Dalek, 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 : 635-637

Genus DALEK gen.nov.

Type species: Dalek nationi sp.nov. Gender masculine.

Female. Length about 1.3-2.1mm.

Body robust, generally dark with a weak to moderate metallic sheen; flagellum variable, usually unicolourous dark brown, sometimes paler or bicoloured; palpi white to very pale orange; dorsum of thorax with dark setae; tegula dark brown; wings hyaline or with a small infuscate area below marginal vein, rarely very weakly suffused brown, venation pale orange to brown; 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 1.6-2.0X as high as deep, anteriorly fairly evenly curved from occipital margin to top of scrobes, more strongly curved or angled at top of scrobes and virtually straight to mouth margin, interantennal prominence hardly protuberant; occipital margin sharp, carinate; frontovertex about 0.4-0.5X head width and with irregular, polygonally reticulate to imbricate sculpture and sparse, shallow piliferous punctures, usually 2-8 setae medially between anterior ocellus and top of scrobes; ocelli forming an obtuse angle; no shiny, oval depression adjacent to eye margin behind posterior ocellus; temple and gena with shallow, longitudinally elongate, polygonally reticulate to striate-reticulate sculpture; eye not quite reaching occipital margin, with setae sparse, usually conspicuous; scrobes shallow, ∩-shaped, weakly margined dorsally and laterally; antenna attached below lower eye margin but well above mouth, dorsal margin of torulus about level with lower eye margin or only slightly below; scape about 2.5-7.0X as long as broad, about 0.4-0.5X as long as head width; all funicle segments longer than broad, usually subequal in length, F6 occasionally quadrate, segments gradually becoming slightly broader distally, linear sensilla often conspicuous and on all segments or absent from F1; clava shorter than funicle, 3-segmented, sutures subparallel, sensory area slightly enlarged, hardly extending along ventral surface giving apex of clava a rounded or weakly truncate appearance; malar sulcus absent or present, but very indistinct when present; mouth about 0.40-0.46X head width, clypeal margin often with a distinct medial lobe; mandible tridentate, upper tooth truncate or rarely rounded; palp formula 4-3.

Thorax with pronotum short, its posterior margin distinctly concave; mesoscutum without notaular lines, with polygonally reticulate to imbricate-reticulate sculpture; scutellum convex and usually with side and apex partially mirror smooth and shiny, with sculpture only rarely reaching apex of scutellum, apex and side of scutellum often vertical; sculptured parts with coarse sculpture that is almost always conspicuously deeper than that on mesoscutum; mid tibial spur variable in length; fore wing fully developed; about 2.4-2.6X as long as broad; costal cell with at least 1-2 complete lines of setae ventrally and a line of setae dorsally in apical half or so; submarginal vein with an apical hyaline break; marginal vein about 3.5-6.0X as long as broad, about as long as stigmal vein and about 1.3-2.0X as long as postmarginal vein; linea calva open; filum spinosum present, consisting of a line of about 2-5 stouter setae; posterior margin of mesopleuron not reaching level with posterior margin of propodeum, falling short by distance equivalent to about diameter of propodeal spiracle; mesopleuron posteriorly not reaching level of posterior margin of propodeum, falling short by about diameter of spiracle or a little less; propodeum fairly short, medially with irregular sculpture, side smooth or with rough sculpture, almost always with a carina posteriorly above hind coxa that runs almost vertically finishing in a posterolateral tooth behind spiracle; about 15-30 setae near spiracle, sometimes extending towards hind coxa.

Gaster with hypopygium not reaching apex; paratergites absent; syntergum shorter than mid tibia, apex variable; ovipositor slightly exserted; ovipositor longer than mid tibia, rarely shorter, second valvifer with up to 2 subapical seta, proximal part broadly C-shaped; hypopygium W-shaped, mid anterior process short, lateral arms quite long each with a shallow but distinct notch on external margin, posterior margin with a shallow to moderately deep invagination.

Male. Length about 1.2-1.9mm.

Generally very similar to female but for slightly wider frontovertex, higher placement of antenna and structure of antenna and genitalia. Frontovertex about 0.5X head width; antennal torulus with lower margin about level with lower eye margin; flagellum filiform, all funicle segments longer than broad and clothed with setae that are 1.5-2X as long as diameter of segments; phallobase with relatively short digiti, each about 1.4-1.5X as long as broad with a single apical tooth and a short outer seta; aedeagus about 0.5X as long as mid tibia with apex acute.

DISTRIBUTION. Known only from Mexico and Costa Rica, but likely to be more widespread in the Neotropics.

