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Stauroneis ancepsfallax

L.L.Bahls 2010      Category: Symmetrical biraphid

REPORTED AS: Stauroneis (?nov.) spec. (Werum and Lange-Bertalot, 2004, Pl.50, Fig. 4) | Stauroneis spec. cf. amphicephala Kützing (Lange-Bertalot and Genkal, 1999, Tafel 31, Fig. 8) | Stauroneis (?nov.) spec. 2 Julma Olkky cf. anceps (Lange-Bertalot and Metzeltin, 1996, Tafel 32, Figs 5-6) 

Stauroneis anceps


Stauroneis angustilancea

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - December 2011
Length Range: 52-70 µm
Width Range: 11.4-14.2 µm
Striae in 10 µm: 17-23


Valves are lanceolate with capitate apices. The axial area is narrow and nearly linear, widening slightly near the stauros. The stauros is shaped like a bow tie and is strongly expanded near the valve margins. External raphe fissures are moderately lateral. Proximal raphe ends are nearly straight. The proximal raphe pores are small and only slightly expanded. Striae are radiate throughout. Areolae are fine and number 22-26 in 10 µm.

Original Description

Author: L.L.Bahls 2010
Length Range: 52-70 µm
Width Range: 11.4-14.2 µm
Striae in 10 µm: 17-23

Original Description

Valves lanceolate with capitate ends. Length 52-70 µm, width 11.4-14.2 µm. Axial area narrow, nearly linear, widening slightly near the central area. Central area shaped like a bow tie, strongly expanded toward valve margins. Raphe fissures moderately lateral, proximal endings nearly straight, weakly deflected to the secondary side. Central pores small, only slightly inflated. Striae radiate throughout, 17-23 in 10 µm. Striae puncta fine, 22-26 in 10 µm. For measurements, n = 14 valves.

Original Images

Cite This Page:
Bahls, L. (2011). Stauroneis ancepsfallax. In Diatoms of the United States. Retrieved May 25, 2018, from

Species: Stauroneis ancepsfallax

Contributor: Loren Bahls

Reviewer: Sarah Spaulding


Bahls, L. (2010). Stauroneis in the Northern Rockies: 50 species of Stauroneis sensu stricto from western Montana, northern Idaho, northeastern Washington and southwestern Alberta, including 16 species described as new. Northwest Diatoms, Volume 4. The Montana Diatom Collection, Helena, 172 pp.

Lange-Bertalot, H. and Genkal, S.I. (1999). Diatoms from Siberia I. Islands in the Arctic Ocean (Yugorsky-Shar Strait). Iconographia Diatomologica 6: 1-292.

Lange-Bertalot, H. and Metzeltin, D. (1996). Indicators of oligotrophy - 800 taxa representative of three ecologically distinct lake types, Carbonate buffered - Oligodystrophic - Weakly buffered soft water. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 2. Ecology, Diversity, Taxonomy. Koeltz Scientific Books. Königstein, Germany, 2:390 pp.

Werum, M. and Lange-Bertalot, H. (2004). Diatoms in springs, from Central Europe and elsewhere under the influence of hydrogeology and anthropogenic impages. Iconographia Diatomologica 13: 1-417.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Stauroneis ancepsfallax CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

Stauroneis ancepsfallax has been collected from several ponds and small lakes in the Northern Rockies. These waters have circumneutral pH (range 6.7-8.6) and low to moderate specific conductance (range 22-250 µS/cm). An unidentified taxon with similar features was reported from Siberia (Lange-Bertalot & Genkal 1999), from an oligo-dystrophic lake in Finland (Lange-Bertalot & Metzeltin 1996), and from springs in central Europe (Werum & Lange-Bertalot 2004).


Blakiston Beaver Pond A, Waterton Lakes National Park, Alberta: type locality for Stauroneis ancepsfallax.

Credit/Source: Barb Johnston, Parks Canada