Megastigmus bipunctatus (Swederus)

Roques, A. & Skrzypczyńska, M., 2003, Seed-infesting chalcids of the genus Megastigmus Dalman, 1820 (Hymenoptera: Torymidae) native and introduced to the West Palearctic region: taxonomy, host specificity and distribution, Journal of Natural History 37 (2), pp. 127-238 : 159-163

Megastigmus bipunctatus (Swederus)

(figures 4, 15, 35, 52, 72, 91, 110, 128, 148)

Pteromalus bipunctatus Swederus, 1795: 205 . Sex and number unknown, Sweden (depository unknown).

Torymus erythrothorax Nees, 1834: 65 . Syntypes W, locality unknown (destroyed; Grissell, 1999). Synonymy by Dalla Torre, 1898: 286.

Megastigmus microspilus Thomson, 1876: 62 . Syntype X, Sweden ( Museum of Zoology , Lund [not examined]. Synonymy by Hoffmeyer, 1931b: 266.

Megastigmus microphilus Thomson, Dalla Torre, 1898: 287 [misspelling].

Megastigmus kuntzei Kapuściński, 1946: 12–19 , 120–129. Holotype X, Myslenice , Poland (NHMK [not examined]); 1 X paratype, same data as holotype (NHMK [examined]); 1 W paratype, Wąbrzeżno, Poland (NHMK [examined]). Synonymy by Nuorteva 1967: 123.

Female

Body length (without ovipositor) 2.7 mm. Body colour predominantly brownish olive-grey and black. Head olive to grey brownish except vertex, gena and lower face brownish black, and occipital area black. Pilosity pale on lower face, black on remainder of head. Antenna grey brownish with scape, pedicel and anellus brownish yellow. Pronotum light olive brown. Mesoscutum brownish with anterior parts of mid-lobe and lateral lobes darker; notuli black. Scutellum and axilla brownish yellow except anterior part of axilla dark brown. Remaining parts of thorax black. Pilosity black on thoracic dorsum. Fore coxa brown at basis, remainder yellowish brown; mid- and hind coxa brown; remainder of legs yellowish brown except hind femur brown on dorsal side. Wings slightly blackened, very setose; forewing stigma brown. Propodeum black except callus brown. Gaster brownish yellow to black, with the last tergum grey. Ovipositor sheaths black.

Head about 1.3× as broad as long in dorsal view (figure 4). Eyes hardly protruding, large and wide-oval; temple in dorsal view about 0.4× length of eye. Postocellar distance about 2× as long as ocellocular distance. Relative measurements: eye 17:15, malar space 5, width of head 22, width of frons 14. Antenna scape slightly longer (1.1×) than combined length of pedicel, anellus and first funicular segment; pedicel about 2× as long as broad, slightly longer (1.1×) than first funicular segment; funicular segments about 2× as long as wide (figure 15). Pronotum and mid-lobe of mesocutum with strong transverse carinae. Scutellum about 1.1× as long as broad, the anterior part with arcuate, coarse rugae; frenal area smooth with a few strong longitudinal carinae (figure 128). Propodeum with central carina (figure 128). Forewing stigma roughly ovoid, about 1.3× as long as broad; upper part of stigmal vein half as long as width of stigma; uncus very short, 0.4× as long as upper part of stigmal vein (figure 52). Ovipositor sheaths much shorter (0.4×) than body, slightly shorter than gaster (0.9×). Distal part of the dorsal valve of ovipositor with a very large third median tooth (figure 91).

Male

Body length 3.0 mm. Body colour predominantly brownish olive-grey and black. Head black except parascrobal area and clypeus olive-brown. Pilosity pale on lower face, black on remainder of head. Antenna grey brownish with scape, pedicel and anellus brownish yellow. Pronotum light olive-brown. Mesoscutum brownish with anterior parts of mid-lobe and lateral lobes darker; notuli black. Scutellum and axilla brownish yellow except anterior part of axilla dark brown. Metanotum with dorsellum yellowish and lateral panel dark brown. Lateral parts of thorax mostly dark brown except prepectus, tegula and acropleuron brownish. Pilosity black on thoracic dorsum. Anterior part of fore coxa light brown, mid-and hind coxa dark brown, remainder of legs yellow. Wings slightly blackened, very setose; forewing stigma dark brown. Propodeum shining black. Gaster mostly brownish black with a few lighter stripes on sides.

Head about 1.3× as broad as long. Antenna scape slightly longer (1.1×) than combined length of pedicel, anellus and first funicular segment; pedicel slightly smaller (0.9×) than first funicular segment; funicular segments 1–6 twice as long as broad (figure 35). Pronotum and mid-lobe of mesocutum with strong transverse carinae. Scutellum more elongate than in female, about 1.3× as long as broad, the anterior part with arcuate, coarse rugae; frenal area smooth with a few strong longitudinal carinae (figure 148). Forewing stigma oval-elongate, about 1.4× as long as broad; upper part of stigmal vein comparatively short, about as long as onethird of stigma width; uncus short, 0.6× as long as upper part of stigmal vein (figure 72). Propodeum without median carina. Aedeagus rounded, digitus with

three teeth (figure 110).

Variation

The above description is based on the type material of M. kuntzei . In the other specimens we examined, body length varied from 1.8 to 3.1 mm in females, from 1.8 to 3.2 mm in males. Little variation was observed in female colour all over Europe. In specimens originating from the French Alps, the olive-grey colour of pronotum was replaced by dark orange-yellow. Most males of the same origin emerging from Juniperus communis were much darker than the type material, with the dorsum and lateral parts of thorax entirely dark brown except the pronotum orange-yellow, the coxae mostly black except distal end of fore coxa and a conspicuous black patch on femurs. In contrast, the Alpine specimens emerged from J. sabina showed a thoracic dorsum predominantly orange-yellow except indefinite small brownish spots on anterior parts of mesoscutum. However, the propodeum was always partly black at least, with a brownish callus, and the gaster quite entirely black with a few small, lateral brownish spots at the apical extremity. A few individuals from both sexes presented a central carina on propodeum.

