Teloganodidae (Allen, 1965)

Sartori, Michel, Peters, Janice G. & Hubbard, Michael D., 2008, A revision of Oriental Teloganodidae (Insecta, Ephemeroptera, Ephemerelloidea), Zootaxa 1957 (1), pp. 1-51 : 47

Notes on Teloganodidae egg structure

Prior to this study, eggs of Teloganodidae were virtually unknown, having not been treated by Koss (1968) and Koss & Edmunds (1974) in their study of Ephemeroptera eggs, nor by McCafferty & Wang (1997; 2000) in their revision of Teloganodidae .

Although only 5 among 13 Oriental species are now known in that stage, some general patterns may be drawn. All examined eggs lack chorionic attachment structures, compared, for instance, to those of most Ephemerellidae ( Studemann et al. 1995; Studemann & Landolt 1997). They all possess a single polar cap, but the epithema is not uniform and is always comprised of two kinds of structures.

Teloganodes eggs are pear-shaped and seem characterized by the presence of triangular, tooth-like structures arising from the chorion and delimiting the polar cap; the micropyle is located close to the polar cap and directed to the opposite pole. The threads of the epithema are non-coiled.

Dudgeodes eggs are ovoid; the micropyle is located in the equatorial area and directed transversely to the egg axis. The threads of the epithema are non-coiled for part of them and coiled for those forming the lateral attachments. Dudgeodes hutanis possess a very peculiar structure on the pole opposite to the polar cap, whose function is unknown at the moment (secondary attachment structure? remains of a second polar cap?).

Derlethina eggs are almost round, the micropyle is located near the polar cap and directed transversely to the egg axis. The threads of the epithema are all coiled.

Based on the terminology of Koss and Edmunds (1974), the polar cap of Teloganodes and Dudgeodes would be intermediate between type I (non-coiled, single unit cap) and II (non-coiled, multi-unit cap), whereas Derlethina eggs are close to type III (multi-threaded coiled cap). Obviously, more detailed investigations are needed on the ultrastructure of Teloganodidae eggs.