Cheiloneurus pistaciae Manickavasagam and Mehrnejad, 2008

Manickavasagam, S., Mehrnejad, M. R. & Noyes, John S., 2008, Cheiloneurus pistaciae sp. nov. (Hymenoptera: Encyrtidae) a facultative hyperparasitoid of Kermania pistaciella Amsel (Lepidoptera: Tineidae), a pest of pistachio trees in Iran, Zootaxa 1958, pp. 61-64 : 62-64

Cheiloneurus pistaciae Manickavasagam and Mehrnejad sp. nov.

( Figs 1–3)

Diagnosis. Female entire body dark greenish, mixed purple or brassy; scape dark brown, slightly expanded, flat and slightly more than 4X as long as broad, funicle and clava uniformly brown; funicle segments subcylindrical and all longer than wide, clava round at tip; malar space about 0.5X as long as eye width; frontovertex broader than the distance between the toruli; fore wing with uniformly dark setae present in medial and apical infuscate areas (except linea calva), but bare and hyaline in basal 1/3 and hyaline vertical band located at about 2/3 the length of the wing; costal cell bare; parastigma not downcurved; marginal vein about 2X as long as stigmal vein; postmarginal vein virtually absent; ovipositor slightly exserted, exserted part about 0.25X as long as mid tibial spur.

Female (holotype) length, including ovipositor, 1.48 mm.

Head with frontovertex polished green with interscrobal area more coppery with bluish green reflections; inner eye margin with small silvery setae; radicle light brown; scape and basal 2/3 of pedicel dark brown, apical 1/3 of pedicel, funicle and clava uniformly brown; thorax dark green with base of tegula metallic green and apex brown; fore leg uniformly testaceous except tarsomere 5 and claw dark brown, middle leg testaceous except basal 1/3 and tip of tibia and T1-4 white; hind leg dark brown except trochanter and T4 light brown and base of tibia and T 1-3 white; fore wing with dark setae and hyaline band ( Fig. 3); hind wing hyaline; gaster dark metallic greenish with silvery setae near tip, hypopygium dark brown; ovipositor sheath yellowish.

Head in facial view slightly broader than long, eye reaching occipital margin which is sharp, inner eye margins weakly divergent ventrally; frontovertex with polygonally reticulate sculpture, deeper at top of interscrobal area than on sides; posterior ocellus separated from eye by less than its own diameter; antennal torulus with dorsal margin slightly below eye and separated from mouth margin by slightly more than own length; scrobes subparallel and more or less meeting dorsally; setae in interscrobal area very sparse; malar space about 0.5X as long as maximum eye width; antenna with scape flat, thin and more than 4X as long as broad; F1 shorter than pedicel, all funicular segments subcylindrical, each longer than broad and subequal in size and shape; other proportions of antenna as in Fig. 1. Relative measurements: HW 27.5; HH 25; FV 7; POL 4.5; AOL 5.0; OOL 0.5; OCL 3.0; MS 11; EL 17.0

Thorax dorsally quite flat with pronotum, mesoscutum, axillae and basal 1/3 of scutellum almost in one plane, sculpture on pronotum and mesoscutum finely polygonally reticulate but deeper than on frontovertex; mesoscutum and basal 1/3 of scutellum more densely reticulate than apical 2/3 of scutellum which distinctly slopes posteriorly and laterally, virtually smooth and very shiny with very shallow sculpture; fore wing ( Fig. 3) with costal cell narrow, about 2X as wide as submarginal vein, without dorsal setae; marginal vein about 2X as long as stigmal; postmarginal vein virtually absent ( Fig. 2); linea calva open but posteriorly interrupted by few lines of setae. Relative measurements: FWL 76; FWW 27; mid basitarsus length 151; mid tibial spur length 12.5.

Gaster slightly shorter than mesosoma; ovipositor slightly exerted, exserted part about 0.25X as long as midtibial spur.

Paratype. Relative measurements: mid tibia length 43: syntergum (from anterior margin of cercal plate to apex of gaster) 36; ovipositor length 56; third valvula length 14.

Variation. Length 1.30 – 1.48 mm. There is some variation in the intensity of the brown colour of the flagellum. In some specimens the flagellum is pale brown, whilst in others it is dark brown; there is also a corresponding variation in the intensity of the brown colour of the legs.

Male. Length, 1.05 mm. Body colour similar to female except antenna is yellowish brown and legs are uniformly pale yellow; frontovertex coppery blue with green reflections and with small silvery setae along inner eye and mouth margins, conspicuously longer above labrum; fore wing completely hyaline with pale setae; frontovertex polygonally reticulate; first funicular segment bearing long setae about 3X as long as diameter of F1, remaining flagellar segments missing; venation similar to female; tip of gaster broad and blunt.

