A single micropyle in the eggs of the most basal living actinopterygian fish, Polypterus (Actinopterygii, Polypteriformes)

Breeding of Polyterus, the most basal living actinopterygian, provided the opportunity to study the surface structure of its eggs with SEM for the first time. The investigation; revealed the previously overlooked presence of a micropyle at the animal egg pole, thus rejecting recent textbook belief that the eggs of Polypterus lack a micropyle. Comparison with data for other gnathostomes demonstrates that eggs with a micropyle are a further synapomorphy for Actinopterygii and confirm membership of the Cladistia in that group.