Fragilaria crotonensis
Kitton 1869 Category: Araphid
BASIONYM: Fragilaria crotonensis Kitton 1869
LM scalebar = 10 µm = 40 pixels.
Observations
Contributor: Eduardo Morales | Barry Rosen | Sarah Spaulding - May 2013
Length Range: 60-72 µm
Width Range: 2-3 µm
Striae in 10 µm: 17-18
Description
Valves are lanceolate with capitate ends. The central area is wider than rest of the valve. The valve margins may be undulate, with a central swollen middle of the valve. The valve face is undulate due to raised virgae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of the mantle is shallower toward the valve apices, producing detachment of contiguous cells in girdle view. In girdle view, frustules are lanceolate, wider near the center of the valve. Cells form ribbon-like colonies joined by linking spines. The axial area is lanceolate, with clear fascia at the central area. Striae are distinct, composed of apically elongated areolae (lineolae). Striae are interrupted by spines. Striae are parallel throughout the valve and extend midway onto the valve mantle. Costae are wider than the striae. Spines are dimorphic; spatulate near the valve center and conical near the valve ends. Spines are present along the valve face margin, positioned in line with the striae. Well-developed apical pore fields with round poroids are present on the mantle at both valve ends. One rimoportulae is present on each valve. The rimoportula is located along a stria, close to the axial area. Copulae, or girdle bands, were not observed.
Original Description
Basionym: Fragilaria crotonensis
Author: Kitton 1869
Length Range: µm
Striae in 10 µm:
Original Description
Fragillaria crotonensis, n.s., F. Kitton.-Frustules linear, inflated at the central part, where they cohere and form ribbon-like filament; valve narrow, acicular; striae faint, moniliform (fig.81).-Croton water, New York, Dr. Edwards.
Original Images
Cite This Page:
Morales, E., Rosen, B., and Spaulding, S. (2013). Fragilaria crotonensis. In Diatoms of the United States. Retrieved April 24, 2014, from http://westerndiatoms.colorado.edu/taxa/species/fragilaria_crotonensis
Species: Fragilaria crotonensis
Contributor: Eduardo Morales | Barry Rosen | Sarah Spaulding
Reviewer: Sam Rushforth
Image Credit: Barry Rosen, Eduardo Morales, Sarah Spaulding
- Valves lanceolate
- Ribbon-like colonies
- Central valve margin inflated
- Spines present
Valves of F. crotonensis are lanceolate, with an inflated central margin. Valve apices are rounded to capitate. Spines are positioned at the end of a stria. Frustules are joined in ribbon-like colonies.
Compare
Fragilaria tenera has narrowly lanceolate valves with no inflated central margin. Colonies are rarely formed by F. tenera, whereas F. crotonensis commonly forms long ribbon-like colonies with 10-40 (or more) cells.
Fragilaria tenera
(W. Smith) Lange-Bertalot 1980
Citations
Canter, H.M. and Jaworski, G.H.M. . (1983). A further study on parasitism of the diatom Fragilaria crotonensis Kitton by chytridiaceous fungi in culture. Annals of Botany 52(4): 549-563 .
Crawford, R.M., Canter, H.M. and Jaworski, G.H.M. . (1985). A study of two morphological variants of the diatom Fragilaria crotonensis Kitton using electron microscopy . Annals of Botany 55(4): 473-485.
Saros, J.E., Michel, T.J., Interlandi, S.J. and Wolfe, A.P. (2005). Resource requirements of Asterionella formosa and Fragilaria crotonensis in oligotrophic alpine lakes: implications for recent phytoplankton community reorganizations. Canadian Journal of Fisheries and Aquatic Sciences 62: 1681-1681. doi:10.1139/f05-077
Wolfe, A.P., Cooke, C.A. and Hobbs, W.O. (2006). Are current rates of atmospheric nitrogen deposition influencing lakes in the eastern Canadian Arctic?. Arctic, Antarctic, and Alpine Research 38: 465-476.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
NCBI Genbank Taxonomy
North American Diatom Ecological Database (NADED)
NADED ID: 34017
Autecology Discussion
Fragilaria crotonensis is a common species in temperate, mesotrophic lakes of North America. Cells can be joined in large ribbon-like colonies. These colonies are resistant to sinking in the water column and help F. crotonensis maintain position in the phytoplankton. Fragilaria crotonensis, along with Asterionella formosa, is considered a marker of the onset of threshold levels of nitrogen (N), altering diatom assemblages in oliogotropic lakes of the western United States (Saros et al. 2005, Wolfe et al. 2006).
Images
Living colony of F. crotonensis.
Credit/Source: S. Spaulding