Mallomonas siderea sp. nov. (Synurales, Chrysophyceae), a new tropical species from the section Torquatae

Abstract

Mallomonas siderea sp. nov. is described from Vietnam based on silica-scale morphology studied with transmission and scanning electron microscopy. This species is similar to taxa from the Mallomonas pumilio group and is characterized by small scales with large or small annular and horseshoe-shaped rimmed pits on the shield. Delicate papillae, oriented longitudinally with the scale border on anterior submarginal ribs and joined by ribs in triangular net on the shield, are also characteristic features for the new species. Scales of Mallomonas siderea were found in two localities from two provinces of Northern and Central Vietnam.