Prochiloneurus, Silvestri, 1915

Noyes, John Stuart, 2023, ENCYRTIDAE OF COSTA RICA (HYMENOPTERA: CHALCIDOIDEA), 4 Subfamily Encyrtinae: tribes Arrhenophagini, Habrolepidini, Cerapterocerini, Cheiloneurini, Trechnitini, Cercobelini, Polaszekiini, Protyndarichoidini, Gahaniellini and Syrphophagini (part), mainly primary parasitoids and hyperparasitoids of Coccoidea and Psylloidea (Hemiptera), Taxonomic Monographs on Neotropical Hymenoptera (Oxford, England) 2 (11), pp. 1-921 : 458-459

Genus PROCHILONEURUS Silvestri

Prochiloneurus Silvestri, 1915:350 . Type species: Prochiloneurus pulchellus Silvestri , by original designation and monotypy.

Achrysopophagus Girault, 1915a:89 . Type species: Achrysopophagus oviductus Girault , by original designation. Synonymy with Prochiloneurus by Viggiani (1966:224).

Parachrysopophagus Agarwal, 1965:65 . Type species Achrysopophagus insolitus Alam , by original designation (as subgenus of Achrysopophagus ). Synonymy with Prochiloneurus by Hayat (2006:96).

Neoprochiloneurus Viggiani, 1966:95 . Type species: Prochiloneurus bolivari Mercet , by monotypy. Synonymy with Prochiloneurus by Noyes (1978:223).

Prochiloneuroides Hayat, Alam & Agarwal, 1975:61 . Type species: Prochiloneurus clavatus Compere , by original designation. Synonymy with Prochiloneurus by Hayat (1981:22- 23).

Female. Overall length about 0.8-2.5mm.

Body varying from completely yellow or orange to dark brown and largely metallic green; mesoscutum often posteriorly with a strong metallic dark band clothed with dense silvery setae; legs varying from completely yellow or pale orange to mostly dark brown; fore wing distinctly infuscate, apex hyaline, the hyaline area about as wide as length of marginal vein, distal margin of infuscate area curved, subparallel to apical wing margin.

Head with a sometimes inconspicuous, narrow, shiny bottomed groove along eye margin from posterior ocellus almost to occipital margin; malar sulcus absent or present and conspicuous; antenna attached very near to mouth margin, torulus separated by not more than one-third its own width; pedicel and flagellum subcylindrical, segments becoming broader distally, clava much broader than F1, with a distinct oblique apical truncation that is at least half its length; mandible with 3 acute teeth; palp formula 4-3.

Mesoscutum without notaular lines, mostly with imbricate-reticulate reticulate sculpture, cells rarely uniform, mostly at least some anterior cells obliquely, longitudinally elongate, rarely all sculpture longitudinally elongate striate-reticulate to striate and slightly diverging posteriorly; scutellum with similar or distinctly deeper imbricate-reticulate sculpture, sometimes very elongate and arranged in whorls; scutellum with a subapical tuft composed of tightly packed, scale-like setae that are arranged in paired submedian straight lines, tuft rarely completely absent; fore wing fully developed, very rarely shortened; fully developed fore wing relatively narrow, about 2.7-3.2X as long as broad with a naked, hyaline streak connecting apex of postmarginal and stigmal veins; submarginal vein with parastigma at least slightly broadened and conspicuously downcurved; marginal vein long, at least 5X as long as broad, at least 3X as long as the stigmal vein, postmarginal vein about half as long as stigmal vein; filum spinosum present.

Hypopygium reaching apex of gaster; syntergum with apex broadly truncate, very slightly concave; ovipositor always conspicuously exserted, sheaths together forming a uniform, slender cylindrical tube; gonostylus free.

Male. Length about 0.6-1.8mm.

Body dark brown with a slight to moderate metallic sheen; fore wing hyaline; antenna with 6 funicle segments, all longer than broad and clothed with whorls of long setae that are at least about 3X as long as diameter of segments; clava entire and usually slightly shorter than F5 and F6 combined; sculpture of mesoscutum and scutellum usually similar to that of female; scutellum without a subapical tuft but sometimes with a distinct group of longer setae; fore wing with venation similar to that of female but marginal vein usually relatively shorter; phallobase with parameres distinct and fairly elongate, each with a subapical seta; cuspis seta present; digiti each about 3-4X as long as broad and with a single apical tooth; aedeagus mostly about two-thirds as long as mid tibia, slender, about 20X as long as broad with apex broadly rounded, nearly truncate.

DISTRIBUTION. Cosmopolitan (see Noyes, 2019).

HOSTS. Secondary parasitoids of mealybugs ( Hemiptera : Pseudococcidae ) via encyrtid ( Hymenoptera : Encyrtidae ) primary parasitoids, e.g. Anagyrus Howard (see Noyes, 2019). One species may be a secondary parasitoid of ladybirds ( Coleoptera : Coccinellidae ) (see Trjapitzin, 1989).

COMMENTS. Prochiloneurus is very similar to Cheiloneurus and may be problematic when trying to separate the two since the species of both genera are mostly secondary parasitoids of Coccoidea (Hemiptera) . However, it is likely that Prochiloneurus is restricted to secondary parasitism in mealybugs ( Hemiptera : Pseucoccidae) whilst Cheiloneurus has a much broader range of primary hosts (several families of Coccoidea, leaf hoppers and possibly predators associated with various sternorrhynchous hemipterans). Prochiloneurus can be distinguished from Cheiloneurus by the combination of the relatively close placement of the antennal torulus to the mouth, the curved distal margin of the fore wing infuscation, the setae of the subapical tuft on the scutellum arranged in distinct submedian lines, the hypopygium reaching the apex of the gaster, the broadly truncate, slightly concave, apex of the syntergum and the well-exserted ovipositor with the gonostyli together forming a uniform, cylindrical, slender tube. In Cheiloneurus the antennal torulus is separated from the mouth margin by at least its own width, the distal margin of the infuscation of the forming is rarely curved, the setae forming the subapical tuft are scattered and not placed in distinct submedian lines, the hypopygium rarely extends to the apex of the gaster, the apex of the syntergum is always convex, rounded or acute and the gonostyli of the ovipositor, if exserted, do not form a cylindrical or slender tube.

The ovipositor structure in Prochiloneurus is probably an adaptation to oviposition into primary hosts that are covered in protective waxy filaments, i.e. mealybugs. It would allow the female to exsert the ovipositor to its full length enabling the parasitoid to “reverse” into the primary host from the side, thus avoiding the waxy filaments. On the other hand the ovipositor of Cheiloneurus would probably only allow the female to oviposit into the host directly from above. This would inhibit oviposition into primary hosts covered in waxy filaments but facilitate oviposition into primary hosts such as Coccidae and Dryinidae .

IDENTIFICATION. 42 species Worldwide, including 12 described as new below. Trjapitzin, 1989 (key to 8 Palaearctic species); Sunita & Khan, 2011 (key to 12 Indian species); Wang et al. (key to 4 Chinese species).