Megastigmus wachtli Seitner, 1916

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 : 216-218

Megastigmus wachtli Seitner

(figures 10, 31, 47, 68, 86, 106, 144, 162)

Megastigmus wachtli Seitner, 1916: 320–321 . 2 X and 2 W syntypes, Sinj , Dalmatia, Croatia (NMW [examined]).

Female

Body length (without ovipositor) 3.9 and 4.1 mm. Body entirely dirty yellow. Head light yellow. Pilosity pale on face, black on head dorsum. Antenna dark brown, scape and pedicel yellow. Thorax predominantly dirty yellow to straw yellow, with pronotum lighter than other parts, and anterior margin and sides of mesonotum darker, orange to light brownish. Pilosity black on thoracic dorsum. Legs dirty yellow. Wings subhyaline; forewing stigma light brown, without any infuscation. Propodeum brownish yellow. Gaster dirty yellow but base of first apparent tergum brown to black. Ovipositor sheaths black.

Head about 1.2× as broad as long in dorsal view, with large scrobes. Antennal scape very elongate, as long as combined length of pedicel, anellus, first and half of second funicular segments; funicular segments elongate, about twice as long as wide, except the first segment (figure 31). Pronotum and mesoscutum with strong, transverse striae. Scutellum 1.2× as long as broad, the anterior part with coarse transverse striation, the frenal area mostly smooth with a few short longitudinal carinae extending from the frenal line and weak longitudinal wrinkles on the lateral parts (figure 144). Forewing stigma oval-elongate, about 1.6× as long as broad; upper part of stigmal vein comparatively very short, 0.2× as long as stigma length; uncus as long as upper part of stigmal vein (figure 68). Propodeum without median carina. Ovipositor sheaths about 1.3× longer than body. Distal part of dorsal valve of ovipositor with a large third median tooth (figure 106).

Male

Body length 3.5 and 3.8 mm. Body colour mostly dirty yellow. Head light yellow. Face brownish to brownish black, dorsum of head yellowish. Pilosity pale on face, black on remainder of head. Antenna dark brown, except scape and pedicel yellow. Thorax predominantly straw yellow, with pronotum lighter than other parts, and anterior margin and sides of mesonotum darker, orange to light brownish. Pilosity on thoracic dorsum black. Wings very setose; forewing stigma dark brown, surrounded by a distinct infuscation. Propodeum yellowish. Gaster mostly dark brown with more or less large lateral yellow patches; distal segment mostly yellowish.

Head about 1.2× as broad as long in dorsal view. Antennal scape elongate, 1.1× as long as combined length of pedicel, anellus, first and half of second funicular segments; funicular segments elongate, twice as long as wide (figure 47). Pronotum and mesoscutum with coarse transverse striae. Scutellum 1.1× as long as broad, the anterior part densely cross-striated, the frenal area mostly smooth with a few longitudinal wrinkles (figure 162). Forewing stigma enlarged, about 1.4× as long as wide; upper part of stigmal vein very short, about 0.1× as long as stigma length; uncus slightly longer than upper part of stigmal vein (figure 86). Propodeum without median carina. Aedeagus small, narrow, sinuated at the apex; digitus with six teeth (figure 10).

Variation

The above description is based on the type material from Croatia. In the other examined specimens, body length varied from 3.0 to 4.5 mm in females, from 3.0 to 4.3 mm in males. Few variations in female colour were noticed. An additional basal brownish stripe was sometimes observed on pronotum, and dark brownish, narrow lateral stripes were noticed on gaster of females from Tunisia. Males appeared more variable. Specimens lighter than the type were observed in most of the examined populations, these chalcids being quite entirely light yellow except a few brown spots on dorsum of gaster. Darker forms were observed in most populations from Greece and North Africa , especially in Tunisia. These specimens differed from the type colour by the following patterns: thoracic dorsum mostly dark brown with a greyish pronotum and a noticeable black anterior margin of mid-lobe of mesoscutum; mesopleuron, metapleuron and propodeum black except callus dark brown; gaster black except the apical part brown; mid- and hind coxa entirely black; fore coxa, mid-and hind femur black on dorsal part .

