Megastigmus amicorum Boucĕk, 1969

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 : 149-152

Megastigmus amicorum Boucĕk

(figures 1, 12, 33, 49, 70, 88, 108, 125, 146) Megastigmus amicorum Boucĕk, 1970a: 37–39 . Holotype X, Biograd na Moru, Dalmatia

( NMP [not examined]. 2 X, 1 W paratypes, same data as holotype (MNHN [1 X examined]).

1 W paratype, Cmorg, Sutomore ( NMP [1 W examined]) .

Female

Body length (without ovipositor) 3.7 mm. Body orange yellow to dark brown. Head dark testaceous, darker than thorax, except supraclypeal and clypeal area yellowish. Pilosity pale on face, dark on remainder of head. Funicular segments of antenna dark brown but scape, pedicel and anellus yellow. Thoracic dorsum, including the sutures, uniformly orange yellow. Pilosity black on thoracic dorsum, pale on lateral parts. Legs orange yellow, distal part of tarsi black. Wings very setose;

†For France, numbers in brackets correspond to administrative departments. forewing stigma dark brown. Propodeum orange. Pilosity on callus and legs whitish, arising from black dots. Gaster dark brown. Ovipositor sheaths black.

Head about 1.5× as broad as long in dorsal view. Antennal scape elongate, about 4× as long as broad, 1.2× longer than pedicel, anellus and first funicular segment combined; pedicel relatively long, as long as first funicular segment; funicular segments 1–4 elongate, about 2.5× as long as wide (figure 12). Pronotum and mid-lobe of mesoscutum with coarse cross-striation. Anterior part of scutellum with fine transverse rugae, the frenal area with strong longitudinal carinae (figure 125). Forewing stigma roughly oblong, 1.6× as long as wide; upper part of stigmal vein comparatively short, about 4× as small as stigma length; uncus short, 0.7× as long as upper part of stigmal vein (figure 49). Propodeum without central carina. Ovipositor sheaths distinctly shorter (0.6×) than body, only 0.8× as long as thorax and gaster combined, 1.4× as long as gaster. Distal end of dorsal valve of ovipositor with strong teeth, the third median tooth broader than others (figure 88).

Male

Body length 3.8 mm. Body darker than in female. Face dark brown except clypeus light brown, temple and gena dark brown, frons and occiput yellow-orange to orange-brown. Antenna light brown except scape dark brown above. Pilosity pale on face, dark on remainder of head. Thoracic dorsum yellow to orange-brown but lateral parts (prepectus, mesopleuron, metapleuron) dark brown to black except lower mesepisternum brownish apically. Pilosity black on thoracic dorsum, pale on lateral parts. Anterior part of fore coxa dark brown, mid- and hind coxa entirely dark brown; middle part of femurs brown; remainder of legs yellowish. Wings very setose, forewing stigma little infuscated, dark brown. Propodeum black. Gaster black with small orange-yellow patch on both extremities.

Head about 1.3× as broad as long in dorsal view (figure 1). Antennal scape elongate, 1.3× as long as pedicel, anellus and first funicular segment combined; funicular segments 1–5 elongate, 2.2× as long as broad, about 1.2× longer than pedicel (figure 33). Anterior part of scutellum with fine transverse rugae, the frenal area with strong longitudinal carinae (figure 146). Forewing stigma quite circular, 1.2–1.3× as long as broad; upper part of stigmal vein comparatively very short, about 5.2× as small as stigma length; uncus short, 0.75× as long as upper part of stigmal vein (figure 70). Aedeagus elongate, with a narrow aedeagus, digitus with three teeth (figure 108).

Variation

In specimens other than type material, body length varied from 2.5 to 4.0 mm in females, from 2.5 to 4.5 mm in males. The relative length of the exserted part of female ovipositor varied from 0.6× to 0.7× the body length. Some male specimens, especially from Juniperus phoenicea (e.g. from Ericeira, Portugal) were lighter than the typical form, with the thorax entirely orange-yellow, and the stigma not infuscated at all .

Sex ratio Generally balanced (Roques, 1983).

Hosts

Develops in seeds of Mediterranean junipers ( Juniperus spp. , Cupressaceae ). Observed in J. oxycedrus (Boucĕk, 1970a, 1977; Nikol’skaya and Zerova, 1978; Roques, 1983 as Megastigmus sp. ; Roques et al., 1984; El Hassani and Messaoudi, 1986 as Megastigmus sp. ; Bouaziz, 1993; Zerova and Seryogina, 1994; Bouaziz and Chakali, 1998; El Alaoui El Fels, 1998), J. phoenicea (Roques, 1983; Roques et al., 1984; El Alaoui El Fels, 1998) and likely to occur in J. excelsa in the eastern Mediterranean basin. Damage to seeds of J. thurifera were recorded in Corsica (Roques et al., 1984), but not in continental France where these seeds were attacked by M. bipunctatus . M. amicorum was not observed in seeds of common juniper ( J. communis ) in the areas where common juniper co-exists with Mediterranean junipers, e.g. in southern France (Roques et al., 1984). Limited shifts of M. amicorum on to two exotic species of cypress, Cupressus arizonica and C. goveniana , were recently observed in cypress seed orchards of southeastern France (Roques et al., 1999b).

