Symbiodinium microadriaticum
Diagnosis
Original description, Freudenthal : Single cells. spherical to broadly ellipsoidal. when in compact colonies polygonal or ovoid. 5-15 micrometers in diameter (usually 10- 12 micrometers ) ; surface smooth. lacking reticulation, pores or extensions. Color ochraceous to greenish. Wall cellulose, thin and plastic when vegetative. slightll- thicker when cystic. Chloroplast lubolate or stellate. peripheral. Pyrenoid or deep orange-brown assimilation-product perhaps embedded in the chloroplast. Oil droplets. crystals. and numerous spherules in the cytoplasm. Nucleus indistinct. spherical, granular, typically dinoflagellate, approximately 2 micrometers in diameter. Encysted walls containing either 2 daughter cells or a gymnodinioid zoospore which closely resernhies the 2-celled stage.
Zoospore: “Body stout, ellipsoidal with hemispherical apices. its length 1.5 transdiameter, widest at the girdle; epicone and hypocone subequal : girdle equatorial without displacement or overlap ; sulcus straight, slight sulcal notch : ochraceous.” (Kofoid and Swezy, 1021, G. adriaticum).