Rhoptromeris dichromata, Costa Baião & Forshage, 2018

Costa Baião, Guilherme & Forshage, Mattias, 2018, Revision of the West Palaearctic species of Rhoptromeris Förster, 1869 (Hymenoptera: Figitidae: Eucoilinae), Journal of Natural History (J. Nat. Hist.) 52 (17 - 20), pp. 1201-1224 : 1211-1214

Rhoptromeris dichromata sp. nov.

( Figure 3a,b )

Diagnosis

Head and mesosoma dark brown or black, female metasoma lighter, usually with reddish or orange tinge ventrally, 1.5–1.6 mm ( Figure 3a ), male metasoma brown. The species can be distinguished from R. heptoma or R. villosa by the long and narrow marginal cell, elongate antennae and more strongly sculptured scutellum, and from R strobigena or R. koponeni by the long and narrow marginal cell, the medial bridge on the pronotal plate and the smaller eyes. Specimens show considerable variation in size of female flagellomeres, height of scutellum and sculpture of the dorsal scutellar surface. It is possible that future molecular studies or analysis of additional material will reveal that the species as conceived here can be split into two or more distinct species.

Description

Compound eyes and ocelli small. Female antenna 0.8–0.9× body length, 13-segmented, scape, pedicel and first three flagellomeres light brown, flagellomeres 4–13 brown. Flagellomeres subequal in size. Indistinct club of 8 articles, bearing rhinaria, not much wider than pre-club flagellomeres. Male antennae approximately 1.6× body length. Flagellomeres elongate, brown, F1 and F2 sometimes lighter. F2 moderately bent, forming a weak ‘S’ shape when viewed from above. F2 from 1.5 to almost 2 times the length of F1.

Mesonotum smooth, with a few scattered setae, weakly arched. Pronotal plate with lateral bridges, foveae large and separated by a medial bridge ( Figure 2a ). Lateral aspect of pronotum with a few scattered setae. Scutellar plate drop-shaped ( Figure 6a ), sometimes more elongate, surface flat, with a large posterior glandular pit and small setal pits anteriorly, a few scattered setae. Scutellar foveae of normal size and depth, sometimes more shallow. Lateral bars sometimes with a few striae basally. Dorsal scutellar surface with ridges forming a reticulate pattern, more or less radiating from scutellar plate. Dorsal surface with a line of setae along its rim, separated from lateral surface by a carina. Lateral surface mostly smooth, with a few ridges. Scutellum rather short. Mesopleural line present as a ridge. Metapleura glabrous, except for 2 or 3 long setae on dorsal region. Anteroventral cavity present, round ( Figure 1a ), filled with hair. Posterior margin straight, with a few weak ridges running anterodorsally. Posterior incision of metapleura absent.

Propodeum pubescent laterally, with tuft of hair above metapleural ventral callus. Propodeal carinae straight, converging dorsally.

Metasoma darker on its dorsal portion, in females often much lighter ventrally, with a yellowish or reddish tinge. Hairy ring with a small dorsal opening, dense, especially in females.

Legs yellow or light brown. Metacoxae with a small posteroproximal tuft of short hair.

Wings relatively narrow, hyaline, pubescent, apex rounded, hair fringe not particularly long. Marginal cell closed or diffusely closed, narrow, elongate, 3 times as long as deep, veins Rs and 2r straight, the same size or with Rs slightly longer. Venation light brown, accessory veins sometimes very lightly indicated by colouration.

Etymology

In allusion to the often yellowish or reddish metasoma which contrasts with the black head and mesosoma.

Distribution

Europe: specimens seen from Austria, Denmark, Finland, Norway, Slovenia, Sweden.

Holotype

Female: SWEDEN, Västerbotten, Vindelns kommun, Kulbäckslidens f.-park, Kulbäcken , meadow, birch wood on fine alluvial sediments, (64.190217°N 19.605700°E), 1–18 August 2003, Swedish Malaise Trap Project ( NHRS).

Paratypes

(4 females): SWEDEN: Småland, Nybro kommun, Bäckebo , Grytsjöns naturreservat, 56.931407°N 16.085536°E, Old moist haymaking meadow in forest edge, 27 June–2 July 2005, Swedish Malaise Trap Project ( NHRS) (1 female, NHRS); Småland, Nybro kommun, Bäckebo, Grytsjöns naturreservat, 56.921656°N 16.101228°E, Old aspen forest in boulder terrain, 2–12 July 2005, Swedish Malaise Trap Project ( NHRS) (1 female, NHRS); Halland, Halmstad kommun, Gårdshult, Buskastycket, Moist hay meadow (56.694883° N 13.150500°E) 1–25 April 2004, Swedish Malaise Trap Project ( NHRS) (1 female, NHRS); Västerbotten, Vindelns kommun, Kulbäcken meadow, birch wood on fine alluvial sediments, (64.190217°N 19.605700°E), 5–20 August 2004, Swedish Malaise Trap Project ( NHRS) (1 female, NHRS) .

