Notes on the rare Cretaceous species Syndetocystis uralensis Strelnikova leading to the description of a new monotypic genus Monoportula P.A.Sims et D.M.Williams nov. gen.

Syndetocystis uralensis, an Upper Cretaceous species from the ‘Tyumen Oblast, Ust’-Man’ya, N. Sos’va River’, first described by Strelnikova, is described in detail using light and electron microscopy. Its unique morphology precludes its inclusion in either Syndetocystis or Rutilaria as the projection extending from the external surface of the valve is not a periplekton. Although some suggestions are made as to its more appropriate place, for the moment it is best placed in the monotypic genus Monoportula uralensis and as incertae sedis. Some speculations on its higher-level relationships are considered.