• Category
  • Length Range
    25-46 µm
  • Width Range
    6.4-8.3 µm
  • Striae in 10 µm
  • Synonyms
    Cymbella arcus A.Cleve 1955 (replaced synonym)



Valves are arcuate, with slightly protracted, broadly rounded ends. Striae are weakly radiate at mid-valve, becoming strongly radiate at the apices. The central area is circular, with 2-4 isolated stigmata present on the ventral side. The raphe is noticeably reverse-lateral, with inflated proximal ends. Areolae are punctate and lineate, measuring 23-26 in 10 µm.

Note that the C. arcus Cleve-Euler 1955 is not a basionym according to the ICBN, but is instead a replaced synonym. It is a valid but illegitimate junior homonym, as the specific epithet arcus was already found in this genus (Cymbella arcus Hassal 1845) .


This taxon was imaged from the north slope of Alaska.

Original Description

Cymbella cleve-eulerae [Figs 105: 8-12; 107: 1-101]

Replaced synonym: Cymbella arcus Cleve-Euler 1955 in Kungl. Svensk. Vetensk. Handl, 5/4: p. 162, fig. 1248
non Cymbella arcus Hassall 1844, fig. 100: 6
non Cymbella arcus Gregory 1856, p. 6, fig. 1: 21

Type locality: Sweden, Skövde.

Valves arcuate, dorsal side strongly arched, ventral sides concave, straight in the middle portion. Ends not or barely protracted and narrowly rounded. Length 25-45 um, breadth 6.5-8.5 um, maximal length/breadth ratio about 5.3. Axial area narrow, in post-initial cells moderately wide (Fig. 106: 2), curved. Central area absent or not well expressed. Raphe at or near mid-line of valve moderately to strongly lateral, becoming filiform near the distal and the proximal ends or reverse-lateral near the proximal ends (Fig. 104: 9). Central pores nearly absent, ventrally bent, terminal fissures dorsally deflected. Striae slightly radiate, more radiate towards the ends, indistinctly punctate. Up to 3 indistinct stigmata ventral from the central nodule and distant from the middle ventral striae, sometimes barely visible in the LM. Striae in the middle 8-10/10 um (dorsal and ventral), towards the ends a few more, puncta about 25/10 um.

Differential diagnosis: Distinguished from other similar taxa by the combination of size, outline, lack of central area and the finely punctate striae. C. botellus is smaller and differs in outline.

Distribution: Northern Sweden. CLEVE-EULER (loc. cit.) gives a number of sites, in her opinion abundant in places.

  • Author
    Krammer 2002

Original Images

Cymbella Cleve Eulerae Orig Desc Plate
Cymbella arcus orig descr

Cite This Page

Bishop, I. (2016). Cymbella cleve-eulerae. In Diatoms of North America. Retrieved September 28, 2023, from https://diatoms.org/species/cymbella-cleve-eulerae


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Cymbella cleve-eulerae 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.