• Category
  • Length Range
    75-167 µm
  • Width Range
    11.4-15.4 µm
  • Striae in 10 µm
    Dorsal: 10-11 in the center, 11 striae near the ends. Ventral: 10-11 in the center, 12 near the ends.
  • Synonyms
    Amphora eulensteinii Grunow 1875
    Amphora angusta var. eulensteinii (Grunow) Cleve 1895



Valves are semi-lanceolate, with a curved dorsal margin and a distinct concave ventral margin. Valve ends are cuneate. The axial area is broad along the dorsal side and unornamented. The axial area on the dorsal side is wider than that on the ventral side and becomes gradually smaller toward the valve ends. The dorsal mantle is well developed, whereas the ventral mantle development is minimal.

Areolae are lineolate. The raphe is situated on a ridge, as in some Navicula. The raphe is straight and lying along the ventral edge, as in some Amphora. The proximal raphe ends lay on a fortified central nodule that is elongated in the direction of the main axial. Distal raphe ends are dorsally hooked slits.

Ventral striae are uniform, uninterrupted, and slightly radiate. Dorsal striae are parallel at the dorsal center and slightly radiate toward the valve apices.


Seminavis eulensteinii has been found in mangrove estuaries of Biscayne Bay Coastal Wetlands (BBCW) in areas having a salinity gradient from as low as 2.7 ppt - 25 ppt. Specimens of this species have been located at various placed in BBCW, most commonly in areas where pH averaged 7.6 and surface water conductivity ranged about 5.7-29.1 mS. This level of salinity and conductivity prevail in brackish/saline environments that are mesohaline to euhaline.

Seminavis eulensteinii was originally described from material collected from a raised marsh near Gowan's Bay, New Jersey. Other distributional and ecological records include the work done on the transfer of this species from the genus and species name Amphora eulensteinii to Seminavis eulensteinii. Cores taken from Quonochontaug Pond had specimens identical to the original drawings of Grunow’s Amphora eulensteinii from the A. Schmidt’s Atlas. This species of Seminavis is typically associated with muddy brackish or marine sediments.

The habitat of the original description for Amphora eulensteinii was listed as "probably marine". Seminavis eulensteinii has also been found as a common diatom in coastal mangroves near Biscayne Bay and Florida Bay from shallow water with salinity ranging from 10-25 ppt (Wachnicka et al. 2007).

DONA semin girdle jay
Autecology section
IMG 6039
IMG 6037 1

Original Description

  • Basionym
    Amphora eulensteinii Grunow
  • Author
    A. Schmidt 1875

Original Images

Picture1 seminavis original
Picture2 seminavis orginal

Cite This Page

Hormiga, S. (2022). Seminavis eulensteinii. In Diatoms of North America. Retrieved June 08, 2023, from https://diatoms.org/species/seminavis-eulensteinii


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