Moroccan specimens of both sexes emerged from Juniperus thurifera appeared to differ largely from the type material. Both male and female presented a predominant dark yellow colour on head and thorax, with a pronotum pale yellow, and black markings limited to notuli, suture of axilla and a line on lateral panel of metanotum. In female, gaster was predominantly orange-yellow with a dark brown patch on dorsum of terga III–V. In male, gaster presented a dark brown petiole and four dark brown lateral stripes alternating with dark yellow lateral stripes. Genetic tests are presently carried out to understand whether these Moroccan specimens correspond to a different species.

Sex ratio Balanced in most cases (Vikberg, 1966; Lessmann, 1974b; Roques, 1983).

Hosts

Specialized in seeds of alpine junipers ( Juniperus spp. , Cupressaceae ). Many records from J. communis (= J. nana ; among others, Kapuściński, 1946; Vikberg, 1966; Nuorteva, 1967; Lessmann, 1974a; Göttsche, 1976; Stadnickii et al., 1978; Roques, 1983; Voolma, 1986; Krístek et al., 1992; Dolgin, 1994; García, 1997, 1998), and J. sabina (Roques, 1983; García et al., 1997). The submediterranean species, J. thurifera , was attacked in the Alps (Roques et al., 1984) and Morocco (El Hassani and Messaoudi, 1986 as Megastigmus sp. ; El Alaoui El Fels et al., 1999 as Megastigmus sp. ; AR). Records from J. excelsa Bieb. (Seitner in Wall, 1984) may refer to M. amicorum .

Distribution

Widely distributed all over Europe. Extends to western Siberia at least. Recorded from Austria (Milliron in Lessmann, 1974b; Wall, 1984); former Czechoslovakia (Cĕrmak, 1952; Boucĕk, 1954; Krístek et al., 1992); Denmark (Hoffmeyer, 1931b; Jespersen and Lomholdt, 1983; Ochsner, 1998; Jensen and Ochsner, 1999); Estonia (Voolma, 1986; Luik and Voolma, 1988); Finland (Vikberg, 1966; Nuorteva, 1967); France including Corsica (Roques, 1983; Roques et al., 1984); Germany (Gäbler, 1962; Lessmann, 1974a, 1974b; Göttsche, 1976; Schneider, 1985); Great Britain (Laidlaw, 1931; Boucĕk, 1970b); Hungary (Györfi, 1962); Italy (Lessmann, 1974b; AR); Morocco (El Hassani and Messaoudi, 1986 as Megastigmus sp. ; El Alaoui El Fels et al., 1999 as Megastigmus sp. ; AR); Poland (Kapuściński, 1946; Borusiewicz and Kapuściński, 1948); Romania (Kapuściński, 1946); Russia from Kola peninsula and Karelia to Komi Republic, Transcaucasia, Uzbekistan, Khazakhstan and western Siberia (Nikol’skaya, 1952, 1966; Vikberg, 1966; Nikol’skaya and Zerova, 1978; Stadnickii et al., 1978; Dolgin, 1994); Sweden (Wall, 1984; AR); Spain (García, 1997, 1998; García et al., 1997; AR); Switzerland (Wall, 1984; Hanson, 1991); Ukraine (Zacher, 1932); former Yugoslavia: Montenegro, Serbia, Slovenia (Boucĕk, 1977).

Comments

Another species, M. amicorum , may infest seeds of incense cedar, J. thurifera , in some parts of the range. Diagnostic characters for separating the two species are given in the chapter concerning M. amicorum .

Material examined

France: 2 X, 3 W, ex. Juniperus communis, Fontainebleau (45), May 1979 ( AR); 8 X, 5 W, ex. J. communis, Marcillac (12), elev. 400 m, July 1991 ( AR); 6 X, 8 W, ex. J. communis, Névache (05), elev. 1600 m, August 1988 ( AR); 5 X, 10 W, ex. J. communis ( J. nana ), Névache, elev. 1850 m, August 1988 ( AR); 22 X, 25 W, ex. Juniperus communis, Briançon (05), elev. 1550 m, July 1983 ( AR); 6 X, 4 W, ex. J. sabina, Saint Crépin (05), elev. 990 m, July 1990 ( AR); 4 X, 3 W, ex. J. thurifera, Saint Crépin , July 1990 ( AR). Italy: 6 X, 5 W, ex. J. communis,Vittignano (BO) , May 1992 ( AR). Morroco: 3 X, 2 W, ex. J. thurifera, Tizrag , July 1999 ( AR); 4 X, 5 W, ex. J. thurifera, Lazaden , July 1999 ( AR); 3 X, 2 W, ex. J. thurifera, Tizrag , July 2000, M. A. El Alaoui El Fels ( AR). Poland: 1 W, ex. J. communis, Wąbrzeżno , forest district Leśno, 15 June 1946, T. Wiśniewski (coll. S. Kapuściński, Kraków, MS); 4 X, 4 W, ex. J. communis, Karpaty, Pochyba (Kraków) , 9 August 1957, S. Kapuściński ( MNHN). Sweden: 2 X, 1 W, ex. J. communis, Bogesund , July 2000 ( AR). Spain: 10 X, 10 W, ex. J. communis, Sierra Nevada, 1997 , D. García ( AR); 10 X, 10 W, ex. J. sabina, Sierra Nevada, 1997 , D. García ( AR).