Occurrence of dinoflagellate cyst genera Wanaea and Komewuia in Upper Jurassic strata, coastal Tanzania

Species of the dinoflagellate cyst genera Komewuia and Wanaea are well represented in surface and subsurface, Upper Jurassic strata of coastal Tanzania. One new species of Wanaea, W. tendaguruensis, is described from the Trigonia smeei Bed of the Tendaguru Formation in the Mandawa Basin; it appears to be a useful index of the Kimmeridgian. Wanaea clathrata, W. spectabilis, and W. talea are rare to common constituents of the Oxfordian strata of the middle part of the Bagamoyo Formation in the Ruvu Basin. Komewuia glabra, characteristic of the Kimmeridgian-Tithonian in the southern hemisphere, is recorded from the offshore Kipatimu Formation and from the Trigonia smeei Bed. The Kipatimu Formation was previously dated as Early Cretaceous, but is now considered Late Jurassic due to its content of K. glabra. The informally designated Komewuia sp. A occurs sporadically in the Nerinea Bed (Oxfordian-Kimmeridgian) of the Tendaguru Formation. The species documented herein have short stratigraphic ranges in the Upper Jurassic of coastal Tanzania and are thus potentially useful for regional biozonation and correlation.