Evolutionary significance of the embryological development of the daphniid cladocerans Ceriodaphnia Dana, 1853 and Scapholeberis Schoedler, 1858 (Branchiopoda: Cladocera: Daphniidae)

Abstract

Abstract The embryological development of Ceriodaphnia reticulataDumont & Pensaert, 1983 and Scapholeberis rammneriJurine, 1820 were investigated using scanning electron microscopy. A carapace spine did not develop and there was no fusion of the first antennae. These are apparent apomorphies of DaphniaMüller, 1785, which suggests that the common ancestor of Daphniidae Straus, 1820 did not have a carapace spine during its embryological development, and its first antennae were short and separated during embryogenesis. Morphological evidence thus appears congruent with molecular interpretations showing that ScapholeberisSchoedler, 1858 is basal to other genera of Daphniidae, Ceriodaphnia being a sister taxon to Daphnia.