Distribution

Widely distributed in the Mediterranean basin within the range of Mediterranean junipers, i.e. coastal, Mediterranean and sub-Mediterranean vegetation levels. Observed in Bulgaria (Boucĕk, 1970a; Nikol’skaya and Zerova, 1978); southern France, including Corsica (Boucĕk, 1977; Roques et al., 1984; Sellenschlo, 1984b); Greece, including Crete (Roques et al., 1984; AR); Italy, including Sardinia (Boucĕk, 1977; Roques et al., 1984; AR); Portugal (AR); Spain (AR) but not observed in the Canary Islands although we reared large numbers of juniper cones from that area; Ukraine: Crimea (Nikol’skaya and Zerova, 1978); former Yugoslavia: Croatia, Bosnia, Montenegro, Serbia (Boucĕk, 1970a, 1977; AR). Present in North Africa: Morocco (High and Middle Atlas; El Hassani and Messaoudi, 1986; El Alaoui El Fels, 1998; AR); Algeria (Bouaziz, 1993; Bouaziz and Chakali, 1998; AR); Tunisia (AR).

Comments

Another species, M. bipunctatus , develops in seeds of junipers in the West Palearctic region. Females of M. amicorum are easily distinguished by comparing the relative size of the ovipositor sheaths (1.2× longer than gaster versus 0.9× as long as gaster or less in M. bipunctatus ). The males of M. amicorum , even of dark form, show a lighter thoracic dorsum, entirely orange-yellow to orange-brown, than most specimens of M. bipunctatus whose mesoscutum is olive-brown. Light forms of M. bipunctatus with a thoracic dorsum entirely yellowish can be confusing but the stigma shape, quite circular in M. amicorum (figure 70) versus oval-elongate (figure 72) in M. bipunctatus , allows one to differentiate between the two species. In addition, the aedeagus of M. amicorum is narrow and elongate (figure 108) whilst that of M. bipunctatus is short and rounded (figure 110).

Two other species, M. wachtli and M. atlanticus , attack cypress seeds within the region. Diagnostic characters allowing separation of the females are given in the chapter concerning M. atlanticus . For males, the upper part of the stigmal vein is comparatively longer in M. amicorum (1.5–2× as long as uncus; figure 70) than in M. wachtli (2.0x smaller than uncus; figure 86). The two species also differ by the genital apparatus, digitus bearing six teeth in M. wachtli (figure 8) and only three in M. amicorum (figure 108). Males of M. atlanticus are not yet known.

Material examined

Algeria: 1 X, 2 W, ex. J. oxycedrus, Meurdja Arboretum , June 1993, K. Bouaziz ( AR) . Croatia: 2 X, 1 W paratype, Biograd na Moru , 12 July 1969, Z. Boucĕk ( MNHN) ; 7 X, 8 W, ex. J. oxycedrus, Dubrovnik , July 1990 ( AR) . France: 8 X, 5 W, ex. Juniperus oxycedrus, Ponte Leccia (Corsica) , June 1981 ( AR) ; 11 X, 12 W, ex. J. oxycedrus, Cassis (13), June 1983 ( AR) ; 6 X, 5 W, ex. J. oxycedrus, Sigean (11), June 1983 ( AR) ; 4 X, 6 W, ex. J. phoenicea, Rondinara (Corsica) , June 1982 ( AR) ; 10 X, 8 W, ex. J. phoenicea, Lubéron Mt (84), July 1983, J. P. Fabre ( AR) ; 5 X, 8 W, ex. J. thurifera, Cuccia (Corsica) , June 1982 ( AR) ; 1 X, 2 W, ex. Cupressus arizonica, Le Rouet seed orchard (83), August 1996, ( AR) ; 4 X, 2 W, ex. C. goveniana, Le Rouet seed orchard (83), August 1995 ( AR) . Greece: 6 X, 7 W, ex. J. phoenicea, Kalogria (Peloponnesis) , June 1991 ( AR) ; 9 X, 8 W, ex. J. phoenicea, Romanu (Peloponnesis) , June 1991 ( AR) . Italy: 8 X, 4 W, ex. J. oxycedrus , Bari , July 1990 ( AR) . Morroco : 4 X, 4 W, ex. J. phoenicea, Asni, Marrakech , 27 June 1989, A. El Hassani ( AR) ; 6 X, 5 W, ex. J. oxycedrus, Tizrag , July 1999 ( AR) ; 3 X, 2 W, ex. J. thurifera, Tizrag , July 1999 ( AR) . Portugal: 2 X, 1 W, ex. J. phoenicea , Cabo Espichel , July 1993 ( AR) ; 2 X, 1 W, ex. J. phoenicea, Corveiro (Algarve) , July 1993 ( AR) ; 10 X, 8 W, ex. J. phoenicea, Ericeira , July 1994 ( AR) . Spain: 3 X, 5 W, ex. J. phoenicea, Pueblo San Miguel (Valencia) , July 2001, P. García-Fayos ( AR) . Tunisia: 2 X, 3 W, ex. J. oxycedrus, Tabarka , June 1987 ( AR) . Yugoslavia: 1 X paratype, Cmorg, Sutomore ( Montenegro ), 6 July 1968, Z. Boucĕk ( NMP) ; 5 X, 4 W, ex. J. oxycedrus, Boka Kotorska ( Montenegro) , June 1990 ( AR) .