Fallacia latelongitudinalis

(R.M.Patrick) Potapova 2013      Category: Symmetrical biraphid
BASIONYM: Navicula latelongitudinalis R.M.Patrick 1959

Eupodiscus radiatus


Fallacia pygmaea

LM scalebar = 10 µm = 80 pixels.


Contributor: Marina Potapova - February 2013
Length Range: 22-32 µm
Width Range: 4.6-5.6 µm
Striae in 10 µm: 45-50


Valves are linear, with rounded ends. Striae are strongly radiate in the central part of the valve and strongly convergent at the ends. The striae are not visible under LM The striae continue onto the valve mantle. The axial area is very narrow and the central ares is small and elliptic. The raphe is filiform, with proximal ends very close together and slightly bent to the primary side of the valve. The terminal raphe fissures are hooked to the secondary side of the valve and extend to the mantle. The upper surface of the valve is covered by a conopeum that merges with a fold formed at the valve face/mantle junction around most of the valve. At the apices the conopeum does not merge with the fold and thus, two openings at each apex are formed. The conopeum has small pores that form branching fascicles that are visible in LM along the raphe. Thse branching fascicles may be mistaken for the striae.

Original Description

Basionym: Navicula latelongitudinalis
Author: R.M.Patrick 1959
Length Range: µm
Striae in 10 µm:

Original Description

Valve linear with rounded ends. Axial area narrow. Central area not differentiated from axial area. Striae parallel, thickened near the axial area, producing an apparent band on each side of the axial area. Striae very fine, difficult to resolve. Striae, 29-31 in 10 µ. Length, 24-31 µ (type, 29 µ). Breadth, 5-6 µ (type, 6 µ).

Original Images

Cite This Page:
Potapova, M. (2013). Fallacia latelongitudinalis. In Diatoms of the United States. Retrieved April 26, 2018, from http://westerndiatoms.colorado.edu/taxa/species/fallacia_latelongitudinalis

Species: Fallacia latelongitudinalis

Contributor: Marina Potapova

Reviewer: Rex Lowe


Patrick, R.M. (1959). New species and nomenclatural changes in the genus Navicula (Bacillariophyceae). Proceedings of the Academy of Natural Sciences of Philadelphia, 111, 91-108.

Rumrich, U., Lange-Bertalot, H. and Rumrich, M. (2000). Diatoms of the Andes. From Venezuela to Patagonia/Tierra del Fuego and two additional contributions. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 9. Phytogeography-Diversity-Taxonomy. Koeltz Scientific Books, Königstein, Germany, 9:673 pp.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Fallacia latelongitudinalis CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion