Observations on embryological and larval stages of Macandrevia cranium (Müller, 1776) (Brachiopoda, Articulata)

Summary

For the first time, embryos and larvae of the articulate brachiopod Macandrevia cranium (Müller, 1776) have been obtained and scanning electron microscopy has been used to study their development. Their morphology corresponds to the classical ground plan described in other species of Articulata, although the larva is characterized by the lack of mesosomal bristles. Ten successive stages of development between the gastrula and the beginning of metamorphosis have been identified, described and defined. We propose a nomenclature for these stages that can be extrapolated to other articulate brachiopods. Metamorphosis constitutes a critical phase and probably requires very precise environmental conditions.

Key words:

• Embryology
• nomenclature of developmental stages
• Macandrevia cranium
• Brachiopoda
• Articulata