LM scalebar = 10 µm = 80 pixels.
Observations
Contributor: Paula Furey - December 2011
Length Range: 18-26 µm
Width Range: 2.7-3.8 µm
Striae in 10 µm: 15-17 in the center valve
Description
Frustules in girdle view appear rhomboid. Valves are more or less asymmetric to the apical and transapical axes, with one apex wider than the other. The ventral margin is straight to weakly concave, and the dorsal margin is convex. The apices are rounded. The helictoglossae lie close to or are a short distance from the apices. The distal raphe end curves a short distance onto the valve face. Striae are evenly spaced becoming slightly denser near the valve apices.
Some specimens have been observed with one apical rimoportula (Furey et al. 2011, pl 31 fig. 8) and in other specimens, a rimoportula is absent (Siver et al. 2005 pl 28, fig. 1,3,4).
Original Description
Basionym:
Author: Hust. 1950
Length Range: 15-20 µm
Width Range: 2-4 µm
Striae in 10 µm: 16-18
Original Description
- Eunotia rhomboidea nov. spec. Zellen in Gürtelbandansicht rhomboidisch. Schalen mit geradem bis wenig konkavem Ventral- und nur schwach konvexem Dorsalrand und stumpf gerundeten Enden, oft unsymmetrisch, etwa 15-20 µ lang und 2-4 µ breit. Endknoten sehr klein, Rapheenden in der Valvarfläche kaum sichtbar. Transapikalstreifen etwa 16-18 in 10 µ, an den Enden etwas dichter als in der Mitte, aber sorest ziemlich regelm Big gestellt. Taf. XXXVI, Fig. 34-41. Taf. XXXIV, Fig. 28. Sehr häufig im Litoral des Pinnsees, vereinzelt auch im Grundlosen Kolk bei Min . Unterscheidet sich von ähnlichen kleinen Arten, wie Eunotia tenella, E. exigua u. a., insbesondere durch die schiefwinklige Gürtelbandansicht, die beim ersten Anblick als Anomalie oder auch als Präparationsprodukt erscheinen ‘nag. Es handelt sich hier jedoch um eine konstante Eigentümlichkeit, die die sowohl zeitlich als örtlich getrennten Individuen auszeichnet. Ich gebe auf Taf. XXXIV, Fig. 28, eine Photographic aus dem litoralen Aufwuchs im Pinnsee, auf der neben einzelnen Schalenansichten zahlreiche Zellen in Gürtelbandlage erkennbar sind, zum Teil in kurzen Bändern, die naturgemäß ebenfalls schief orientiert sind.
Original Images
Cite This Page:
Furey, P. (2011). Eunotia rhomboidea. In Diatoms of the United States. Retrieved April 19, 2018, from http://westerndiatoms.colorado.edu/taxa/species/eunotia_rhomboidea
Species: Eunotia rhomboidea
Contributor: Paula Furey
Reviewer: Marina Potapova
Image Credit: Paula Furey
- Rhomboid in girdle view
- Asymmetric to the apical and transapical axis
- One apex wider than the other
- Helictoglossae close to or a short distance from apices
- Distal raphe curves on to valve face
Frustules appear rhomboid in girdle view. Valves are asymmetric to the apical and transapical axes, with one apex wider than the other. The ventral margin is straight to weakly concave, and the dorsal margin is convex. The apices are rounded. The helictoglossae lie close to or are a short distance from the apices. The distal raphe end curves a short distance onto the valve face.
Compare
Eunotia rhomboidea is similar to E. papilioforma because the widths of valve apices are not symmetric (one end is wider than the other). Valves of E. rhomboidea are, on average, narrower than valves of E. papilioforma. In E. papilioforma the positions of the helictoglossae relative to the valve apices can vary between valve apices within a specimen and among specimens within a population, where in E. rhomboidea, the positions of the helictoglossae are more consistent among specimens and within populations. Valves of E. rhomboidea are asymmetric in regard to apex width. Also, the helictoglossa are not as inset (or far) from the apices, in contrast to valves of E canicula and E. incisa which are symmetrical to transapic axis and have helictoglossae farther from (more inset) from the apices. The terminal raphe end curves on to the valve face in E. rhomboidea in contrast to E. incisa where the small groove of the distal raphe end lies in the mantle.
Eunotia papilioforma
Eunotia incisa
Eunotia canicula
Citations
Furey, P.C., Lowe, R.L. and Johansen, J.R. (2011). Eunotia Ehrenberg (Bacillariophyta) of the Great Smoky Mountains National Park, USA. Bibliotheca Diatomologica 56: 1-134.
Hustedt, F. (1950). Die Diatomeenflora norddeutscher Seen mit besonderer Berücksichtigung des holsteinischen Seengebiets V-VII. Seen in Mecklenburg, Lauenburg und Nordostdeutschland. Archiv für Hydrobiologie 43:329-458, Tafs 21-41.
Siver, P.A., Hamilton, P.B., Stachura-Suchoples, K. and Kociolek, J.P. (2005). Diatoms of North America. The Freshwater Flora of Cape Cod. Iconographia Diatomologica 14: 1-463.
Wuthrich, M. (1975). Contribution à la connaissance de la flore algologique du Parc National Suisse. Le Diatomées. [Résultats des recherches scientifiques au Parc National suisse]. Druck Lüdin, AG Liestal. Band XIV: 273-369.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID: 33051
Autecology Discussion
Eunotia rhomboidea has been found in streams, including as epilithon and epiphytic on bryophytes.
EMAP Assessment
The Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Over 1200 streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.
EMAP Distribution
Eunotia rhomboidea
Distribution
The distribution map represents the relative abundance of this Eunotia rhomboidea in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Eunotia rhomboidea was not recorded, or with a red circle indicating the relative abundance of Eunotia rhomboidea.
Note that the size of the proportional symbols varies between species to help show both abundant and rare species.
Scale for the map to the left
EMAP Response Plots
Eunotia rhomboidea
EMAP citations
Results are published in:
Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.
Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.
Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.