• Category
  • Diameter
    35.0-72.5 µm
  • Reported As
    Hydrosera triquetra (Fungladda 1982, pg. 46, Pl. 19, Fig 317, Pl. 20, Fig 323)
    Hydrosera triquetra (Simonsen 1965, pg. 49, Figs 1-7)
    Hydrosera triquetra (Li and Chiang 1977, pg 203, Figs 1-32)



The valve face is flat, with a deep mantle and broad cingulum. In valve view, the valve margin is in the shape of two superimposed triangles. Porefields, containing pseudocelli, are positioned at the three apices of one of the apparent triangles.the valve face is triangular with pseudocelli positioned between each apex. Pseudoseptae are present. The areolae are loculate, externally with,large irregularly spaced foramina. Internally, the areolae open in small pores arranged in radial rows. Short spines may be visible in LM distal to the pseudocelli. A single, large rimoportula is present.

Hydrosera whampoensis and H. triquetra have been confused with one another. In fact, their differences have been variously recognized (Skortzow 1930, Hustedt 1938, Voigt 1939, Frenguelli 1953, Qie et al. 1982). At this time, the taxa are each considered to be distinct species, based on size of the external foramina and undulate margins (Qi et al. 1982). Reports of H. triquetra appear, instead, to be aligned with H. whampoensis (Simonsen 1965, Li and Chiang 1977 and Fungladda 1982). Hydrosera whampensis is considered be widespread in higher conductivity waters of lower latitudes, while H. triquetra is restricted to tropical, saline waters (Qi et al. 1982).


Hydrocera whampoensis is found in more southern sites, usually in higher conductivity waters. For example, it has been reported from rivers in California, Georgia, Louisiana, Texas, South Carolina (Qi et al. 1982) and Hawaii (Sherwood and Kido 2002, Julius 2007). This taxon can be dominant, in terms of biomass, in Hawaiian streams (Sherwood and Kido 2002) and forms the largest filamentous colonies streams with infrequent flood events (Julius 2007). Cells are joined in large zig-zag colonies by mucilage secreted from the pseudocelli. This taxon has also been reported (as H. triquetra) from Brazil, growing epiphytically on the red alga Bostrychia (Simonsen1965, Figs 1-2).

Live Hwhamp  Smain
Credit: Image and collection from Steve Main
Living cells of H. whampoensis, showing multiple, discoid chloroplasts
Hywhamp Lower48
Credit: USGS BioData
Distribution of Hydrosera whampoensis in rivers of the continental U.S. based on the USGS National Water Quality Assessment program. Retrieved 26 July 2016.
Hywhamp  Hawaii
Credit: USGS BioData
Distribution of Hydrosera whampoensis in rivers of Hawaii based on the USGS National Water Quality Assessment program. Retrieved 26 July 2016.

Original Description

Triceratium whampoense n. sp. Valvis triangularibus, margine undulatis (lateribus indole concavis sed medio globoso inflatis) anguila rotundatis costa transversali ab area separatis, area et ima parte angulorum subtiliter areolato-granulatis; membrana connectiva angusta et transverse punctato-striata. Magn. 0,089mm. = 0,0035" engl. Sehr selten. Mit keiner anderen Form von Triceratum zu verwechslende schöne Art, nur einmal aufgefunden.

  • Basionym
    Triceratium whampoense
  • Author
    Schwarz 1874
  • Length Range
    89 µm

Original Images

Trwhamp Image
Twhampoense Original Text

Citations & Links


Cite This Page

Burge, D, and Edlund, M. (2017). Hydrosera whampoensis. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/hydrosera_whampoensis


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