Surirella arctica

(R.M.Patrick and Freese) J.Veselá and Potapova 2014      Category: Surirelloid
BASIONYM: Surirella terryi var. arctica R.M.Patrick and Freese 1961

REPORTED AS: Surirella sp. [cf. S. angusta Kützing 1844] (Antoniades et al. 2008, pg. 296, Pl. 79, Figs 1-5, Pl. 132, Figs 7-9)) 

Surirella angusta


Surirella atomus

LM scalebar = 10 µm = 40 pixels.


Contributor: Jana Veselá - February 2017
Length Range: 19-56 µm
Width Range: 6–9 µm
Striae in 10 µm: 22–25


Valves are isopolar, or barely heteropolar, linear with cuneate apices and 4.3–6.4 length-to-width ratio (in very small specimens, down to 2.7). The most peculiar feature of this taxon is the massive craticula-like structure, in which the median area and transverse costae are internally thickened. The thickening occurs on the inner valve surface, and is clearly visible in LM. In some specimens, especially small ones, the thickened median area can be wider and less prominent, thus not as prominent as in longer specimens. Costae are arranged more or less regularly, and there are usually 3–6 striae in between each pair of costae (1–6 in small specimens). Density of costae/fibulae is 43–61 in 100 μm (up to 70 in 100 μm in small specimens). Median area is very narrow, but appears much wider when focusing on the internal valve surface. Striae are parallel, slightly radiating toward the apices. Visible under SEM, striae are mostly triseriate (2–4 rows of areolae in 1 stria) and are externally separated by ridges. Each 4th or 5th ridge is depressed (corresponding to an internal costa) below the valve face level. Frustules are rectangular in girdle view with visible costae in LM.

Original Description

Basionym: Surirella terryi var. arctica
Author: R.M.Patrick and Freese 1961
Length Range: 26–49 µm
Width Range: 6–8 µm
Striae in 10 µm: 22–30

Original Description

Valva lineari apicibus rotundatis, cuneatis. Axe apicali designato linea, clara, angusta. Alis 5-6 in 10 μ, angustis. Summa valva striata. Striis, 22-30 in 10 μ. Longitudo, 26-49 μ. Latitudo, 6-8 μ.

Valve linear with wedge-shaped, rounded apices. Apical axis marked by a clear narrow line. Alae 5-6 in 10 μ, narrow. Surface of valve striated. Striae, 22-30 in 10 μ. Length, 26-49 μ. Breadth, 6-8 μ. This variety is distinguished from the nominate variety, Surirella terryi Ward var. terryi, by the shape of the ends of the valve and the number of the alae. Specimen illustrated.–Station 109 (A-G.C. 8225B). Holotype. Type locality.–Alaska, Sec. Jud. Div., Driftwood. Coll. L. R. Freese, 1 August 1951.

Original Images

Cite This Page:
Veselá, J. (2017). Surirella arctica. In Diatoms of the United States. Retrieved April 25, 2018, from

Species: Surirella arctica

Contributor: Jana Veselá

Reviewer: Elizabeth Ruck


Antoniades, D., Hamilton, P.B., Douglas, M.S.V. and Smol, J.P. (2008). Diatoms of North America: The freshwater floras of Prince Petrcik, Ellef Ringnes and northern Ellesmere Islands from the Canadian Arctic Archipelago. Iconographia Diatomologica 17.

Patrick, R.M. and Freese, L.R. (1961). Diatoms (Bacillariophyceae) from Northern Alaska. Proceedings of the Academy of Natural Sciences of Philadelphia 112(6):129-293.

Veselá, J. and Potapova, M. (2014). Surirella arctica comb. et stat. nov. (Bacillariophyta)—a rare arctic diatom. Phytotaxa 166 (3): 222–234. 10.11646/phytotaxa.166.3.3

Links & ID's

Index Nominum Algarum (INA)

Transfer INA
Original INA

California Academy of Sciences (CAS)

Surirella arctica CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

Surirella arctica was encountered in small freshwater pools and seepages around Driftwood, North Slope, in the northeastern Alaska, USA (including the type locality), with the following water characteristics: pH 7.4–8.4, water temperature 7°–12° C, alkalinity 310 ppm (as CaCO3), hardness 350 ppm (as CaCO3), chloride 200 ppm, and total Fe 0.06 ppm (Patrick & Freese 1961). This taxon was also found in Ellef Ringnes Island, Canada. Surirella arctica probably occurs in other freshwater localities in the high Arctic of North America (north of 68°N latitude).