Eomedina Mesnil, 1960

Cerretti, Pierfilippo & Wyatt, Nigel, 2006, A new species of Eomedina Mesnil (Diptera: Tachinidae) from Namibia, Zootaxa 1147, pp. 61-68 : 62-63

Eomedina Mesnil, 1960

Eomedina Mesnil, 1960: 651 [original description].

Recognition

Within the Old World Blondeliini (the concept of the tribe Blondeliini adopted here follows Mesnil (1939), Herting (1960) and Wood (1985)), specimens of Eomedina can be identified by the following combination of characters: %Ψ Head. Eye bare. Ocellar setae well developed, proclinate. One or 2 upper reclinate orbital setae. Facial ridge straight or convex with stout, erect setae over most of its length ( Fig. 2 ). Occiput flat or slightly concave. Thorax. Scutum with 2 + 3 dorsocentral setae, 0 + 3 intraalar setae. Scutellum with apical setae horizontal, divergent or sub­parallel; lateral scutellar setae clearly shorter and weaker than the subapical pair. Legs. Fore tibia with 2 posterior setae. Mid tibia with 1 anterodorsal seta. Wing. Cell r4+5 open or just closed at wing margin. Abdomen. Middorsal depression on abdominal syntergite 1+2 confined to the anterior 1/2–2/3 of the segment. Tergites 3–5 with median discal setae.

Ψ: with or without proclinate orbital setae. Outer vertical setae not differentiated from the postocular setae. Mid­ventral parts of abdominal tergites 3 and 4 without short thornlike setae. Ovipositor blunt and scoop­like ( Figs. 3–5 ).

Distribution

Presently known from Sierra Leone (Waterloo), Nigeria, Democratic Republic of Congo (Bukama, Stanleyville), Kenya (Rabai), Namibia ( Fig. 1 ).

Existing keys for the identification of specimens of Eomedina

Mesnil (1960), Crosskey (1984). It is necessary to modify couplet 15 on page 266 of Crosskey’s key as follows: Ψ with 0–1 pairs of proclinate orbital setae.

Remarks

As mentioned in the Introduction, the genus Eomedina appears to belong to the Medina genus­group (sensu Herting 1960). The general structure of the ovipositor shared by members of this group could be considered not only homologous but also commonly derived a priori, and the sister group of Eomedina should therefore be looked for within this group. However, the relationship between the Blondeliini with a blunt seventh sternite and those with a pointed seventh sternite developed into a piercing organ (e.g. Blondelia Robineau­Desvoidy , Celatoria Coquillett , Compsilura Bouché , Vibrissina Rondani ) remains unclear. For instance, the presence of the pointed state in Medinodexia Townsend and of the blunt state in Medinomyia Mesnil , two genera which are otherwise indistinguishable (cf. Crosskey 1976), suggests that the transition between these two forms may have taken place several times independently. This would confer to the Medina ­group a mere unnatural phenetic similarity. At present it is impossible to know whether all representatives of the Medina ­group lack an ovisac and lay non­embryonated eggs as in Medina ( Wood 1985) and Eomedina (in contrast to Blondelia and allies, which are ovolarviparous); if this was the case, then the hypothesis of a common ancestor to the group would be strengthened.

Figures

FIGURES 1 – 3. 1. Known distribution of Eomedina spp. 2. Eomedina hamoyensis (paratype), head in lateral view, scale bar 0.5 mm. 3. Eomedina hamoyensis (paratype), female postabdomen in posterior view.

FIGURES 4 – 5. Postabdomen of Eomedina hamoyensis (paratype). Scale bar = 0.5 mm. 4. Dorsal view. 5. Left lateral view.