(Schumann) Edlund, Morales and Spaulding 2006 Category: Araphid
BASIONYM: Fragilaria elliptica Schumann 1867
SYNONYM(S): Staurosira elliptica (Schumann) Williams and Round
Contributor: Eduardo Morales - October 2011
Length Range: 6-14 µm
Width Range: 3-3.5 µm
Striae in 10 µm: 14-16
PSEUDOSTAUROSIRA ELLIPTICA HAS NOT BEEN VERIFIED IN NORTH AMERICA
Valves elliptic to lanceolate. Valves with cuneate to rounded ends. The central area is broad and lanceolate. The valve face connects gradually with the mantle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view frustules are rectangular. Cells form ribbon-like colonies, joined by linking spines. Striae are distinct and composed of one, rarely two or more, areolae on the valve face and mantle. Areolae bear branched volae. Areolae on the valve mantle may bear flaps partially occluding the external areolar opening. The striae are interrupted at the valve face/mantle junction by spines. Costae are broader than the striae. Spines are flat, spatulate and hollow. Spines are present along the valve face edge, except at the apices. Reduced, ocellulimbus type, apical pore fields with round poroids are present at both valve ends. Pore fields are located at the junction between valve face/mantle. Rimoportulae are absent. Copulae, or girdle bands, are open and do not bear perforations. Valvocopulae are wider than other girdle elements.
This taxon is difficult to recognize under the light microscope and a clear separation from Pseudostaurosira brevistriata may not be possible with small specimens. Here, the Schumann type material studied in detail by Edlund et al. (2006) is presented.
Basionym: Fragilaria elliptica
Author: Schumann 1867
Length Range: µm
Striae in 10 µm:
Fragilaria elliptica. Fr. minima, elliptica, striis granulatis interruptis, taenia longitudinali plus minusive aperta. long 2-4, lat.= 4-5/10 longitudinis, striae 25 in 1/100 L.
Edlund, M.B., Morales, E.A. and Spaulding, S.A. (2006). The type and taxonomy of Fragilaria elliptica Schumann, a widely misconstrued taxon. In: Witkowski, A. (Ed.). Proceedings of the 18th International Diatom Symposium. Miedzyzdroje, Poland. pp 53-59. Biopress Limited, Bristol, England.
Schumann, J. (1867). Preussiche Diatomeen. Schriften der Physikalisch-Ökonomischen Gesellschaft zu Könisberg 8: 37-68.
Williams, D.M. and Round, F.E. (1987). Revision of the genus Fragilaria. Diatom Research 2: 267-288.