The eggs of Afronurus LESTAGE, 1924 (Ephemeroptera: Heptageniidae): a cue for phylogenetic relationships

Belfiore, C. and Barber-James, Helen Margaret and Gaino, E. (2003) The eggs of Afronurus LESTAGE, 1924 (Ephemeroptera: Heptageniidae): a cue for phylogenetic relationships. In: Research Update on Ephemeroptera & Plecoptera: Proceedings of the Tenth International Conference on Ephemeroptera, 8-11 August 2001, Perugia, Italy. University of Perugia, Perugia, Italy, pp. 113-116.



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Scanning electron microscopy (SEM) investigation carried out on the eggs of Afronurus scotti, A. harrisoni, A. peringueyi, and A. ugandanus, has provided some chorionic details useful for a comparison between these species. In all the species, the egg chorion is decorated with sparse granules and shows two kinds of knob-terminated coiled threads (KCTs). The first kind is represented by small KCTs (5-7 ?m in diameter) densely concentrated at each egg pole; the second kind encompasses large KCTs (60- 80 ?m in length) situated equatorially. The micropyle has an oval to round sperm guide (15-20 ?m long; 12- 18 ?m wide), and a well-defined rim. The polar KCTs expand towards the equatorial KCTs in A. scotti, A. harrisoni, and A. peringueyi, but in A. ugandanus there is a large clear area between polar and equatorial KCTs. A chorionic pattern very close to that of these Afronurus species is shared only by species belonging to the Asiatic genus Cinygmina. In addition, examination of the labrum of the nymphs belonging to both genera, indicates a very similar morphology, in the curved sclerification in the basal region of the labrum, a feature that contrasts with the almost straight shape presented by other heptageniid genera (e.g. Electrogena species). Egg and labrum characteristics are advocated to hypothesise a close phylogenetic relationship between the South-African Afronurus and the Asiatic Cinygmina genera.

Item Type:Book Section
Uncontrolled Keywords:chorionic pattern; knob-terminated coiled threads; Cinygmina genus; SEM.
Subjects:Y Unknown > Subjects to be assigned
Divisions:Research Institutes and Units > Albany Museum
ID Code:1153
Deposited On:02 Oct 2008
Last Modified:01 Aug 2012 07:28
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