SPECIES OF THE GENUS MELICERITA MILNE EDWARDS (BRYOZOA, CHEILOSTOMATIDA) IN THE EARLY MIOCENE OF PATAGONIA (ARGENTINA)

Abstract

Species of the cellariid genus Melicerita Milne Edwards develop bilaminar flattened colonies consisting of alternate transverse rows of hexagonal zooids. In South America, its stratigraphic range extends from the early Miocene to the Recent. Re-examination of the type material of M. triforis Ortmann from the Monte León Formation at Río Chalía, and scanning electron microscope images of M. ortmanni Canu from the early Miocene Chenque Formation, confirmed that the latter is a junior synonym of M. triforis. Vicarious avicularia are described for the first time in M. triforis. Lectotypes are herein chosen for both nominal species. M. imperforata sp. nov. is described from material obtained in Monte León Formation (early Miocene). It differs from all known Melicerita species in the size and shape of its vicarious avicularia, which are marginal and much larger than the autozooids. The Recent Magellanic species M. temaukeli Moyano and M. blancoae López Gappa share morphological similarities with M. triforis.

Keywords

• Cellariidae
• Monte León Formation
• Chenque Formation
• Argentina