Cosmioneis grossepunctata

Taxon ID: 123
Author: Hustedt    
Synonym: Navicula grossepunctata



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LM image scalebar = 10 µm = pixels not measured     



Observations: Bart Van de Vijver
Length: 24-38µm
Width: 9-12µm
Striae: 19-22 striae in 10µm


Valves linear-elliptic with broadly rounded, rostrate ends (L 24-38µm, W 9-12µm). Axial area narrow, linear. Central area elliptic to circular. Raphe straight with slightly expanded central pores and terminal fissures clearly curved towards the secondary side. Internally, the central raphe endings are anchor-shaped. Transapical striae radiate, more spaced in the middle, 7-9 in 10µm. Striae more and more convergent towards the poles, 19-22 in 10µm.

Morphology: Naviculoid




Very rare on Ile de la Possession, mostly found as singles valves near the coastline. The overall accepted ecology of this taxon points to a marine origin. However, during the last sampling campaign, a large, viable population has been found in the soil of a small cavern at more than 1 km from the sea. The physico-chemical analysis of the soil material showed no increased salinity levels (Chloride 8,0 mg/l, specific conductance 108 µS/cm). PH was circumneutral (7,14) while nutrient values remained extremely low.First record for the Subantarctic Region.Witkowski et al. consider this taxon to be marine. However, together with the description, Hustedt (1944) already expressed his doubts about the marine origin of this taxon. It was described from a lagune on the coast of Kamerun. But, it seemed likely that the Cosmioneis valves had been washed in into the lagune by the river. This freshwater ecology corresponds more to the ecology we found for this taxon.



Other sites with Cosmioneis grossepunctata

  • Ile de la Possession (moist habitats), Crozet Archipelago

Original Type Description

Author: Hustedt

Original Description:


New combination

Author: Mann 2000



Index Nominum Algarum (INA):

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  • The INA is a bibliographic reference "card file" for algal taxonomy, containing nearly 200,000 names of algae (in the broad sense).

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