(Ehrenberg) Cleve 1894 Category: Asymmetrical biraphid
BASIONYM: Gomphonema mammilla Ehrenberg 1854
Contributor: Pat Kociolek - February 2011
Length Range: 95-271 µm
Width Range: 25-45 µm
Striae in 10 µm: 7-9
Valves are distinctly clavate in shape. The headpole is either subrostrate, or broadly rounded. The footpole is broadly rounded. The axial area is relatively narrow, straight, widening only slightly to form a narrowly elliptical central area. A single stigma is present in the central area. The raphe is lateral and weakly undulate. The external distal raphe ends are deflected at the poles onto the mantle, in the direction opposite the side bearing the stigma. External proximal raphe ends are dilated. Striae are distinctly biseriate, radiate throughout the length of the valve. Longitudinal lines are evident on either side of the axial area, positioned 1/5-1/4 of the way between the valve margin and the axial area. Two conspicuous spines are present at the headpole. The footpole bears distinct apical pore fields. Septa and pseudosepta are present at the apices.
Distribution: Gomphoneis mammilla has been verified from the west coast and at higher elevations in the Rocky Mountains of the U.S.
Basionym: Gomphonema mammilla
Author: Ehrenberg 1854
Length Range: µm
Striae in 10 µm:
Kociolek, J.P. and Rosen, B.H. (1984). Observations on North American Gomphoneis (Bacillariophyceae) I. Valve ultrastructure of G. mammilla with comment on the taxonomic status of the genus. Journal of Phycology 20: 361-368.
Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.