Pholetesor thuiellae, Whitfield, 2006

Whitfield, James B., 2006, Revision of the Nearctic species of the genus Pholetesor Mason (Hymenoptera: Braconidae), Zootaxa 1144 (1), pp. 1-94 : 49-51

Pholetesor thuiellae , new species

( figs. 50 , 70 )

Holotype female. Body length 1.9 mm, forewing length 2.1 mm.

Head. Frons 1.3x as broad as medially long, weakly punctate; inner margins of eyes weakly converging towards clypeus. Antennae mostly deep brown, with lighter brown pedicel; regions between placode bands appearing darker; length slightly shorter than forewing but as long as or slightly longer than body; all but distal 5–6 flagellomeres with 2 ranks of placodes; flagellomere 2 3.3x longer than broad; flagellomere 14 3.0x longer than broad. Palpi pale yellow­brown. Head in dorsal view 2x broader than medially long.

Mesosoma . Mesoscutum shallowly punctate (becoming less distinctly so posteriorly); surface between punctures dull, with weak metallic sheen; width just anterior to tegulae just narrower than head in dorsal view. Scutoscutellar scrobe narrow, composed of fine distinct pits, virtually straight medially. Scutellar disc weakly, sparsely punctate, slightly longer than anteriorly broad. Metanotum sublaterally very weakly excavated; transverse carinae at about midlength on either side well­developed, setting off narrow transverse troughs crossed by several short carinulae. Propodeum twice broader than long at longest point, anteriorly somewhat transversely sculptured medially, becoming weakly punctate laterally; posteriorly with oblique irregular ridging crossing lateral corners and short ridges radiating from nucha.

Legs. Pro­ and mesothoracic legs with coxae, trochanters and femoral bases (esp. dorsally) deep brown; remainder of legs except tips of tarsi lighter yellow­brown. Metathoracic legs mostly deep brown except light yellow­brown proximal 0.4 of tibiae. Outer faces of hind tibiae with approximately 30 scattered small spines. Inner hind tibial spur very slightly longer than outer.

Wings. Tegulae dark brown, barely translucent. Most of proximal venation of forewing very weakly brown­pigmented. 2r, 1Rs, C+Sc+R, stigma and R1 darker than remaining venation. R1 longer than stigma, about 4–5x as long as distance from its tip to end of 3Rs fold along wing edge. 2r slightly longer than 1Rs, weakly curved, meeting 1Rs at distinct obtuse angle. Vannal lobe of hindwing with even fringe of moderate length.

Metasoma. Tergite I somewhat barrel­shaped, nearly parallel­sided, broadest at just past midlength, 1.4x longer than maximum breadth, coarsely rugose except anteriorly around broad medial excavation. Tergite II subquadrate, about 2.2x broader posteriorly than medially long, with strongly rounded anterolateral corners, rugose throughout. Tergum III separated from II by crenulate straight furrow, anterolaterally with some roughened sculpturing but mostly smooth and similar in appearance to succeeding terga. Remaining terga partially overlapped by preceding 3, unsculptured and unmodified. Laterotergites deep brown, more or less concolorous with hind femora. Hypopygium at least 1.2x as long as hind basitarsi, very weakly creased sublaterally over apical half, setting off slightly more translucent medial fold; sharply acuminate apically. Ovipositor sheaths weakly decurved, thick, elongate­fusiform, broadest subapically, about same length (including basal hairless portion) as hypopygium, bluntly pointed at apex. Ovipositor weakly decurved.

Males. Not definitely associated with female (but see below under Comments). Probably virtually indistinguishable from males of P. bedelliae .

Variation. Body length 1.8–2.2 mm, forewing length 2.0– 2.4 mm. The available material is relatively uniform in coloration and sculpturing, but some variability exists in the degrees of desclerotization of the hypopygium, the shape of the first metasomal tergite (from more or less parallel­sided to strongly bulging just past midlength) and the relative lengths of 2r and 1Rs (from 2r much longer to more or less equal in length).

Final instar larva. Not examined. I expect it is similar to that of the rest of the bedelliae ­group.

Cocoon. When parasitizing Argyresthia spp. , this species spins an elongate­oval, opaque white cocoon within the spindle­shaped cocoon of the host, after emerging from the host larva/prepupa. The form of the cocoon when parasitizing Bucculatrix canadensisella is probably similar (but not visible within the densely spun, ribbed, cigarshaped host cocoon.

