Megastigmus suspectus Borries, 1895

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 : 210-213

Megastigmus suspectus Borries

(figures 5, 8, 29, 45, 66, 84, 104, 122, 142, 160)

Megastigmus suspectus Borries, 1895: 29 . X Syntypes (number unkown), Bornholm , Denmark (?ZMUC, according to Hussey, 1954b; not found in ZMUC [not examined]).

Megastigmus piceae Seitner, 1916: 315–317 . 3 X syntypes, Idria, ‘ Tannensamen’ (NMW [examined]). Synonymy by Escherich, 1938: 369.

Megastigmus bornmülleriana Hussey, 1957: 253 . Holotype X, Yenice , Turkey (BMNH [examined]). Synonymy by Boucĕk, 1970b: 269.

Female

Body length (without ovipositor) 5.2 mm. Body mostly black with a few yellowish patterns. Head with face yellow except a brown, triangular patch on clypeus and a small brown spot on supraclypeal area; remainder of head with a large black patch extending from antennal scrobe to frons, ocellar area, occiput, temple and reaching outer part of gena; eye surrounded by yellow on ventral margin. Pilosity mostly black on head, including lower face. Antenna brown with scape yellow beneath. Thorax mostly black, except lateral panel of pronotum yellow. Pilosity black on thoracic dorsum. Legs brownish yellow, with fore- and mid-coxa black at the base but yellow apically and hind coxa entirely black; remainder of legs brownish yellow except hind femur brown dorsally. Propodeum black. Gaster dark brown to black on dorsum, brownish yellow latero-ventrally. Ovipositor sheaths black.

Head 1.5× as broad as long in dorsal view. Antennal scape as long as pedicel, anellus and first funicular segment combined (figure 29). Pronotum and mesoscutum with coarse cross-striae, the striae being V-shaped near the posterior margin of the mid-lobe of mesoscutum. Scutellum 1.3× as long as broad, the anterior part reticulate-striate, the frenal area longitudinally wrinkled (figure 142) or reticulate (Hussey, 1957). Forewing stigma very elongate, 2.6× as long as wide; upper part of stigmal vein comparatively very elongate, 1.6× as long as stigma width; uncus 0.5× as long as upper part of stigmal vein (figures 8, 66). Propodeum with a double median carina (Hussey, 1954). Ovipositor sheaths 1.1× longer than body. Distal part of the dorsal valve of ovipositor with a large second tooth (figure 104).

Male

Body length 3.8 mm. Body colour black and yellow. Head mostly yellow except a rounded, brown marking at the centre of each cheek, and a black patch extending on frons, ocellar area, occiput and temple and reaching gena. Pilosity mostly dark on lower face, but including some pale hairs, remainder of head with black pilosity. Antenna brown with scape and pedicel yellowish beneath. Thoracic dorsum entirely black. Lateral panel of pronotum, prepectus, mesopleuron yellow except a light brown patch on upper mesepisternum and lower mesepimeron. Fore coxa yellow, mid-coxa light brown, hind coxa black except apical extremity yellow; remainder of legs yellow. Propodeum black. Gaster with dorsum dark brown except on last tergum; lateral and ventral parts orange-yellow except first sternum and base of second sternum dark brown.

Head rounded, 1.2× as broad as long in dorsal view. Antennal scape smaller (0.9×) than pedicel, anellus and first funicular segment combined; first funicular segment 2× as long as broad, the following segments tending to subquadrate (figure 45). Pronotum and mesoscutum with coarse cross-striae, the striae being V-shaped near the posterior margin of the mid-lobe of mesoscutum. Scutellum 1.3× as long as broad, the anterior part reticulate-striate, the frenal area with longitudinal carinae (figure 160). Forewing stigma elongate-oval, 1.8× as long as wide; upper part of stigmal vein comparatively elongate, 1.1× as long as stigma width; uncus 0.4× as long as upper part of stigmal vein (figure 84). Propodeum with a sinuous median carina. Aedeagus rounded, smaller than digitus; digitus with four teeth (figure 122).

Variation

The above description is based on the type material of M. piceae for female and, from male, on a specimen emerged from Abies alba at Piwniczna, Poland (1977, M. Skrzypczyńska leg.), deposited at MNHN. In the other examined specimens, body length varied from 3.5 to 5.7 mm in females, from 3.5 to 4.2 mm in males. The dark markings on lower face of female may be reduced to a small spot on supraclypeal area (type material of M. bornmülleriana ) or to a brownish spot at the centre of each cheek (some specimens from Poland). Conversely, black could invade most of the face, yellow being limited to a small spot below each torulus, and a lateral band from side of clypeus to gena, then extending along inner egde of eye to parascrobal area (specimens from eastern and southeastern France). The yellow colour on lateral panel of pronotum also disappeared in the type material of M. bornmülleriana . Colour variations affected coxae. The fore coxa was entirely yellow and the midcoxa entirely black in some paratypes of M. piceae . Variation in the sculpture of scutellum were also observed. The frenal area could be reticulate ( M. bornmülleriana ; Hussey, 1957). The median carina on propodeum was simple and sinuous in some specimens from Poland but absent in most specimens from the arboretum of Les Barres, France. The relative length of the exserted part of ovipositor sheaths varied from 1.1 to 1.2× the body length.

