Revision of the generaSphaerodinellaKeupp and Versteegh, 1989 andOrthopithonellaKeuppinKeupp and Mutterlose, 1984 (Calciodinelloideae, calcareous dinoflagellate cysts)
The genusSphaerodinellaKeupp and Versteegh, 1989, became obsolete by the assignment of its typeS. albatrosiana(Kamptner, 1963) to the genusCalciodinellumDeflandre, 1947. For the single remaining species ofSphaerodinella,which does not fit into the genusCalciodinellum,the new genusCaracomiais proposed, whose type isC. arctica(Gilbert and Clark, 1983) new genus, new combination. Additionally, a new species ofCaracomiais described:Caracomia Stellanew genus and species. The regional distribution of the two species ofCaracomiashows distinct regional preferences:Caracomia arcticais restricted to cold waters of both hemispheres, whereasCaracomia stellaas yet has only been described from warmer environments. Thus,C. arcticacan be used as a cold water indicator. Comparison ofCaracomiawith other genera has shown a close relationship to the type ofOrthopithonellaand exposed a common misinterpretation of this genus. Therefore, the genusOrthopithonellaKeuppinKeupp and Mutterlose, 1984, is emended to unquestionably accommodate only the typeO. gustafsonii.