Cheiloneurus elegans (Dalman)

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 : 372-374

Cheiloneurus elegans (Dalman)

( Figs 945-949; Hab. E 136)

Encyrtus elegans Dalman, 1820:151-152 . Syntypes, NHRM, Sweden, lost.

Cheiloneurus elegans (Dalman) ; Westwood, 1833a:343.

Cheiloneurus elegantissmus De Santis, 1964:343-345 . Holotype E, MLP, Argentina, digital image examined, as subspecies of elegans (Dalman) . syn.nov.

DIAGNOSIS. Female (length about 1.3-1.6mm): body generally orange to orange-brown (darker and paler colour forms occur in extralimital specimens, see comments below), gaster mostly dark brown, generally with a weak to moderate metallic sheen, darker areas with a stronger metallic sheen; antenna ( Fig. 947) with scape pale orange; pedicel mostly pale orange, some dark brown dorsally; funicle with F1-F5 pale orange to orange-brown, F6 dark brown; clava dark brown; posterior one-third of mesoscutum with dense silvery setae; fore and hind coxae white, mid coxa pale orange; legs generally pale orange, hind femur and tibia mostly brown; fore wing ( Fig. 948) mostly infuscate with basal cell mostly hyaline, a small hyaline area at apex of venation and another opposite; head ( Fig. 946) about 2.8X as wide as frontovertex, in facial view slightly broader than long, subcircular, genae converging, virtually straight; frontovertex with about 13 setae medially between anterior ocellus and scrobes; eye separated from scrobe by about 2.0X diameter of anterior ocellus, area between eye and scrobe with distinct sculpture, scrobes shallow, weakly margined; interantennal prominence with about 18 inconspicuous setae and dorsally rounded; mandible tridentate; antenna ( Fig. 947) with scape about 4.3X as long as broad; all funicle segments quadrate or slightly longer than broad; linear sensilla on F4-F6; clava 3-segmented, slightly longer than F4-F6 combined, apex rounded, sensory area small, not extending along ventral surface; head width slightly greater than flagellum length; mesoscutum ( Fig. 945) anteriorly with coarse, lineolate sculpture, posteriorly with very shallow polygonally reticulate sculpture; scutellum with a distinct, apical tuft of setae; wings fully developed (brachypterous forms occur in extralimital specimens, see comments below); fore wing ( Fig. 948) about 3.3X as long as broad; parastigma strongly downcurved; costal cell dorsally naked, ventrally with a complete line of setae; area below proximal part of parastigma with a group of about 10-12, paler setae; apices of postmarginal and stigmal veins connected by a naked, hyaline area that hardly extends into disc ( Fig. 949); seta at apex of postmarginal vein about 0.4X as long as marginal vein; mid tibial spur very slightly shorter than basitarsus; propodeum with only about three setae adjacent to spiracle; gaster without “gland-like” structures on Gt1 or Gt5; syntergum about 1.1X as long as mid tibia; ovipositor about 5.0X gonostylus or about 1.8X as long as mid tibia; gonostylus about 1.2X as long as mid tibial spur; exserted part of ovipositor about 0.5X as long as mid tibial spur. Male: unknown.

Male. Unknown.

DISTRIBUTION. Canada, USA, Mexico, Costa Rica (new record), Argentina, throughout Europe, east of the Urals to Primorsky Kray, Middle East, India, Mongolia and Nigeria (see Noyes, 2019). The record from Nigeria requires confirmation.

HOSTS. Recorded as a hyperparasitoid of various Coccoidea ( Aclerdidae , Coccidae , Kermesidae and Pseudococcidae ) and Cecidomyiidae ( Diptera ) (see Noyes, 2019). It is probably a hyperparasitoid of encyrtid primary parasitoids of scale insects ( Hemiptera : Coccoidea) and Cecidomyiidae occurring on grasses ( Poaceae ) and other low herbaceous vegetation (e.g., Asteraceae ).

MATERIAL EXAMINED.

Type material. Cheiloneurus elegans elegantissimus : Holotype E, on card “MUSEO DE LA PLATA holotipo Cheiloneurus elegans elegantissimus Det. De Santis ” “s/Cochinilla del quilo-quillo.” “CHACRAS de CORIA (Prov. Mendoza) Co: Exp. Museo 25/II/1957 ” “1968/1”. Paratypes EE, 5 slides, “ Cheiloneurus elegans elegantissimus Det. De Santis PARATIPO 1968/2 MUSEO DE LA PLATA ” “CHACRAS de CORIA (Prov. de Mendoza) s/quillo-quillo con cochinilla y diptera Col : Exp. Museo 25/II/1957 E”; other slides with same labels but1968/3 to 1968/6 consecutively ( MLP) .

Non type material. COSTA RICA, 1E, Puntarenas, Monteverde, 15-16.vii.1986 (L. Masner); 1E, Puntarenas, Est. Altamira, Send. a Casa Coca, LS 331750 574400, 1700m, ii.2002 (C. Hansson, D. Rubi, J. Azofeifa ); plus a further 286E, 89G, from SWEDEN, DENMARK, UNITED KINGDOM, FRANCE, SPAIN, Heredia, CZECHIA, SLOVAKIA, HUNGARY, ROMANIA, BULGARIA, CROATIA, MONTENEGRO, NORTH MACEDONIA, GREECE, NORTH CYPRUS, TURKEY and UZBEKISTAN (all in NHMUK) .

COMMENTS. The syntypes of Encyrtus elegans Dalman are missing (see Claridge, 1958; confirmed by Hege Vårdal, NHRM, pers. comm., 2022). However, there is no doubt about the identity of elegans which is a well-known species in NW Europe and therefore there is currently no necessity for designating a neotype for the species. However, European material identified as elegans , as a whole, does exhibit a wide range of variation which may represent the equivalent of several species currently recognised in the group (see Trjapitzin & Triapitsyn, 2008). These include fully winged specimens occurring throughout its range to a proportion of brachypterous females appearing in Spain and Greece. Specimens from northwest Europe tend to be darker and mostly brown and metallic and often with a completely dark brown flagellum, whilst those from the Mediterranean countries, especially Spain and Greece, are usually much paler with occasional females being almost completely yellow (Crete and Rhodes) and some males being almost completely orange ( Spain and Greece). Intermediate colour forms occur in southern France, Spain and Greece. I believe that this material represents only one very variable species. There is no doubt that the “elegans group”, as defined by Trjapitzin & Triapitsyn requires a more comprehensive study, using morphological and molecular data, in order to determine a better understanding of its taxonomy.

I have examined a digital image of the holotype of Cheiloneurus elegans elegantissimus De Santis and it is clear that it is the same as Cheiloneurus elegans as defined by Claridge (1958). The holotype of elegantissimus has more extensive yellow colouration on the mesoscutum than is usual for north-west European specimens of elegans but several specimens examined from Spain and Greece show a similar extensive yellow colouration. I therefore have no hesitation in treating elegantissimus as a synonym of elegans .