Polaszekius, 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 : 532-533

Genus POLASZEKIUS gen.nov.

Type species: Polaszekius nemesis sp.nov. Gender masculine.

Female. Length about 1.5-1.7mm.

Body robust, generally dark with a weak to moderate metallic sheen; funicle with unicolourous pale segments; dorsum of thorax with dark setae; legs generally dark with pale areas; wings hyaline with a small infuscate area below marginal and stigmal veins; propodeum dark with a weak metallic sheen, side more strongly metallic, some silvery setae near spiracle; gaster dark with a metallic sheen.

Head in profile about 1.7X as high as deep, anteriorly fairly evenly curved from occipital margin to top of scrobes, more strongly curved at top of scrobes and virtually straight to mouth margin, interantennal prominence hardly protuberant; occipital margin carinate; frontovertex about half head width and with irregular, polygonally reticulate sculpture and sparse, shallow piliferous punctures; ocelli forming a strongly obtuse angle; temple and gena with shallow, longitudinally elongate, polygonally reticulate sculpture; eye nearly reaching occipital margin, with fairly conspicuous setae; scrobes shallow, ∩ -shaped; antenna attached slightly below lower eye margin; scape slightly broadened and flattened, a little more than 2X as long as broad, about 0.4X as long as head width; funicle segments subquadrate, mostly transverse, linear sensilla only on distal segments; clava shorter than funicle, 3-segmented, sutures subparallel, sensory area slightly enlarged and extending a little way along ventral surface, giving apex of clava a slight, obliquely truncate appearance; malar sulcus absent; mouth about 0.4X head width, clypeal margin very slightly produced medially; mandible with a long lower tooth a short median tooth and a broad truncation; palp formula 3-3.

Thorax with pronotum short; mesoscutum without notaular lines; scutellum convex, but dorsally quite flat, with deeper sculpture than mesoscutum, extreme apex and side completely smooth and shiny; mid tibia with a minute elongate invagination on its external surface about mid-way along its length (see below), spur about as long as basitarsus; fore wing fully developed; about 2.3X as long as broad; costal cell with only 1 line of setae ventrally and a line of setae dorsally in apical half or so; submarginal vein with an apical hyaline break; marginal vein about 2.5X as long as broad, slightly shorter than stigmal vein and about 2X as long as postmarginal vein; linea calva open; filum spinosum present, consisting of a line of about 5 slightly stouter setae; posterior margin of mesopleuron not reaching level with posterior margin of propodeum, falling short by distance equivalent to about half diameter of propodeal spiracle; propodeum short, with some shallow, irregular sculpture posteriorly, side sharp above hind coxa, with a minute posterolateral tooth behind spiracle; about 20 setae near spiracle, not extending part way towards hind coxa.

Gaster with hypopygium reaching slightly past apex; paratergites absent; syntergum shorter than mid tibia, apex rounded; ovipositor (Fig. 1342) strongly exserted, slender, longer than mid tibia, outer plates narrow, ribbon-like; second valvifer without a subapical seta, proximally with posterior, outer margin of semicircular sheet (see below) hardly concave, almost straight; hypopygium (Fig. 1343) subtriangular, longer than broad and with posterior margin somewhat trident-shaped.

Male. Unknown.

DISTRIBUTION. Known only from Costa Rica, but possibly more widespread in the Neotropics.

HOSTS. Unknown.

COMMENTS. The minute, elongate invagination about mid-way along the mid tibia appears to be unique to this genus, unfortunately this character seems to be visible only on slide-mounted material and even then with some difficulty.

Polaszekius may be close to Dalek and other genera (e.g. Hebynthus , Alkonia , Raquanus , Mendisa , Caldencyrtus , etc., see comments under Alkonia , p. 708). However, it can be separated from these genera and others by the unique structure of the hypopygium and ovipositor. The hypopygium (Fig. 1343) is subtriangular, much longer than broad, with a trident-shaped posterior margin. The (Fig. 1342) is slender, strongly exserted and it has outer plates that are slender and ribbon-like and the outer margin of the proximal part of the second valvifer (semi-circular sheet; see Copland & King, 1972) is hardly concave. In the vast majority of encyrtids the semicircular sheet has the posterior, outer part of the semicircular sheet broadly C-shaped. The connection between the distal part of the second valvifer with the third valvula also appears to be unique.

The genus is named in honour of Andrew Polaszek, a colleague and friend, who facilitated this study during the Covid-19 lockdown and who is also an authority on Aphelinidae .