Material examined. Holotype female: QUEBEC. Hull , 1­VI­1960, ex Argyresthia sp. on western cedar (C.D. Miller) . Paratypes: CONNECTICUT. New Haven , 2 females, 5­ VI­1921, reared from Argyresthia thuiella material (M.P. Zappe) . NEW BRUNSWICK. Frederickton , 1 female, 4­VI­1953, host Argyresthia n. sp. on arborvitae (Forest Insect Survey), 1 female, 16­VI­1952, host Argyresthia n. sp. on arborvitae (F.I.S.) . NEW YORK. Westbury, Long Island , 1 female, 22­V­1915, reared from Recurvaria thujaella (C. Heinrich) .

Holotype in CNC, paratypes in CNC, USNM.

Other material: NEW BRUNSWICK. W. Haliburton, F'ton., 1 female, 10­VIII­1939, ex Bucculatrix canadensisella (no collector given) . ONTARIO. Homepayne, 1 female, 24­ VIII­1942, ex Bucculatrix canadensisella (F.I.S.). South Bay , 1 female, 15­VIII­1941, ex A.(?) canadensisella (F.I.S.) . QUEBEC. Ste. ­ Foy, 1 female, 26­VIII­1956, ex Fenusa pusilla (F.I.S.). Locality uncertain, 1 female, found dead 27­X­1941, ex Bucculatrix canadensisella Chambers, F.I.S. Rec. 339 (F.I.S.) .

Hosts. Argyresthia thuiella (Packard) ; apparently several other Argyresthia spp. (Argyresthiidae) on western cedar and arborvitae; Coleotechnites thujaella (Kearfott) ; Bucculatrix canadensisella Chambers. I regard the record from Fenusa pusilla (Lepeletier) ( Hymenoptera : Tenthredinidae ) to be suspect until confirmed.

Comments. This species is exceedingly similar to both P. bedelliae (Viereck) and P. powelli n. sp., differing most noticeably in the shape and length of the ovipositor sheaths, the slightly longer metacarp and the less strongly medially desclerotized and sharply pointed hypopygium.

I have associated a single male from Ontario, based mainly on the host record, similarities in tergite shape and the length of the metacarp. The legs (especially the tibiae) are darker brown generally than in the females, but the most striking sexual difference, if associated correctly, is the more colorless forewing venation in the male; only C+Sc+R, stigma, R1, 2r and 1Rs have any noticeable brown pigmentation. This male would be, by itself, considerably difficult to distinguish from males of P. bedelliae , which also apparently occasionally parasitize Bucculatrix canadensisella .

Figures

FIGURES 39–59. Anterior metasomal tergites, dorsal view, of: 39, Pholetesor masneri (Mason); 40, P. bucculatricis (Muesebeck); 41, P. zelleriae Whitfield; 42, P. masoni Whitfield; 43, P. dixianus Whitfield; 44, P. pinifoliellae Whitfield; 45, Pholetesor rhygoplitoides Whitfield; 46, P. bedelliae (Viereck); 47, P. chiricahuensis Whitfield; 48, P. longicoxis Whitfield; 49, P. powelli Whitfield; 50, P. thuiellae Whitfield; 51, P. rohweri (Muesebeck); 52, P. variabilis Whitfield; 53, P. viminetorum (Wesmael); 54, P. caloptiliae Whitfield; 55, Pholetesor ornigis (Weed); 56, P. salalicus (Mason); 57, P. salicifoliellae (Mason); 58, Pholetesor circumscriptus (Nees); 59, P. pedias (Nixon).

FIGURES 60–71. 60–62, Ovipositor apparati, lateral view, of: 60, Pholetesor bucculatricis (Muesebeck); 61, P. zelleriae Whitfield; 62, P. masoni Whitfield. 63–65: Apex of female metasoma, lateral view, of: 63, P. dixianus Whitfield; 64, P. pinifoliellae Whitfield; 65, P. rhygoplitoides Whitfield. 66: Ovipositor apparatus, lateral view, of P. bedelliae (Viereck). 67, 68: Apex of female metasoma, lateral view, of: 67, P. chiricahuensis Whitfield; 68, P. longicoxis Whitfield. 69: Ovipositor apparatus, lateral view, of P. powelli Whitfield. 70, 71: Apex of female metasoma, lateral view, of: 70, P. thuiellae Whitfield; 71, P. rohweri (Muesebeck).