The Western Palaearctic species of Psilophrys Mayr (Hymenoptera, Chalcidoidea: Encyrtidae), parasitoids of kermesids (Hemiptera, Coccoidea: Kermesidae) attacking oaks (Quercus spp.)

The genus Psilophrys Mayr is defined by means of a brief diagnosis, and an identification key to the females of all five known western Palaearctic species is provided. Two species (P. aristotelei and P. bella) are described as new. The known hosts and distribution of all species are summarized.


Introduction
Species of Kermes (Hemiptera: Kermesidae) are specialist sap-feeders on oaks and can be economically important where they occur, especially on white oak (Quercus alba) and bur oak (Q. macrocarpa) in north America (Brant and Mason 2004). The scale insect induces leaf yellowing, leaf distortion, flagging terminals and twig dieback, thus resulting in reduced growth and vigour of the tree (Krischik and Davidson 2004). Amongst the most important natural enemies of Kermes are encyrtids of the genus Psilophrys. Species of this genus are specialist endoparasitoids of Kermes and undoubtedly exert some level of control on populations of these scales.
During a survey of the parasitoids of scale insects conducted in the Caucasus and Turkey between 1984 and 2004, a new species of Psilophrys was reared from a Kermes in Turkey. This species is here described as a new species together with a second new species reared from Kermes in Greece, present in the collections of the Natural History Museum, London. This brings the total number of species of the genus known for the Western Palaearctic, to five and therefore, to facilitate their identification, a key to these five species is presented below together with their diagnostic features.

Acronyms for depositories
The following acronyms are used: AFSDU, Agricultural Faculty, Suleyman Demirel University, Isparta, Turkey; BMNH, Natural History Museum, London, UK; DEZP, Department of Entomology and Agricultural Zoology, University of Naples of Frederico II, Naples, Italy; OUM, Oxford University Museum, Oxford, UK; IZGAS, Institute of Zoology, Georgian Academy of Sciences, Tbilisi, Georgia.

Diagnosis
Body dark brown with metallic reflections. Head 1.7-2.06 as wide as frontovertex; ocelli forming obtuse angle; maxillary and labial palpi four-and three-segmented respectively; mandible with one tooth and a truncation; antenna inserted near mouth margin; scape cylindrical; funicle six-segmented, segments gradually increasing in width distally and all segments longer than wide; pedicel at most 1.76 as long as F1. Fore wing usually infuscate around marginal and stigmal veins, rarely entirely hyaline; postmarginal vein not longer than stigmal vein; marginal vein longer than wide. Ovipositor hardly exserted; third valvula freely articulated with second valvifer.

Comments
The genus Psilophrys is most similar to Aphycoides, species of both taxa being of generally similar habitus, having similar venation and the cercal plates situated near the apex of the gaster. It is likely that with further study the two genera will be considered synonymous, but for the present Psilophrys can be separated from Aphycoides by the mandibles having only one tooth and a truncation, and the flagellum generally relatively longer and more slender, with the pedicel at most only 1.76 as long as F1, and all funicle segments longer than wide. In Aphycoides the mandible has two teeth and a truncation and the pedicel is at least 26 as long as F1, and the funicle has at least F6 transverse. Psilophrys parvulus Guerrieri and Viggiani Psilophrys parvulus Guerrieri and Viggiani 1991, p 139-150 wide and with marginal fringe at apex; stigmal vein proximally slightly bent, not straight. Ovipositor slightly exserted, exserted part at most as long as mid tibial spur.
Male. Similar to female except for genitalia, partially two-segmented clava and setae on funicle relatively longer, about as long as diameter of segments.
Female paratype (slide-mounted). Toruli separated by own lengths and from anterior ocellus by about 2.56 distance of torulus from eye margin; eye about 1.56 as long as malar space, the latter rounded in facial view; mouth width subequal to eye length. Sculpture on mesoscutum and scutellum similar, composed of small rounded cells. Syntergum about 36 as wide as long. Variation. The length varies from 1.4 to 1.9 mm, otherwise little variation in material examined.

Comments
Psilophrys aristotelei is most similar to tenuicornis and bella, all three species having similar body shape, general colour, and wing venation. They can be separated using the characters given in Table I.

Diagnosis
Female. Length 1.26-1.68 mm. Head dark brown, almost black; thorax and gaster dark brown; fore and mid coxae dirty yellow, hind coxa yellow, only hind femora and tibia are dark brown, rest of legs are yellow. Head about 1.76 as wide as frontovertex which is almost 36 as long as its minimum width; scape about 5.46 as long as wide and about 1.46 as long as club; pedicel equal to F1 or very slightly longer; OOL.OCL; ocelli forming an obtuse angle. Fore wing about 2.16 as long as wide; fore wings with marginal fringe present; base of stigmal vein straight; ovipositor slightly exserted, exserted part twothirds as long as mid-tibial spur.
Male. Similar to female except for genitalia and antenna. F1 about 1.56 as long as pedicel, setae on funicle about 0.56 as long as diameter of segments and clava solid.
Psilophrys bella sp. n. (Figures 4-6) Diagnosis Female holotype. Length 1.67 mm. Body generally dark brown, with metallic silver reflection; scape yellow, pedicel slightly dusky yellow, flagellum and club brown; legs yellow, only hind femur dark brown; fore wing hyaline. Head about 1.16 as wide as high; and about 1.86 as wide as frontovertex; occipital margin sharp; eye about 1.26 as long as malar space; scape about 1.76 as long as club which is longer than F5-F6 combined, and about 3.46 as long as wide, other proportions of antenna as in Figure 5; palp formula 4-3; mandible with one tooth and a truncation; ocelli forming obtuse angle; OCL about 0.56 diameter of ocellus; distance between torulus and anterior ocellus about 3.36 length of torulus; first segment of maxillary palp as long as first segment of labial palp. Relative measurements: HW 40,FV 21,FVW 13,TT 5,TM 2,POL 11,AOL 6,EL 20,MS 18, Mesoscutum with well-developed cell structure; sculpture on scutellum with relatively larger mesh than that of mesoscutum; fore wing ( Figure 6) about 26 as long as wide; apex of fore wing with a well-developed marginal fringe; hind wing about 46 as long as wide; mid basitarsus segment equal to segments II-IV combined together.
Hypopygium well developed, about 2.86 as wide as long, but not reaching apex of gaster; ovipositor slightly exserted, the exserted part about 0.16 as long as gaster.
Female paratype (slide mounted). Outer plates of ovipositor (Figure 4)  Variation. The length varies from 1.5 to 1.8 mm, otherwise little variation in material examined.
Male. Length 1.25-1.38 mm. Generally similar in colour to female, but legs dusky yellow with hind femur and tibia dark brown. Antennae with F1 about 26 as long as pedicel and almost 36 as long as wide; F4-F6 each about 26 as long as wide; setae on funicle about half as wide as segments; clava solid.

Distribution
Turkey.