Gomphonema caperatum

Ponader and Potapova 2017      Category: Asymmetrical biraphid

REPORTED AS: Gomphonema sp. 2 ANS NEW JERSEY KCP (ANSP Algal Image Database) 

Gomphonema californicum


Gomphonema christenseni

LM scalebar = 10 µm = 80 pixels.


Contributor: Ian Bishop - January 2017
Length Range: 22-32 µm
Width Range: 4.4-5.2 µm
Striae in 10 µm: 14-16


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.

Original Description

Author: Ponader and Potapova 2017
Length Range: 18-31 µm
Width Range: 3.7-5 µm
Striae in 10 µm: 13-16

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.

Original Images

Cite This Page:
Bishop, I. (2017). Gomphonema caperatum. In Diatoms of the United States. Retrieved April 21, 2018, from http://westerndiatoms.colorado.edu/taxa/species/gomphonema_caperatum

Species: Gomphonema caperatum

Contributor: Ian Bishop

Reviewer: Marina Potapova


Ponader, K.C., Potapova, M.G., Desianti, N., Hamilton, P.B., Lavoie, I., and Campeau, S. (2017). Gomphonema caperatum sp. nov., G. obstipum sp. nov. and similar taxa from rivers of North America. Diatom Research 32 (1): 59-73.

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)


Autecology Discussion

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.