Euplectrus bicolor (Swederus)

Hansson, Christer & Schmidt, Stefan, 2018, Revision of the European species of Euplectrus Westwood (Hymenoptera, Eulophidae), with a key to European species of Euplectrini, Journal of Hymenoptera Research 67, pp. 1-35 : 13-15

Euplectrus bicolor (Swederus)

Figures 1-2 , 7-12 , 48 , 55

Pteromalus bicolor Swederus, 1795:204. Neotype female, designated here, in MZLU. Combined to Eulophus by Walker (1839:173), and to Euplectrus by Haliday (1844:297).

Elachertus albiventris Spinola, 1811:151. Combined to Eulophus by Haliday (1842:plate J) and to Euplectrus by Walker (1872b:112); synonymized with E. bicolor by Bouček and Askew (1968:15).

Material.

Type material: Neotype female labelled " Sweden: Skåne, Kranke, Ekskogen , 55°41'10.3N, 13°27'40.2E, 5.vii.2015, C. Hansson ", "BC- ZSM-HYM-25460-C11" in MZLU . Additional material (440♀ 306♂): Finland: 13♀ 8♂ (VV) , 163♀ 125♂ (MZH, MZLU) , this material includes 1♀ 1♂ from Eugraphe subrosea , 1♀ 4♂ from Agrotis sp., 4♀ 14♂ from Orthosia opima , 1♀ from Xylina sp., 4♀ 2♂ from a "polyphagous noctuid"; France: 18♀ 4♂ (NHM) ; Greece: 1♀ (MZLU) ; Hungary: 1♂ (MZLU) ; Norway: 1♀ 1♂ (VV) ; Slovenia 6♂ (MZLU) , this material includes 6♂ from Orthosia sp. on raspberries ( Rubus idaeus ); Sweden: 179♀ 211♂ (MZLU, NHM, ZSM) ; United Kingdom: 65♀ 54♂ (NHM) , this material includes 6♀ from Diarsia mendica , 7♀ 14♂ from Mamestra brassicae , 9♀ 26♂ from Polia hepatica , 14♀ 8♂ from Polia nebulosa . Detailed geographic information of all barcoded specimens is listed in Suppl. material S1.

Diagnosis.

Frons below level of toruli with pale area not extending laterally to the eye but with a dark stripe between pale area and eye, in the female dark area is wider (Figs 9 , 10 ) than in the male (Figs 11 , 12 ); midline on midlobe of mesoscutum usually indicated by either a median carina (Fig. 48 ) or a median groove in posterior ½, in some specimens midline indicated just through a change in the reticulation; posterior part of midlobe mesoscutum narrow (Figs 48 , 55 ), ratio width base of midlobe (a)/width base of one sidelobe (b) = 0.57 ± 0.070 (female), 0.55 ± 0.070 (male), width base of midlobe/width base of entire mesoscutum = 0.22 ± 0.019 (female), 0.21 ± 0.019 (male), n= 10 for female and male respectively.

Description (neotype).

Length of body 2.8 mm (2.0-3.1 mm in additional material). Antenna with scape yellowish-brown with dorsal edge pale brown, pedicel and flagellomeres 1+2 yellowish-brown, flagellomeres 3-6 pale brown. Mandibles and palpi yellowish-brown. Head black and shiny, lower face with median part yellowish-brown reaching laterally to level of outer edge of toruli (Figs 9 , 10 ). Frons smooth except a reticulate band closer to anterior ocellus than to toruli, reaching from eye to eye, close to eyes with two rows of setae (Fig. 9 ). Vertex smooth and shiny. Occipital margin with a carina behind ocellar triangle.

Mesosoma black and shiny; midlobe with raised and strong reticulation, meshes isodiametric, midline on midlobe of mesoscutum usually indicated by either a median carina (Fig. 48 ) or a median groove in posterior ½, in some specimens midline indicated just through a change in the reticulation. Scutellum 0.9 × as long as wide; with engraved reticulation, meshes elongate, except smooth and shiny posterior margin (Fig. 48 ). Dorsellum with a very narrow groove along anterior margin (Fig. 48 ), groove medially 0.1 × as long as length of dorsellum. Propodeum smooth and shiny medially, with very weak reticulation laterally (Fig. 48 ); anteromedially with strongly raised triangular cup in posterior part; propodeal callus with 17 setae. Legs yellowish-brown. Forewing: costal cell with two rows of setae on ventral surface, and margin with four setae close to marginal vein; with 17 admarginal setae.

