Pholetesor pedias (Nixon)

Whitfield, James B., 2006, Revision of the Nearctic species of the genus Pholetesor Mason (Hymenoptera: Braconidae), Zootaxa 1144 (1), pp. 1-94 : 78-80

Pholetesor pedias (Nixon)

( figs. 32 , 59 , 78 )

Apanteles pedias Nixon, 1973 . Bull. Ent. Res. 63: 211.

Assigned to Pholetesor by Mason (1981).

Females. Body length 1.6–2.5 mm, forewing length 2.0– 2.3 mm.

Head. Frons 1.1–1.3x broader at midheight than long down midline, indistinctly punctate with dull metallic sheen. Inner margins of eyes slightly converging towards clypeus. Postgenae, vertex and occiput indistinctly punctate, with dull metallic sheen as on frons. Antennae chestnut brown, clearly lighter than head color throughout, approximately same length as to slightly shorter than forewing; all but distal 5–6 flagellomeres with 2 ranks of placodes; flagellomere 2 3.4–3.7x as long as broad; flagellomere 14 1.2–1.4x as long as broad. Palpi entirely pale yellow­brown. Lateral ocelli slightly greater than 1 ocellar diameter from medial ocellus, just over 2 ocellar diameters from each other. Head in dorsal view 1.8–1.9x as broad as medially long.

Mesosoma . Mesoscutum shallowly, finely punctate, with dull, vaguely metallic sheen between punctures; punctation becoming indistinct posteriorly near scutellum; width just anterior to tegulae barely less than that of head. Pronotal furrow shallow, indistinctly crenulate. Propleuron punctate, evenly hairy except smoother and hairless anteriorly near head. Scutoscutellar scrobe narrow, fine, deep, with 12–15 fine, occasionally confluent pits; weakly arched medially. Scutellar lunules asymmetrically semicircular (broadest point nearer medial end). Mesopleural depression very broad, indistinct. Metanotum anteriorly less strongly excavated than in most ornigis­ and circumscriptus­group members, exposing only narrow sliver of mesothoracic postphragma; sublateral setiferous projections touching (or nearly so) posterior edge of scutellum; transverse carina at midlength on either side bounded by a mostly smooth, polished anterior region and a posterior, transverse depression crossed by irregular small longitudinal carinulae; posteromedial raised boss with scattered hairs. Metapleuron centrally and ventrally smooth; otherwise finely punctate and hairy. Propodeum 1.6–1.7x broader than long at longest point, mostly very weakly sculptured, with fine ridges radiating from nucha, these disappearing anteriorly into a region of more or less indistinct transverse sculpturing medially.

Legs. All legs entirely light yellow­brown except infuscate tips of fore­ and midtarsi, hind coxal bases, distal.2–.3 of hind tibiae and virtually entire hind tarsi (except extreme proximal end). Spines on outer faces of hind tibiae 20–25 in number, irregularly scattered. Inner apical spur of hind tibiae 1.2–1.4 as long as inner.

Wings. Tegulae pale yellowish, translucent. Venation pale yellowish­brown, with C+Sc+R, stigma, R1, 2r and 1Rs more strongly pigmented than remainder of venation; R1 shorter than stigma (.8–.9 of stigma), at most 1.5x as long as distance from its distal end to end of 3Rs fold along wing edge. 1Rs slightly longer than 2r but meeting at rather rounded, indistinct angle; stigma 2.3–2.5x as long as broad. Hindwing with vannal lobe very weakly flattened subapically, evenly fringed with hairs of moderate length.

Metasoma. Tergite I evenly narrowing posteriorly, nearly straight but rounding somewhat at posterior end, virtually unsculptured throughout, with vague hint of longitudinal sculpturing at posterior end; broad depression anteriorly over basal.3–.4; coloration pale yellow­orange over anterior.3–.4, then becoming dark brown apically except medial yellow­orange spot at posterior tip. Tergite II subtriangular, entirely smooth, yellowish, 3x broader posteriorly than anteriorly, approximately 2x broader posteriorly than medially long. Tergum III unsculptured, longer than II and similar to succeeding terga; anteriorly yellowish, posteriorly darker brown. Laterotergites very pale yellowish; this coloration extends laterally into 4th tergum. Hypopygium 1.2–1.3x longer than hind basitarsi, sclerotized evenly to medial fold, apically angled in lateral view at about 6C degrees; tip not acuminate or truncate. Ovipositor sheaths 1.1–1.2x longer than hind basitarsi, proximally slender, decurved; distal.7 weakly decurved, evenly tapering wider to a blunt, slightly bevelled point; hairy over most of distal broader portions, more densely so apically. Ovipositor evenly and strongly decurved.

