Encyonema hamsherae

Winter and L.L.Bahls 2013      Category: Asymmetrical biraphid

REPORTED AS: Encyonema hebridicum (Krammer 1997, Taf. 123, Fig. 9) 

Encyonema evergladianum


Encyonema hebridicum

LM scalebar = 10 µm = 80 pixels.


Contributor: Diane Winter - November 2012
Length Range: 19-30 µm
Width Range: 6.5-7.5 µm
Striae in 10 µm: 16-18 in middle of dorsal side, 15-18 in middle of ventral side


Valves are moderately to strongly dorsiventral. The dorsal margin is arched and the ventral margin is slightly convex. The apices are protracted and slightly capitate. The raphe is straight, with slightly dorsally deflected proximal ends and strongly ventrally deflected distal ends. The axial area is narrow, with the central area slightly expanded. A stigma is absent. Striae are slightly radiate in the center valve, becoming nearly parallel at the apices.

Janus cells are observed in this taxon. Such frustules have valves of distinctly different stria density on each valve. Janus cells are illustrated in Figures 11a and 11b in the plate from the original publication (Winter and Bahls 2013).

This taxon was illustrated in Krammer (1997) within the images of E. hebridicum, leading to later misidentification in North American material. This taxon was also referred to as ‘Encyonema sp. 1 MONTANA HAMSHER’.

Original Description

Author: Winter and L.L.Bahls 2012
Length Range: 19-30 µm
Width Range: 6.5-7.5 µm
Striae in 10 µm: (14) 16-18 in middle of dorsal side, (11) 15-17 (18) in middle of ventral side

Original Description

Valves moderately to strongly dorsiventral. Dorsal margin arched, ventral margin slightly convex, ends protracted and slightly capitate. Raphe straight, proximal ends slightly dorsally deflected, distal ends strongly ventrally deflected. Axial area narrow, central area slightly expanded, stigma absent. Striae slightly radiate in center becoming nearly parallel at ends. Valve length 19-30 µm, valve width 6.5-7.5 µm, dorsal central striae (14) 16-18 in 10 µm, ventral central striae (11) 15-17 (18) in 10 µm.

Original Images

Cite This Page:
Winter, D. (2012). Encyonema hamsherae. In Diatoms of the United States. Retrieved April 21, 2018, from http://westerndiatoms.colorado.edu/taxa/species/encyonema_hamsherae

Species: Encyonema hamsherae

Contributor: Diane Winter

Reviewer: Sarah Spaulding


Krammer, K. (1997). Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 2. Encyonema part., Encyonopsis and Cymbellopsis. Bibliotheca Diatomologica 37:1-469.

Winter, D. and Bahls, L. (2013). Encyonema hamsherae, a new species from the Northern Rocky Mountains, USA. Phytotaxa 127(1): 58-65. 10.11646/phytotaxa.127.1.9

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)

NADED ID: 110042

Autecology Discussion

The highest abundance of E. hamsherae is from sites on small headwater streams suggesting a preference for cold, nutrient-poor waters. In general, Encyonema hamsherae is found at elevations ranging from about 1000 to 2100 m. Encyonema hamsherae appears to prefer moderate levels of alkalinity and dissolved solids.