• Category
  • Length Range
    44–132 µm
  • Width Range
    18–30 µm
  • Striae in 10 µm
    5–6 in the center, 20 at the apices
  • Synonyms
    Amphiprora navicularis Ehrenb. 1843
    Placoneis navicularis (Ehrenb.) E.J.Cox 2003



Valves are broadly lanceolate, with apices protracted to broadly rounded. The axial area is narrow and straight, forming a narrow, linear to ovoid central area. The raphe is lateral and undulate, with large, rounded external proximal ends and hooked external distal ends. Striae are radiate, with the 1st or 2nd stria at each apex parallel or, rarely, convergent. Within a stria, the marginal areola are large and coarsely arranged. The middle portion has areola comparatively smaller and rounded, and the areolae near the axial area form two rows per stria. The central area has large, round, isolated puncta. The smallest striae at the apices are multiseriate throughout their length.


Original Description

  • Basionym
    Navicula semen
  • Author
    Ehrenb. 1841

Citations & Links



  • Index Nominum Algarum
  • North American Diatom Ecological Database
    NADED ID: 93028

Cite This Page

Kociolek, P. (2011). Rexlowea navicularis. In Diatoms of North America. Retrieved May 24, 2024, from https://diatoms.org/species/rexlowea_navicularis1


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