• Category
  • Length Range
    13.4-40.3 µm
  • Width Range
    8.0-14.5 µm
  • Striae in 10 µm



Valves are elliptic to nearly oval, with bluntly rounded apices. Valve margins are highly arched, making the valve/mantle interface appear poorly differentiated when the central valve face is in focus. The central area is small with variable outline, often apically elliptic. The raphe is filiform and straight. The proximal raphe ends are slightly expanded and moderately spaced. The axial area is narrow, expanding to lanceolate at the central nodule. Striae are arranged uniformly throughout the valve. Striae are uniseriate along the axial area, becoming biseriate distal to the longitudinal canal . Note that the biseriate nature of the striae is only visible in SEM.

Other features require SEM to observe. The distal raphe fissures are deflected to the same side. The longitudinal canals form a rhombic-lanceolate area and are marked externally by transapical striae composed of 3-4 areolae. The biseriate areolae occur in linear pairs, rather than in alternating pairs.

There are differences between the North American and European specimens, based on our measurements of the original images. California specimens have 12-15 striae in 10 µm in the center valve, while original specimens have 12-14 striae in 10 µm in the center valve. California valves have an areola density of 18-25 in 10 µm, compared to the original specimen's 20 in 10 µm.


The images shown on this page were collected from rock scrapings in Lichau Stream, California in 2017 and 2018. It was also collected in Windsor Creek, California (USGS California Regional Survey).

The species was described from a pond formed by mining excavation in Sachsen–Anhalt, Germany (Lange-Bertalot and Fuhrmann 2016).

Original Description

Valves elliptical to linear–elliptical with bluntly rounded ends. Only central parts of the valve face are almost flat, whereas marginal parts become arcuate as they gently merge into the poorly differentiated mantle. Length 18–40 µm, breadth 8–15 µm. Length– to–breadth ratio 1.8–2.7. Raphe filiform, straight, with slightly expanded central endings which are moderately widely spaced; longer terminal fissures bent onto the same side of the valve mantle. Axial area narrow but expanded lanceolate towards the centre. Central area rather small with variable outlines, often apically elliptical, but clearly separated in all cell–cycle stages. H–shaped appendices barely developed. Axial internal canals are marked outside by transapical striae composed of three or four areolae, altogether forming a conspicuous rhombical–lanceolate area being softly arched around the central nodule. Adjacent regular striae radiate throughout, 13–15 in 10 µm, uniseriate but becoming biseriate near the valve margins onto the mantle. The areolae are opposed, not alternating, appearing here as single puncta in LM (cf. SEM Figs 106–107). Number of areolae in 10 µm is 13–18. SEM external view see Figs 106–108. Note in particular the raphe central and distal endings and the arrangement of cribrate areolae gradually cleaved with opposed parts.

  • Author
    Lange-Bert. and Fuhrmann 2016
  • Length Range
    18-40 µm
  • Width
    8-15 µm
  • Striae in 10µm

Original Images

Diploneis abscondita Orig Illus
Diploneis Abscondita Orig Illus 02
Diploneis Abscondita Orig Desc

Cite This Page

Phillips, N., Jovanovska, E., Polaskey, M. (2019). Diploneis abscondita. In Diatoms of North America. Retrieved July 17, 2024, from https://diatoms.org/species/diploneis-abscondita


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