Some males from Poland showed colour patterns lighter or darker than that of the type. Lighter forms presented a face entirely yellow, and lateral parts of thorax quite entirely yellow with only a small, indefinite light brown spot on lower mesepimeron. However, hind coxa always remained mostly black. In darker forms, the thorax was quite entirely jet black with only the lateral panel of pronotum yellow, and the basal part of fore coxa, mid-coxa and hind coxa were black as well as the dorsal part of hind femur, the remainder of legs being yellow .

Sex ratio

Reproduces usually by thelytokous parthenogenesis, only a few males having been recorded (e.g. 3 W:192 X, Skrzypczyńska, 1978; 0 W:441 X, Lessmann, 1974b; 0 X:125 X, Ostermeyer, 1990).

Hosts

Develops primarily in seeds of firs ( Abies spp. , Pinaceae ) native to central Europe, North Africa and Asia Minor. Damage was recorded in the natural range of A. alba (among others, Kapuściński, 1966; Lessmann, 1974b; Nanu, 1976, 1980; Skrzypczyńska, 1978, 1989b, 1998; Krístek et al., 1992; Skrzypczyńska et al., 1998), A. bornmülleriana (Schimitschek, 1944; Hussey, 1957; Çanakçioglü, 1959, 1969, 1993; Boucĕk, 1970b), A. cephalonica (Kailidis and Georgevits, 1970, 1972), A. equitrojani (USNM) , A. nordmanniana (Nikol’skaya, 1952; Boucĕk, 1970b; Stadnickii et al., 1978) and A. numidica (JPF) . The chalcid has extensively colonized plantations of the same species well outside their natural range (e.g. A. alba , A. bornmülleriana , A. equi-trojani , A. nordmanniana and A. pinsapo in Denmark, Ochsner and Jensen, 1998; A. cephalonica in Italy, USNM). Most of the Mediterranean fir species planted in arboreta in France were also attacked ( A. borisii-regis , A. cilicica , A. nebrodensis , A. numidica and A. pinsapo ; Roques, 1983; Ostermeyer, 1990; AR). Damage observed in the range of the northern Abies sibirica and in that of the far-eastern A. nephrolepis (Stadnickii et al., 1978) may be caused by Megastigmus specularis and M. borriesi , respectively. However, M. suspectus was observed to shift on A. sibirica in French arboreta (AR) as well as on the eastern Asian species, A. homolepis , in Denmark (Ochsner and Jensen, 1998). Attacks were recorded on some North American firs introduced in Europe, such as A. grandis (McNeill, 1946, Wall, 1984; Krístek et al., 1992) and A. concolor (Jespersen and Lomholdt, 1983) , but Ochsner and Jensen (1998) did not find any damage of M. suspectus on North American firs during a large survey in Denmark. Damage to seeds of Cedrus brevifolia were also observed, but very scarcely, in French arboreta (Ostermeyer, 1990; AR) as well as damage to C. atlantica in southern France (Fabre, unpublished observations). Records on Picea species (e.g. Lessmann, 1962) are probably misidentifications to be attributed either to M. strobilobius or to M. atedius .

Distribution

Widespread over Europe to the Caucasus, at least. Presently recorded from: Austria (Schimitschek, 1935); former Czechoslovakia (Cĕrmak, 1952; Krístek et al., 1985, 1992); Denmark (Hoffmeyer, 1931b; Jespersen and Lomholdt, 1983; Ochsner, 1998; Ochsner and Jensen, 1998; Jensen and Ochsner, 1999); France (Roques, 1983; Pintureau et al., 1991; AR); Germany (Lessmann, 1974b); Great Britain (Laidlaw, 1931; McNeill, 1946; Hussey, 1954b; Boucĕk, 1970b); Greece (Kailidis and Georgevits, 1970, 1972); Hungary (Györfii, 1956); Italy (AR; USNM); Ireland (Boucĕk, 1970b); Poland (Kozikowski and Kuntze, 1936; Tyszkiewicz, 1949; Kapuściński, 1966; Skrzypczyńska, 1978, 1981b, 1984b, 1985, 1989b, 1996, 1998; Bąk, 1994, 1995, 1999; Skrzypczyńska et al., 1998; AR); Romania (Nanu, 1976, 1980; Olenici and Olenici, 2000); Russia: European part to the Caucasus (Milliron, 1949; Nikol’skaya, 1952; Nikol’skaya and Zerova, 1978; Stadnickii et al., 1978, as M. strobilobius ; Zerova and Seryogina, 1994); Sweden (Hansson, 1991); Slovakia (Kelbel, 1995); Turkey (Schimitschek, 1944; Hussey, 1957; Çanakçioglü, 1959, 1968, 1969, 1993; USNM); Ukraine: Crimea (Padii, 1974; Nikol’skaya and Zerova, 1978); Yugoslavia: Slovenia (Seitner, 1916). Also present in North Africa: Algeria (JPF).

