Bahls and Potapova 2015 Category: Symmetrical biraphid
BASIONYM: Navicula subwalkeri Bahls and Potapova 2015
Valves are lanceolate with subrostrate apices. The valve face is convex in transapical plane, gradually merging with the mantle. The axial area is narrow, widening gradually from apices to central area. The central area is small and rhombic. The raphe is lateral and slightly bowed, concave to the primary side. Proximal raphe ends are inflated and bent towards the secondary side. Terminal raphe fissures are shaped like question marks. Striae are radiate, becoming parallel and then convergent near the apices. Striae are curved and alternately long and short around the central area. Internally, the striae are partially covered by an axial plate, the edges of which are visible in LM as longitudinal lines located about one-third of the distance from the axial area to the valve margin. Areolae are apically elongated and number 22–26 in 10 μm.
Basionym: Navicula subwalkeri
Author: Bahls and Potapova 2015
Length Range: 101-165 µm
Width Range: 17-27 µm
Striae in 10 µm: 8-11
Valves lanceolate with subrostrate apices. Length 101–165 μm, width 17–27 μm. Valve face convex in transapical plane, gradually merging with the mantle. Axial area narrow, widening gradually from apices to central area. Central area small, rhombic. Raphe lateral and slightly bowed, concave to the primary side. Proximal raphe ends inflated and bent towards the secondary side. Distal raphe ends shaped like question marks. Striae radiate, becoming parallel, then convergent near the apices, 8–11 in 10 μm. Striae curved, alternately long and short around central area. Internally, striae partially covered by axial plate. Edges of axial plate visible in LM as longitudinal lines at about one-third distance from axial area to valve margin. Areolae apically elongated, 22–26 in 10 μm. Cells solitary with two plate-like chloroplasts lying along the girdle on each side of the valve.
Cite This Page:
Bahls, L., and Potapova, M. (2015). Navicula subwalkeri. In Diatoms of the United States. Retrieved November 27, 2015, from http://westerndiatoms.colorado.edu/taxa/species/navicula_subwalkeri
Species: Navicula subwalkeri
Reviewer: Sarah Spaulding
Bahls, L.L. and Potapova, M. (2015). Two new species of Navicula (Bacillariophyta, Naviculales) from the Cascade Mountains of the American Northwest. Phytotaxa 218 (3): 253–267. 10.11646/phytotaxa.218.3.4
Navicula subwalkeri is known from two adjacent headwater streams in the Cascade Mountains of Oregon and from a fossil deposit near Chiloquin, Oregon. Measured pH values in the two Cascade streams range from 6.7 to 7.7 and conductivity values range from 38 to 61 µS/cm.
North Umpqua River, Oregon: type locality of Navicula subwalkeri.
Credit/Source: Kurt Carpenter, USGS