Pycnococcaceae

Marine picoplanktonic, unicellular (rarely colonial), surrounded by a wall, and lack flagella; a channel in the pyrenoid contains a protrusion from the mitochondrion, a very unusual character shared with the flagellated prasinophyte Pseudoscourfieldia; studies on the Rubisco-gene have confirmed phylogenetic relationship between these coccoid species and Pseudoscourfieldia.

Pycnococcaceae is a family of green algae in the order Pseudoscourfieldiales. The defining features of this family include the single invagination of the pyrenoid where the mitochondrial membrane fits into it and the "decapore" - a ring of 10 pores through the thick cell wall.