Comments

To date, six other species of seed chalcids were observed in fir seeds of the West Palearctic region: M. milleri , M. pinsapinis , M. pinus , M. rafni , M. schimitscheki and M. specularis . For separating these species, see the chapter concerning M. milleri .

A species closely resembling those originating from the Far East, M. borriesi Crosby was found in seeds of A. veitchii in a Danish arboretum (Ochsner, 1998; Jensen and Ochsner, 1999) but its establishment in Europe needs to be confirmed. We examined specimens of M. borriesi from Japan (1 X from A. sachalinensis, Bibai , Hokkaido, 12 June 1992, K. Kamijo leg.) and Korea (1 X from A. veitchii , April 1969, D. C. Poe, USNM). The body was entirely black except gaster dark brown. They differed from the female of M. suspectus by a much longer scape, about as long as the combined length of the first two and a half of the third funicular segment, a pedicel as long as the first funicular segment, the pilosity mostly pale on lower face, a smooth shining frenal area, and an elongate-oval stigma as Kamijo (1962) already pointed out.

Material examined

Algeria: 1 X, Abies numidica, Djebel Ouahch , June 1998 ( JPF). Denmark: 1 X (slide), ex. A. nordmanianna, Langesø, Fyn , 10 April 1929, Hoffmeyer coll. ( ZMUC); 1 X (slide with wing, head, thorax), ex. A. nordmanianna, Langesø, Fyn , 10 April 1929, Hoffmeyer coll. ( ZMUC); 4 X (slide with wings), ex. A. nordmanianna, Langesø, Fyn, 1930 , Hoffmeyer coll. ( ZMUC). France: 15 X, ex. A. alba, Les Barres (45), May 1981 ( AR); 4 X, ex. A. bornmülleriana, Les Barres , May 1981 ( AR); 6 X, ex. A. cephalonica, Les Barres , May 1981 ( AR); 5 X, ex. A. cilicica, Les Barres , May 1981 ( AR); 12 X, ex. A. nordmanianna, Les Barres , May 1981 ( AR); 2 X, A. nebrodensis, Les Barres , May 1993 ( AR); 4 X, ex. A. numidica, Les Barres , May 1997 ( AR); 7 X, ex. A. pinsapo, Les Barres , May 1990, R. Ostermeyer ( AR); 3 X, ex. A. sibirica, Les Barres , May 1990, R. Ostermeyer ( AR); 4 X, ex. A. alba, La Joux (39), June 1993, French National Forestry office ( AR); 10 X, ex. A. alba, Gerardmer (88), June 1993, French National Forestry office ( AR); 1 X, Rouillon (76), 12 May 1935, Granger ( MNHN); 2 X, ex. Cedrus brevifolia , les Barres, May 2000, M. Auger-Rozenberg ( AR). Italy: 2 X, ex. A. alba, Vallombrosa (FI) , May 2000, M. Auger-Rozenberg ( AR); 1 X, ex. A. cephalonica, PQ US quarantine service ( USNM). Poland: 2 W, ex. A. alba, Piwniczna , 26 March 1977 (in laboratory); 1 W, ex. A. alba, Piwniczna, Łomnica Forest , 29 March 1977 (laboratory conditions) ( MS); 1 W, ex. A. alba, Piwniczna , 22 February 1980 (laboratory conditions) ( MS); 7 X, ex. A. alba, Roztoczański Natl. Park , March 1986 (laboratory conditions) ( MS); 1 W, ex. A. alba, Lesko, Monasterzec Forest , April 1987 (laboratory conditions) ( MS). Slovenia: 3 X syntypes M. piceae , Idria ( NMW). Turkey: 1 X, holotype M. bornmulleriana , ex. A. bornmülleriana, Yenice , 10 March 1956 ( ZMUC); 1 X, K. Baş ( MNHN); 1 X, ex. A. equi-trojani, PQ US quarantine service ( USNM).