taxonID	type	description	language	source
073487890E52FFFCFF70FA28FD42FEE3.taxon	diagnosis	Diagnosis: Cells 1.2 – 1.4 times as long as broad with a moderately deep, linear, largely closed sinus. Semicells in frontal view semi-oblong to semirectangular with a crenate margin. Each lateral side with 3 – 4 deep crenations (including the basal angle), apex with 4, more flattened, crenations. Semicells in frontal view just above the isthmus with a broad inflation furnished with 4 – 6 flattened, longitudinal costae, often indistinctly granulate and / or paired with a separate granule near the isthmus. Supraisthmial ornamentation separated from radiate series of intramarginal crenulations by an unsculptured zone. Intramarginal crenulations smooth or furnished with one or two minute granules. Outline of semicells in lateral view about rectangular with broadly rounded angles, the basal part inflated. Outline of semicells in apical view elliptic with subtruncate poles, the central part inflated. Chloroplast with a single, central pyrenoid. Dimensions: cell length 27 – 32 µm, breadth 22 – 25 µm, L / B = 1.2 – 1.37, thickness ca 16 µm, breadth of isthmus 12 – 14 µm.	en	Van Westen, Marien C., Coesel, Peter F. M. (2021): Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species. Phytotaxa 522 (3): 240-248, DOI: 10.11646/phytotaxa.522.3.7, URL: http://dx.doi.org/10.11646/phytotaxa.522.3.7
073487890E52FFFCFF70FA28FD42FEE3.taxon	diagnosis	Type: — THE NETHERLANDS. Overijssel: quaking fen in estate Rottige Meente near Nijetrijne, 52.82664 ° N, 5.906261 ° E, between mosses, mainly Campylium and Calliergon species, pH 7.2, conductivity 236 µS cm- 1. Van Westen, 27 June 2015 (holotype L! Hugo de Vries Lab 2021.01, preserved as a fixed natural sample and represented by our Fig. 5). The algal cells depicted in our figs 5, 14 and 31 are much alike those represented in the well-known flora by West & West (1912, pl. 98: 9 – 10) under the name of Cosmarium crenatum Ralfs. Based on West & West (l. c.), in most later publications, e. g. the floras by Prescott & al. (1981), Förster (1982), Croasdale & Flint (1988), Lenzenweger (1999) and Coesel & Meesters (2007), Cosmarium crenatum is characterized by a supraisthmial series of longitudinal costae or series of granulae. For that matter, it was Nordstedt (1872, p. 29, pl. 6: 7 – 8) who marked the concept of C. crenatum in this way. However, Ralfs (1848, p. 96, pl. 15: 7) in his original diagnosis neither mentions nor depicts such a supraisthmial ornamentation. On the contrary, he talks about ‘ segments, the surface of which is punctate and even’. A form that superficially looks like our C. neocrenatum was described from Greenland by Larsen (1907, p 333, pl 7: 11) as C. ordinatum (illeg.) with ‘ a series of large dentiform protuberances and a series of five oblong strong protuberances’. In our species the ornamentation consists of sometimes hardly visible flattened granules. So in our opinion he described another species. From Brazil, Grönblad (1945, p. 16, pl. 5: 95) described Cosmarium crenatiforme, in rough outline resembling Ralfs’ Cosmarium crenatum but characterized by some supraisthmial granules joining a series of longitudinal costae. In respect of that latter feature it meets our newly diagnosed C. neocrenatum. Yet, we do not think that we have to do with identical species as Grönblad’s poorly known C. crenatiforme is marked by a distinctly deeper cell sinus than our C. neocrenatum.	en	Van Westen, Marien C., Coesel, Peter F. M. (2021): Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species. Phytotaxa 522 (3): 240-248, DOI: 10.11646/phytotaxa.522.3.7, URL: http://dx.doi.org/10.11646/phytotaxa.522.3.7