HOSTS. More than likely parasitoids of triozids ( Hemiptera : Triozidae ). Dalek pleione was reared from an unidentified triozid on Oreomunnea costaricensis D.E. Stone ( Fagales : Juglandaceae ), Dalek orthia was reared from an unknown gall (possibly of Triozidae ) on Vernonia and Dalek arax was collected on Psidium guajava L. ( Myrtales : Myrtaceae ) infested with Triozoida limbata (Enderlein) ( Triozidae ) and some unidentified males were reared from Leuronota flavipennis Brown & Hodkinson (det. D. Hollis) ( Triozidae ) on Weinmania pinnata L. (Oxalidales: Cononiaceae).

COMMENTS. Dalek is close to Caldencyrtus and perhaps other similar genera (e.g. Hebynthus , Alkonia Raquanus , Mendisa , etc.) that may form a monophyletic group (see comments under Alkonia , p. 708). Females of Dalek can be separated from those of other genera in this group by having all funicle segments longer than broad, F6 occasionally quadrate, the scape at least 3X as long as broad, the mandible tridentate with a truncate upper tooth and the hypopygium W-shaped with lateral arms quite long, each with a distinct notch on the external margin.

Females of Dalek differ consistently from those of Caldencyrtus in the shape of the hypopygium. In Caldencyrtus the hypopygium is transverse, not W-shaped, anteriorly weakly concave, posteriorly strongly biconvex with a deep median invagination. Additonally, in Dalek the sculpture on the scutellum is generally deeper than that on the mesoscutum, the apex of the scutellum is at least narrowly smooth and shiny and the posterior margin of the propodeum has a distinct carina that runs almost vertically from above the hind coxa finishing in a posterolateral tooth behind the spiracle. In Caldencyrtus the sculpture on the scutellum is similar to that on the mesoscutum and extends to the apex and the propodeum has at most a very indistinct, sloping carina above the hind coxa that does not end in a conspicuous tooth-like projection. Males of Dalek have the clava entire, whilst those of Caldencyrtus have the clava 2-segmented.

Dalek is also close to Syrphophagus Ashmead (1900) , species of both genera having similarly structured mandibles (three teeth with upper tooth truncate), carinate occipital margin, wing venation (relatively long marginal vein and postmarginal veins) and strong association with psyllids (many species of Syrphophagus are hyperparasitoids of psyllids). Females of Dalek differ from those of Syrphophagus in having the scutellum very strongly sculptured with the apex always at least narrowly smooth and shiny, a posterior carina and tooth on the propodeum above the hind coxa and a strongly W-shaped hypopygium with notched anterolateral arms. In Syrphophagus the sculpture of the scutellum is usually relatively shallow, not deeper than that on mesoscutum, and reaches the posterior margin of the scutellum, the side of the propodeum never has a posterior carina and does not have a lateral tooth and the anterolateral arms of the hypopygium, if present, do not have a notch on their external margin. The Costa Rican species of Syrphophagus will be dealt with in detail in the next contribution to the taxonomy of the Encyrtidae of Costa Rica.

Host relationships suggest that Dalek may also be close to Ginsiana Erdös & Novicky (1955) because some of North American species currently placed in this genus ( arbuticola ( Gahan & Waterston, 1926) , richardsi ( Barron, 1970) and vectius ( Walker, 1847)) have been associated with psyllids or triozids. No European species, including the type species of the genus, obscura, has a known host. Ginsiana vectius (Walker) , from Florida, does show some similarities to Dalek in that it has a carina on the propodeum terminating in a tooth behind the spiracle, similar mandibular structure, hypopygium and fore wing venation. Ginsiana vectius differs from species of Dalek by having the sculpture on the scutellum extending all the way to the apex. Ginsiana arbuticola from California, is similar to Dalek orthia , ananke and carme but differs from these species in having the postmarginal vein about 0.5X as long as the stigmal vein and the hypopygium reaching the apex of the gaster. It is possible that vectius , arbuticola and the other north American species would be better placed in Dalek , but this requires further study. None of the European species currently placed in Ginsiana has a carina posteriorly on the propodeum that ends in a tooth and the venation is different in that the stigmal vein forms a much greater angle with the anterior margin of the fore wing than in any species of Dalek , although the hypopygium of longicornis is somewhat similar to that of Dalek species. All European species of Ginsiana have the gena straight in facial view, the malar sulcus very strong and conspicuous, the mandible with 1 tooth and a broad, slightly concave truncation and the stigmal vein forming an angle of about 45-50° with the anterior wing margin. In Dalek the gena is distinctly curved in facial view, the malar sulcus is absent, or very weak and inconspicuous, the mandible is tridentate with the upper tooth truncate and the stigmal vein forms an angle of about 30° with the anterior wing margin.