• Category
  • Length Range
    27-38 µm
  • Width Range
    5-7 µm
  • Striae in 10 µm
    Coarse valve: 6-8, Fine valve: 11-14
  • Synonyms
    Gomphonema angustatum var. sarcophagus (W.Greg.) Grunow
    Gomphonema angustatum f. sarcophagus (W.Greg.) Hust.
    Gomphonema angustatum var. sarcophagus (W.Greg.) Cleve
  • Reported As
    Gomphonema angustatum (Reavie and Smol 1998, p. 49, Pl. 20, Fig. 14)
    Gomphonema angustatum (McBride and Edgar 1998)



Valves are linear- to elliptic-lanceolate, with rostrate to truncate apices. Valves are asymmetric to the transapical axis, with the footpole slightly more tapered than the headpole. The axial area is distinctly linear. A stigma is present in the central area, in line with a stria. The raphe is undulate with slightly expanded proximal ends. Striae are slightly radiate to parallel, bending inward at the center of the valve. There are typically 1-2 shortened striae at the central area. Areolae are not easily visible in the light microscope, but appear larger at the center of the valve along the axial area.

The appearance of enlarged areolae in LM is due to biseriate striae, which are visible by SEM (Reichardt 1999).

Valve morphology of specimens within populations of G. sarcophagus may vary considerably, including that irregular undulations may be present along the valve margin. Additionally, the presence of Janus cells was observed with this species. Janus cells are frustules that have two morphologically different valves, often of differing stria densities. A few species of Gomphonema have been documented to produce Janus cells, including G. parvulum and G. sarcophagus (McBride and Edgar 1998, Reichardt 1999). In this study, two valve types were observed: valves with low stria densities (coarse striae) and valves with higher stria densities (fine striae). Valves with coarse striae were more commonly observed, but over 25% of examined valves (n=55) had fine striae.

Note that G. sarcophagus and G. angustatum are very similar taxa and further investigation may show that they are environmental variants and conspecific. A lectotype was designated for G. sarcophagus (Reichardt 1999).


Gomphonema sarcophagus was found in periphytic samples from a kettle hole at the Freda Haffner Kettlehole State Preserve in Dickinson County, Iowa, and epiphytic samples from a small stream in Cayler Prairie, Dickinson County, Iowa. Both sampling locations had pHs near 7 and temperature near 20°C. Conductivity was 190 μS/cm in the kettle hole and 489 μS/cm in the prairie stream.

Gomphonema sarcophagus has also been found in eutrophic ponds across Europe (Hofmann et al. 2011), as well as the San River in the upper San basin of Poland (Noga et al. 2014). The species has also been found in a stream in the Dolina Kobylanska valley, Poland, which has moderate conductivity and neutral pH. It has also been recorded across Germany (Reichardt 1999). In the United States, it has been reported to inhabit primarily mesotrophic waters with moderate conductivity (Patrick and Reimer 1975).

G Sarcophagus Emap1
Credit: USGS BioData
Distribution of Gomphonema sarcophagus in rivers of the continental U.S. based on the National Water Quality Assessment program. Retrieved 10 June 2016.
G Sarcophagus Emap2
Credit: USGS BioData
Distribution of Gomphonema sarcophagus in rivers of Alaska based on the National Water Quality Assessment program. Retrieved 10 June 2016.
Kettlehole 1
Credit: Image by Sylvia Lee
Photo of the Kettlehole, Dickinson Co., Iowa, United States in June of 2016.

Original Description

Gomphonema Sarcophagus, W. G. - This species occurs abundantly in the Lochleven gatherings, but it occurs also in several gatherings made near Edinburgh, and in others from Fife, Stirlingshire, Lanarkshire, and elsewhere. Indeed it would seem not to be uncommon. In form it is linear, rather narrow, the sides gently curved, so as to form a sort of shoulder at the widest part, after which it contracts a little, and again expands to a somewhat truncate extremity. The opposite end is narrower, and, with the exception of a trifling expansion at the apex, becomes continuously narrower. These things give to it very nearly the shape of a coffin. The F. V. is, as usual in this genus, cuneate. Length about .0014 inch. Striae 20 to 22 in .001".

  • Author
    W.Greg. 1856
  • Length Range
    35.6 µm
  • Striae in 10µm

Original Images

G Sarcophagus Origpic  Jw
G Sarcophagus Lectotypes
G Sarcophagus Origdes  Jw

EMAP Assessment

EMAP Distribution

Gomphonema Sarcophagus  Gregory 3
Map 3

Response Plots

Gomphonema Sarcophagus  Gregory

Cite This Page

Walls, J. (2016). Gomphonema sarcophagus. In Diatoms of North America. Retrieved July 23, 2018, from https://diatoms.org/species/gomphonema_sarcophagus


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