Euastrum neogutwinskii Van Westen et Coesel, 2020

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), pp. 107-115 : 109-110

Euastrum neogutwinskii Van Westen et Coesel spec. nov. ( Figs 6 , 11, 12, 13, 14, 15 , 30 )

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: 8b, 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.

Figures

FIGURES 1–6. Drawings 1. Cosmarium logiensiforme. 2. C. mandosii. 3. C. arcuatiporosum (with zygospore). 4. Euastrum tumoriferum. 5. Eu. dubioides. 6. Eu. neogutwinskii (with zygospore).

FIGURES 7–15. LM photographs. 7, 8. Euastrum tumoriferum. 9, 10. Eu. dubioides. 11–15. Eu. neogutwinskii (14, 15 zygospore). Scale bar = 10 µm.

FIGURES 26–34. SEM photographs. 26. Cosmarium mandosii. 27. C. arcuatiporosum. 28. C. logiensiforme. 29. Euastrum tumoriferum. 30 Eu. neogutwinskii. 31.Eu. dubioides. 32. Eu. dubium var. dubium. 33 Eu. dubium var. ornatum. 34. Eu. denticulatum. Scale bar = 10 µm.