• Category
  • Length Range
    7.4-8.4 µm
  • Width Range
    2.4-4.0 µm
  • Striae in 10 µm



Valves are linear elliptic with convex margins and capitate, rostrate or blunt apices. Specimens within a population may be irregular (asymmetric) and are often variable in the shape of the apices. In general, the axial area is narrow near the apices, becoming more broad near the central area. The central area is lanceolate, with a thickened and distinct central nodule. The raphe is filiform and straight, with slightly expanded external proximal raphe ends. Internally, the helictoglossae are small and indistinct. The striae are parallel to slightly radiate in the central valve. The striae are variable in the center valve; some stria may be shorter or curved in the center of the valve. Striae are composed of a single, elongate areola on the valve face. A smaller areola is positioned on the valve mantle. Internally, the proximal raphe has short, deflected ends.

Note that Hustedt's original description of this taxon, was as Navicula schmassmanni, named for Herr Dr. W. Schmassmann of Liestal. To accord with Latin grammatical rules the orthographic correction to "schmassmannii" is made.


Original Description

Navicula Schmassmanni Hust., in A.S. Atl., T. 400, F. 48 bis 52. Im Davoser Gebiet ziemlich verbreitet: Kleiner Flüelasee, Schwarzsee und in dessen Abfluss, oberer und unterer Grialetschsee. Wurde 1934 (l.c.) als neue Art aus diesem Material veröffentlicht:

Schalen im Umriss linear-elliptisch mit stark konvexen Rändern und breiten, kopfig abgeschnürten Enden, 6-10 µ lang, 2,5-3 µ breit. Raphe gerade, mit zeimlich entfernt gestellten Zentralporen. Axialarea und Zentralarea einen schmal lanzettlichen Raum einnehmend, ohne besonders abgesetzte Zentralarea. Transapikalstreifen durchweg leicht radial, im mittleren Teil der Schale 24-30 in 10 µ, gegen die Enden allmählich enger werdend, vor der Polen 36-40 in 10 µ. (Abb. 36, 37)

  • Basionym
    Navicula schmassmanni
  • Author
    Hust. 1943
  • Length Range
    6-10 µm
  • Width
    2.5-3 µm
  • Striae in 10µm
    24-30 in the center valve, 36-40 at the ends

Original Images

Img 2969
N Schmassmani Origdes


Dec 08, 2016 - Transfer from Navicula to Humidophila

From March 2011 until December 2016, this taxon appeared on Diatoms of the United States as Navicula schmassmanni Hustedt 1943. Based on (Buczkó et al. 2015), this taxon updated to Humidophila schmassmannii (Hustedt) Buczkó et Wojtal 2015. - S. Spaulding

Cite This Page

Otu, M., Spaulding, S. (2011). Humidophila schmassmannii. In Diatoms of North America. Retrieved June 23, 2024, from https://diatoms.org/species/humidophila_schmassmannii


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