• Category
  • Length Range
    20-33 µm
  • Width Range
    7.3-9 µm
  • Striae in 10 µm
    12-15

Identification

Description

Valves are dorsiventral and are 20-33 μm long and 7.3-9 μm wide. Valves taper toward rounded to rostrate ends. Striae are 12-15 in 10 μm and costae are 6-8 in 10 μm. There are 2 (sometimes 3) striae between costae. The dorsal margin is strongly convex and the ventral margin is weakly concave. The raphe canal lies against the ventral margin at distal ends of the valve and arches toward the dorsal margin in the valve center. The central arch of the canal reaches almost to the dorsal margin.

Autecology

Similar to other species of Epithemia, E. sorex frustules contain nitrogen-fixing endosymbiotic cyanobacteria which enable this taxon to become abundant in microhabitats with a low N/P ratio. It is frequently very abundant as an epiphyte on Cladophora and other coarse filamentous algae in western rivers and similar N-limited habitats.

Esorexepiphytes009
Credit: Rex Lowe
SEM of E. sorex epiphytic on Cladophora in the Eel River, a N-limited river in California.

Original Description

E. minuta a latere secundario dorso valde convexa, apicibus acutis prominentibus; striis convergentibus (in 1/100"' parte 12); a latere primario elliptica, apicibus abtusiusculis prominentibus.

  • Author
    Kütz. 1844
  • Length Range
    25 µm
  • Striae in 10µm
    5.3 costae in 10 μm

Original Images

Epithemia sorex orig illus
Epsor  Orig Descr

Cite This Page

Lowe, R. (2010). Epithemia sorex. In Diatoms of North America. Retrieved February 20, 2025, from https://diatoms.org/species/45317/epithemia_sorex