Kociolek and Thomas 2010 Category: Symmetrical biraphid
BASIONYM: Navicula semen Ehrenberg 1841
SYNONYM(S): Placoneis navicularis (Ehrenberg) Cox 2003
Contributor: Pat Kociolek - March 2011
Length Range: 44–132 µm
Width Range: 18–30 µm
Striae in 10 µm: 5–6 in the center, 20 at the apices
Valves are broadly lanceolate, with apices protracted to broadly rounded. The axial area is narrow and straight, forming a narrow, linear to ovoid central area. The raphe is lateral and undulate, with large, rounded external proximal ends and hooked external distal ends. Striae are radiate, with the 1st or 2nd stria at each apex parallel or, rarely, convergent. Within a stria, the marginal areola are large and coarsely arranged. The middle portion has areola comparatively smaller and rounded, and the areolae near the axial area form two rows per stria. The central area has large, round, isolated puncta. The smallest striae at the apices are multiseriate throughout their length.
Basionym: Navicula semen
Author: Ehrenberg 1841
Length Range: µm
Striae in 10 µm:
Kociolek, J.P. and Thomas, E.W. (2010). Taxonomy and ultrastructure of five naviculoid diatoms (class Bacillariophyceae) from the Rocky Mountains of Colorado (USA), with the description of a new genus and four new species. Nova Hedwigia 90:195-214. 10.1127/0029-5035/2010/0090-0195
Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.