Valves are rhombic-lanceolate with sightly drawn-out apices. The axial area is narrow and linear. The central area is small, round or transversely elliptical. The raphe is straight, filiform, with slightly expanded external proximal ends. The distal raphe ends are deflected to the secondary valve side. The striae are mostly biseriate, radiate in the valve center and convergent at the apices. The areolae are elongated, mostly oriented along the apical axis. Internally the striae open into shallow alveoli. A hyaline area and one apical row of areolae are present at each end of the valve.
Differential diagnosis compared to Hippodonta capitata ssp. capitata. Valves all more or less rhombic-lanceolate to lanceolate, tapeing gradually to the ends that are at most very gently protracted and broadly rounded (not distinctly set off capitate or rostrate-subcapitate). Length 18-25 μm, breadth 4-6 μm (not 6-7 and eventually up to 10 μm as reported in Patrcick & Reimer 1966). Raphe, areae, striae not significantly different. Hence the valve putlines combined with lower breadth are the only differential characters.
Potapova, M. (2011). Hippodonta capitata subsp. iberoamericana. In Diatoms of North America. Retrieved December 12, 2024, from https://diatoms.org/species/46518/hippodonta_capitata_subsp._iberoamericana
The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Hippodonta capitata subsp. iberoamericana 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.
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