Stephanodiscus hantzschii fo. tenuis

(Hustedt) Håkansson & Stoermer 1984      Category: Centric
BASIONYM: Stephanodiscus tenuis Hustedt 1939

Stephanodiscus hantzschii

 

Stephanodiscus niagarae

LM scalebar = 10 µm = 80 pixels.



Observations

Contributor: David R.L. Burge | Mark Edlund - October 2016
Diameter: 15.5-19 µm
Rows of areolae in 10 µm: 5.7-7.5 based on circumferential density

Description

The valve flat is flat and lightly silicified. Areolae are fine, occurring 26-28 in 10 µm, arranged in multiseriate fascicles. The fascicles number 5.7- 7.5 in 10 µm based on circumferential density. Areolae in the valve center are always arranged in an annulus. Fascicles are often not straight, showing a slight wavy pattern, and branching in some specimens. Long spines occur at each interfascicle. A single rimoportula is present on an interfascicle, near the valve face/mantle junction, replacing a spine. Central fultoportulae are absent.

This taxon is considered to be an environmental forma, favored in particular conditions (Anderson 1990). Stephanodiscus hantzschii and S. hantzschii fo. tenuis often co-occur, with forma having a higher total phosphorus optimum than the nominate variety (Reavie and Kireta 2015). Others have suggested the forma is indicative of silica limitation (Stoermer et al. 1979). Heterovalvar frustules may be found, further supporting the conclusion that the environment shapes the morphology of this taxon (Anderson 1990).



Original Description

Basionym: Stephanodiscus tenuis
Author: Hustedt 1939
Diameter: 8-28 µm
Rows of areolae in 10 µm:

Original Description

  1. Stephanodiscus tenuis nov. spec. Schalen fast flach, nur wenig konzentrisch gewellt, dünnwandig, 8-28 µ ins Durchmesser, durch zarte radiale Ripen in mehr oder weniger zahlreiche Sektoren geteilt, die aus breiter Basis gegen das Zentrum allmählich schmäler werden. Zwischenräume zart areoliert. Areolenreihen am Rande etwa 4-5 in jedem Bündel. Vor den radialen Rippen innerhalb des Schalenrandes lange Randdornen.

Original Images


Cite This Page:
Burge, D., and Edlund, M. (2016). Stephanodiscus hantzschii. In Diatoms of the United States. Retrieved May 23, 2017, from http://westerndiatoms.colorado.edu/taxa/species/stephanodiscus_hantzschii_f._tenuis

Species: Stephanodiscus hantzschii

Contributor: David R.L. Burge | Mark Edlund

Reviewer: Euan Reavie

Citations

Anderson, N.J. (1990). The biostratigraphy and taxonomy of small Stephanodiscus and Cyclostephanos species (Bacillariophyceae) in a eutrophic lake, and their ecological implications. British Phycological Journal 25(30: 217-235.

Håkansson, H. and Stoermer, E.F. (1984). Observations on the type material of Stephanodiscus hantzschii Grunow in Cleve & Grunow. Nova Hedwigia 39:477-495.

Hustedt, F. (1939). Die Diatomeenflora des Küstengebietes der Nordsee vom Dollart bis zur Elbemündung. I. Die Diatomeenflora in den Sedimenten der unteren Ems sowie auf den Watten in der Leybucht, des Memmert und bei der Insel Juist. Abhandlungen des Naturwissenschaftlichen Verein zu Bremen 31(2/3):571-677.

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

Stoermer, E.F., Kingston, J.C., & Sicko-goad, L. (1979). The morphology and taxonomic relationships of Stephanodiscus binderanus var. oestrupii (A. Cl.) A. Cl. Nova Hedwigia, Beih. 64: 65-78.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA
Original INA

California Academy of Sciences (CAS)

Stephanodiscus hantzschii f. tenuis CAS

North American Diatom Ecological Database (NADED)

NADED ID:

Autecology Discussion

Stephanodiscus hantzschii fo. tenuis was reported from nearshore and high energy zones of lakes Erie and Ontario (Reavie and Kireta 2015). It is considered characteristic of eutrophic lakes, particularly in higher total phosphorus concentrations (Reavie and Kireta 2015), and under silica limitation (Stoermer et al. 1979).