073487890E56FFF8FF70FA43FBA8FD3E.taxon	diagnosis	Diagnosis: Cells 1.4 - 1.6 times longer than broad with a shallow, linear sinus closed or narrowly open for the greater part. Semicells in frontal view trapeziform-oblong with slightly convex lateral sides and a truncate apex. Each semicell with 12 - 14 marginal crenations / undulations, those at the apex less deep than those on the lateral sides. Cell wall ornamentation consisting of 2 - 3 intramarginal, concentric series of flattened verrucae corresponding with the marginal crenations. Just above the isthmus sometimes another series of most flattened, hardly visible granules. Lateral cell view elliptic with a shallow, obtusely angled constriction. Apical view elliptic. Chloroplast with a single, central pyrenoid. Dimensions: cell length 22 – 31 µm, breadth 16 – 23 µm, L / B = 1.35 – 1.6, thickness about 15 µm, isthmus 10 – 13 µm. Type: — THE NETHERLANDS. Province of Noord-Holland in estate Laegieskamp near Bussum, 52.278072 ° N, 5.138113 ° E. Van Westen, 5 September 2020 (holotype L! Hugo de Vries Lab 2021.02, preserved as a fixed natural sample and represented by our fig. 3). Differential diagnosis: — The above-diagnosed taxon much resembles C. notabile Brébisson as depicted in the flora by West & West (1908, pl. 66: 15). However, the original illustration of C. notabile by De Brébisson (1856, pl. 1: 15) shows cells with a higher number of marginal crenations (14 – 16 per semicell) and, more essentially, a distinctly narrower cell isthmus. Whereas isthmus to cell breadth ratio in our alga under discussion equals 0.55 – 0.64, that in De Brébisson’s one equals 0.4. For that matter, it has to be noticed that the intramarginal series of verrucae in our C. neonotabile may be flattened to such an extent that they are easily overlooked. That might explain the fact that West & West (1908: 16) designate C. notabile as ‘ smooth-walled’. Unfortunately, De Bary (1858, pl. 6: 52 – 54) under the name of C. notabile Brébisson depicted an alga most probably relating to C. benedictum Ducellier (Van Geest & Coesel, 2019). As De Bary’s concept of C. notabile was adopted in the flora by West & West (1908, p. 15), a lot of confusion was to be expected in later publications. It was only Croasdale (in Prescott et al. 1981: 173) who emphasized the difference in concept of C. notabile between De Breìbisson (1856) and De Bary (1858). She rightly recognizes the need of a new name for the many (seemingly?) smooth-walled forms figuring in desmid literature under the name of C. notabile and newly describes C. levinotabile to meet that need. Unfortunately, as holotype of that species she mentions figs 6: 1 – 5 of C. notabile in De Bary (must be 6: 52 – 54) and as iconotypes figs 198: 1 – 5 in Prescott et al. (1981) representing both the drawings of C. notabile in De Bary and drawings of C. notabile in the flora by West & West (1908) in our opinion representing distinctly different species. Consequently, Croasdale’s description of C. levinotabile should be considered to be invalid. Next to the trapeziform semicell shape rendered by our type material of C. neonotabile (figs 3, 15 and 17) elsewhere in the Netherlands we encountered populations with predominantly semi-oblong semicells (figs 4, 16 and 32). That latter form largely matches C. cedercreutzii Grönblad (1921, p. 27, pl. 6: 12 - 13) but is to be distinguished by much deeper marginal crenations. As the two cell forms found in our Dutch material appeared to be mutually connected by transitional forms we concluded to deal with one and the same species.	en	Van Westen, Marien C., Coesel, Peter F. M. (2021): Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species. Phytotaxa 522 (3): 240-248, DOI: 10.11646/phytotaxa.522.3.7, URL: http://dx.doi.org/10.11646/phytotaxa.522.3.7
073487890E54FFF8FF70FD02FF6CFA2B.taxon	diagnosis	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.	en	Van Westen, Marien C., Coesel, Peter F. M. (2021): Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species. Phytotaxa 522 (3): 240-248, DOI: 10.11646/phytotaxa.522.3.7, URL: http://dx.doi.org/10.11646/phytotaxa.522.3.7
073487890E54FFF9FF70FA0EFF41FE1E.taxon	diagnosis	Diagnosis: Cells about as long as broad with a rather deep, widely V-shaped to U-shaped sinus. Semicells in frontal view triangular with deeply concave apex and downward bent apical angles. Semicell margin furnished with some six blunt dentations: two on either side of the apical indentation, usually two on each lateral side. Lateral parts of the semicell with a variable number (1 - 4) of scattered intramarginal dentations. Apical view elliptical-fusiform with on either side a blunt dentation near the poles. Semicells in lateral view subcircular. Chloroplast with a single, central pyrenoid. Dimensions: cell length 7 – 10 