Aulacoseira nivalis
(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)
LM scalebar = 10 µm = 80 pixels.
Observations
Contributor: Marina Potapova | Jonathan English -
Length Range: 6-18 µm
Width Range: 2.5-6 µm
Striae in 10 µm: 12-16
Description
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.
Original Description
Basionym: Melosira nivalis
Author: W. Smith in Greville 1855
Length Range: 5-18 µm
Striae in 10 µm:
Original Description
Frustules subcylindrical; valves sub-hemispherical,• distinctly cellulate; cellules circular; extremities of valves more or less truncate. Breadth of filament •0002" to •0007". v.v.
Original Images
Cite This Page:
Potapova, M., and English, J. (). Aulacoseira nivalis. In Diatoms of the United States. Retrieved May 19, 2013, from http://westerndiatoms.colorado.edu/taxa/species/aulacoseira_nivalis
Species: Aulacoseira nivalis
Contributor: Marina Potapova | Jonathan English
Image Credit: Jonathan English, Marina Potapova
- Ratio of mantle height to valve diameter < 1
- Rows of mantle areolae straight, inclined to the right
- Valve face flat
- Valve face with large areolae
- Spines located at the end of each pervalvar costa
Valves are 6-18 µm in diameter, mantle height is 2.5-6 µm. The ratio of the mantle height to valve diameter is less than 1. Rows of pervalvar areolae are straight, slightly inclined to the right, 12-16 in 10 µm, with 2-6 elongated areolae in each row. The valve face is flat, covered by large areolae. The spines originate from every costa. The ringleiste is very shallow. One rimoportula is present on the mantle, near the ringleiste.
Compare
In valve view of A. nivalis, the large areolae on the flat valve face and spines originating from every pervalvar costa are visible. Both A. tenella and A. nivaloides have smaller areolae and spines originating from every second or third costa. In girdle view, A. nivalis differs from other species by the straight dextrorse rows of mantle areolae consisting of 2-6 elongated areolae.
Aulacoseira tenella
Aulacoseira nivaloides
Citations
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.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID: 10065