Encyonema silesiacum

Taxon ID: 141
Author: Bleisch in Rabenhorst    
Synonym: Cymbella silesiaca



Click any image to enlarge...
LM image scalebar = 10 µm = pixels not measured     



Observations: Bart Van de Vijver
Length: 22-37µm
Width: 6-9µm
Striae: 12-14 striae in 10µm


Valves strongly dorsiventral, half-lanceolate with rounded ends (L 22-37µm, W 6-9µm, 12-14 striae in 10µm, 25-27 puncta in 10µm, L/W ratio 3-3,7). The dorsal side is quite convex while the ventral side is straight or slightly concave. Axial area narrow, in larger valves slightly lanceolate. Central area lacking. Striae parallel and more spaced in the middle, radiate towards the poles. Individual puncta clearly visible in LM. Raphe filiform, straight or curved ventrally with central endings marked, bending towards the dorsal side. Terminal fissures sharply hooking ventrally, not always visible in LM (i.c. smaller specimen).

Morphology: Cymbelloid




Quite uncommon on Ile de la Possession. Mostly found in relatively dry mosses, in the immediate vicinity of running water or waterfalls. This may lead to the assumption that water spray might be an important factor for the presence/absence of this taxon. Records from waterbodies are rare. When present, E. silesiacum seems to prefer slightly running water such as small ditches and brooklets.Kerguelen (Van de Vijver et al. 1998a, 2001), South Georgia (Van de Vijver & Beyens 1996). It is possible that, due to earlier confusion with Cymbella minuta Hilse, several records of C. minuta also include data on the distribution of E. silesiacum.Krammer (1997) splits E. silesiacum in several varieties based on L/W ratio, number of striae and number of puncta/stria. In our samples, we encountered several of these varieties (var. silesiaca, distigmata, lata) but their characteristics always overlapped with each other. Therefore, it did not seem useful to us to separate all these different varieties.



Other sites with Encyonema silesiacum

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

Original Type Description

Author: Bleisch in Rabenhorst

Original Description:


New combination

Author: Mann 1997



Index Nominum Algarum (INA):

  • Original
  • If an INA link is available, it will be shown above
  • The INA is a bibliographic reference "card file" for algal taxonomy, containing nearly 200,000 names of algae (in the broad sense).

See full publication info assembled for this website