Arianus, Noyes, 2023

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 : 622-623

Genus ARIANUS gen.nov.

Type species: Arianus porusos sp.nov. Gender masculine

Female. Length about 2.7mm.

Generally dark brown with a weak to moderate metallic sheen; fore wing very weakly infuscate; hind wing hyaline.

Head with occipital margin sharp, carinate; frontovertex about half head width, with large, conspicuous piliferous punctures, similar in appearance to surface of a thimble; ocelli forming a slightly obtuse angle; antennal scrobes moderately deep, short and ∩-shaped, more or less meeting dorsally so that interantennal prominence does not meet frontovertex; malar sulcus absent; dorsal tentorial arm meeting face very close to torulus; torulus separated from mouth margin by about 1.4X its own length, its upper margin about level with lower eye margin; clypeal margin very slightly convexly produced medially; occiput, near mouth margin either side of the labiomaxillary complex, with a pair of circular, gland-like structures (Fig 1695, highlighted); funicle with segments subequal in size, each slightly longer than broad; clava 3-segmented, about half as long as funicle, sensory area enlarged, extending about half way along ventral surface; eye almost naked, clothed with inconspicuous setae, each about half as long as diameter of facet; mandible with one acute tooth and broad truncation; palp formula 4-3.

Thorax with pronotum short; mesoscutum and scutellum with polygonally reticulate sculpture, slightly shallower on scutellum; notaular lines absent; mesoscutum and scutellum slightly convex, posterior margin of mesoscutum roundly produced, separating axillae medially; scutellum densely setose, clothed in about 100 subequal, setae, those at apex hardly longer than those at base; posterior margin of scutellum rounded; mid tibial spur very slightly shorter than basitarsus; fore wing about 2.4X as long as wide; costal cell very setose, dorsally with a complete line of submarginal setae and ventrally with up to 6 lines of setae; linea calva present, virtually closed posteriorly; filum spinosum present, composed of about 6 modified setae; submarginal vein with parastigma not swollen, junction with marginal vein with a hyaline break, marginal vein punctiform, stigmal vein long with a distinct apical uncus, postmarginal vein extending a little way past apex of stigmal vein; hindwing about 2.8X as long as broad, costal cell broad with 2 or 3 lines of conspicuous setae ventrally; mesopleuron nearly reaching level with posterior margin of propodeum; propodeum medially quite short, less than 0.1X as long as scutellum, spiracle large, about equal to diameter of anterior ocellus, nearly touching anterior margin of propodeum, and about half as long as dorsal part of propodeum laterally, posterolateral margin of propodeum forming a sharp, acute angle, posterior margin, above hind coxa forming a very thin, elongate flange that, in dorsal view, forms a very sharp, acute angle at the posterolateral margin of the propodeum.

Gaster with syntergum shorter than mid tibia, apex truncate, Gt2 to apex each divided longitudinally by a median membranous suture; sternites with Gs2 (Fig. 1698) to apex similarly but more weakly, divided and each V-shaped and bearing a pair slender anteromedian apodemes; hypopygium (Fig. 1700) more or less reaching apex of gaster and with a pair of short, median, “gonostylus-like” structures bearing sensory setae; ovipositor shorter than mid tibia, not exserted, about 10X as long as gonostylus; outer and inner plates of ovipositor very slender, semicircular sheet greatly modified (Fig. 1699), subrectangular, more than 5X as long as wide with 1 st and 2 nd valulae bent almost at right angles medially.

Male. Unknown.

DISTRIBUTION. Peru and Costa Rica

HOSTS. An unidentified species of the genus, perhaps porusos sp.nov., has been observed parasitizing nymphs of Tuthillia cognata Hodkinson, Brown & Burckhart ( Hemiptera : Liviidae ) causing blister galls on leaves of Myrciaria dubia ( Myrtales : Myrtaceae ) in Ucayali, Perú (Bladimir Guerra Ambrosio, pers. comm. 2020).

COMMENTS. The gland-like structures on the occiput near the labiomaxillary complex (Fig. 1695) are reminiscent of the structures in a similar position of the occiput in Merlen Noyes & Woolley (1994) . The function and phylogenetic importance of these structures is unknown. The dorsal tentorial arms surfacing very close to the torulus is also unusual and worthy of note as is the densely hairy, convex scutellum and densely setose ventral surface of the costal cell.

The structure of the gaster and ovipositor are highly unusual and are probably an adaptation to enable the female to oviposit into psyllid host nymphs that live inside leaf galls produced by their host plant. The gaster is telescopic (as in Cercobelus ) and the ovipositor is strongly modified with the right-angle bend of the 1 st and 2 nd valvulae of the ovipositor appearing to be a unique modification.