• Category
  • Length Range
    22.4-31.9 µm
  • Width Range
    4.4-5.2 µm
  • Striae in 10 µm
  • Reported As
    Gomphonema sp. 2 ANS NEW JERSEY KCP (ANSP Algal Image Database)



Valves are linear-lanceolate, very slightly apically asymmetric, with narrowly rounded ends. A single, isolated stigmoid is located near the proximal raphe ends. Raphe is lateral throughout, with deflected, expanded proximal ends. Axial area is broadly rhombic-lanceolate. Apical porefield is present at footpole.

As this taxon’s etymology suggests, the valve face has “wrinkles” that can usually be observed under SEM. These wrinkles may be oriented transapically, but are often randomly oriented, particularly near the footpole. Areolae are linear, with some areolae near the axial area nearly c-shaped and variably oriented toward both the center and margin of the valve.


In their description, Ponader and Potapova note that this taxon has a wide distribution across eastern North America, from the southern Appalachian and Piedmont regions in the south, through the mid-Atlantic coastal plain and up into Quebec (Ponader et al. 2017). They also note its occurrence in Oregon. We have confirmed its presence across a much larger geographic range in the west, as far south as San Antonio Creek in the Stanislaus National forest in California up through the Willamette and Puget Sound basins of Oregon and Washington, respectively.

Original Description

Gomphonema caperatum Ponader & Potapova sp. nov. (Figs 1–11, 29–38, 68)

Description. Valves linear to linear-lanceolate, 3.7–5μm wide, 18–31μm long. Head pole acutely rounded, foot pole narrow. Frustules rectangular in girdle view. Axial area wide and lanceolate. Striae uniseriate, short, slightly radiate, 13–16 in 10μm. External openings of the areolae mostly slit-like, apically elongated. External openings of the last and first areola in a stria C-shaped or small and circular. Shallow grooves or wrinkles on external valve surface often aligned with the striae. Raphe slightly lat- eral and undulate. Narrow pseudosepta at both poles. One stigmoid present at central nodule.

Holotype. Circled specimen on slide ANSP GC59144, deposited at the Diatom Herbarium of the ANSP (Fig. 1).

Isotypes. Circled specimens on slide ANSP GC59145, deposited at the Diatom Herbarium of the ANSP and CANA 125944 deposited at the Canadian Museum of Nature.

Type locality. Riga Run, Virginia, USA. 38.21874 N, 77.9406 W. Sample ANSP VA000276 collected 22 September 2009 by Virginia DEQ staff.

Etymology: The specific epithet caperatum meaning ‘wrin- kled’ refers to the characteristic wrinkles or transapically oriented shallow grooves seen on the external surface of the valves in SEM.

  • Author
    Ponader and Potapova 2017
  • Length Range
    18-31 µm
  • Width
    3.7-5 µm
  • Striae in 10µm

Original Images

Gomphonema caperatum orig illus 1
Gomphonema caperatum orig illus 2
Gomphonema caperatum orig illus 3
G Caperatum Orig Desc Text

Cite This Page

Bishop, I. (2017). Gomphonema caperatum. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/gomphonema_caperatum


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