Lucrările Simpozionului „Entomofagii şi rolul lor în păstrarea echilibrului natural” Universitatea „Al.I. Cuza” Iaşi, 2008
CONSIDERATIONS ON THE MORPHOLOGY OF THE WEST-
PALAEARCTIC PTEROMALIDAE (HYMENOPTERA: CHALCIDOIDEA)
“Al. I. Cuza” University Iaşi, Faculty of Biology, Bd. Carol I 20A, 700505 Iaşi, Romania, [email protected]
Abstract. The morphology of the head, mesosoma and metasoma of the adult West-Palaearctic pteromalids is reviewed and illustrated. The state of the characters taken into consideration is discussed. The analyzed genera show a mixture of plesiomorphic and apomorphic traits, making difficult to reveal the phyllogenetic relationships within this family. The subfamilies displaying more plesiomorphic characters seem to be Cleonyminae, Asaphinae, Spalangiinae and Diparinae, while the subfamilies Pireninae, Eunotinae, Colotrechninae and Pteromalinae seem to have more apomorphic traits. Key words: Hymenoptera, Chalcidoidea, Pteromalidae, morphology, evolution of characters. Rezumat. Consideraţii asupra morfologiei pteromalidelor vest palearctice (Hymenoptera: Chalcidoidea). Morfologia capului, mezosomei şi metasomei adulţilor de pteromalide vest palearctice este revizuită şi ilustrată. Este discutată starea caracterelor luate în considerare. Genurile analizate prezintă un amestec de trăsături plesiomorfe şi apomorfe, făcând dificilă stabilirea relaţiilor filogenetice din cadrul acestei familii. Subfamiliile cu mai multe caractere plesiomorfe par a fi Cleonyminae, Asaphinae, Spalangiinae şi Diparinae, în timp ce subfamiliile Pireninae, Eunotinae, Colotrechninae şi Pteromalinae par a avea mai multe trăsături apomorfe. Cuvinte cheie: Hymenoptera, Chalcidoidea, Pteromalidae, morfologie, evoluţia caracterelor.
Introduction The pteromalids are one of the most diverse groups of parasitic wasps, with more
than 600 genera and 4000 species in the world and 200 genera and 1000 species in the West-Palaearctic (Bouček & Rasplus, 1991; Bouček & Heydon, 1997).
The morphology of the adult Pteromalidae is presented in the main revisions of the group e.g. Graham (1969), Bouček (1988), Bouček & Rasplus (1991), but the only papers treating this subject in a greater extent are those of Dzhanokmen (1994; 2004; 2007). Bouček (1988a) briefly discussed possible relationships between the pteromalid subfamilies. Cladistic analyses were carried out by Dzhanokmen (2000) and Török & Abraham (2002), but no common agreement on the phylogenetic relationships could be established.
Unfortunately, no single character or group of characters proved to be specific for this family, thus most of the authors agree that Pteromalidae is probably a paraphyletic group (Bouček & Heydon, 1997; Török & Abraham, 2002). As it is common for the complex, poorly studied and diverse groups of organisms, the phylogenetic relationships of Pteromalidae are far from being understood. In this context an important task is to identify new characters, including molecular ones, which can be used to reveal the phylogeny of this group. Another important aspect is to establish correctly the synapomorphies and to separate them from the homoplasies (Gibson, 1986). This is not always simple and speculation cannot always be avoided.
The aim of this paper is not to perform a cladistic analysis of the group, but to review the morphological characters used in the taxonomy of Pteromalidae, as well as to discuss their possible evolution.
Material and Methods The head capsule, mesosoma and gaster of several West-Palaearctic pteromalid
genera from the subfamilies Asaphinae, Cleonyminae, Colotrechninae, Diparinae, Eunotinae, Herbertiinae, Miscogasterinae, Ormocerinae, Pireninae, Pteromalinae and Spalangiinae were analyzed using optical and electronic microscopy. The classification follows Bouček (1988). The articulated appendages were not included in this study, but will be treated in a further paper.
Results and Discussion Head (Figs. 1-3, 8-34, 60, 62, 63). In most pteromalids the position of the head is orthognathous, its main axis being perpendicular on the longitudinal axis of the body. In this case, the mandibles are oriented downwards and the occipital foramen is situated at about the middle point between the vertex and the mandible insertion. Two exceptions are the members of the subfamilies Spalanginae and Cerocephalinae, where the head is almost prognathous, the mandibles being oriented forward and the occipital foramen being situated closer to the vertex than the mandibles insertion (Fig. 25). This character could be regarded as a plesiomorphy because the primitive apocritans have a rather prognathous head. Dzhanokemen (1994) instead considers the prognathous head to be secondary (reversion) in pteromalids, a specialization related to host location in narrow places. The general shape of the head is very diverse. Some genera have a round head in frontal view, its width being approximately equal to its height as in Pteromalus Swederus (Pteromalinae) (Fig. 10), Notanisus Walker (Cleonyminae) (Fig. 11) or Systasis Walker (Ormocerinae) (Fig. 12). In some species the height can be greater than the width, the head being strongly elongated as in Spalangia Latreille (Spalangiinae) (Fig. 9); sometimes the height is smaller than the width as in Herbertia Howard (Herbertiinae) (Fig. 13) or Sphegigaster Spinola (Pteromalinae) (Fig. 21). In Asaphes Walker (Asaphinae) (Fig. 8) and Eunotus Walker (Eunotinae) (Fig. 17) the head is approximately triangular. Dorsally the head can be either thin (short) as in Spintherus Thomson (Pteromalinae) or very massive (broad) as in Cratomus Dalman (Cratominae).
