Navicula genovefae

Fusey 1951      Category: Symmetrical biraphid


Navicula galloae


Navicula germainii

LM scalebar = 10 µm = 80 pixels.


Contributor: Ian Bishop | Rosalina Stancheva - October 2017
Length Range: 19-25 µm
Width Range: 5.5-5.9 µm
Striae in 10 µm: 14-16 at midvalve; 19-21 toward the apices


Valves are linear to linear-lanceolate, with protracted, rostrate to sub-capitate, broadly rounded apices. Striae are radiate and curved, becoming nearly parallel at the apices. Striae are considerably less dense at mid-valve, and striae here are occasionally shortened. Areolae are dense and difficult to visualize under LM, except along the axial area at mid-valve, where individual areolae are less dense and can be discriminated. The axial area is very narrow and expands slight to a small, round central area. The raphe is straight with inflated proximal ends.

The specimens shown above conform to the type illustration and dimensions of Navicula genovefae Fusey 1951. Unfortunately, however, we were unable to obtain Fusey material (it was either lost or destroyed).

This taxon should be compared to Prestauroneis protractoides (Hust.) Liu and Kociolek 2015, as the two taxa have been confused in surveys in North America. The identity of this taxon, however, is also problematic to resolve. The lectotype specimen of N. protractoides Hust. is difficult to reconcile with the type illustration. Hustedt mentions an expanded mid valve (“Schalen linear in der Mitte konvexen Rändern” OR “medio convexis”) that is not present in the lectotype specimen. It appears that the illustration is not representative of the specimen, or the specimen selected as the lectotype is not of the taxon Hustedt intended. Alternatively, one could argue that there are two similar taxa on the Hustedt slide; resolution requires further work.

Note that a Parlibellus protractoides (Hust.) Witkowski and Lange-Bertalot 2000 is a homotypic synonym of P. protractoides.

Original Description

Author: Fusey 1951
Length Range: 20-30 µm
Width Range: 5-7 µm
Striae in 10 µm: 10-12 at center valve, 20-22 at poles

Original Description

N. Genovefae sp. nov. (Pl. I, fig. 30) 8, 9, 18.

Valve linéaire, parfois légèrement constricteé au centre, longuement rostrée aux extrémités, pôles arrondis parfois très légèrement subcapités. 20-30 µ. * 5-7 µ. Raphé droit, aréa axial lináire étroit, aréa central arrondi petit, plus ou moins régulier. Stries radiales, les 2 ou 3 derniéres parallèles aux pôles, peu distinctement lignées-ponctuées au centre, assez fortes et écartées; souvent une des stries centrales est écourtée; plus fines et serrée vers lés pôles.

Au centre 10-12 en 10 µ. 20-22 aux pôles.

Original Images

Cite This Page:
Bishop, I., and Stancheva, R. (2017). Navicula genovefae. In Diatoms of the United States. Retrieved April 23, 2018, from

Species: Navicula genovefae

Contributor: Ian Bishop | Rosalina Stancheva

Reviewer: Marco Cantonati


Fusey, P. (1951). Contribution à la flore algologique de Bretagne. Diatomées de la Region de Corlay (Côte-du-Nord). Bulletin de microscopie appliquée 2(1): 31-50.

Hustedt, F. (1957). Die Diatomeenflora des Flußsystems der Weser im Gebiet der Hansestadt Bremen. Abhandlungen des Naturwissenschaftlichen Verein zu Bremen 34(3):181-440.

Liu, Q., Kociolek, J.P., Wang, Q.X. and Fu. C.X. (2015). Two new Prestauroneis Bruder & Medlin (Bacillariophyceae) species from Zoigê Wetland, Sichuan Province, China, and comparison with Parlibellus E.J. Cox. Diatom Research. 0.1080/0269249X.2014.988292

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.

Witkowski, A., Lange-Bertalot, H. and Metzeltin, D. (2000). Diatom Flora of Marine Coasts I. Iconographia Diatomologica 7: 1-925.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)


Autecology Discussion

To date, this taxon has only been reported from California, Oregon and Washington. It may have a broader distribution, as it has been reported also as Prestauroneis protractoides (Hust.) Liu and Kociolek 2015.

In Oregon, it was found in Fanno Creek, a nearly completely urban, and highly impacted watershed of the Portland metropolitan area.


Fanno Creek, Durham OR

Credit/Source: Wikimedia Commons