Encyonema reimeri

S.A.Spauld., Pool and S.Castro 2010      Category: Asymmetrical biraphid

REPORTED AS: Cymbella muelleri ((Patrick and Reimer 1975, pl.7, fig. 1)) 

Encyonema reichardtii


Encyonema sibericum

LM scalebar = 10 µm = 40 pixels.


Contributor: Sarah Spaulding - April 2010
Length Range: 30-89 µm
Width Range: 16-26.5 µm
Striae in 10 µm: 10


Valves are strongly dorsi-ventral. The dorsal margin is broadly arched, while the ventral margin is expanded. The valve apices are acute. The axial area is relatively broad in the central part, narrowing at the valve ends. The raphe branches have a slight arch towards the ventral margin. Each raphe branch is positioned nearly centrally within the axial area. Proximal raphe ends are slightly expanded and dorsally deflected. Distal raphe ends curve slightly to the dorsal margin, but are deflected ventrally near the valve apices. The dorsal striae are divergent. Externally, the rows of dorsal areolae closest to the central area are oval, and become lineolate, the length of the lineolae becoming greater towards the dorsal margin. Dorsally, central striae number 10 in 10 μm and distal striae number 5 in 5 μm. Ventrally, central striae number 8 in 10 μm, and distal striae number 6 in 5 μm. The density of areolae within a central, dorsal stria is 7-8 in 5 μm. The striae continue continue onto the mantle, but stop short of the valve margin. Internally, the striae are lineolate and positioned between thickened internal costae. The proximal raphe ends are deflected dorsally at a 90° angle. Distally, the raphe ends at a terminal nodule. A single chloroplast possesses two lobes and ventral fold.

Original Description

Author: S.A.Spauld., Pool and S.Castro 2010
Length Range: 30-75 µm
Width Range: 17-22 µm
Striae in 10 µm: 10

Original Description

Valvulae sunt valde dorsiventrales. Dorsualis margo ample arcuata est, sed ventralis margo inflatosa est. Valvulae longitudo 30-75 μm est; amplitudo 17-22 μm est. Valvulae terminationes acutae sunt. Axialis superficies est relative ampla in centrali valvula et astringitur in extrema valvula. Suturae ramificationes levem habent arcum ad ventralem marginem. Unaquaeque suturae ramificatio posita est fere centrali positione intra axialem superficiem. Suturae extrema proxima leviter sunt expansi et dorsualiter deflexi. Suturae extrema distalia suturae curvaminis leviter inflectuntur marginem ad dorsualem, sed ventraliter sunt deflexa prope valvulae apices. Dorsuales striae sunt in diversum vergentes. Externe, primae series sunt ovales fiuntque lineolatae, maiorque fit lineolatarum longitudo ad dorsualem marginem. Dorsualiter, striae numeris 10 sunt in 10 μm; centraliter sunt 9 in 10 μm. Striae continuantur super dorsualem marginem valvulae. Interne, striae lineolatae sunt et positae intra cubicula, cum internis costis super dorsualem marginem spissatae. Suturae extrema proxima dorsualiter sunt deflexa angulo 90 graduum. Distaliter, sutura terminali nodulo finit. Chloroplasti duas habent auriculas, ventrali plica.

Original Images

Original text and images reproduced with permission by Proceedings of the Academy of Natural Sciences of Philadephia.

Cite This Page:
Spaulding, S. (2010). Encyonema reimeri. In Diatoms of the United States. Retrieved April 22, 2018, from http://westerndiatoms.colorado.edu/taxa/species/encyononema_reimeri

Species: Encyonema reimeri

Contributor: Sarah Spaulding

Reviewer: Mark Edlund


Spaulding, S.A., Pool, J., Castro, S. and Hinz, F. (2010). Species within the genus Encyonema Kützing, including two new species Encyonema reimeri sp. nov. and E. nicafei sp. nov. and E. stoermeri nom. nov., stat. nov. Proceedings of the Academy of Natural Sciences of Philadelphia 160(1):57-71. 10.1635/053.160.0107

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

NCBI Genbank Taxonomy

Cymbella muelleri NCBI

North American Diatom Ecological Database (NADED)


Autecology Discussion

Colonies of Encyonema grow within mucilagious tubes.


Encyonema reimeri living cells growing in mucilaginous tubes. Such tubes are typical for species within Encyonema. These tubes are shown surrounded by the cyanobacteria Planktothrix.

Credit/Source: Kalina Manoylov

Sexual reproduction in E. reimeri may follow Geitler’s Type IA1a (Fig C, D) or possibly Type IC (Fig. B). Two parental cells are paired ventral to ventral within a common copulation mucilage that is further covered in organic and mineral debris (Fig. A). Each parental cell appears to produce two gametangia that are released into the mucilage for pairing. The two resultant auxospores undergo expansion and silicification to become initial cells, but it was unclear if there was a distinct orientation (parallel or non-oriented) to the parental cells.

Credit/Source: Nick Schulte and the 2015 Iowa Lakeside Lab class

Size range of population of E. reimeri collected from in the wave zone near Triboji Beach, West Lake Okoboji, Iowa on May 26, 2015.

Credit/Source: Nick Schulte and the 2015 Iowa Lakeside Lab class

Analysis showed E. reimeri ranges in size from 38 to 89 µm in length and 16 to 26.5 µm in breadth; these measurement extended the reported size metrics (L 30-75 µm, B 17-22 µm; Spaulding et al. 2010). Shorter valves had less attenuated ends and less tumid ventral inflations. There is a positive relationship between valve length and breadth (Fig. 2), and a weak negative relationship between striae density and cell size.

Credit/Source: Nick Schulte and the 2015 Iowa Lakeside Lab class


- Extension of size range

Prior to this date, length was documented as 30-75 µm and width as 17-22 µm. These values were revised based on the 2015 diatom class observations. which were presented in a poster at the North American Diatom Symposium (Schulte et al. 2015). See AUTECOLOGY tab for details. - S. Spaulding