Pulvinus veneticus gen. et sp nov (Compsopogonales, Rhodophyta) from Vanuatu

Pulvinus veneticus gen. et sp. nov. is a small (< 500 [Lm in diameter), cushion shaped epiphyte isolated into culture from Caloglossa vieillardii that was collected from Vanuatu. Molecular analysis places Pulvinus veneticus in the Compsopogonales. It has prostrate-adherent filaments or free filaments with one or more discoid to spiral bluish-green plastids without pyrenoids per cell. Pulvinus is euryhaline, growing and reproducing in salinities of 2 to 30 practical salinity units (psu). Monosporangia are formed successively by terminal branch cells or when a sector of a thallus gelatinises, releasing masses of spores. Monospores are round (6-10 mu m diameter) and glide at speeds up to 4.5 mu m s(-1). Some monospores have an extracellular polysaccharide tail and move more slowly, 0.25 to 1.0 mu m s-1. Spores avoid contact with other objects and do not require substrate contact during movement. The ultrastructure of Pulvinus is very similar to that of Compsopogon and Boldia in that the cis-region of Golgi bodies is not associated with a mitochondrion and plastids have a peripheral thylakoid. No pit connections occur between derivative cells.