• Category
  • Length Range
    20-29 µm
  • Width Range
    11-13 µm
  • Striae in 10 µm



Valves are elliptical to oblong-elliptical, with broadly rounded ends. The axial area is wide and lanceolate, expanding near the central area. The central area is round to elongate, 3.2–4.0 μm wide. The longitudinal canal is linear to lanceolate, expanded in middle of the valve, and composed of one (rarely two) rows of areolae throughout its whole length. The raphe is straight with slightly expanded proximal ends. The terminal raphe ends are indistinguishable in LM. In SEM, the distal raphe ends can be seen to be unilaterally deflected. The striae are radiate and wide. Striae are triseriate, becoming multiseriate (4-6) at the valve margin. The areolae number approximately 25 areolae in 10 μm. The areolae may be undistinguishable under LM.

Note that the original description states that the striae of D. texana are biseriate. However, that statement is likely due observations based on LM (Lange-Bert. and Fuhrmann 2020). SEM images demonstrate that the striae are triseriate, to mutiseriate, with 4-6 areolae in each striae toward the valve margin.


This taxon was described from material collected early in the 1900's from a site in San Antonio, Texas. The images presented here are from the Diploneis-rich site of Four Colors Spring, Rocky Boy Reservation, Montana.

Original Description

Valves elliptical to oblong-elliptical with broadly rounded ends. Length 22–44 μm, breadth 12–18 μm; ratio length-to-breadth 1.8–2.4. Raphe branches almost straight or slightly curved with very little expanded central ends; distal ends appear indistinct, apparently straight. Parallel internal depressions discernible with appropriately focussing. Central area appears lanceolate together with its appendices and the axial area, extended to ca. 1/3 of the valve breadth. The canal system is 5–10 μm wide in the slightly inflated centre depending on the size of specimens. Canal areolae for the most part uniseriate, only rarely biseriate, appearing very coarse and distinctly set off from the fine striae and areolae. Striae radiate throughout, more strongly so closer to the ends, 9.5–11 in 10 μm; the striae are uncommonly broad between the relatively narrow virgae. With appropriate focus the areolae can be counted, 22–24/10 μm, both in adaxial and in marginal parts of striae.

  • Author
    Lange-Bert. and Fuhrmann 2020
  • Length Range
    22–44 µm
  • Width
    12–18 µm
  • Striae in 10µm

Original Images

Diploneis texana Orig Illus
Diploneis texana Orig Desc

Cite This Page

Jovanovska, E., Polaskey, M. (2021). Diploneis texana. In Diatoms of North America. Retrieved September 17, 2021, from https://diatoms.org/species/diploneis-texana


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