µm, breadth 7.5 – 10.5 µm, L / B = 0.8 – 1.1, thickness 4 – 5 µm, isthmus 3.5 – 4.5 µm Type: — THE NETHERLANDS. Drenthe: moorland pool Kliplo near Dwingeloo, 52.834545 ° N, 6.438517 ° E, in Sphagnum squeezing, pH 6.9 conductivity 26 µS cm- 1. Van Westen, 27 June 2015 (holotype L! Hugo de Vries Lab 2021.05, preserved as a fixed natural sample and represented by our fig. 8). Differential diagnosis: — As its name indicates, C. regnesiforme resembles C. regnesi described by Reinsch (1867, p. 116, pl. 22 AIII: 1 – 5). Main difference is in the shape of the semicell: triangular instead of rectangular. Concomitant to that, apical angles are bent downward giving the impression of drooping shoulders. Although the species C. regnesi is known for its multiformity, morphological variability mainly concerns its pattern of granulation (West & West 1908; Förster 1982). In view of the essentially different shape of our above described algal form we are of opinion that it deserves the status of a separate species. The find of a similar form on several locations in the Dutch province of Drenthe and near Ambleside in the English Lake District renders it likely that it does not concern an incidental aberration. Morphological details: — With respect to the ornamentation pattern of C. regnesiforme as revealed in scanning electron microscopy a remarkable dentate character of the bigger granules can be observed (figs 36, 37). As a similar feature is to be seen in SEM pictures of C. regnesi (fig. 38) a common characteristic of the C. regnesi kinship group is likely. Although the dentations in question look like acutely shaped mucous extrusions they actually are minute spines.	en	Van Westen, Marien C., Coesel, Peter F. M. (2021): Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species. Phytotaxa 522 (3): 240-248, DOI: 10.11646/phytotaxa.522.3.7, URL: http://dx.doi.org/10.11646/phytotaxa.522.3.7
073487890E55FFF9FF70FC4EFEC4F9F3.taxon	diagnosis	Diagnosis: Cells a little bit broader than long with a rather shallow, U-shaped, open sinus. Semicells in frontal view more or less hexagonal, the lateral angles variously pronounced, the basal angles sometimes papillate. Cell wall furnished with two blunt, asymmetrically disposed granules: one in the upper right angle close to the apical margin, the other one in the left part of the semicell approximating the lateral angle. Semicells in lateral view about globose, in apical view elliptical with a papilla on each side near the somewhat attenuate poles. Zygospores irregularly elliptical-oblong, smooth-walled. Chloroplast with a single, central pyrenoid. Dimensions: cell length 6.5 – 9.5 µm, breadth 6.5 – 10 µm, thickness about 5 µm, isthmus 4.5 – 5.5 µm, zygospore (fig. 29) somewhat irregularly oblong, 13 x 10 µm. Type: — THE NETHERLANDS. Drenthe: rain puddle on loamy sand in estate De Haar near Assen, 52.942598 ° N, 6.519883 ° E, pH 7.9 conductivity 11 µS cm- 1. Van Westen, 8 August 2015 (holotype L! Hugo de Vries Lab 2021.04, preserved as a fixed natural sample and represented by our fig. 7). Differential diagnosis: — C. sphagnicoliforme much resembles C. sphagnicola. Mean cell dimensions are a little bit smaller but the main difference is in the outline of the semicell when seen in frontal view. Whereas in C. sphagnicola semicells are widest near the apex, those in C. sphagnicoliforme are widest in their basal part including the lateral angles. Next to those morphological differences we could assess also a possible difference in ecology: whereas C. sphagnicola is characteristic of acidic Sphagnum vegetation, C. sphagnicoliforme was encountered in shallow rain puddles on loamy substrates. Because of the close resemblance to C. sphagnicola confusion with that species in desmid literature is likely. For instance, when consulting the flora by Coesel & Meesters (2007), we now have to conclude that the C. sphagnicola labeled cell depicted on pl. 69: 12 refers to that species indeed, but those on pl. 69: 10 – 11 better be identified as C. sphagnicoliforme.	en	Van Westen, Marien C., Coesel, Peter F. M. (2021): Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species. Phytotaxa 522 (3): 240-248, DOI: 10.11646/phytotaxa.522.3.7, URL: http://dx.doi.org/10.11646/phytotaxa.522.3.7
