• Category
  • Length Range
    15-40 µm
  • Width Range
    5-7 µm
  • Striae in 10 µm
    17-21 at center, 22-24 near apices
  • Synonyms
    Amphora coffeaeformis (C.Agardh) Kütz. 1844



Valves are semi-lanceolate to semi-elliptical and strongly dorsiventral. The dorsal margin is smoothly to flatly arched. The ventral margin is straight to slightly concave. The valve ends are protracted, narrowly rostrate to subcapitate, and slightly ventrally deflected. The raphe is positioned close to the ventral margin. The raphe is straight or may have a gradual dorsal bend near the central valve. The proximal raphe ends are weakly inflated with a slight dorsal deflection. The dorsal axial area is narrow narrow, while the ventral side is wider. A dorsal fascia is absent, a ventral fascia is present but difficult to resolve in the light microscope due to the indistinct ventral striae. The dorsal striae are uninterrupted, slightly radiate, becoming more radiate at the poles. The ventral striae are often difficult to resolve and are radiate near the center, and convergent at the poles.


Original Description

  • Basionym
    Frustulia coffeaeformis
  • Author
    C.Agardh 1827

Cite This Page

Stepanek, J. (2011). Halamphora coffeaeformis. In Diatoms of North America. Retrieved June 23, 2024, from https://diatoms.org/species/halamphora_coffeaeformis


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