• Category
  • Length Range
    46.4-98.7 µm
  • Width Range
    18-24 µm
  • Striae in 10 µm



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).


Neidium sacoense is rare in low alkalinity lakes from Florida, Maine, Wisconsin (Reimer 1959, Patrick and Reimer 1966, Camburn and Charles 2000) and on the Olympic Peninsula of Washington (Bahls, see images on this page). 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.

Eusacoense  Usgsbiodata
Credit: USGS/Biodata
The distribution of Neidium sacoense in rivers of the continental United States. Retrieved on 18 May 2017
Bear   Meadows  Bog
Credit: Photo by Lynn Brant
Bear Meadows Bog, a collection site of Neidium sacoense for this page.

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.

  • Author
    Reimer 1966
  • Length Range
    60-80 µm
  • Width
    19-25 µm
  • Striae in 10µm

Original Images

N Sacoense  Orig Ill
N Sacoense  Orig Descr

Cite This Page

Burge, D, and Brant, L, and Edlund, M. (2017). Neidium sacoense. In Diatoms of North America. Retrieved June 22, 2018, from https://diatoms.org/species/neidium_sacoense1


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Neidium sacoense from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.