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Observations
| Observations: | Sarah Spaulding and Rhea Esposito |
|---|---|
| Length: | 15-19 µm |
| Width: | 7-9 µm |
| Striae: | 16-18 in 10 µm at the center; 22-25 in 10 µm at the ends |
Description:
Valves elliptical with rostrate ends that curve in opposite directions at either end of the valve. Valve length 15-19 µm, width 6.5-8.5 µm. Frustule heterovalvar. Raphe valve with linear, simple raphe. Raphe curves in opposite direction at either end of valve. Short striae present in the central area of the raphe valve. Pseudoraphe valve with more evenly spaced striae in the central valve than raphe valve. In both raphe and pseudoraphe valves, axial area narrow at ends and widening to an oval in the center of the valve. Central area asymmetrical to the apical axis with one half expanding to the margin in an acute-angled fascia and the other half circular and with irregularly spaced striae. Striae consist of many small areolae and range from 14-17 in 10 µm at the center to 20-23 at the ends. Striae radiate throughout and are more broadly spaced in the central valve area. Valve mantle is shallow. SEM: Internally, the pseudoraphe valve possess striae that extend to the valve margin, and are composed of rounded, areolae covered by vela. Central sternum raised slightly.
| Morphology: | Monoraphid |
|---|---|
| Distribution: | Antarctic endemic |
Autecology:
Notes:
Our specimens of Psammothidium germainii (Manguin) Sabbe differ slightly from what has been identified previously as P. germainii, however, we believe these specimens to represent variation in the species. The distal ends are more rostrate and often exhibit distinct sinusoidal curving in our specimens, a variable character within the McMurdo Dry Valley specimens. Van De Vijver et al. (2002) illustrate a sub-Antarctic species, which they call P. germainii, but lacks the rostrate ends of the type (basionym Achnanthes germainii) illustrated by Bourelly and Manguin (1954). The valve margin of this taxon is similar to that described by Bourrelly and Manguin (1954), but it differs in significant respects. The striae are not as broadly spaced in the central area and the ends are more elongate in our specimens. Thus, the taxon illustrated here is a distinct variety of A. germainii or possibly even a distinct species. The Dry Valley taxon was also has more elongate endings than the A. germainii illustrated in Lange-Bertalot and Krammer (1989) and Van de Vijer et al. (2002). However, because of this diatom's rare occurrence in the Dry Valley collections, we did not separate it as a new taxon.
McMurdo Dry Valleys Waterbodies with Psammothidium germainii
- Aiken Creek
- Bohner Stream
- Bowles Creek
- Canada Stream
- Green Creek
- Harnish Creek Tributary
- Onyx River
- Von Guerard Stream
Original Type Description
| Author: | (Manguin) Sabbe 2003 |
|---|---|
| Length: | 19 µm |
| Width: | 8.5 µm |
| Striae: | 16-18 in 10 µm in the center, 25 in 10 µm at the ends. |
Original Description:
Valves elliptiques, ètirèes rostrèes et largement arrondies aux extrèmitès, long. 19 . larg. 8,5 µm. Valve à raphè avec une area axiale lancèolèe, raphè filiforme ; area centrale hèmicirculaire, limitèe sur un côtè par 2 stries medianes très distantes l?une de l?autre, largement ouverte jusqu?au bord de la valve du côtè opposè. Valve sans raphè aved une aire longitudinale linèaire, ètroite, area centrale ègalement hèmicirculaire, mais limitèe sur le côtè opposè à l?ouverture par des stries plus nombreuses et moins distantes que chez la valve à raphè. Pour les 2 valves, environ 16 à 18 stries transapicales en 10 µm, dans la partie mèdiane, et environ 25 vers les extèmitès, radiales et paraissant finement ponctuèes.
New combination
| Author: | Sabbe 2003 |
|---|
Citations
Index Nominum Algarum (INA):
- Original
- New Combination
- If an INA link is available, it will be shown above
- The INA is a bibliographic reference "card file" for algal taxonomy, containing nearly 200,000 names of algae (in the broad sense).
Publications (by year):
- Bourrelly and Manguin 1954. p.20, Pl. 2, fig. 19 [citation 10(3)]
- Lange-Bertalot and Krammer 1989. p. 60, Tafel 18, figs 21, 22 [citation 74(55)]
- Van de Vijver et al. 2002. Bibliotheca Diatomologica 46: 104-105, 184-187. [citation 127(119)]
- Sabbe et al. 2003. p. 242, figs 11,12. [citation 135(125)]
- Esposito et al. 2008. Botany 86: 1378-1392. [citation 137(136)]
