Bahls and Potapova 2015 Category: Symmetrical biraphid
BASIONYM: Navicula volcanica Bahls and Potapova 2015
REPORTED AS: Navicula ludloviana (Diatoms of the United States)
Valves are broadly rhombic with rounded apices. The axial and central areas are moderately wide, one-third to one-half the valve width, together forming a narrow lanceolate shape with a tumid center. The central area is rhombic, surrounded by alternately long and short striae. The raphe is lateral and somewhat bowed, concave to the primary side of the valve. The proximal raphe ends are inflated and tipped slightly to the secondary side. The terminal raphe fissures are shaped like question marks. Striae are curved and strongly radiate. Internally, the striae are within deep grooves, 6–8 in 10 μm. Areolae number about 28 in 10 μm. Internally, the areolae are apically elongated and occluded by hymens. The external openings of the areolae are small and fused into a narrow slit on the external valve surface. Cells are solitary with two plate-like chloroplasts lying along the girdle on each side of the valve.
Basionym: Navicula volcanica
Author: Bahls and Potapova 2015
Length Range: 100-176 µm
Width Range: 30-37 µm
Striae in 10 µm: 6-8
Valves broadly rhombic with rounded apices. Length 100–176 μm, width 30–37 μm. Axial and central areas moderately wide, one-third to one-half the valve width, together forming a narrow lanceolate shape with a tumid center. Central area rhombic, surrounded by alternately long and short striae. Raphe lateral and somewhat bowed, concave to the primary side of the valve. Proximal raphe ends inflated and tipped slightly to the secondary side. Terminal raphe fissures shaped like question marks. Striae curved, strongly radiate, structured internally as deep grooves, 6–8 in 10 μm. Areolae about 28 in 10 μm. Internally, areolae apically elongated, occluded by hymens. External areolae openings small and fused into a narrow slit on external valve surface. Cells solitary with two plate-like chloroplasts lying along the girdle on each side of the valve.
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
Cleve-Euler, A. (1953). Die Diatomeen von Schweden und Finnland. Teil III. Monoraphideae, Biraphideae 1. Authorized Reprint 1968, Bibliotheca Phycologica, Band 5, J. Cramer, Lehre.
Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.
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.
Schmidt, A. (-). (1874-1959). Atlas der Diatomaceen-Kunde, von Adolf Schmidt, continued by Martin Schmidt, Friedrich Fricke, Heinrich Heiden, Otto Muller, Friedrich Hustedt. Reprint 1984, Koeltz Scientific Books, Konigstein, 480 plates.
To date, Navicula volcanica has been recorded from two adjacent headwater streams in the Cascade Mountains of Oregon: North Umpqua River and the upper Clearwater River. Measured pH values in these two 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 volcanica.
Credit/Source: Kurt Carpenter, USGS
Preserved specimen of Navicula volcanica with intact chloroplast and four large oil droplets. Scale bar = 10 µm.
Credit/Source: Loren Bahls
This taxon was originally posted on Diatoms of the US as Navicula ludloviana in 2011. Later, the taxon was examined further and found to be a new taxon. It was described as N. volcanica Bahls and Potapova 2015. The text on this taxon page was adjusted to reflect the change. - S. Spaulding