTYPE female “ Sta Catalina Mts. , Arizon ”, “13643 Hopk US ”, “ Chrisman M. Colo ”, red label “Type No 27185 U.S. N.M.”, “ Diplolepis aggregata Weld ”, deposited in USNM, examined by GM.

Material examined. Ten females “ USA, Arizona, Chiricahua Mnts. summit, ex Q. arizonica, AZ 13, gall type 38, leg. J.A. Nicholls 2007.10.26 ”; 56 females “ USA, Arizona, Chiricahua Mnts. nr Portal , ex Q. arizonica, AZ 14, gall type 38, leg. J.A.Nicholls 2007.10.25 ”; 11 females “ USA, Arizona, Molino Basin campground, Santa Catalina Mnts., ex Q. oblongifolia, AZ 15, gall type 38, leg. J.A.Nicholls 2007.10.28 ” .

Diagnosis. Atrusca aggregata belongs to the couplet characterized by a reddish brown to black body color, with conspicuous black stripes in parts of the mesoscutum and mesopleuron, with a complete and conspicuous fore wing venation, the Rs vein of radial cell being strongly curved distally, never almost straight, the cubital cell of the fore wings lacking a row of dark spots parallel to the Rs vein, the presence of distinct piliferous points in the mesoscutum, the entirely rugose mesoscutellum usually with a posterocentral invagination, the mesopleuron and speculum sculptured to some degree, with or without piliferous points, and a ventral spine of the hypopygium long and setose, 7.7–11.3× as long as wide with setae extending beyond the apex of the spine, as in A. bulla . Atrusca aggregata differs from A. bulla by the presence of the median mesoscutal line, the posterior margin of the mesoscutellum mostly rounded, with a small medina invagination, and all metasomal terga lacking micropunctures, while in A. bulla the mesoscutum lacks the median mesoscutal line, the mesoscutellum is bilobate due to the deep central invagination in the posterior margin, and the second metasomal terga exhibits a posterior band of micropunctures, and the subsequent terga display finer micropunctures.

Re-description. Asexual female ( Figs 15–32 View FIGURES 15–20 View FIGURES 21–24 View FIGURES 25–28 View FIGURES 29–32 ). Head reddish brown, central part of frons, lower face black, posteriorly black; antenna uniformly reddish brown; mandibles dark reddish brown, palpi maxilaris and labialis light brown; pronotum reddish brown, propleuron light brown, mesoscutum reddish brown with black stripes along parapsidal lines and in between notauli in anterior 1/2–2/3; mesoscutellar impression black, mesosoma laterally and propodeum dark brown to black; legs uniformly dark brown; second metasomal tergum reddish brown, black in posterior 1/3, third tergum black, subsequent terga and hypopygium reddish brown.

Head quadrangular in frontal view, alutaceous, with sparse white setae, 1.2× as broad as high and as broad as mesosoma in frontal view, 1.8× as broad as long in dorsal view. Gena alutaceous, not or very slightly broadened behind eye in frontal view, narrower than transverse diameter of eye in lateral view. Malar space alutaceous, with delicate striae radiating from clypeus and reaching eye; malar sulcus absent; eye 2.8× as high as height of malar space. Inner margins of eyes parallel. POL 1.8× as long as OOL; OOL 1.5× as long as diameter of lateral ocellus and nearly equal to LOL; all ocelli ovate, of same size. Transfacial distance 1.3× as long as height of eye and 1.5× as long as height of lower face; diameter of antennal torulus 1.5× as long as distance between them, distance between torulus and eye slightly longer than diameter of torulus; lower face alutaceous along eyes, dull rugose centrally, under toruli, with few setae; slightly elevated median area rugose, shining, without setae. Interocellar area elevated above head in frontal view, lateral ocelli prominent. Clypeus impressed, uniformly coriaceous to rugose, rectangular, 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 rugose, without striae, with short setae. Small rounded impressed area below central ocellus smooth, shining. Vertex, occiput, postgena 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 run parallel ventrally, bent outwards towards occipital foramen, postgenal bridge dorsally broader than width of occipital foramen. Antenna slightly shorter than body, with 12 flagellomeres, pedicel slightly longer than broad, F1 1.2× as long as scape+pedicel and equal F2; F2 1.2× as long as F3; F3=F4, F5=F6, F7=F8, subsequent flagellomeres till F11 shorter, nearly equal in length, F12 slightly longer than F11; placodeal sensilla on F3–F12.

Mesosoma 1.3× as long as high, with dense setae. Pronotum laterally dull rugose in dorsal half and along posterior edge, smooth to alutaceous in ventral half, with setae; propleuron along sides alutaceous, smooth, shining centrally. Mesoscutum alutaceous-reticulate in posterior 2/3, dull rugose in anterior half 1/3, with numerous piliferous points and sparse white setae; slightly longer than broad (greatest width measured across mesoscutum at level of base of tegulae). Notaulus complete, deep, broad, with smooth, shining bottom, posteriorly broader and slightly converging; anterior parallel lines delicately impressed in anterior 2/3 of mesoscutum length, with black stripes, parapsidal lines indistinct, hardly traceable, indicated by smooth dark stripes; median mesoscutal line absent; parascutal carina narrow, smooth, reaching notaulus. Mesoscutellum uniformly dull rugose, elongated, longer than broad, with subparallel sides, posteriorly rounded, with invagination posterocentrally; overhanging metanotum; mesoscutellar foveae semilunar, transverse, broader than high, with smooth, shining bottom and some irregular rugae, separated by broad elevated rugose central carina. Circumscutellar carina complete but obscured by sculpture. Mesopleuron coriaceous in anterior 1/4, smooth, shining in posterior 3/4, speculum smooth, shining, with sparse setae; mesopleural triangle delicately rugose, with dense setae; dorsal and lateral axillar areas smooth, shining, with dense 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 delicately coriaceous, as high as height of smooth, shining ventral impressed area; metanotal trough smooth, shining, with sparse setae; central propodeal area broad with rugae or striae; lateral propodeal carinae strongly bent outwards; lateral propodeal area smooth, shining, with long dense white setae. Nucha with strong irregular rugae laterally, with delicate longitudinal sulci dorsally. Tarsal claws toothed, with basal lobe.

Fore wing longer than body, uniformly infuscated, margin with long dense cilia, with few darker spots and stripes, veins dark brown, radial cell open, 2.3× as long as broad; second abscissa of Rs strongly curved distally; R1 and Rs nearly reaching wing margin; areolet triangular, Rs+M traceable along entire length, reaching basalis in lower half of its height.

Metasoma slightly longer than head+mesosoma, higher than long in lateral view; second metasomal tergum extending over half the length of metasoma in dorsal view, with dense white setae anterolaterally, with band of micropunctures posteriorly; subsequent tergites with delicate micropunctures. Hypopygium without micropunctures, prominent part of ventral spine of hypopygium 11.3× as long as broad in ventral view, with long setae ventrally extending beyond apex of spine.

Body length 4.7–5.1 mm (n = 10).

Gall ( Fig. 28 View FIGURES 25–28 ). Globular oak apples, up to 35 mm in diameter, occurring in clusters of 12, usually 2–4, on a twig of previous seasons growth. The gall with an abrupt slender pedicel

The fresh galls are creamy white with a reddish blush on one side and spotted with numerous small red spots. Later they become yellowish and are often covered with a bluish bloom. The central cell is supported by a dense mass of fine silky ‘radiating fibers and the wall is 0.7 mm thick.

Biology. The asexual generation is only known to induce stem galls on Q. arizonica , Q. oblongifolia , Q. toumeyi . Mature galls were collected by the end of October.

Distribution. USA: Arizona.