• Category
  • Length Range
    46-60 µm
  • Width Range
    20-21.5 µm
  • Striae in 10 µm
  • Reported As
    Diploneis ovalis ssp. ovalis (Lange-Bertalot and Genkal 1999 Taf. 44b, Fig 1-4)



Valves are elliptic-lanceolate, with obtusely rounded ends. The axial area is narrow and linear to lanceolate. The axial area expands near the large, round central area, 6.5–8.0 µm wide. The longitudinal canal is linear to lanceolate and expanded in the mid-valve. Two rows of areolae are external to the middle of the longitudinal canal, narrowing into one towards the valve apices. The raphe is straight, with slightly expanded proximal raphe ends. The distal raphe ends are short and curved. The striae are radiate. Striae are composed of one row of coarse, round areolae, 9–15 in 10 μm.


This diatom has been documented from No Name Hanging Fen, Glacier National Park, Montana.

Original Description

Valves strictly elliptical with obtusely rounded ends. Length 27–60 μm, breadth 15–25 μm; length-to-breadth ratio 1.8–2. Raphe filiform, almost straight with considerably expanded central and indistinct distal ends. Axial area narrow, linear, ca. 1 μm wide. Central area large, broadly elliptical, extended to 1/3 of valve breadth, set off with distinct appendices. Internal depressions parallel to the valve slit, visible in LM by focussing. Zone of apical internal canals broadly arcuate around the central nodule (central area), then tapering towards the ends. Striae radiate throughout, 11–12 in 10 μm, consisting of uniserate coarse areolae, 10–13 in 10 μm.

SEM external view see Figs 132: 5, 6; 134: 4–6. Central raphe ends deeply depressed into the valve surface, distal ends shortly deflected. Areolae on the apical canal system uniseriate around the central nodule, becoming pluriseriate in other parts of the canals. Regular cribrate areolae, uniseriate throughout the valve face and mantle.

  • Author
    Lange-Bert. and Furhmann 2020
  • Length Range
    27–60 µm
  • Width
    15–25 µm
  • Striae in 10µm

Original Images

Diploneis mollenhaueri Orig Illus
Diploneis mollenhaueri Orig Illus 2
Duploneis mollenhaueri Orig Desc

Cite This Page

Polaskey, M. (2019). Diploneis mollenhaueri. In Diatoms of North America. Retrieved May 25, 2024, from https://diatoms.org/species/diploneis-mollenhaueri


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Diploneis mollenhaueri 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.