The antennal insertion (torulus, toruli) can vary from being placed at about the same distance from the anterior ocellus and the lower clypeal margin as in Systasis (Fig. 12) and Colotrechnus Thomson (Colotrechninae) (Fig. 19) or closer either to the median ocellus as in Panstenon Walker (Panstenoninae) and Dipara Walker (Diparinae) (Fig. 18), or to the clypeal margin as in Asaphes (Fig. 8), Herbertia (Fig. 13), Macroglenes Westwood (Pireninae) (Figs. 14, 15) and Eunotus (Fig. 17). An extreme case is found in Spalangia (Fig. 9) where the toruli are situated just above the oral fosa. The inferior position of the toruli can be regarded as a plesiomorphy and their higher position as an apomorphy since the first case characterizes the most primitive groups of apocritans.
The frons can have two more or less deep furrows (scrobes) where the antennal scape can lay. Sometimes, in the centre of the frons, an interantennal crest may be present, especially in the parasitoids which develop in xylophagous coleopterans as in Cerocephala Westwood (Cerocephalinae), perhaps as an antennal protection when the females enter the dirty galleries in wood. The face can be almost flat or more or less protruding at the level of toruli as in Coelopisthia Förster (Pteromalinae). The temples can be very large as in Conomorium Masi (Fig. 60) (Pteromalinae) or very small, almost indistinct, as in Peridesmia. The genae are usually flat, but there are not rare the cases when a depression exists just above the mandible insertion as in Catolaccus Thomson
Consideration on the morphology of the west-palearctic Pteromalidae (…)
(Pteromalinae) or Sphegigaster (Fig. 23). This may allow a wider opening of the mandibles and it is regarded as an apomorphy (Dzhanokmen, 1994).
Figures 1-7. General morphology of Pteromalidae: 1. Pteromalus elevatus (Walker), female, head
in frontal view; 2. Idem, head in posterior view; 3. Idem, head in dorsal view; 4. Idem, mesosoma in dorsal view; 5. Idem, mesosoma in lateral view; 6. Halticoptera andriescui Mitroiu, detail of
posterior part of scutellum, metanotum and propodeum; 7. P. elevatus, female, metasoma in lateral view (ao = anterior ocellus; ax = axilla; axi = axillula; bf = basal fovea; ca = callus; ce = compound eye; cl = clypeus; c1-c3 = coxae 1-3; do = dorsellum; el = eye length; fa = face; far = frenal area; fl
= frenal line; fm = foramen magnum; fr = frons; ge = gena; hca = hypostomal carina; hp = hypopygium; hy = hypostome; ltb = lower tentorial bridge; ma = mandibles; mar = median area; mc
= median carina; mes = mesosternum; met = metanotum; mlc = maxillo-labial complex; mp = mesepimeron; mpl = metapleura; ms = malar sulcus; msp = mesepisternum; mspa = malar space; nu
= nucha; occ = occiput; of = oral fosa; OOL = oculo-ocellar line; ovi = ovipositor; pc = pronotal colar; pe = petiole; pge = postegena; pl = plica; pn = pronotal neck; po = posterior ocellus; pocc =
postocciput; POL = postocellar line; pr = propleura; pre = prepectus; pro = propodeum; sc = scutellum; sp = spiraculum; sps = spiracular sulcus; te = temple; teg = tegula; tel = temple length; to
= torulus; t1-t7 = gastral tergites 1-7; utb = upper tentorial bridge).
The clypeal margin can be straight, not very large, as in Notanisus (Fig. 11) or unusually wide as in Habritys Thomson (Pteromalinae), convex (protruding downwards) as in Macroglenes (Figs. 14, 15), more or less concave (emarginated) as in Dipara (Fig. 18) or with 1-3 teeth that can be symmetrical or not. The first case can be found in Stenomalina Ghesquière or Cyrtogaster Walker (Pteromalinae), both with 3 symmetrical teeth, the middle one being the largest. Two symmetrical teeth can be found ,for example, in Sphegigaster (Fig. 23). A sing
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