• Category
  • Length Range
    20–32 µm
  • Width Range
    11–15 µm
  • Striae in 10 µm
  • Reported As
    Diploneis ovalis (Foged 1976 Fig 2:13)
    Diploneis parma (Lange-Bertalot and Metzeltin 1996 Fig 85:5)
    Diploneis parma (Hofmann et al. 2013 Fig 65:10)



Valves are elliptic to oblong–elliptical, with rounded ends. The axial area is narrow and linear, with an expanded central area, 2.5–3.0 µm wide. The longitudinal canal is narrow and includes one row of areolae in the middle of the valve. The longitudinal canal narrows toward the valve apices. The raphe is straight. The proximal raphe ends are slightly expanded. The distal raphe fissure is deflected at nearly 90 degrees. The striae are radiate and uniseriate. The areolae are round to nearly rectangular and number 10-15 in 10 µm.

Note that the original description contains discrepancies concerning valve dimensions (Lange-Bertalot and Fuhrmann 2016). The Latin description states "Longitudo 20–45 μm, latitudo 12–17 μm" and "Areolae 12–15 in 10 μm". In contrast, the English decription states "Length 20–40 μm, breadth 12–16 μm" and "Areolae 13–15 in 10 μm". It is not clear which set of morphometrics is correct.


This taxon was documented from lake sediments of the northeast US: Holland Lake, Vermont and Little Watchic Lake, Maine (EPA National Lakes Assessment, 2018).

It was also found in streams of the western United States: Duncan Canyon Creek near French Meadows, California, Fanno Creek at Durham, Oregon, Jenkins Creek near Covington, Washington; Bear Creek at Union Hill Road at Redmond, Washington (USGS Pacific Northwest Regional Survey). Additional records are from streams of the Sierra Nevada Mountains, California (USGS). These lakes and streams span a wide range of condition, from remote and unimpacted to highly impacted site (Fanno Creek).

The species was described from Lake Bohinj, a calcium carbonate–rich lake in the Julian Alps, Slovenia. The specific epithet refers to the rich habitat - calcium (calx) with the adjective lacustris (from lacus = lake).

Original Description

Outlines strictly elliptical to oblong–elliptical, more or less cuneately rounded ends. Length 20–40 μm, breadth 12–16 μm, length–to–breadth ratio 1.6–2.7. Raphe filiform, straight with distinctly expanded central ends and shortly curved distal ends. Axial area narrow. Central area elliptical, expanded transapically 1/4 to 1/5 of the valve breadth. H–shaped appendices (so–called horns in the literature) weakly developed. Internal depressions parallel to the raphe slit, visible in LM view by focusing. Apical internal canals marked by a single or two apertures to the valve outside, closely adjacent to the transapical striae, being moderately radiate throughout or somewhat stronger radiate close to the apices, 10–12 in 10 μm. Areolae 13–15 in 10 μm, appearing uniseriate with exception of a few ones close to the margins where they become biseriate in each stria. SEM external and internal view see Figs 109–111.

  • Author
    Lange-Bert. and Fuhrmann 2016
  • Length Range
    20–40 µm
  • Width
    12–16 µm
  • Striae in 10µm

Original Images

Diploneis Calcilacustris Orig Illus2
Diploneis Calcilacustris Orig Illus
Diploneis calcilacustris Orig Desc

Citations & Links



Cite This Page

Jovanovska, E., Phillips, N., Polaskey, M. (2019). Diploneis calcilacustris. In Diatoms of North America. Retrieved May 20, 2024, from https://diatoms.org/species/diploneis-calcilacustris


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