Hosts. A facultative hyperparasitoid of pistachio twig borer moth, Kermania pistaciella ( Lepidoptera : Tineidae ), via Chelonus kermakiae ( Hymenoptera : Braconidae ) (see below).

Distribution. Iran

Material examined. Type material. Holotype ♀: IRAN: Kerman: Zarand, ex Kermania pistaciella on Pistacia vera , 10.iv.2006 (M. R. Mehrnejad). Paratypes: IRAN, 6 ♀, same data as holotype; 4 ♀, 1 ♂, Kerman: Rafsanjan, ex Chelonus kermakiae on P. vera , 20.iv.2003; 2 ♀, Rafsanjan, ex Kermania pistaciella on P. vera , 5.iv.2003 (M. R. Mehrnejad). Holotypes and paratypes in BMNH, London.

Comments: The species is provisionally placed in Cheiloneurus although several character states normally associated with this genus are not in agreement. For instance, the scutellum is strongly convex in the apical two thirds and lacks a subapical tuft of setae, the postmarginal vein is absent and there is no bare line connecting the apex of the stigmal vein to the anterior wing margin. However, species from Hawaii previously placed in Aulonops and Hypergonatopus (both synonymised with Cheiloneurus ( Guerrieri & Viggiani 2005)) also lack a bare line connecting the postmarginal vein to the anterior wing margin and have a convex scutellum which lacks a subapical tuft of setae, but in these the scutellum is not abruptly convex as in C. pistaciae . The strongly convex, apically shiny scutellum and fore wing with a complete, well defined, subapical, hyaline band are unique within Cheiloneurus , although an interrupted, hyaline band can be found in C. bifasicatus (Timberlake) . In related genera, only Tobiasia and Cheiloneuromyia have a similar complete hyaline band. The relationship of these genera with Cheiloneurus is unclear, and in a broader context both might be considered synonymous with Cheiloneurus . However, in Tobiasia the ovipositor is strongly exserted and bilaterally flattened, whilst in Cheiloneuromyia the body is completely yellow to pale orange and the scutellum is relatively flat with evenly reticulate sculpture.

Biology: Observations suggest that Cheiloneurus pistaciae is a gregarious facultative hyperparasitoid of Kermania pistaciella via its primary parasitoid Chelonus kermakiae .

Kermania pistaciella lays its eggs on the flower clusters of pistachio and these eggs are parasitized by the solitary, endoparasitic egg-larval parasitoid, Chelonus kermakiae . When the host egg hatches, the caterpillar penetrates the cluster tissue and tunnels into the twig where it develops for about 10 months. The fully developed caterpillar emerges from the twig from early March and, after about a day, spins a 2mm thick, pale brown cocoon nearby. At this stage the braconid larva emerges from the host’s larva, feeds on the remains of the host and then and spins a very thin, delicate, whitish cocoon within the cocoon of its host ( Achterberg & Mehrnejad, 2002).

During the three year survey, 1600 K. pistaciella cocoons were collected. Cheiloneurus pistaciae adults emerged from about 0.07% of these cocoons from late April through early May. Two to five adult encyrtids emerged from a single cocoon. Subsequent dissection of these cocoons revealed that the encyrtids had emerged directly from either the lepidopteran pupae, or in similar numbers from C. kermakiae pupae. This suggests that C. pistaciae is a facultative hyperparasitoid of K. pistaciella , directly attacking either the primary host or its primary parasitoid.

It is not known at which stage C. pistaciae attacks either host species. It is unlikely to attack the caterpillar when it is inside the twig of its food plant. The pupa of the primary host (and thus the parasitoid host) is also protected by a 2mm thick cocoon that would probably be impenetrable to the tiny parasitoid. However, the host caterpillar would be vulnerable to attack between leaving its burrow in the twig and commencing spinning its cocoon, or before the cocoon becomes too thick to penetrate. Several species of Cheiloneurus are known to parasitise the pupae of Dryinidae (Hymenoptera) parasitoids whilst they are in a cocoon (see Guerrieri & Viggiani 2005), but the exact mechanism is not known. Oviposition by C. pistaciae could also take place into the moth egg, which is not hidden in plant tissue. The majority of Cheiloneurus species are hyperparasitoids of scale insects ( Hemiptera : Coccidae ) via other chalcidoid parasitoids, but a switch to parasitizing host eggs is quite possible. This may have occurred in C. pyrillae Mani which has been recorded as a primary parasitoid of the eggs of Pyrilla perpusilla ( Hemiptera : Lophopidae ) ( Yadav & Chaudhary 1989), while species of the closely related genus Baeoanusia are known to be primary parasitoids or hyperparasitoids of eggs of Cerambycidae and Chrysomelidae (Coleoptera) ( Schmidt & Noyes 2003; Tribe 2000).