Euastrum dubioides 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 : 107-108

publication ID

https://doi.org/ 10.11646/phytotaxa.443.1.10

DOI

https://doi.org/10.5281/zenodo.13878379

persistent identifier

https://treatment.plazi.org/id/397C8781-FFAF-FF94-FE9B-FA57A9BF3985

treatment provided by

Felipe

scientific name

Euastrum dubioides Van Westen et Coesel
status

sp. nov.

Euastrum dubioides Van Westen et Coesel spec. nov. ( Figs 5 View FIGURES 1–6 , 9, 10 View FIGURES 7–15 , 31 View FIGURES 26–34 ).

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 View FIGURES 26–34 ), 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 View FIGURES 26–34 ).

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.

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