• Category
  • Length Range
    14.6-28.9 µm
  • Width Range
    8.4-11 µm
  • Striae in 10 µm



Valves are oblong to oblong-elliptic, with broadly-rounded apices. The central nodule is small and orbicular. Longitudinal canals are narrow, and follow along the margin of the central nodule and axial areas. The longitudinal canals have a single row of areolae. The raphe sternum widens near the proximal raphe ends. Proximal raphe ends are expanded. Terminal raphe fissures are unilaterally deflected. Striae are uniseriate. Striae are parallel at the central nodule, becoming radiate toward the axial area. Striae are composed of round areolae, which are discernible with LM.

Note that this taxon has been considered previously within a broad concept of Diploneis parma Cleve. Some of those citations include Krammer and Lange-Bertalot (1986, Fig 109: 6-7), Lange-Bertalot and Metzeltin (1996, Fig 85: 6-7), Metzeltin et al. (2009, Fig 109:3), and Hofmann et al. (2013, Fig 65: 9,11).


The images presented on this page are from the National Ecological Observation Network (NEON) site at Kings Creek, Riley County, Kansas. It is the only NEON site within undisturbed native tallgrass prairie. The site is part of the USGS Hydrologic Benthic Network.

According to NEON, the site is underlain by mafic metavolcanic rock. Geologically, the site is part of the Council Grove Group, which is described as an unglaciated, early Permian age limestone interbedded with shales. The benthic substrate consists of cobble, boulder, pebbles, sand, and clay. Kings Creek is a second-order stream within a watershed draining agricultural, pasture, and tallgrass prairie. The flow regime is intermittent and flashy. The stream may dry for several months of the year, with high rainfall events resulting in high flows, even intense flooding.

The images are from the only known records in North America. This taxon was described from a disjunct site, the Loisach River, Austria. The sample collection was from bryophytes, growing on wood. The Latin epithet comes from calciocola (thriving in calcium rich habitats) and frequens (frequently). The original description, however, did not provide an indication of the geographic distribution of this taxon.

Original Description

Valve outlines elliptical to oblong-elliptical with obtusely rounded ends. Length 15–34 μm, breadth 10–14 μm; ratio length-to-breadth 1.6–2.6. Raphe filiform, straight with slightly expanded proximal and indistinct distal ends. Parallel internal depressions discernible with light microscopy but rather difficult to differentiate from the raphe. Axial area linear, width 1 μm or less, expanding only slightly towards the valve centre. Central area at most barely set off from the axial area in smallest cell cycle stages, in largest stages up to 2.5 μm, i.e. 1/10 to 1/5 of the valve breadth. Canal system also very narrow, appearing almost linear but arcuate in the centre, marked by a single apical row of puncta on either side. Striae radiate throughout, 13–17 in 10 μm. Areolae uniseriate except of the valve mantles where they become opposedly biseriate, 15–20 in 10 μm.

SEM external view see Figs 27: 2; 28: 24; 29: 29. Only the marginal areolae of the mantle are cleaved into opposed pairs, never being arranged alternately. Central raphe ends strongly bent shortly, distinctly expanded, lying in a particular raphe rib which is likewise bent. Distal raphe ends gently and somewhat longer deflected rather than bent shortly. The cribra appear particularly large.

SEM internal view. The usual pattern of alternating virgae and alveoli, the latter—in uncorroded state—covered by undivided membranes, is rather undistinctive.

  • Author
    Lange-Bert. and Fuhrmann 2020
  • Length Range
    15–34 µm
  • Width
    10–14 µm
  • Striae in 10µm

Original Images

Diploneis calcicolafrequens Orig Illus
Diploneis calcicolafrequens Orig Desc

Citations & Links



Cite This Page

Jovanovska, E., Winter, D. (2021). Diploneis calcicolafrequens. In Diatoms of North America. Retrieved September 17, 2021, from https://diatoms.org/species/diploneis_calcicolafrequens


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