taxonID	type	description	language	source
397C8781FFAFFF94FE9BFA57A9BF3985.taxon	diagnosis	Diagnosis: Cells 1.4 times longer than broad, with a deep median constriction. Sinus linear, closed for the greater part. Semicells in frontal view composed of a rectangular-trapezoid basal part and a much narrower, rectangular apical part. Apices truncate with a rather deep, narrow, median invagination. Apical angles furnished with a blunt granule. Lateral and basal lobes rounded, the lateral ones furnished with a single, the basal ones with two blunt marginal granules. Marginal granules in radial series with a number of intramarginal ones. Semicells with a slight central inflation furnished with some four granules arranged in a square. Semicells in apical view elliptic, with central inflation. Chloroplast with a single, central pyrenoid. Dimensions: cell length 25 – 29 µm, cell breadth 17.5 – 21 µm, breadth of apex 10.5 – 13 µm, cell thickness 12 – 13 µm, isthmus 5 – 7 µm. Type: — THE NETHERLANDS. Drenthe: wet meadow with Juncus effusus in estate Eexterveld near Eext, 53.014058 ° N, 6.695333 ° E, between mosses and filamentous algae. Van Westen, 1 April 2011 (holotype L! Hugo de Vries Lab 2019.01, preserved as a fixed natural sample). Differential diagnosis: — At first glance, the above-described alga reminds of Euastrum dubium Nägeli, especially its var. ornatum Woloszynska. However, where semicells in Eu. dubium are characterized by gradually converging lateral sides with a distinct curve midway (Figs 32, 33), semicells in our alga are partitioned into a more or less rectangular basal part abruptly passing into a much narrower, rectangular apical part. In that feature it also differs from Eu. denticulatum F. Gay which species moreover is characterized by a lower cell length to breadth ratio and less pronounced lateral lobes (Fig 34). Actually, in rough cell outline our alga could be rather compared with Eu. insulare (Wittrock) Roy. However, Eu. insulare is characterized by a wide, very shallow median apical indentation and is in want of any marked cell wall ornamentation. Therefore we think it justified to describe our alga as a new species. In the province of Drenthe, Euastrum dubioides is found mainly in wet meadows between mosses and in slightly acidic oligo-mesotrophic shallow pools dug for nature restoration purposes.	en	Van Westen, Marien C., Coesel, Peter F. M. (2020): Taxonomic notes on desmids from the Netherlands III, with a description of five new species. Phytotaxa 443 (1): 107-115, DOI: 10.11646/phytotaxa.443.1.10, URL: http://dx.doi.org/10.11646/phytotaxa.443.1.10
397C8781FFADFF96FE9BFA48ABCE3A74.taxon	diagnosis	Diagnosis: Cells 1.3 – 1.5 times longer than broad, with a deep median constriction. Sinus linear, closed for the greater part. Semicells in frontal view trapeziform with a lateral lobe about half way in between the apical lobe and the basal lobes. Apical lobe towards the top slightly dilated, in breadth equalling 0.65 – 0.75 of total semicell breadth. Apex truncate with a wide, shallow, median indentation and about rectangular angles sometimes provided with a small papilla. Lateral lobes broadly rounded. Basal lobes obliquely truncate towards the sinus and often slightly emarginate. Semicells with a faint central inflation surrounded by closely placed scrobicles, particularly at the isthmial side. Semicell lobes provided with some intramarginal blunt granules. Chloroplast with a single, central pyrenoid. Dimensions: cell length (20 –) 24 – 28 (– 30) µm, cell breadth (14 –) 17 – 20 (– 22) µm, breadth of apex 12 – 15 µm. Isthmus 5 – 7 µm. Zygospore globose, diameter without spines 22 – 27 µm, with spines 34 – 42 µm, spines robust, slightly bent, length 6 – 8 µm. Type: — THE NETHERLANDS. Drenthe: wet meadow in estate Eexterveld near Eext, 53.012564 ° N, 6.699890 ° E, between mosses and grass. Van Westen, 5 May 2019 (holotype L! Hugo de Vries Lab 2019.02, preserved as a fixed natural sample). Taxonomy: — The above-described species has much to do with Euastrum binale var. gutwinskii (Schmidle) Homfeld 1929 as represented in well-known floras such as those by West & West (1905, pl. 38: 31 - 31, as forma gutwinskii Schmidle), Prescott et al. (1977, pl. 70: 9), Růžička (1981, pl. 77: 1 – 9) and Lenzenweger (1996, pl. 10: 15). Eu. binale Ralfs is a polymorphic species. Among the many infraspecific taxa, var. gutwinskii as described by Schmidle (1894: 552, as forma gutwinskii), comes to the fore as the most common one, differing much from the nominate variety of Eu. binale (Ralfs 1848: 90, pl. 14: 8 b, e and h, as selected by West & West 1905: 51). Therefore, in our opinion it deserves the status of a separate species. However, a simple raise to species level under the name of Eu. gutwinskii is not eligible as that latter name was already used for quite another species by Bernard (1908: 124, fig. 204). Moreover, considering the original figure of Eu. binale var. gutwinskii in Gutwiński (1892: 73, pl. 3: 25, as Eu. binale ‘ forma’) it resembles Eu. tumoriferum Van Westen et Coesel (see below) rather than the illustrations of Eu. binale var. gutwinskii in most floras. Moreover, Gutwiński (l. c.) mentioned accompanying species that indicate an environment characteristic of Eu. tumoriferum rather than of Eu. neogutwinskii, so for those reasons we cannot suffice with referring to Eu. binale var. gutwinskii as a basionym.	