Entomoneis ornata

(J.W.Bailey) Reimer 1975      Category: Asymmetrical biraphid
BASIONYM: Amphiprora ornata J.W.Bailey 1851

Entomoneis alata


Entomoneis paludosa

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - February 2012
Length Range: 71-93 µm
Width Range: 23-43 (girdle view) µm
Striae in 10 µm: 20-24


Frustules almost always come to rest in girdle view, a view which is dominated by highly arched bilobate keels. The keels are strongly torsioned so that only one lobe is in focus at one time. In complete frustules in girdle view, diagonally opposing lobes lie at approximately the same level of focus. Lobes are flattened in large specimens and more rounded in smaller specimens. Several girdle bands are present, each with a linear series of short transverse dashes that appear to cross at mid-valve. The junction line between the valve and the keel is marked by a series of prominent and irregularly shaped bulges or swellings. Striae on the valve face continue onto the keel. Areolae within a stria on the valve face are very fine and number 26-30 in 10 µm. Areolae within a stria on the keel are more prominent and number 14-20 in 10 µm.

Original Description

Basionym: Amphiprora ornata
Author: J.W.Bailey 1851
Length Range: µm
Striae in 10 µm:

Original Description

AMPHIPRORA ORNATA, B. Pl. 2, figs. 15 and 23. Small, deeply constricted, ends truncated and rounded, sides marked with a longitudinal row of undulations or pinnulæ, as in Surirella. Often contorted. The ruffle-like rows of pinnulæ distinguish this species from all others. It probably has minute striæ also, but I did not have an opportunity to examine with high powers. Hab. Withlacoochee River, where it is crossed by the road from Pilatka to Tampa, Fa.

Original Images

Cite This Page:
Bahls, L. (2012). Entomoneis ornata. In Diatoms of the United States. Retrieved April 26, 2018, from http://westerndiatoms.colorado.edu/taxa/species/entomoneis_ornata

Species: Entomoneis ornata

Contributor: Loren Bahls

Reviewer: Rex Lowe


Bailey, J.W. (1851). Microscopical observations made in South Carolina, Georgia, and Florida . Smithsonian Contributions to Knowledge 2(8): 1-48.

Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Süsswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.

Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Entomoneis ornata CAS

NCBI Genbank Taxonomy

Entomoneis ornata NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 31002

Autecology Discussion

In Montana, Entomoneis ornata has been found in 23 lakes, marshes, large rivers and small creeks, both east and west of the Continental Divide. These waters have an abundance-weighted mean pH of 8.1 and an abundance-weighted mean specific conductance of 2188 µS/cm, which is considerably lower than the conductivity preferred by other species of Entomoneis. But like E. alata, E. ornata prefers waters with elevated concentrations of sodium and sulfate. Common diatom associates of Entomoneis ornata include Gomphonema turgidum, Gomphonema coronatum, Neidium iridis, Placoneis explanata, Cavinula jaernefeltii, Stauroneis heinii, and Nitzschia obtusa. Patrick and Reimer (1975) report this species as widely distributed in in the United States in larger lakes and rivers, where it is an oligohalobe and “indifferent” to small changes in ionic content.


Kintla Lake, Glacier National Park, Montana: home of Entomoneis ornata.

Credit/Source: Loren Bahls