Neidium sacoense

Reimer 1966      Category: Symmetrical biraphid

Neidium fogedii


Neidium undulatum

LM scalebar = 10 µm = 40 pixels.


Contributor: David R.L. Burge | Lynn Brant | Mark Edlund - May 2017
Length Range: 46-99 µm
Width Range: 18-24 µm
Striae in 10 µm: 15-16


Valves are broad and linear. The valve margins are nearly straight over most of the length, but toward the apices the margins abruptly taper to cuneate, apicuate apices. Specimens at the smallest end of the size range have convex, rather than straight, margins. Relatively wide longitudinal canals are positioned at the valve margins. The axial area is narrow, and is especially narrow at the central area and apices. The central area is small and elliptic to round. The raphe is filiform near the ends, becoming laterally expanded in the mid-way between the central valve and apices. Proximal raphe ends are deflected in opposite directions. The deflected ends are perpendicular to the raphe in smaller specimens and recurved in larger specimens. Striae are slightly radiate at the center of the valve, parallel throughout most of the valve and become slightly convergent at the apices. Prominent Voigt discontinuities are present. Striae are composed of round to transapically elongate areolae occurring 16-18 in 10 µm. Areolae are elongate on the valve face/mantle junction.

We observed a greater size range of N. sacoense (60-80 µm) than that reported previously (Patrick and Reimer 1966).

Original Description

Author: Reimer 1966
Length Range: 60-80 µm
Width Range: 19-25 µm
Striae in 10 µm: 15-16

Original Description

Valve broadly linear with abruptly narrowing, acutely rounded and apiculate ends. Axial area straight, narrowing toward the center and the ends of the valve. Raphe straight, narrowing at the proximal and the distal ends. Proximal ends curving in opposite directions; distal ends bifurcate. Central area small, orbicular. Primary longitudinal band marginal, quite wide and with very coarse, elongate puncta which are irregularly placed. Striae generally parallel or somewhat radiate at the center, becoming convergent at the ends; oblique at least on some part of the valve. Striae, 15-16 in 10µ. Puncta, 18 in 10µ on either side of the axial area; 12-14 in 10µ near the longitudinal band. Length, 60-80µ. Breadth, 19-25µ.

Original Images

Cite This Page:
Burge, D., Brant, L., and Edlund, M. (2017). Neidium sacoense. In Diatoms of the United States. Retrieved April 20, 2018, from

Species: Neidium sacoense

Contributor: David R.L. Burge | Lynn Brant | Mark Edlund

Reviewer: Sarah Spaulding


Gaiser, E.E. and Johansen, J. (2000). Freshwater diatoms from Carolina bays and other isolated wetlands on the Atlantic Coastal Plain of South Carolina, USA, with descriptions of seven taxa new to science. Diatom Research 15(1): 75-130. 10.1080/0269249X.2000.9705487

Lefebvre, K.E. and Hamilton, P.B. (2015). Morphology and molecular studies on large Neidium species (Bacillariophyta) of North America, including an examination of Ehrenberg’s types. Phytotaxa 220(3): 201-223. 10.11646/phytotaxa.220.3.1

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.

Reimer, C.W. (1959). The diatom genus Neidium. I. New species, new records, and taxonomic revisions. Proceedings of the Academy of Natural Sciences of Philadelphia 111: 1-36.

Siver, P.A. and Hamilton, P.B. (2011). Diatoms of North America: The Freshwater Flora of Waterbodies on the Atlantic Coastal Plain. Iconographia Diatomologica 22.

Siver, P.A. and Hamilton, P.B. (2005). Observations on new and rare species of freshwater diatoms from Cape Cod, Massachusetts, USA. Canadian Journal of Botany 83:362-378.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Neidium sacoense CAS

NCBI Genbank Taxonomy

Neidium sacoense NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 47022

Autecology Discussion

Neidium sacoense is rare in low alkalinity lakes from Florida, Maine and Wisconsin (Reimer 1959, Patrick and Reimer 1966, Camburn and Charles 2000). It is abundant in wetlands such as Bear Meadows Bog, Pennsylvania. Neidium sacoense tends to live in low pH habitats (Geiser and Johansen 2000, Siver and Hamilton 2005, Siver and Hamilton 2011).

Bear Meadows Bog is low in conductivity and pH (Edlund and Brant 2010). Armstrong Creek Bog, Forest County, Wisconsin also had abundant specimens, along with acid organisms such as Sphagnum moss, Pinnularia and Eunotia.


The distribution of Neidium sacoense in rivers of the continental United States. Retrieved on 18 May 2017

Credit/Source: USGS/Biodata

Bear Meadows Bog, a collection site of Neidium sacoense for this page.

Credit/Source: Photo by Lynn Brant