• Synonyms
    Gomphonema abbreviatum C.Agardh
    Rhoicosphenia curvata (Kütz.) Grunow

Identification

Description

Valves are clavate. with rounded apices. Frustules are heteropolar, appearing bent in girdle view. The ventral valve is concave, with a fully developed raphe system. The dorsal valve is convex, with short raphe slits situated close to the poles. The central area is oval to elliptic. A pseudoseptum is present at both poles on valve margins. Striae are uniseriate. Areolae are apically elongated. Cells occur on stalks, forming colonies.

Autecology

Cells are found in freshwater high in ionic content and in brackish waters.

Rhoi  Triboji Sand0019
Credit: Marina Potapova
Rhoicosphenia abbreviata on Cladophora filament, Lake Okoboji, Iowa

Original Description

G. abbreviatum, pedunculo subramoso cymbellis conicis fastigiatis breviore.

  • Basionym
    Gomphonema abbreviatum
  • Author
    Agardh 1831

Original Images

Goabbrev  Orig Descr

EMAP Assessment

EMAP Distribution

R Abbreviata 10
Map 10

Response Plots

Rhoicosphenia Abbreviata

Updates

Sep 18, 2018 - Change in species circumscription

Investigation of Rhoicosphenia in North America has resulted in recognition of species in addition to R. abbreviata. Previously, the concept presented here was broad and included R. californica. An image of R. californica was removed and the text adjusted to reflect a more narrow concept. A pdf copy of the original species page is available upon request. - S. Spaulding

Cite This Page

Potapova, M. (2009). Rhoicosphenia abbreviata. In Diatoms of North America. Retrieved September 18, 2018, from https://diatoms.org/species/rhoicosphenia_abbreviata

Responses

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