Psammothidium scoticum
(Flower and Jones) Bukhtiyarova and Round 1996 Category: Monoraphid
BASIONYM: Achnanthes scotica Flower and Jones 1989
LM scalebar = 10 µm = 80 pixels.
Observations
Contributor: Marina Potapova - August 2010
Length Range: 7.5-12 µm
Width Range: 3.9-4.6 µm
Striae in 10 µm: 27-30
Description
Valves are linear-elliptical. The raphe valve has a linear to linear-lanceolate axial area, which widens toward the center of the valve, and a transversely elliptical to rectangular central area. The raphe is straight, without terminal fissures. The central and terminal raphe ends are slighlty expanded. The central raphe ends curve toward opposite sides internally. The rapheless valve has a rhomoid axial area, which often sharply widens in the valve center. Striae are radiate on both valves, 27-30 in 10 µm. One row of areolae is present on the mantle of both valves. The external openings of the areolae are mostly isodiametric.
Original Description
Basionym: Achnanthes scotica
Author: Flower and Jones 1989
Length Range: 7-13 µm
Width Range: 3.5-5 µm
Striae in 10 µm: 25-28
Original Description
Frustule elliptical, always strongly curved in girdle view, especially towards the broadly rounded apices; length 7-13 μm and width 3.5-5 μm. Raphe valve striae slightly radiate, shorter in the centre, usually 25-28 in 10 μm. Central area broadly rounded to elliptical, slightly asymmetrical, occupying about half of the valve width, and surrounded by 3 or 4 short striae with slightly wider interstriae. Axial area narrow, raphe straight, central nodule thickened, distal nodules indistinct. On both valves striae similar in density, areolae unresolvable (in LM). Rapheless valve striae short, more so in the central area; axial area short, extending into a large approximately rhomboidal central area, about half the valve width, faintly grooved in the mid-line.
Original Images
Cite This Page:
Potapova, M. (2010). Psammothidium scoticum. In Diatoms of the United States. Retrieved May 24, 2013, from http://westerndiatoms.colorado.edu/taxa/species/psammothidium_scoticum1
Species: Psammothidium scoticum
Contributor: Marina Potapova
Reviewer: Sarah Spaulding
Image Credit: Marina Potapova
- Valves linear-elliptical
- Rapheless valve with rhomoid axial area
- Striae radiate, 27-30 in 10 µm.
Valves are linear-elliptical. The raphe valve has a linear to linear-lanceolate axial area, which widens toward the center of the valve, and a transversely elliptical to rectangular central area. The raphe is straight, without terminal fissures. The rapheless valve has a rhomoid axial area, which often sharply widens in the valve center. Striae are radiate on both valves, 27-30 in 10 µm.
Compare
P. scoticum differs from P. daonense and P. ventralis by its linear-elliptical shape. Valves of P. daonense are larger and elliptical, while valves of P. ventralis are more gibbous with wide subrostrate to subcapitate ends. P. marginulatum differs from P. scoticum by its wider axial area on rapheless valve and elliptical-lanceolate valve shape. Both P. marginulatum and P. ventralis have lower striae density than P. scoticum.
Psammothidium marginulatum
Psammothidium daonense
Psammothidium ventralis
Citations
Bukhtiyarova, L. and Round, F. E. (1996). Revision of the genus Achnanthes sensu lato. Psammothidium, a new genus based on Achnanthidium marginulatum. Diatom Research 11: 1-30.
Flower, R.J. and Jones, V.J. (1989). Taxonomic descriptions and occurrences of new Achnanthes taxa in acid lakes in the U.K. Diatom Research 2: 227-239.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID: 186017