Pholetesor rohweri (Muesebeck)

Whitfield, James B., 2006, Revision of the Nearctic species of the genus Pholetesor Mason (Hymenoptera: Braconidae), Zootaxa 1144 (1), pp. 1-94 : 30-32

Pholetesor rohweri (Muesebeck)

( figs. 51 , 71 )

Apanteles (Pseudapanteles) nigripes Rohwer, 1914 (1913) . Proc. Ent. Soc. Wash. 15: 187. Preoccupied by Ratzeburg, 1844.

Apanteles rohweri Muesebeck, 1921 . Proc. U.S. Nat. Mus. 58: 55. New name for nigripes Rohwer.

The following redescription is based on the holotype and two other specimens from the same host, and is, due to the condition of the specimens, somewhat incomplete.

Holotype female. Body length approximately 2.0 mm, forewing length approx. 2.2mm.

Head. Frons 1.3–1.4x broader at midheight than medially long, weakly punctate; inner margins of eyes strongly converging towards clypeus. Antennae mostly dark brown but apical portions missing. Palpi light yellow­brown. Head in dorsal view 1.7–1.8x broader than medially long.

Mesosoma . Mesoscutum slightly broader than head, shallowly punctate, with strong satiny­metallic sheen. Scutellar disc with widely spaced punctures, otherwise similar in appearance to mesoscutum. Metanotum weakly retracted from scutellum, excavated mesad sublateral setiferous projections but not so strongly as in ornigis­group. Propodeum approximately twice as broad as long, rugulose throughout, with coarse sculpture radiating from nucha, overlaying hint of medial depression; posterolateral corners strongly sunken, enhancing suggestion of areola and transverse carinae (which are not well­defined).

Legs. Proximal regions of all legs deep brown, tarsi apparently lighter yellow­brown but specimen is dirty, obscuring precise color. Spines on outer faces of hind tibiae about 30 in number, irregularly scattered. Hind tibial spurs subequal in length, less than half as long as hind basitarsi.

Wings. Tegulae dark brown. R1, stigma, C+Sc+R, 2r and 1Rs pigmented medium brownish; remainder of venation paler. 2r slightly longer than 1Rs, weeting at weakly rounded junction. R1 clearly longer than stigma.

Metasoma. Tergite I barrel­shaped, of about equal width at base and apex, similar to that of P. bedelliae but more roughly rugose; faint hint of posteromedial depression anterior to smooth raised medial boss at extreme apex. Tergite II 2.2–2.3x broader posteriorly than medially long, rugose, weakly raised along medial line. Tergum III longer than II, sculptured very weakly but over much of medial area, somewhat raised medially as well. Laterotergites moderate brown. Succeeding terga unsculptured, overlapping. Hypopygium slightly longer than hind basitarsi, not strongly acuminate but apparently slightly less pigmented medially—presence/absence of submedial crease difficult to determine. Ovipositor sheaths apparently similar to those of P. bedelliae but unusually straight and slightly more slender; entire length longer than hind basitarsi but expanded, hairy distal portion shorter. Ovipositor very weakly decurved.

Males. Unknown.

Variation. I have been able to associate only 2 other specimens with the type, both from the same host and locality. Neither specimen is intact; the antennae are mostly broken and the hypopygial region is obscured, shriveled or damaged. Variation exists in the strength and distinctness of the medfial propodeal areolar depression and costulae, and in the lightness of the tibial coloration.

Final instar larva. Unknown.

Cocoons. One cocoon is preserved with one of the two associated non­type specimens, spun within a small host shelter at the edge of a leaf, and similar in shape to the cocoons of P. bedelliae and allies. The cocoon is much more delicate, flimsy and translucent than in that group. It is possible that the associated cocoon does not belong to this species, since it is cryptically placed and the only cocoon known.

Material examined. Holotype female: VIRGINIA. Falls Church , 22­VII­1913, parasite on Gracilaria strigifinitella Clem. , 11171d Hopkins U.S. (C. Heinrich). Also labelled " Pseudapanteles nigripes Rohw. type male, Apanteles rohweri Mues. type" and type no. 16475 USNM.

Other material: 2 females, same locality, collector and host as type but 20­IX­1914, both from USNM .

Hosts. Neurobathra strigifinitella (Clemens) (Gracillariidae) on chestnut. Possibly occurring on Neurobathra on oaks as well.

Comments. Interpretation of the identity and placement of this species is difficult, due to the poor available material. Four species of Pholetesor and one of Dolichogenidea were found under this name in collections, perhaps due to the reliance upon color patterns and superficial appearance. An attempt was made to determine the critical hypopygial and sternal structure in one of the associated non­type females by soaking the detached metasoma on chloralhydrate (which softens, distends and partially clears the exoskeleton) and examining it at 100x. Sternites 3–5 were not split anteromedially, in contrast to the bedelliae ­ and ornigis ­groups, but damage to the metasomal apex made it impossible to determine whether the hypopygium is creased submedially or not. Using characters which are visible, it seems reasonable to provisionally group this species with P. masoni n. sp.

Due to the reduction of chestnut trees by blight, rather specialized collection may be required to recover this parasite again from the same host and host plant. It is also possible that P.rohweri will be found to parasitize the same or related leafminer species on oaks.

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).