• Category
  • Length Range
    5.1-12.0 µm
  • Width Range
    2.2-3.4 µm
  • Striae in 10 µm



Valves are very small and elliptic and slightly asymmetric to the apical axis. The apices are narrowly rounded. The axial area is narrow and positioned on a thickened sternum. The raphe is filiform and slightly curved toward the ventral margin. A distinct central area is absent. The middle of the valve has a lower stria density than the apices. Striae are nearly parallel to weakly radiate on the dorsal margin. In contrast, striae are weakly radiate to radiate on the ventral margin.

Externally, the proximal raphe ends are positioned opposite to one another. The terminal raphe ends are deflected toward the ventral side of the valve.

Internally, the proximal raphe ends are strongly deflected to the dorsal side of the valve. The raphe terminates in a helictoglossa.

The striae are composed of round areolae which are occluded by fine hymenes. The cingulum is composed of at least two bands. The valvocopula is wide and with the pars interior is composed of a single row of areolae.


This taxon was described from the Cahaba Valley Creek at Cross Creek Road at Pelham, Alabama.

Full range of images examined.

Original Description

Description.-- Valvae ellipticae, 5-14 μm longae, 1.5-3.7 μm latae. Striae parallelae vel leviter radiantes ad dorso, radiantes ad ventere, 18-28 in 10 μm. Striae constans ex areolas rotundatas numero variantes secus striam. Aliquot striae limbo valvari ad apices. Areolae occulsae hymnibus tenuibus versus superficiem valvaris. Raphe filiformis modice curvata versus laterem valvaris ventralis. Extremitas proximalis raphis oppositas inter se aspectu externo fortiter deflexas ad eadem directiones versus laterem valvaris dorsalis aspectu interno. Extremitas terminalis deflexas ad apices ad eadem directiones versus laterm valvaris ventralis. Interne apices helictoglassa modice elevata. Area axialis in sterno incrassato. Cingulum constans ex duabus elementibus per frustulum demum. Valvocopula lata parte interiori contans ex singularem seriem areolarum. Copulae non visae.

Valves elliptical, 5-14 μm long, 1.5-3.7 μm wide. Striae parallel or slightly radiate on the dorsal side and radiate on the ventral side. Striae composed of round areolae that vary in number along each striae. A few areolae are found on the valve mantle at the apices. Areolae occluded with fine hymens that are placed toward the outer surface of the valve. Raphe filiform and slightly curved toward the ventral side of the valve. Proximal raphe ends opposite to each other in external view and strongly deflected to the same side and towards the dorsal side of the valve from an internal view. Terminal raphe ends bend at the apices in the same direction and towards the ventral side of the valve. Internally, the apices present a slightly raised helictoglossa. The axial area represents a thickened sternum. Cingulum composed of at least 2 elements per frustule. Valvocopula wide with the pars interior composed of a single row of areolae. Copulae not observed.

  • Author
    E.Morales and Manylov 2009
  • Length Range
    5-14 µm
  • Width
    1.5-3.7 µm
  • Striae in 10µm

Original Images

Mcahabaensis Origfig1
Mcahabaensis Origfig2
Mcahabaensis Origfig3
Mcahabaensis Origdesc

Cite This Page

Polaskey, M. (2020). Mayamaea cahabaensis. In Diatoms of North America. Retrieved July 19, 2024, from https://diatoms.org/species/mayamaea_cahabaensis


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