Cosmarium sphagnicola West & G.S.West

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), pp. 240-248 : 247

Cosmarium sphagnicola West & G.S.West ( Figs 6 , 24, 25, 26 , 34 )

Cosmarium sphagnicola (in the original diagnosis linguistically incorrectly named ‘s phagnicolum ’) was described by West & West (1897: 486, pl. 6: 13-14) from southern England and reproduced in their monography of British desmids ( West & West 1908: 71, pl. 71: 11–14). In their diagnosis it is characterized (among other things) by a short, open sinus and subtrapeziform semicells, the upper angles of which are furnished with an intramarginal, minute papilla. Close inspection by light microscope of empty cells and particularly SEM pictures showed us that the granules mentioned by West & West are blunt and not sharply marked in outline. Moreover, they are asymmetrically disposed (figs. 6 and 34). Whereas the granule in the upper right angle is close to the apical margin, the one in the left part of the semicell is located distinctly lower, approximating the lateral angle. For that matter, such an asymmetrical ornamentation was already demonstrated in Kouwets (1988, pl. 1: 24–26) in cells from the French Jura.

In the Dutch province of Drenthe, C. sphagnicola is a rather common species, not seldom abundantly occurring in Sphagnum vegetation.

Figures

FIGURES 1–8. Drawings 1. Cosmarium grantii (from Eexterveld, province of Drenthe, the Netherlands). 2. C. palatiniforme. 3, 4. C. neonotabile (no 4 from Holmers, province of Drenthe, the Netherlands). 5. C. neocrenatum. 6. C. sphagnicola. 7. C. sphagnicoliforme (with zygospore). 8. C. regnesiforme.

FIGURES 24–29. LM photographs. 24–26. Cosmarium sphagnicola (from Nolderveld, province of Drenthe, the Netherlands). 27–29. C. sphagnicoliforme (from type location) (29. zygospore). Scale bar = 10 µm

FIGURES 30–38. SEM photographs. 30. Cosmarium grantii (from Eexterveld). 31. C. neocrenatum (from Iceland). 32. C. neonotabile (from Holmers). 33. C. palatiniforme (from type location). 34. C. sphagnicola (from Eexterveld). 35. C. sphagnicoliforme (from type location). 36, 37. C. regnesiforme (from type location). 38. C. regnesi (Zeijen, province of Drenthe, the Netherlands). Figures 30–33: Scale bar = 10 µm, Figures 34–38: Scale bar = 5 µm