Additional material

AUSTRIA: Niederösterreich Lunz / See 47.85°N 15.0333°E, 5–14 August 2005 leg H . Malicky (1 female, OLML) , FINLAND: Southern Finland, Mikkelin mlk 26 June 1983 M . Koponen leg (1 female, coll Koponen), Savonia australis, Mikkelin mlk 6840:507 28 July 1996 M . Koponen leg (1 male, coll Koponen), Kuusamo, Kuusamo 7371:609 3 July 1998 M . Koponen leg (2 males, coll Koponen) Ks, Kuusamo 30 June 1979 M . Koponen leg (1 male, coll Koponen) Ostrobothnia media, Lappajärvi 7014:327 31 July 1995 (1 male, coll Koponen ) Southern Finland , Ristiina 25 June 1983 M . Koponen leg (1 male, coll Koponen ) ; SLOVENIA: Radovljica 2–13 August 1978 malaise trap, Phragmites swamp Lars Huggert (2 females, NHRS) ; SWEDEN: Småland, Högsby kommun, Hornsö, kronopark, birch fen (57.006550°N 16.109350°E), 20–30 June 2004 (coll. Event ID 340), Swedish Malaise Trap Project ( NHRS) (1 female, NHRS); Södermanland, Huddinge kommun, Sofielunds återvinningsanläggning, pine forest with garbage (59.176533°N 17.993850° E), 30 June–13 July 2004, Swedish Malaise Trap Project ( NHRS) (1 female, NHRS); Uppland, Älvkarleby kommun, Båtfors . Pine forest with blueberry (60.46065° N 17.317817°E), 14 June–04 July 2005, Swedish Malaise Trap Project ( NHRS) (2 females, NHRS); Uppland, Uppsala kommun, Ekdalens naturreservat, tall herbs and young trees mixed with old oaks (59.971517°N 18.354983°E), 7–21 July 2003, Swedish Malaise Trap Project ( NHRS) (1 female, NHRS); Skåne, Skäralid , SW of Lierna N 56° 01 ʹ E 13° 13 ʹ 18–30 August 1994 . Leg M. Söderlund (1 female, MZLU); Västerbotten, Hällnäs , 18 August 1982 Leg K .J. Hedqvist (1 female, MZLU); Hälsingland, Älgesjön, RN689312/152201 Leg Erik Sahlin , Fönsterfälla 15 May–15 June 2002 (2 females, NHRS); Hälsingland , Älgesjön , RN689312/152201 Leg Erik Sahlin , Fönsterfälla 24 July–11 September 2002 (1 female, NHRS) .

Biology

Specimens were collected from the end of June to August in mostly forested habitats (both coniferous and deciduous forests, as well as forest edges towards meadows). The relatively narrow wings suggest that the species is not a very good flier and possibly

attacks hosts living on low vegetation. Probably a parasitoid of Chloropidae (Diptera) , like other known Rhoptromeris species.

Figures

Figure 1. Scanning electron microscopy (SEM) images of the metapleura of (a) Rhoptromeris dichromata sp. nov., (b) R. koponeni sp. nov., (c) R. leptocornis sp. nov. and (d) R. macaronesiense sp. nov. Vertical arrows point to the anterior cavity of the metapleura (present in a, b and c, absent in D) while diagonal arrows indicate the posterior incision of the metapleura (present in c and d, absent in a and b).

Figure 2. Scanning electron microscopy (SEM) images of the pronotal plate of (a) female Rhoptromeris dichromata sp. nov., (b) male R. leptocornis sp. nov., (c) female R. koponeni sp. nov., and (d) female R. macaronesiensis sp. nov.

Figure 3. Habitus of Rhoptromeris dichromata sp. nov. (a: female, b: male), Rhoptromeris koponeni sp. nov. (c: female, d: male), Rhoptromeris leptocornis sp. nov. (e: female, f: male) and Rhoptromeris macaronesiesis sp. nov. (g: female, h: male).

Figure 6. Scanning electron microscopy (SEM) images of the scutellum of (a) female Rhoptromeris dichromata sp. nov., (b) female R. koponeni sp. nov., (c) male R. leptocornis sp. nov., and (d) female R. macaronesiensis sp. nov.