What is the correct name for the type of Haematococcus Flot. (Volvocales, Chlorophyceae)?

The type of Haematococcus Flot. (Volvocales, Chlorophyceae) accumulates astaxanthin in its dormant stage. Currently, only one species is recognized in the genus; however, it is referred to by two names: H. lacustris (Gir.-Chantr.) Rostaf. and H. pluvialis Flot. This confusion arose partly because of misunderstanding over the nomenclature and partly because of inadequate descriptions of Volvox lacustris Gir.-Chantr. and H. pluvialis. Here, we designate an epitype based on a single cryopreserved culture that supports the newly designated lectotype of V lacustris. Our treatment objectively synonymizes the two names and designates the correct name for the type of Haematococcus as H. lacustris, not H. pluvialis. In addition, we provide light microscopy descriptions and ITS rDNA information regarding the strain related to the epitype.