Stephanodiscus parvus

Stoermer and Håk. 1984      Category: Centric
SYNONYM(S): Stephanodiscus hantzschii fo. parva Grunow in Cleve and Grunow 1880 

Stephanodiscus oregonicus


Stephanodiscus reimeri

LM scalebar = 10 µm = 80 pixels.


Contributor: David R.L. Burge | Mark Edlund - September 2016
Diameter: 4.3-9.5 µm
Rows of areolae in 10 µm: 8-12 based on circumferential count


Valves are disc-shaped with a flat to slightly undulate face and shallow mantle. A single fultoportula is present in a slightly eccentric position in the center valve. Areolae are present across the valve face, weakly organized into rows at the valve center and forming more distinct fascicles toward the valve margin. Fascicles are uniseriate in the valve center, and may become biseriate at the valve face/mantle interface. The number of fascicles ranges from 17-31 per valve and decreases with valve diameter. Areolae are distinct and occur at 18-20 in 10 µm. Small spines are present on each interfascicle, at the valve margin.

The relation between fascicle number and valve diameter can be expressed as total number of fascicles = 0.78 * (diameter) + 5.12. For example, measures of diameter and fascicle count, respectively, are 9.3,31; 7.4,24; 4.5,14.

Original Description

Author: Stoermer and Håk. 1984
Diameter: 5-11 µm
Rows of areolae in 10 µm: 13-15 fascicles in 10 µm

Original Description

Valves circular, almost flat 5-11 µm in diameter. Ornamentation of the valve surface consisting of barely resolvable puncta arranged in biseriate fascicles, 13-15 in 10 µm, each fascicle separated by a distance interfascicle. Each interfascicle subtended by a well developed spine. Marginal strutted processes occur directly below every 3rd to 6th spine. One eccentric strutted process on the valve face present.

Valve ornamentation occurs in a coarsely and a finely structure form. In the coarsely structured form the puncta are arranged in biseriate, straight fascicles, becoming uniseriate or disorganized towards the center of the valve. In the finely structured form the puncta are also arranged in biseriate, straight fascicles, becoming disorganized towards the center where the puncta are grouped in a rosette0like configuration.

Original Images

Cite This Page:
Burge, D., and Edlund, M. (2016). Stephanodiscus parvus. In Diatoms of the United States. Retrieved April 21, 2018, from

Species: Stephanodiscus parvus

Contributor: David R.L. Burge | Mark Edlund

Reviewer: Euan Reavie


Cleve, P.T. and Grunow, A. (1880). Beiträge zur Kenntniss der Arktischen Diatomeen. Kongliga Svenska-Vetenskaps Akademiens Handlingar, 17(2): 121 pp., 7 pls.

Håkansson, H. and Stoermer, E.F. (1988). A note on the centric diatom Stephanodiscus parvus. Diatom Research 3(2): 267-267. 10.1080/0269249X.1988.9705040

Reavie, E.D. and Kireta, A.R. (2015). Centric, Araphid and Eunotioid Diatoms of the Coastal Laurentian Great Lakes. Bibliotheca Diatomologica 62:1-184.

Reavie, E.D. and Smol, J.P. (1998). Freshwater diatoms from the St. Lawrence River. Bibliotheca Diatomologica Band 41. J. Cramer, Berlin. 137 pp.

Stoermer, E.F. (1978). Phytoplankton as indicators of water quality in the Laurentian Great Lakes. Transactions of the American Microscopical Society 97(1): 2-16.

Stoermer, E.F. and Håkansson, H. (1984). Stephanodiscus parvus: Validation of an enigmatic and widely misconstrued taxon. Nova Hedwigia 39: 497-511.

Stoermer, E.F., Ladewski, B.G., & Schelske, C.L. (1978). Population response of Lake Michigan phytoplankton to nitrogen and phosphorus enrichment. Hydrobiolgia 57: 249-265.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Stephanodiscus parvus CAS

NCBI Genbank Taxonomy

Stephanodiscus parvus NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 64003

Autecology Discussion

Stephanodiscus parvus is most common in eutrophic lakes Erie and Ontario under conditions of high total phosphorus and moderate chloride concentration (Stoermer et al. 1978, Stoermer 1978, Stoermer and Håkansson 1984, Reavie and Kireta 2015). This taxon has also been reported from from the St. Lawrence River, with rare abundances from epilithic and epiphytic habitats, and greater abundant in sediment cores (Reavie and Smol 1998)


The record of Stephanodiscus parvus in streams and rivers of the continental United States.

Credit/Source: USGS/Biodata