Pithonella Organica—A New Calcareous Dinoflagellate with an Inner Organic Wall

Abstract

A new calcareous dinoflagellate, Pithonella organica, encountered in Lower Paleocene deposits from southern Sweden, is described. This species was first encountered in palynological preparations, and thus, has an organic wall. Spherical calcareous microfossils were found during SEM studies of the untreated chalk. These microfossils, when submitted to HC1 treatment, dissolved and were shown to contain an inner organic wall, identical to the specimens of P. organica, found in palynological preparations. The organic wall of P. organica displays clear dinoflagellate characteristics, such as dinoflagellate paratabulation, and a possible archeopyle. This is the first recorded case of a calcareous dinoflagellate with an inner organic wall that displays clear dinoflagellate characteristics.