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. Author Williams, David M. 0000-0002-0584-307X The Natural History Museum, Cromwell Road, London, SW 7 5 BD, UK & d. m. williams @ nhm. ac. uk; https: // orcid. org / 0000 - 0002 - 0584 - 307 X d.m.williams@nhm.ac.uk Author Sims, Pat A. 0000-0002-0214-8303 The Natural History Museum, Cromwell Road, London, SW 7 5 BD, UK & p. sims @ nhm. ac. uk; https: // orcid. org / 0000 - 0002 - 0214 - 8303 p.sims@nhm.ac.uk Author Witkowski, Jakub 0000-0002-5635-7880 Uniwersytet Szczeciński, Instytut Nauk o Morzu i Środowisku, Mickiewicza 18, 70 - 383 Szczecin; Institute of Marine and Environmental Sciences, University of Szczecin, Institute of Marine and Environmental Sciences, Mickiewicza 18, 70 - 383 Szczecin, Poland & jakub. witkowski @ usz. edu. pl; https: // orcid. org / 0000 - 0002 - 5635 - 7880 jakub.witkowski@usz.edu.pl text Phytotaxa 2023 2023-05-05 595 2 219 224 http://dx.doi.org/10.11646/phytotaxa.595.2.8 journal article 29844 10.11646/phytotaxa.595.2.8 e9a443cf-5120-48c0-9376-76ea9871e84b 1179-3163 7905940 Monoportula P.A.Sims & D.M.Williams nov. gen. Registration : http://phycobank.org/103661 Type species:— Monoportula uralensis (Strelnikova) P.A.Sims & D.M.Williams nov. comb. Frustules cylindrical, valve face circular, flat. Valve face bordered by expanded marginal ridge separating it from vertical mantle. Areolae poroid, on valve face arranged in interrupted radial and sub-radial rows extending from off-centre hyaline area from which a stout spine extends. Scattered spinules cover valve face disturbing areolar arrangement. Mantle areolae in vertical rows situated between hyaline marginal ridge and hyaline valve margin. Mantle areolae covered by network of anastomosing costae. Internally areolae sunk in rows between hyaline ribs, areolae becoming more numerous towards valve margin. One (1) rimoportula present, its external opening through stout tube expanded at its summit, internally as slit between raised lips.