Euastrum pseudotuddalense Messikommer (1942: 141)

Coesel, Peter & Westen, Marien Van, 2013, Taxonomic notes on Dutch desmids V (Streptophyta, Desmidiales): new species, new morphological features, Phytotaxa 84 (2), pp. 46-54 : 50-51

Euastrum pseudotuddalense Messikommer (1942: 141) (Figs. 9, 10, 19, 20)

The alga represented in our Figs 9, 10, 19 and 20 is quite similar to E. binale var. pseudopapilliferum Förster (1963: 52) described from Swedish Lapland. The figures of that taxon in Förster (1963: pl. 1: 7; 1967; pl. 2: 10–12) fully agree with our findings. Förster’s taxon (originally invalidly published for lack of a nomenclatural type but validated in Förster 1981) in Růžička’s (1981: 473, pl. 77: 17) flora is accounted E. binale var. papilliferum Gutwi ṅski (1909: 467). We do not agree with that point of view as both general cell outline and cell wall ornamentation in those two taxa are distinctly different. For that matter, Růžička (1981: 473) states that the variety in question possibly deserves the rank of a separate species. So an obvious option could be to raise Förster’s E. binale var. pseudopapilliferum in rank to species level. However, when scrutinizing the available desmid literature we encountered E. pseudotuddalense Messikommer (1942) described from Switzerland. Messikommer (1942: pl. 4: 5) provides three frontal cell views of that species. Some two (of which one is copied in Růžička’s 1981 flora) resemble our alga somewhat less, but the third one ( Messikommer 1942: pl. 4: 5a’) is to be considered almost identical. We conclude that E. binale var. pseudopapilliferum Kurt Förster can be synonymized with the earlier published species E. pseudotuddalense , which obviously is a rare taxon with a predominantly arctic-alpine distribution. In connection to E. pseudotuddalense also E. subalpinum var. crassum Messikommer (1942: 140) and E. subalpinum var. granulosum Grönblad (1942: 36) can be considered two infraspecific taxa that morphologically are about intermediate between E. subalpinum Messikommer (1935: 120) and E. pseudotuddalense .

Euastrum pseudotuddalense , once identified, has been recorded from quite a series of sites spread across the province of Drenthe. Like in the other species discussed, records originated from mesotrophic pools on sandy soil. Conductivity values ranged from (12) 22 to 41 µmho, pH from (3.8) 4.6 to 6.9.

aubertianum . Fig. 23: zygospore. Fig. 24: zygospore possibly infected by some parasitic mold. In all figures, scale bar = 10 µm.