en	Van Westen, Marien C., Coesel, Peter F. M. (2020): Taxonomic notes on desmids from the Netherlands III, with a description of five new species. Phytotaxa 443 (1): 107-115, DOI: 10.11646/phytotaxa.443.1.10, URL: http://dx.doi.org/10.11646/phytotaxa.443.1.10
397C8781FFAAFF90FE9BFB31AEF73038.taxon	diagnosis	Diagnosis: cells about as long as broad with a deep, median constriction. Sinus narrowly linear with a dilated extremity. Semicells in frontal view semicircular-trapeziform, the outline in the upper part of the sides often not quite firm. Cell wall smooth. Cell wall pores within the margin confined to two, disjunct zones: a single, arch-shaped series of pores just above the isthmus and some two, transversal series just below the apex. Semicells in lateral view subcircular, in apical view elliptic, in the middle of each side a little bit inflated. Chloroplast with a single, central pyrenoid. Dimensions: cell length 19 – 25 µm, cell breadth 17 – 22 µm, cell thickness 10 – 12 µm, isthmus 6 – 9 µm. Zygospores globose, furnished with furcate spines. Diameter without spines 22 – 24 µm, with spines 31 – 34 µm. Type: — THE NETHERLANDS. Drenthe: shallow pool in estate Dwingelderveld near Lhee, 52.812811 ° N, 6.240110 ° E, between Sphagnum and filamentous algae, pH 5.6, conductivity 27 µS cm- 1. Van Westen, 07 May 2018 (holotype L! Hugo de Vries Lab 2019.03, preserved as a fixed natural sample). Differential diagnosis: — In cell shape, C. arcuatiporosum somewhat resembles C. subtumidum Nordstedt and to a lesser extent C. phaseolus Ralfs. Apart from the fact that those latter species have larger cell dimensions, the main difference is found in the pattern of cell wall pores. Nordstedt (in Wittrock & Nordstedt 1878: 72) for C. subtumidum explicitly mentions a punctate cell wall. Ralfs (1848: 106, pl. 32: 5) describing C. phaseolus does not say anything about pores but depicts them as coarse dots all over the cell wall. So, neither of those species is characterized by the most peculiar pore pattern shown in our newly described species, a pattern for that matter that we do not know either of any other Cosmarium species. Confusion with similar looking species is possible, especially when the characteristic arc of pores above the isthmus is not clearly visible. This species was found at only two locations in the province of Drenthe, between Sphagnum in a shallow artificial pool on loamy, sandy soil that was dug for nature restoration purposes. Fortunately, this species was also found sporulating in a sample taken in 1988 from a pool from the west of Ireland (Frans Kouwets, personal communication), that was kindly put at our disposal. Zygospores (Figs 3, 19) are depicted after Irish material.	en	Van Westen, Marien C., Coesel, Peter F. M. (2020): Taxonomic notes on desmids from the Netherlands III, with a description of five new species. Phytotaxa 443 (1): 107-115, DOI: 10.11646/phytotaxa.443.1.10, URL: http://dx.doi.org/10.11646/phytotaxa.443.1.10
397C8781FFAAFF90FE9BFF1CAEF53CB4.taxon	description	Remarkably, in Croasdale (1955: 530) there is talk of Eu. binale var. tumoriferum Kossinskaja without a formal raise in rank from forma to variety. Also Grönblad (1963: 21) incorrectly makes mention of Eu. binale var. tumoriferum Kossinskaja. For that matter, considering illustrations in desmid literature, the taxon under discussion several times also has been labeled Euastrum binale var. gutwinskii (Schmidle) Homfeld, see e. g. Dick (1919, fig. 11), Messikommer (1942, pl. 4: 2) and Coesel & Meesters (2007, pl. 48: 7). Yet we are of opinion that we have to do with a well distinguishable taxon. As we tend to get rid of infraspecific taxa in desmid taxonomy (Van Westen & Coesel 2018) we herewith raise Euastrum binale forma tumoriferum Kossinskaja to a separate species. The main differentiating feature with respect to Eu. neogutwinskii is in the breadth of the semicell apex (without possible papillae) relative to the total semicell breadth, viz. lower than 0.60 in Eu. tumoriferum versus