(Ralfs) Brun 1880 Category: Araphid
BASIONYM: Meridion constrictum Ralfs 1843
Contributor: Natalie Hoidal - June 2013
Length Range: 12-55 µm
Width Range: 5-8 µm
Striae in 10 µm: 16-20
Frustules are linear-clavate. In valve view, the headpole is rostrate. A narrow sternum extends the length of the apical axis of the valve. Striae are grouped together, 1-6 between costae. Numerous costae are present, positioned along the transverse axis. In some specimens, costae are not visible near the footpole. A rimoportula is present near the headpole, and usually visible under the light microscope. Cells often grow in fan-shaped colonies. Internal valves are common in this taxon.
Basionym: Meridion constrictum
Author: Ralfs 1843
Length Range: µm
Striae in 10 µm:
” M. constrctum. Lateral surfaces constricted below the apex, transversely striated : the ends of the striae forming puncta along the margins of the front view.
Brun, J. (1880). Diatomées des Alpes et du Jura et de la région Suisse et Française des Environs de Genève. Imprimerie Ch. Schuchardt, Genève. 146 pp.
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Ralfs, J. (1843). On the British species of Meridion and Gomphonema. Annals and Magazine of Natural History 12: 457-467.
Rhode, K.M, Pappas, J.L. and Stoermer, E.F. (2001). Quantitative analysis of shape variation in type and modern populations of Meridion Ag. Journal of Phycology 37: 175-183.
Stancheva, R. (2006). Distribution of resting spores of Eunotia soleirolii and Meridion circulare var. constrictum (Bacillariophyta) in sediments of peat bogs from Mt. Central Sredna Gora, Bulgaria. In Ognjanova-Rumenova, N. and Manoylov, K. (eds.) Advances in Phycological Studies, Pensoft, Sofia and Moscow. 111-121 pp.
Williams, D.M. (1985). Morphology, taxonomy and inter-relationships of the ribbed araphid diatoms from the genera Diatoma and Meridion (Diatomaceae: Bacillariophyta). Bibliotheca Diatomologica 8: 1-228.
Meridion circulare var. constrictum was found in a prairie stream north of Iowa Lakeside Lab, Dickinson County, Iowa. Specimens from the Iowa Lakeside Lab Herbarium confirmed this taxon in soils, duffs from prairie swales, moss, a plankton tow from “No Name” creek in Dickinson County, the surface of a small puddle and in sand from the Little Sioux River.
This species has a fairly cosmopolitan distribution, but is most commonly found in streams and creeks. Williams (1985) described the taxon as being sited in Great Britain, France, Hungary, USA, New Zealand, France, and Lapland. As the cells divide, they form fan-like colonies growing on plants and rocks (Ralfs, 1843). Meridion circulare var. constrictum is less common than the nominate variety and considered to survive outside of permanent water bodies in locations such as puddles (Stancheva, 2006).
Live colony from Northern prairie stream at Iowa Lakeside Lab, Dickinson County, Iowa.
Credit/Source: Natalie Hoidal
Live colony from Northern prairie stream at Iowa Lakeside Lab, Dickinson County, Iowa
Credit/Source: Natalie Hoidal