• Category
  • Length Range
    12.2-19.8 µm
  • Width Range
    8.9-11.9 µm
  • Striae in 10 µm



Valves are rhombic to broadly elliptic, scarcely heteropolar. Ends similar and protracted, rostrate-apiculate. The axial area is narrow and linear. Central area unilateral formed by a 1-4 shortened striae. Opposite the unilateral central area is a long stria that terminates in a single stigmoid positioned near the proximal raphe ends. The raphe is filiform, and slightly arched. The proximal ends are barely expanded, while the terminal ends are indistinct. Striae are widely spaced (more widely spaced in the valve center) and mostly radiate throughout, becoming nearly parallel near at the head and footpoles. Striae are punctate, and the areolae difficult to resolve, 25.0-28.8 in 10 µm. An apical pore field is present, but is indistinct.


Gomphoneme montezumense is apparently an endemic, known only from the Montezuma Well National Monument in Arizona. It lives in the epipelon or epilithon. Physical and chemical conditions suggest the well is a stable calcium-bicarbonate thermal spring with an elevated level of sodium chloride. The annual temperature range is 16-26°C. Water quality data are presented by Czarnecki & Blinn (1979): SiO2 = 22 mg/l; Ca = 106 mg/1; Mg = 43 mg/l; Na = 46 mg/l; K = 5.75 mg/l; Cl = 37 mg/l; HCO3 = 680 mg/l; pH = 6.6-6.8.

Montezuma  Well
Credit: D.B. Czarnecki
Montezuma Well National Monument. Only known locality for Gomphonema montezumense.

Original Description

Valves elliptical to elliptical-lanceolate with irregular margins and protracted rostrate-capitate apices and bases. Axial area narrow, linear; central area small, unilateral, formed by a shortened median stria. The opposite median stria terminates in an isolated punctum. Striae punctate, radiate, 11-14 in 10 µm. Puncta 28 or more in 10 µm. Length 12-23 µm. Width 8-13 µm.

  • Author
    Czarn. and Blinn 1979
  • Length Range
    12-23 µm
  • Width
    8-13 µm
  • Striae in 10µm

Original Images

Gomph Montezume Original Image  Czar Et  Blinn 1979
Gomph Montezum Orig Descript Czar Et  Blinn 1979

Cite This Page

Edlund, M, and Burge, D. (2016). Gomphonema montezumense. In Diatoms of North America. Retrieved June 18, 2018, from https://diatoms.org/species/gomphonema_montezumense


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