Sex ratio

Ratio of males to females varies from 0.5 to 1.7 according to location (Bouaziz and Chakali, 1998; Roques et al., 1998a).

Hosts

Develops exclusively in seeds of cypress ( Cupressus spp. , Cupressaceae ). Most records concerned damage to the Mediterranean evergreen cypress, C. sempervirens (Seitner, 1916; Escherich, 1938; Çanakçioglü, 1959, 1968, 1969; Boucĕk, 1977; Roques, 1983; Roques and Raimbault, 1986; Bouaziz, 1993). The Moroccan cypress, C. atlantica , was also attacked in its natural area (AR). In Europe and North Africa, the chalcid shifted on to some exotic cypress species introduced from California ( C. abramsiana , C. arizonica , C. bakeri , C. goveniana [Roques et al., 1999a; AR] and C. macrocarpa [Roques and Raimbault, 1986; Bouaziz, 1993; Bouaziz and Chakali, 1998]) and central America ( C. lusitanica ; AR), but damage was usually limited on these species. Although extensively surveyed in the French seed orchards, some other exotic cypress species did not show any chalcid infestation ( C. cashmeriana Royle , C. chenghiana S. Y. Yu , C. duclouxiana Hickel , C. forbesii (Jeps.) R. M. Beauchamp , C. funebris Hendl. , C. goveniana , C. guadalupensis S. Wats. , C. lusitanica benthami [Endl.] Carr., C. macnabiana Murr. , C. pygmaea (Lemm.) Sargent , C. macnabiana Murr. , C. sargentii Jepson , C. torulosa D. Don. ; Roques et al., 1999a).

Distribution

Recent genetic studies showed that the species probably originated from the native range of the Mediterranean cypresses, i.e. the southeastern Mediterranean basin (Carcreff, 1996; Roques et al., 1999a). At the present time, it is distributed all over the Mediterranean basin, everywhere that cypress has been naturalized. Recorded from most countries of southern Europe: Albania (Roques et al., 1999b; AR); France (Roques and Raimbault, 1986; AR); Greece mainland and islands including Crete, Rhodes, Kos and Samos (Roques and Raimbault, 1986; Roques et al., 1998, 1999b); Italy (Masi, 1944; Covassi and Binazzi, 1979; Roques and Raimbault, 1986; Guido et al., 1995, 1998); Malta (Roques et al., 1999b); Portugal (AR); Turkey (Schimitschek, 1944; Çanakçioglü, 1959, 1969, 1993; Roques et al., 1999b); former Yugoslavia ( Croatia, Montenegro, Slovenia: Seitner, 1916; Escherich, 1938; Boucĕk, 1977; AR). Observed in North Africa: Algeria (Bouaziz, 1993; Bouaziz and Chakali, 1998); Morocco (El Alaoui El Fels, 1998; AR); Tunisia (Ben Jamaa and Roques, 1998; AR). It is probably present in the other countries extending along the Mediterranean and the Black Sea. Also introduced with cypress seeds into European countries of higher latitudes but climate usually prevented naturalization (Roques and Raimbault, 1986). However, adults were recently found near Paris, in northern France (AR).

Comments

Two other species, M. amicorum and M. atlanticus , attack cypress seeds within the area. Diagnostic characters allowing species to be separated are given in the chapter concerning M. atlanticus for females and in the chapter concerning M. amicorum for males.

