Contributor: Loren Bahls - December 2013
Length Range: 12.1-28.3 µm
Striae in 10 µm: 17-20
Cells are cylindrical. The valve face is concentrically undulate, with marginal striae and a central star-shaped cluster of 5 to 12 nearly triangular, punctate fields. The triangular fields lie with their pointed ends oriented toward the valve center. The open area at the center of the star varies in size with valve size and may be ornamented with a few scattered areolae. Marginal striae are slightly unequal in length and composed of very fine areolae. Every third or fourth interstria (costa) is thickened and appears in LM as the so-called shadow lines (Schattenlinien). These thicker costae number about 5 in 10 µm.
Several investigators have published SEM images and descriptions of Cyclotella antiqua (Houk et al. 2010, Kling & Håkansson 1988, Lowe 1975). External SEM views show a domed valve face with the triangular punctate fields and the valve center lying in slight depressions. Each triangular field is separated by a low unornamented ridge. The triangular fields are ornamented with areolae that are larger than those in the striae. Internally, the striae are expressed as alveoli that are presumably covered with cribra (when unaltered by dissolution). These alveoli are separated by thickened costae and are visible in LM with critical focus. Within an eroded alveolus can be seen two or three thinner costae and external openings of areolae in the striae. Internal valve views show 1-3 rimoportulae scattered between the triangular fields in the area between the central star and the marginal striae. Both central and marginal fultoportulae are present internally. One marginal fultoportula lies on each of the thickened costae. Central fultoportulae are scattered among areolae within the triangular fields. Internally, each fultoportula opens to a short central tube, on each side of which is a satellite pore.
Note that stria density of “about 17 in 10 µm” is usually repeated in the literature (Houk et al. 2010, Kling & Håkansson 1988, Krammer & Lange-Bertalot 1991); the stria density of Montana specimens ranges from 17 to 20 in 10 µm.
Basionym: Cyclotella antiqua
Author: W. Smith 1853
Length Range: µm
Striae in 10 µm:
Foged, N. (1981). Diatoms in Alaska. Bibliotheca Phycologica, Band 53, J. Cramer, Vaduz, 317 pp.
Houk, V., Klee, R. and Tanaka, H. (2010). Atlas of freshwater centric diatoms with a brief key and descriptions, Part III. Stephanodiscaceae A. Cyclotella, Tertiarius, Discostella. Fottea 10 (Supplement): 1-498.
Kling, H.J. and Håkansson, H. (1988). A light and electron microscope study of Cyclotella species (Bacillariophyceae) from central and northern Canadian lakes. Diatom Research 3:55-82.
Krammer, K. and Lange-Bertalot, H. (1991). Bacillariophyceae. 3. Teil: Centrales, Fragilariaceae, Eunotiaceae. In Ettl, H., Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.). Süsswasserflora von Mitteleuropa. 2(3): 1-576. Gustav Fisher Verlag, Stuttgart, Germany.
Lowe, R.L. (1975). Comparative ultrastructure of the valves of some Cyclotella species (Bacillariophyceae). Journal of Phycology 11(4): 415-424.
Mahood, A.D., Thompson, R.D. and Goldman, C.R. (1984). Centric diatoms of Lake Tahoe. Great Basin Naturalist 4: 83-98.
Smith, W. (1853). Synopsis of British Diatomaceae. John Van Voorst, London 1853. 89 pp., pls 1-31.
Houk et al. (2010) report Cyclotella antiqua as a littoral resident of lakes or pools with low pH and low conductivity in Finland, Canada, Norway, Sweden, Scotland, and Siberia. U.S. records include Alaska (Foged 1981), the Laurentian Great Lakes (Lowe 1975), and Lake Tahoe (Mahood et al. 1984). The specimens shown here are from two lakes and a stream in Glacier National Park, Montana. The stream, Camas Creek, drains a series of paternoster lakes, the lower one of which, Trout Lake, is presumably the source of the Cyclotella antiqua specimen in Fig. 1. Lake McDonald in Glacier National Park has a pH of 8.7 and specific conductance of 92 µS/cm; Medicine Grizzly Lake (photo below) has a pH of 9.1 and specific conductance of 93 µS/cm.
Medicine Grizzly Lake, Glacier National Park, Montana: home of Cyclotella antiqua. The peak at upper right is Triple Divide Peak, where waters part to the Pacific, Atlantic, and Hudson Bay.
Credit/Source: Loren Bahls