Camburn and Charles 2000 Category: Asymmetrical biraphid
BASIONYM: Gomphonema variostriatum Camburn and Charles 2000
Contributor: Ian Bishop - May 2016
Length Range: 13-25 µm
Width Range: 4-4.4 µm
Striae in 10 µm: 8-9 at mid-valve; 12-15 at the apices
Valves clavate, with variably broad, rounded headpoles and narrowly rounded footpoles. Striae are radiate and alternate throughout, and increase in density as they approach both apices. The axial area is narrow but expands near the central area. The raphe is either straight or undulate and weakly lateral. The central area is robustly siliceous and distinctly asymmetric due to a single extended middle stria, which reaches from one margin to a single isolated stigma near the apical axis. An apical porefield is present at the footpole.
Note that the largest valve of the holotype population below does not conform to the original description, particularly in reference to a dominant central striae on on side of the central area.
Basionym: Gomphonema variostriatum
Author: Camburn and Charles 2000
Length Range: 16-32 µm
Width Range: 3.8-6.0 µm
Striae in 10 µm: 7-9 at mid-valve, up to 14-15 at the ends
Camburn, K.E. and Charles, D.F. (2000). Diatoms of Low-Alkalinity Lakes in the Northeastern United States. Academy of Natural Sciences of Philadelphia, Special Publication 18, 152 pp.
This taxon is commonly encountered in stream and lake systems in the northeastern United States. The imaged valves for this page were found in samples collected in wadeable streams in New York, New Hampshire, Massachusettes, and Connecticut.
In their examination of diatoms in low-alkaline Adirondack lakes, Camburn and Charles (2000) found G. variostriatum in only 5 out of 116 lakes examined. The metrics provided in that publication suggests that G. variostriatum has a preference for relatively low pH waters and an intolerance of higher total P and DOC.