Material examined

Albania: 3 X, 5 W, ex. Cupressus sempervirens, Himaze , August 1987, F. Llubani ( AR); 2 X, 2 W, ex. C. sempervirens , Tirana, September 1996, G. Demolin ( AR); 2 X, 4 W, ex. C. sempervirens, Vajkani , September 1996, G. Demolin ( AR). Algeria: 1 X, 1 W, ex. C. macrocarpa, Meurdja Arboretum , 12 May 1993 (in laboratory), K. Bouaziz ( AR); 2 X, 4 W, ex. C. sempervirens, Meurdja Arboretum , April 1993 (in laboratory), K. Bouaziz ( AR). Croatia: 2 X, 2 W syntypes, Sinj, Dalmatia, 11–15 August 1915, Seitner ( NMW); 2 X, 9 W, ex. C. sempervirens, Dubrovnik , August 1987 ( AR). France: 2 X, 3 W, ex. C. abramsiana, Le Rouet (83), August 1996 ( AR); 3 X, 2 W, ex. C. arizonica, Thedirac (46), August 1982 ( AR); 5 X, 4 W, ex. C.arizonica, Les Caunes (83), August 1996 ( AR); 1 X, 1 W, ex. C. bakeri, Le Caneiret (83), August 1995 ( AR); 2 X, 2 W, ex. C. dupreziana, Ceyreste (13), August 1996 ( AR); 8 X, 3 W, ex. C. goveniana, Le Rouet (83), August 1995 ( AR); 15 X, 12 W, ex. C. sempervirens, Avignon (84), August 1983 ( AR); 8 X, 6 W, ex. C. sempervirens, Chateau-Arnoux (04), August 1983 ( AR); 7 X, 5 W, ex. C. sempervirens , Porto (Corsica), August 1983 ( AR); 8 X, 8 W, ex. C. sempervirens, Fontvieille (13), July 1984 ( AR); 8 X, 10 W, ex. C. sempervirens, Sospel (06), August 1992 ( AR); 7 X, 3 W, ex. C. sempervirens , St- Denis (93), September 2000 ( AR). Greece: 11 X, 15 W, ex. C. sempervirens, Pylos (Peloponnesis) , August 1991 ( AR); 6 X, 7 W, ex. C. sempervirens, Eleftheropolis , August 1993, S. Markalas ( AR); 3 X, 12 W, ex. C. sempervirens, Kavalla , August 1990, S. Markalas ( AR); 14 X, 10 W, ex. C. sempervirens, Heraklion (Crete) , August 1983 ( AR); 12 X, 10 W, ex. C. sempervirens, Aghios Demetrios (Kos) , July 1995; 18 X, 14 W, ex. C. sempervirens, Salakos (Rhodos) , August 1996 ( AR); 22 X, 18 W, ex. C. sempervirens, Metamorphosis (Samos) , August 1996 ( AR). Italy: 5 X, 5 W, ex. C. sempervirens, Peruggia , July 1985 ( AR); 2 X, 4 W, ex. C. sempervirens , Bari, August 1987 ( AR); 14 X, 12 W, ex. C. sempervirens, Fiesole , July 1992 ( AR); 9 X, 8 W, ex. C. sempervirens, Pisa , July 1992 ( AR); 2 X, 1 W, Cogoleto, Liguria, 12 August 1972, Z. Boucĕk ( MNHN). Malta: 2 X, 4 W, ex. C. sempervirens, Msida , September 1996, J. Buhagiar ( AR). Morocco: 4 X, 3 W, Marrakech, ex. C. sempervirens , September 1997, El Alaoui ( AR); 3 X, 2 W, Marrakech, ex. C. atlantica , September 1997, El Alaoui ( AR). Portugal: 1 X, 1 W, ex. C. lusitanica, Caldas de Monchique (Algarve) August 1993 ( AR); 8 X, 5 W, ex. C. sempervirens, Monsanto (Lisboa) , August 1993 ( AR); 3 X, 2 W, ex. C. sempervirens, Montemor o Novo (Evora), August 1993 ( AR). Tunisia: 5 X, 7 W, ex. C. sempervirens, Tabarka , August 1986 ( AR); 4 X, 2 W, ex. C. sempervirens, Beni Ayeche , August 1995, M. Ben Jamaa ( AR); 8 X, 6 W, ex. C. sempervirens, Makthar , August 1996, M. Ben Jamaa ( AR). Turkey: 2 X, 4 W, ex. C. sempervirens, Kuşadasi , August 1995 ( AR).