Some New and Revised Organic-Walled Phytoplankton Microfossil Genera

CT-Taxonomic and systematic problems encountered in the study of organic-walled phytoplankton include the frequently poor quality of illustration and reproduction, inadequacy of descriptions, variation in taxonomic philosophy, inaccurate citation of dates of publication, failure to adequately document localities and geologic occurrence, difficulty of exchanges between East and West and resultant development of a dual system of nomenclature. Four new genera are described herein, Nothooidium, Oligopogonium, and Trunculumarium are based on type species originally assigned to Ooidium Timofeev, 1957 but which do not fit the concept of that genus; Villosacapsula is separated from the genus Veryhachium Deunff ex Downie, 1959 on the basis of its spinose wall sculpture. Six new combinations are made in the genus Villosacapsula, as follows: V. inculta, V. helenae, V. entriche, V. ceratioides, V. leonensis, and V. rosendae, all transferred from Veryhachium. Renamed homonyms include Apiroschadon proposed as a substitute name for Retialetes Sah & Dutta, 1966 non Staplin, 1960 and Vavrdovella which is proposed as a substitute name for Tetradinium Vavrdova, 1973 non Klebs, 1912. The invalid genus Archaeohystrichosphaeridium Timofeev, 1959 is validated by the designation of a type species. A comprehensive annotated synonymy is given for Protoleiosphaeridium Timofeev ex Timofeev, 1960 and the genera Protosphaeridium Timofeev, 1966, Synsphaeridium Timofeev, 1966 non Eisenack, 1965, and Prototrachysphaeridium are suppressed as synonyms
of Protoleiosphaeridium. The authorship, date of publication and excystment mechanism for the genus Veryhachium are discussed.