Encyonema lunatum

(W.Sm.) Van Heurck 1880      Category: Asymmetrical biraphid

REPORTED AS: Cymbella lunata (Patrick and Reimer 1975, p. 46, plate 7, figs. 11-14) | Cymbella gracilis (Krammer and Lange-Bertalot 1986, p. 308, fig. 120: 10-14) 

Encyonema leibleinii


Encyonema minutum var. pseudogracilis

LM scalebar = 10 µm = 80 pixels.


Contributor: Loren Bahls - May 2016
Length Range: 27-41 µm
Width Range: 4.3-5.3 µm
Striae in 10 µm: 9-14


Valves are lunate, or crescent shaped, with rounded apices. The dorsal margin is moderately arched. The ventral margin is concave. The axial area is narrow. The central area is small and asymmetric, formed by a slight shortening of the median dorsal stria. Proximal raphe ends are deflected to the dorsal side and terminate in inconspicuous central pores. Distal raphe fissures are long and curved ventrally. Striae on the dorsal side are radiate and more widely separated at the valve center than they are near the apices. The median dorsal stria may have a single isolated areola near the central valve. Striae are shorter on the ventral side and more or less parallel throughout. Areolae in the striae are very fine and number about 40 in 10 µm.

Original Description

Author: W.Sm. in Grev. 1855
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Bahls, L. (2016). Encyonema lunatum. In Diatoms of the United States. Retrieved April 23, 2018, from http://westerndiatoms.colorado.edu/taxa/species/encyonema_lunatum

Species: Encyonema lunatum

Contributor: Loren Bahls

Reviewer: Diane Winter


Greville, R.K. (1855). Report on a collection of Diatomaceae made in the district of Braemar by Professor Balfour and Mr. Gerge Lawson. Annals and Magazine of Natural History, 2nd series, 15:252-261.

Krammer, K. (1997). Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 1. Allgemeines und Encyonema. Bibliotheca Diatomologica 36: 1-382.

Van Heurck, H. (1880). Synopsis des Diatomées de Belgique. Atlas. Ducaju & Cie., Anvers.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Encyonema lunatum CAS

North American Diatom Ecological Database (NADED)

NADED ID: 110009

Autecology Discussion

The specimens of E. lunatum shown on this web page were collected from wetland habitats on the tundra in Nunavut, Canada (photos below). These wetlands have circumneutral pH, low conductivity, and low concentrations of bioavailable nutrients. This species was described from material collected in Scotland and is widespread in suitable habitats (Krammer 1997).


Wet hummocks near Baillie River, Nunavut, Canada: home of Encyonema lunatum

Credit/Source: Beverly Boynton, Adventurers and Scientists for Conservation

Wetland near Back River, Nunavut, Canada: home of Encyonema lunatum

Credit/Source: Beverly Boynton, Adventurers and Scientists for Conservation