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.
Ultrastructural features include biseriate striae, which are considered diagnostic of the species according to Levkov (2009).
This taxon is considered to be cosmopolitan, found in brackish and saline waters (Levkov 2009, Ács et al. 2023).
From February 22, 2011 until October 25, 2024, this taxon appeared as Halamphora coffeaeformis (C. Agardh) Levkov 2009. In order to confirm to Art. 60.10 of the International Code of Algae, Fungi, and Plants, the specific epithet was edited to "coffeiformis" and now appears as Halamphora coffeiformis (C.Agardh) Mereschokowsky 1903. - S. Spaulding
Stepanek, J. (2011). Halamphora coffeiformis. In Diatoms of North America. Retrieved November 14, 2024, from https://diatoms.org/species/halamphora_coffeiformis
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Halamphora coffeiformis 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.