Gaster dark brown with a yellowish-brown spot in anteromedian part (Fig. 8 ).

Ratios. HE/MS/WM = 1.8/1.0/1.1; POL/OOL/POO = 9.7/5.3/1.0; OOL/DO = 1.5; WE/WF/WH/HH = 1.0/3.0/5.3/3.6; WH/WT = 1.0; PM/ST = 1.6; TS1/TS2/LT/LT1/LT2/LT3/LT4 = 3.6/2.3/2.3/1.3/1.0/1.8; LP/WP = 0.8; MM/LG = 0.9.

Male. Length of body 1.7-2.4 mm. Scape slightly enlarged, widest medially, with sensory pores along entire ventral margin. Similar to female except wider pale clypeal area (Figs 11 , 12 ), wider scape, longer petiole.

Ratios. LC/WS = 3.1-3.4, LP/WP = 1.0-1.2.

Hosts.

Agrotis sp., Diarsia mendica (Fabricius), Eugraphe subrosea (Stephens), Mamestra brassicae (L.), Orthosia opima ( Hübner), Orthosia sp. on raspberries ( Rubus idaeus ), Polia hepatica (Clerck), Polia nebulosa (Hufnagel), Xylina sp., a "polyphagous noctuid". All records are from caterpillars of the Noctuidae .

Distribution.

Sweden ( Swederus 1795), Finland, France, Greece, Hungary, Norway, Slovenia, United Kingdom (new/confirmed records).

Remarks.

Neotype designation: the original type material for E. bicolor is lost ( Graham 1963). Presumably it was originally in the Natural History Museum in Stockholm (Sweden), but cannot be found there. When Swederus described E. bicolor he was very parsimonious with information, which was as usual at that time. The description is very short and fits any European species of Euplectrus . Biological and geographical information were not included. Swederus was working in Sweden but made scientific trips to several European countries ( Waldeck 2018) and it is difficult to be sure from where he had the material forming the base for the description. However, since Swederus was Swedish it is probable that he had access to Swedish material. Therefore, the neotype is selected from Swedish material, and it is selected from material belonging to the species that appears to be the most common in this country. The neotype has a DNA barcode of 621 bp and belongs to one of the two haplotypes that were found within the species (Fig. 63 ).

Genetic data.

Genetically analysed specimens of E. bicolor exhibited comparatively high levels of intraspecific variation (maximum 6.5%) but with a distinct gap to the nearest neighbours ( E. intactus , 10.9% and E. carinifer , 10.2%) (Fig. 63 ). The analysed specimens, all from Sweden, fall into two genetic clusters that occur sympatrically (Suppl. material S2). The absence of morphological characters to separate the two haplotypes does not preclude the possibility that E. bicolor consists of two or more species, but analysis of material of other populations and ideally additional (nuclear) gene regions will be required to clarify the status of each population.

Figures

Figure 63. Neighbour-joining tree of Euplectrus, with colours indicating different Barcode Index Numbers (BINs). For a fully resolved tree with additional terminal taxa information, including sequence length and country of origin, see Suppl. material S 2.

Figures 1 - 2. Euplectrus bicolor (Swederus): 1 larvae on caterpillar of Orthosia sp. (Lepidoptera: Noctuidae) 2 pupae with spin threads. Photo courtesy Spela Modic.

Figures 7 - 16. Euplectrus spp.: 7 - 12 E. bicolor (Swederus) 7 - 9 neotype, female 7 habitus lateral 8 habitus dorsal 9 head frontal 10 non-type female, head front-lateral 11 head frontal, male 12 head front-lateral, male 13 E. flavipes (Fonscolombe), gaster dorsal, male 14 - 15 head including scape lateral, male 14 E. maculiventris Westwood 15 E. geometricida sp. n. 16 E. carinifer sp. n., gaster dorsal, male.

Figures 48 - 51. Euplectrus spp., mesosoma dorsal, female: 48 E. bicolor (Swederus) 49 E. intactus (Walker) 50 E. maculiventris Westwood 51 E. flavipes (Fonscolombe).

Figures 52 - 56. Euplectrus spp. 52 - 54 mesosoma dorsal, female 52 E. geometricida sp. n. 53 E. carinifer sp. n. 54 E. pallidigaster sp. n. 55 - 56 mesoscutum, female, a = width of base of midlobe, b = width of base of sidelobe 55 E. bicolor (Swederus) 56 E. intactus (Walker).