(W. Smith) English & Potapova 2009 Category: Centric
BASIONYM: Melosira nivalis W. Smith in Greville 1855
SYNONYM(S): Aulacoseira distans var. nivalis (W. Smith) Haworth | Melosira distans var. nivalis (W. Smith) Kirchner
REPORTED AS: Aulacoseira pfaffiana ((Reinsch) Krammer 1991)
Frustules are cylindrical and form short chains. Valves are 6-18 µm in diameter, with a mantle height of 2.5-6 µm. The ratio of the mantle height to valve diameter is usually less than 1, so the valves are often observed in valve view. The mantle has straight sides and the valve face is flat. Rows of mantle areolae are straight, slightly inclined to the right (dextrorse), 12-16 in 10 µm, with 2-6 elongated areolae in each row. The height of the collum is approximately 1/3 of the mantle height. The valve face is covered by large areolae, 0.5-0.9 µm in diameter. The spines are pointed and narrow with anchor-shaped ends, and originate from every pervalvar costa. The ringleiste is very shallow. There is one rimoportula on the mantle near the ringleiste.
Basionym: Melosira nivalis
Author: W. Smith in Greville 1855
Length Range: 5-18 µm
Striae in 10 µm:
Frustules subcylindrical; valves sub-hemispherical,• distinctly cellulate; cellules circular; extremities of valves more or less truncate. Breadth of filament •0002" to •0007". v.v.
English, J. and Potapova, M. (2009). Aulacoseira pardata sp. nov., A. nivalis comb. nov., A. nivaloides comb. et stat. nov., and their occurrences in Western North America. Proceedings of the Academy of Natural Sciences of Philadelphia 158(1):37-48. 10.1635/053.158.0102
Greville, R.K. (1855). Report on a collection of Diatomaceae made in the district of Braemar by Professor Balfour and Mr. Gerge Lawson. Annals and Magazine of Natural History, 2nd series, 15:252-261.
Haworth, E.Y. (1988). Distribution of diatom taxa of the old genus Melosira (now mainly Aulacoseira) in Cumbrian waters. In: Round, F.E. (ed.), 1988, Algae and the aquatic environment. Contributions in honour of J.W.G. Lund. Biopress Ltd., Bristol, pp. 138-167.
Tuji, A. and Williams, D.M. (2006). Examination of type material for Aulacoseira pfaffiana (Bacillariophyceae) with special reference to the position of its rimoportula. Bull. Natn. Sci. Mus., Tokyo, Ser. B, 32(3), pp. 117–121.
Tuji, A. (2010). Examination of type material of Melosira nivalis W.Sm. (Bacillariophyceae) and its synonymy with Aulacoseira pfaffiana (Reinsch) Krammer. Bull. Natl. Mus. Nat. Sci. ser. B. 36.
NADED ID: 10065