Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species Author Van Westen, Marien C. 0000-0001-6905-9471 Podzolhamel 26, 9403 XC Assen, The Netherlands. & mvanwesten @ home. nl; https: // orcid. org / 0000 - 0001 - 6905 - 9471 mvanwesten@home.nl Author Coesel, Peter F. M. 0000-0001-7709-4154 Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Box 94240, 1090 GE Amsterdam, The Netherlands. & p. f. m. coesel @ uva. nl; https: // orcid. org / 0000 - 0001 - 7709 - 4154 p.f.m.coesel@uva.nl text Phytotaxa 2021 2021-10-11 522 3 240 248 http://dx.doi.org/10.11646/phytotaxa.522.3.7 journal article 4076 10.11646/phytotaxa.522.3.7 bee17a33-bc94-43a7-8f47-d16e7525dcd3 1179-3163 5560451 Cosmarium palatiniforme Van Westen & Coesel spec. nov. ( Figs 2 , 18, 19, 20 , 33 ) Diagnosis: Cells a little longer than broad with a rather deep, linear, almost closed sinus. Semicells in frontal view sub-oblong with convex lateral sides and broadly rounded angles. Semicell margin with some 14 crenations, those on the lateral sides rather deep and emarginate, those at the apex most flattened. Semicells in frontal view just above the isthmus with a broad inflation furnished with 6-8 flattened, longitudinal costae, usually indistinctly granulate and paired with a separate granule near the isthmus. Supraisthmial ornamentation separated from radiate series of intramarginal granules by an unsculptured zone. Intramarginal granules joining the marginal crenations arranged in pairs. Outline of semicells in apical view elliptic, the central part inflated. Outline in lateral view ovate. Chloroplast with a single, central pyrenoid. Dimensions: cell length 32–35 µm, breadth 27–31 µm, L/B = 1.1–1.2, thickness 18–19 µm, isthmus 10–13 µm. Type :— THE NETHERLANDS . Drenthe : rain puddle on sandy track in estate De Holmers near Elp , 52.911518 ° N , 6.630222° E . Van Westen , 19 Februari 2017 ( holotype L ! Hugo de Vries Lab 2021.03, preserved as a fixed natural sample and represented by our fig. 2) . Differentiating diagnosis:—The above-diagnosed taxon very well agrees with C. palatinum Dick as represented in Grönblad (1936, p. 11, pl. 2: 31). However, semicells of C. palatinum as originally diagnosed by Dick (1930 , p. 43, pl. 8: 7) are characterized by a supraisthmial inflation furnished with distinctly separated granules arranged in a pattern of 5 by 3 series. Because of the questionable identity of our taxon with Dick’s C. palatinum we prefer to describe it as a separate species. As far as could be traced, no other records of C. palatinum have been published. Presumably, we have to do with a rare species with a predominantly boreal distribution. In the Netherlands it is only known from a few locations.