higher than 0.65 in Eu. neogutwinskii, resulting in a more pyramidal outline of the semicell in Eu .. tumoriferum compared with that in Eu. neogutwinskii. A SEM picture of Eu. tumoriferum (Fig. 29) revealed some conspicuous shallow scrobicles near the basal lobes, a feature that we never observed in Eu. neogutwinskii. Moreover, the number of small scrobicles around the central inflation is much lower than that in Eu. neogutwinskii (Fig. 30), compare also Coesel (2009). So, presumably this is an additional discriminating character of Eu. tumoriferum. As far as could be traced, Eu. tumoriferum is of rather rare occurrence in colder regions of Europe and North America. We encountered it recently in the Dutch province of Overijssel, in the wetlands of ‘ Kiersche Wijde’. This location is close to the Dutch province of Drenthe, a province marked by a relatively cold climate where several arcticalpine desmid species were found before (Van Westen 2015). As compared to Eu. neogutwinskii there is probably also a difference in ecology. Whereas in the Netherlands Eu. neogutwinskii is most common in distinctly acidic bogs and moorland pools, Eu. tumoriferum so far was only encountered in slightly acidic fen habitats.	en	Van Westen, Marien C., Coesel, Peter F. M. (2020): Taxonomic notes on desmids from the Netherlands III, with a description of five new species. Phytotaxa 443 (1): 107-115, DOI: 10.11646/phytotaxa.443.1.10, URL: http://dx.doi.org/10.11646/phytotaxa.443.1.10
397C8781FFA9FF93FE9BFF1DA9263BE0.taxon	diagnosis	Diagnosis: cells 1.3 - 1.4 times longer than broad, with a deep, linear constriction. Sinus narrowly linear with a dilated extremity. Semicells in frontal view trapeziform to semi-elliptic with broadly rounded basal angles. Cell wall furnished with evenly distributed granules. Semicells in lateral view about circular, in apical view broadly elliptic. Chloroplast with two pyrenoids. Dimensions: cell length 33 - 41 µm, cell breadth 25 - 30 µm, cell thickness 17 - 20 µm, isthmus 10 – 12 µm. Type: — THE NETHERLANDS. Limburg: shallow pool in estate De Hamert, near Wellerlooi, 51.531886 ° N, 6.183763 ° E, between Sphagnum and Utricularia minor, pH 4.0 and conductivity 383 µS cm- 1. Van Westen, 16 June 2018 (holotype L! Hugo de Vries Lab 2019.04, preserved as a fixed natural sample) Differential diagnosis: — C. logiensiforme resembles C. logiense Bisset as described in the well-known flora by West & West (1908: 163, pl. 80: 1 - 2). However, cell dimensions in our alga are almost twice as small as those in C. logiense and there is also a difference in the pattern of cell wall granules. Where in West & West (l. c.) there is talk of granules that are densely arranged in obliquely decussating and vertical series, granules in C. logiensiforme are evenly distributed without showing any special pattern. For that matter, it has to be remarked that the original description of C. logiense by Bisset (1884: 194, pl. 5: 4) does not indicate the above-mentioned pattern of granulation, neither in the diagnosis nor in the accompanying figure. Moreover, cell dimensions are larger and semicells are more reniform than those represented in West & West (l. c.) so it is questionable whether one and the same species is at issue. Anyhow, it should be clear that our alga under discussion, despite a rough similarity, represents another species than C. logiense either in the original description by Bisset (1884) or in the concept by West & West (1908). The type material of C. logiensiforme originates from an acidic, mesotrophic moorland pool in the Dutch province of Limburg but the species in question was already found earlier in nature reserve ‘ De Teut’ (in adjacent Belgium) where it occurred rather abundantly in oligotrophic bog pools.	en	Van Westen, Marien C., Coesel, Peter F. M. (2020): Taxonomic notes on desmids from the Netherlands III, with a description of five new species. Phytotaxa 443 (1): 107-115, DOI: 10.11646/phytotaxa.443.1.10, URL: http://dx.doi.org/10.11646/phytotaxa.443.1.10
