Afrostilba Benoit, 1956a

Noort, Simon van, Buffington, Matthew L. & Forshage, Mattias, 2015, Afrotropical Cynipoidea (Hymenoptera), ZooKeys 493, pp. 1-176 : 73-74

Taxon classification Animalia Hymenoptera Figitidae

Afrostilba Benoit, 1956a stat. n.

Afrostilba (synonym Amphiglyphosema Benoit, 1956a, syn. n.)

Remarks.

Commonly collected genus of eucoilines throughout Africa, but particularly plentiful in equatorial Africa. The genus is common throughout the Old World Tropics as well as Mediterranean Africa. Quinlan (1986) made it a junior synonym of Gronotoma Förster, and Buffington (2002, 2011) followed this synonymy. The phylogenetic support for the inclusion of Gronotoma nitida Benoit (the only representative of Afrostilba in Buffington 2011) in Gronotoma s.str. was very weak; in that same work, it was noted that there is a distinct lineage of African species. After examination of much more recently collected material, it is clear that the African species reliably cluster with Benoit’s (1956a) generic concept of Afrostilba . Examination of the type specimens of Quinlan’s (1986) Eucoilidea species, as well as Diglyphosema sensu Quinlan, has allowed us to make the new combinations below. Furthermore, examination of the type specimen of Amphiglyphosema , Afrostilba latesulcatum Benoit, allows us to synonymize Amphiglyphosema with Afrostilba . However, there are still species of Afrotropical Gronotoma of which we have not yet been able to examine the types, which may be Afrostilba or true Gronotoma , and these species are still listed under Gronotoma below.

Diagnosis.

Mesopleural triangle distinctly impressed, with both dorsal and ventral margins cleft, delimited by a sharp edge. Lateral pronotal carina present. Notauli present, well developed in nearly all species. Scutellar plate large, glandular pit in center. Hairy ring at base of syntergum absent; metasoma downturned towards ventral position. Most easily confused with Diglyphosema and Gronotoma ; distinguished from these genera by the presence of a distinctly impressed mesopleural triangle, and downturned metasoma. In both Diglyphosema and Gronotoma , the mesopleural triangle is present, but the dorsal and ventral margins are gently rounded, and the metasoma is directed more posteriorly. Distinguished from Paradiglyphosema by the possession in the latter of a genal carina and postero-lateral projections on the scutellum.

Five species groups are recognized within the genus, all based on the morphology of the scutellum. This character system provides a wealth of taxonomic information, and from the hundreds of specimens examined for this paper, the characters appear to be stable through space and time. The most commonly encountered species group is the Afrostilba nitida group, characterized by having a distinctly concave dorsal surface of the scutellar plate. This is best seen in lateral view, and can be characterized as reminiscent of a gentle ‘wave’ or 'ski jump’. From our examination of the type series of all of Quinlan’s (1986) species, several species in this group will be synonymized in a more thorough treatment of the genus. The Afrostilba dubia species group is characterized by having an extremely short, narrow scutellar plate, revealing much of the dorsal surface of the scutellum. Some specimens in this group approach an Ealata in appearance, but lack other characters of that genus. The Afrostilba bucca species group is second in diversity to the Afrostilba nitida species group, and superficially looks similar. However, in the Afrostilba bucca species group, the scutellar plate, in profile, is perfectly flat (wave or ski-jump shaped in the Afrostilba nitida species group), with a large, deep glandular release pit. The last species group to be recognized here is the Afrostilba fercula species group. On first glance, these species look similar to the Afrostilba bucca species group, however, species in the Afrostilba fercula group possess a very small, shallow, glandular release pit. The appearance of the scutellar plate is remarkable in that the rim of the plate appears enormous, when in fact, the rim is of normal width; it is the small glandular release pit contributing to this illusion.

Distribution.

Endemic to Old World Tropics. Afrotropical records: Burundi, Democratic Republic of Congo, Rwanda, (Benoit 1956), Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Mauritius, Nigeria, Senegal, South Africa, Tanzania, Uganda, Yemen, Zambia, Zimbabwe ( Quinlan 1986, 1988), Botswana, Cape Verde, Central African Republic, Gabon, Ivory Coast, Niger, Republic of Congo, Somalia, Tanzania (here).

Biology.

Parasitoids of leaf-mining Agromyzidae ( Buffington 2002, 2011, Greathead 1969).