Males. Not known in introduced nearctic material (apparently unisexual).

Variation. A few specimens have been seen that are half to two­thirds "normal" size and have the metasomal tergites entirely dark. In other essential features (i.e., short R1, leg coloration, propodeal sculpturing), the specimens appear to be conspecific.

All material is from a single source of mass culturing and field release in Guelph, Ontario and shows remarkable uniformity in coloration and sculpturing.

Final instar larva. Labium with 6–7 pairs of setae (not always symmetrical); maxillae each with 3 setae; mandibles set with 16 long teeth (not counting bifid tip).

Cocoons. Pale reddish­tan, subopaque at both ends with more translucent medial band covering 0.2 of length; shape elongate­oval, capsule­like, smooth, with a thread or a few threads at each end.

Material examined. 50 females, ONTARIO: Guelph, summer and overwintering November lots, 1981, collected by J. E. Corrigan and J. M. Heraty; reared from Phyllonoycter blancardella (F.) on apple leaves. W. R. M. Mason (Ottawa) had previously determined the introduced cultures as P. pedias .

I have compared these with 7 specimens, determined by Papp, reared from leafminers on Malus sp. and Alnus glutinosa in Hungary.

Hosts. Phyllonorycter blancardella (F.) on apple, P. restrictella Braun on beech and Parornix geminatella (Packard) on apple (the latter two record supplied by J. M. Heraty, University of Guelph, personal communication, 1982). In Europe, the species apparently attacks mostly Phyllonorycter spp. on Alnus, Corylus , Malus , Pyrus and Populus ( Nixon, 1973; Papp, 1983a).

Comments. Pholetesor pedias was introduced into Canada in 1978 from New Zealand, where it had been introduced earlier (1957) from Italy for control of Phyllonorycter messianella (Zeller) on oak, amidst some confusion as to its identity ( Laing and Heraty, 1981). It has apparently become locally established and may eventually spread through much of the apple­growing regions of eastern North America. The introduced strain apparently is, or has become, thelytokous, as no males have appeared in lab cultures or field populations to date.

Papp (1983a, 1983b) has synonymized P. pedias (Nixon) under the name bicolor (Nees) 1834 , after examination of Wilkinson's (1938) neotype of bicolor and paratypes of pedias . He rejected Wilkinson's treatment of Microgaster bicolor Nees 1834 as a primary junior homonym of Microgaster bicolor Curtis 1830 , on the argument that Curtis' name is a nomen nudum. Curtis originally published the name in synonymy under Microgaster alvearius Fabricius , now placed in the genus Diolcogaster . According to the International Code of Zoological Nomenclature (1964), Article 11, Provision d, "a name first published as a synonym is not thereby made available unless prior to 1961 it has been treated as an available name with its original date and authorship, and either adopted as the name of a taxon or used as a senior homonym". By my reckoning, Wilkinson's (1938) treatment of M. bicolor Curtis 1830 as a senior homonym satisfies these criteria for availability, even though, by modern standards, the name was not properly published originally. I choose, therefore, to accept Nixon's (1973) name, pedias , as the valid name for the species introduced into Canada, and to treat Microgaster bicolor Nees 1834 as a primary junior homonym, and hence to be rejected as a valid name. This approach seems to have been followed not only by Wilkinson and Nixon but also by most field workers in North America (although there may be others who, following Papp, use bicolor for this species in Europe).

Figures

FIGURES 27–32. Forewings of: 27, Pholetesor caloptiliae Whitfield; 28, P. ornigis (Weed); 29, P. salalicus (Mason); 30, P. salicifoliellae (Mason); 31, P. circumscriptus (Nees); 32, P. pedias (Nixon).

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 72–78. Ovipositor apparati, lateral view, of: 72, Pholetesor variabilis Whitfield; 73, P. viminetorum (Wesmael); 74, P. caloptiliae Whitfield; 75, P. ornigis (Weed); 76, P. salalicus (Mason); 77, Pholetesor salicifoliellae (Mason); 78, P. pedias (Nixon).