397C8781FFA9FF92FE9BFC7DAE123B2D.taxon	diagnosis	Diagnosis: Cells about as long as broad, with a deep median constriction. Sinus linear, closed for the greater part. Semicells in frontal view elliptic-oblong. Semicell centre furnished with two pairs of longitudinally disposed nodules, each nodule being set with a variable number of granules. Below the central ornamentation a transversal series of some four supraisthmial granules. Margin of the semicell as well as the zone between margin and midregion furnished with evenly distributed, small, sharp granules. Semicells in lateral view about circular, in apical view elliptic with on either side two prominent, median nodules. Chloroplast with a single, central pyrenoid. Dimensions: cell length 20 – 25 µm, cell breadth 19 – 24 µm, cell thickness 12 – 14 µm, isthmus 7 – 9 µm. Type: — THE NETHERLANDS. Province of Noord Brabant: ‘ Leemkuilen bij Udenhout’, 51.60269 N, 5.1783 E. Loamy bank of large pool with Ranunculus aquatilis, Crassula helmsii and Nymphoides peltata. Maarten Mandos, 24 July 2018 (holotype L! Hugo de Vries Lab 2019.05, preserved as a fixed sample). Etymology: named after Maarten Mandos who collected this species and brought it to our attention. Differential diagnosis: — Cosmarium mandosii should be compared with C. vogesiacum Lemaire and C. polonicum Raciborski, two species that are highly similar and consequently often mutually confused. For a critical discussion of those species including their various infraspecific taxa, see Ducellier (1916) and Laporte (1931). Both species are primarily characterized by a couple of elongate nodules next to each other in the centre of the semicell, particularly well to be distinguished in apical view. Described as first of these two was C. vogesiacum by Lemaire (1883: 20, pl. 1: 4) from the French Vosges. Hardly a year later, C. polonicum was described by Raciborski (1884: 12, pl. 1: 2) from the neighbourhood of Krakow in Poland. In his description of C. polonicum, Raciborski does not refer to Lemaire’s publication, so probably he was not aware of it. Judging from the accompanying illustrations, C. polonicum mainly differs from C. vogesiacum by more numerous and more delicate marginal and intramarginal granules. In view of that, our C. mandosii should be compared in particular with C. polonicum. Most records of C. polonicum in literature refer to its var. alpinum Schmidle (1895: 457, pl. 15: 21) differing from the nominate variety by somewhat more pronounced central nodules but in our opinion with little taxonomic relevance. Soon after Schmidle’s var. alpinum, Borge (1906: 40, pl. 2: 29) described C. polonicum var. quadrinodosum differing from var. alpinum in that each of the two parallel central nodules is transversally split into two smaller entities. In its turn var. quadrinodosum much resembles C. polonicum var. quadrigranulatum Gutwiński (1890: 71; 1892, pl. 2: 31) which is marked by some four granules at each of the two central nodules. Depending on markedness, number and granulation of the central nodules, Ducellier (1916) distinguished in C. polonicum some seven different forms that partially could be linked to formally described infraspecific taxa. None of those forms agrees with the central ornamentation pattern as found in our C. mandosii. Most resembling is Ducellier’s form ‘ g’ corresponding with C. polonicum var. quadrinodosum Borge, marked by 2 x 2 nodules in the semicell centre but lacking the superimposed granulation at each nodule characteristic of our C. mandosii. As Ducellier incidentally encountered cells in which one of the semicells belonged to another ornamentation form than the other one may question whether the above described difference in granulation between our alga and the various forms of C. polonicum justifies the description of a separate species. Presumably a more relevant difference is found in the overall cell shape. Where C. polonicum (just like C. vogesiacum) is characterized by cells that are a bit longer than broad with about trapeziform semicells, cells of C. mandosii are about as long as broad and have elliptic-oblong semicells rendering it an appearance distinctly differing from that in C. polonicum and C. vogesiacum. For that matter, a similar difference in semicell shape can be assessed when comparing C. mandosii with C. quadriverrucosum var. supraornatum described by Skuja (1949, p. 138, pl. 31: 13) from Burma. That latter taxon superficially resembles our C. mandosii but is additionally marked by four instead of two series of longitudinally arranged nodules, nodules that furthermore are destitute of any superimposed granules. Also the apical pore pattern of C. mandosii is different than depicted by Skuja. The great resemblance of C. mandosii to C. polonicum renders mutual confusion plausible. Indeed, C. polonicum as represented by Lenzenweger & Wertl (2001, pl. 3: 4) from Austria obviously refers to our newly described species. Besides, records from Czech Republic (Jan Šťastný, personal communication) and from France (Frans Kouwets, personal communication) indicate that C. mandosii is rather widely distributed in Europe.	en	Van Westen, Marien C., Coesel, Peter F. M. (2020): Taxonomic notes on desmids from the Netherlands III, with a description of five new species. Phytotaxa 443 (1): 107-115, DOI: 10.11646/phytotaxa.443.1.10, URL: http://dx.doi.org/10.11646/phytotaxa.443.1.10
