Van de Vijver et al. 2012 Category: Asymmetrical biraphid
BASIONYM: Encyonopsis neerlandica Van de Vijver et al. 2012
Contributor: Loren Bahls - May 2013
Length Range: 13.7-26.1 µm
Width Range: 3.3-4.4 µm
Striae in 10 µm: 24-28
Valves are lanceolate in smaller specimens, to rhombic-lanceolate in larger specimens. Apices are rostrate to subcapitate in smaller specimens. The apices of larger specimens are not protracted. The axial area is narrow. A central area is absent. The raphe is filiform with weakly expanded proximal ends that are deflected slightly toward the dorsal margin. Raphe branches are somewhat bowed and concave to the dorsal margin. Striae are parallel near the valve center to moderately radiate near the apices.
Basionym: Encyonopsis neerlandica
Author: Van de Vijver et al. 2012
Length Range: 15-26 µm
Width Range: 3.5-4.5 µm
Striae in 10 µm: 24-28
Valves weakly (smaller specimens) to moderately (larger specimens) dorsiventral, narrowly lanceolate (never linear) with convex dorsal margin and slightly convex ventral margin. Apices protracted, acutely rounded, rostrate to subcapitate. Valve dimensions (n = 25): length 15–26 μm, width 3.5–4.5 μm, valve length/width ratio 4.2–6.3. Sternum very narrow, linear. Central area absent, striae rarely occur in central area, more distantly spaced. Raphe filiform, curved to the ventral side but with dorsally deflected central raphe endings terminating in inconspicuous central pores. Transapical striae weakly radiate to moderately radiate near the apices, almost equally spaced throughout the entire valve, dorsally 25–28, ventrally 24–26 in 10 μm although in some cases up to 30 striae can be found near the apices. Areolae not discernible in LM.
Bahls, L. (2013). Encyonopsis from western North America: 31 species from Alberta, Idaho, Montana, Oregon, South Dakota, and Washington, including 17 species described as new. Northwest Diatoms, Volume 5. The Montana Diatom Collection, Helena, 46 pp.
Krammer, K. (1997). Die cymbelloiden Diatomeen. Eine Monographie der weltweit bekannten Taxa. Teil 2. Encyonema part., Encyonopsis and Cymbellopsis. Bibliotheca Diatomologica 37:1-469.
Van de Vijver, B., Verweij, G.L., van der Wal, J. and Mertens, A. (2012). Encyonopsis neerlandica, a new freshwater diatom species (Bacillariophyta) from moorland pools in The Netherlands. Phytotaxa 66: 43-48.
Encyonopsis neerlandica is widely distributed and locally abundant in mountain lakes in the Northern Rockies. At collection sites with water quality data, pH ranges from 6.7 to 7.2 and specific conductance from 14 to 250 μS/cm. In Europe, Van de Vijver et al. (2012) described this species from oligotrophic to mesotrophic, oxygen-rich and circumneutral moorland pools with low to moderate conductivity.
Hoodoo Lake, Mineral County, Montana: home of Encyonopsis neerlandica.
Credit/Source: Google Earth