Revision of the Genus Chroomonas HANSGIRG: The Benefits of DNA-containing Specimens

For years the genus Chroomonas was defined as being a cryptophyte with rectangular periplast plates, with a gullet and with biliprotein types PC 630 or 645. In phylogenetic trees the genus proved to be paraphyletic. Moreover, cells with hexagonal periplast plates were found in an SEM preparation from material of the type species C. nordstedtii. In this study, material of Hansgirg's C. nordstedtii was subjected to PCR and to sequencing of two short DNA tags. These tags allowed for an unambiguous identification of the real C. nordstedtii in the phylogeny of the blue-green cryptophytes. The genus Chroomonas corresponds to subclade 1, whereas subclades 3 and 4 do not belong to Chroomonas, if Hemiselmis is maintained. Additional examination by light and scanning electron microscopy and by spectrophotometry demonstrate that subclade 1 comprises only cells with hexagonal periplast plates and PC 630, whereas rectangular periplast plates are found only in subclades 3 and 4. Consequently the genus Chroomonas and its type species, C. nordstedtii, are revised and two novel species, C. debatzensis and C. gentoftensis sp. nov., are described.