• Category
  • Length Range
    55-123 µm
  • Width Range
    14-24 µm
  • Striae in 10 µm
  • Reported As
    Stauroneis phoenicenteron Morphotype II (Lange-Bertalot and Metzeltin 1996)
    Stauroneis italica (Lange-Bertalot et al. 2003)
    Stauroneis phoenicenteron (Krammer and Lange-Bertalot 1986)



Valves are lanceolate to elliptic-lanceolate with short, broadly rounded sub-rostrate to sub-capitate apices. The axial area is about three times wider than the raphe and nearly linear. The central area is a narrow rectangular stauros, expanding somewhat towards the valve margins. Short striae are sometimes present at the margins of the stauros. The raphe is lateral, becoming filiform near the proximal ends, which are nearly straight and slightly expanded. The striae are curved and radiate throughout, more so towards the valve ends. Striae are more widely spaced near the stauros along the valve margins. Areolae are coarse, 14-22 in 10 µm.

Although Stauroneis conspicua and S. italica are two species that have been recognized in Europe, these species appear to cover a continuous spectrum in size and morphology in North American material. That is, in the western US, the two species cannot be distinguished based on size or shape. As a result, we recognize the name with priority, S. conspicua, and apply to it a wider size range than stated in the original description of S. conspicua.


Stauroneis conspicua is widely distributed in the Northern Rockies in small lakes and ponds with alkaline waters of moderate conductivity. The pH of these waters ranges from 6.8 to 9.1 (mean pH = 8.0) and specific conductance ranges from 10 to 1270 µS/cm (mean SC = 172 µS/cm). Lange-Bertalot et al. (2003) report that S. conspicua is “a rare but possibly cosmopolitan taxon”. The type locality is a waterfall in the Yucatan, Central America. It has also been recorded from an oligo-dystrophic lake in Finland (Lange-Bertalot & Metzeltin 1996). Of all the common Stauroneis species in the Northern Rockies, S. conspicua prefers the highest mean pH and specific conductance levels.

Lake  Josephine  Mt 1
Credit: Loren Bahls
Lake Josephine near Billings, Yellowstone County, Montana: home of Stauroneis conspicua.

Original Description

Valvae late lanceolatae ad elliptico-lanceolatas apicibus plus minusve breviter protractis, rostratis vel subrostratis et late rotundatis, 90-120 µm longae, 21-25 µm latae. Fissurae raphis satis laterales et rectissime in poros centrales parvos pertinentes. Area axialis modice lata, area centralis fasciam modice latam (stauros in forma vittae) formans usque ad margines. Striae transapicales proxime modice, distaliter magis radiantes omnino, 14-16 in 10 µm. Puncta 14-17 in 10 µm. Pseudosepta absunt. A St. phoenicenteron et St. gracilis satis differt.

  • Author
    Metzeltin and Lange-Bert. 1998
  • Length Range
    90-120 µm
  • Width
    21-25 µm
  • Striae in 10µm

Original Images

Sconspic Origimag
Sconspic Origdesc

Citations & Links


Cite This Page

Bahls, L. (2011). Stauroneis conspicua. In Diatoms of North America. Retrieved July 24, 2024, from https://diatoms.org/species/stauroneis_conspicua


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