Prestauroneis protracta

(Grunow) I.W.Bishop, Minerovic, Q.Liu and Kociolek 2017      Category: Symmetrical biraphid
BASIONYM: Navicula (Crucicula var.?) protracta Grunow in Cleve and Grunow 1880
SYNONYM(S): Parlibellus protracta (Grunow) Witkowski, Lange-Bert. and Metzeltin 2000 | Placoneis protracta protracta (Grunow) Mereschk. 1903 

Prestauroneis integra


Psammothidium acidoclinatum

LM scalebar = 10 µm = 80 pixels.


Contributor: Ian Bishop - September 2017
Length Range: 26-33 µm
Width Range: 6.5-7.6 µm
Striae in 10 µm: 18-22


Valves are linear to linear-lanceolate with rostrate, rounded ends. Striae are weakly radiate to parallel at the apices. Striae are less dense in the middle third of the valve. Areolae are visible in less dense striae. The axial area is narrow and expands to a small, elliptic central area. The raphe is straight, with expanded proximal ends. Shallow, curved pseudoseptae are present at both apices.

Original Description

Basionym: Navicula (Crucicula var.?) protracta
Author: Grunow in Cleve and Grunow 1880
Length Range: 22-35 µm
Width Range: 8-10 µm
Striae in 10 µm: 18-21

Original Description

N. (Crucicula var.?) protracta Grun. Linear länglich, mit breiter borgezogener stumpf abgerundeter Spitze. Structur ähnlich wie bei N. Crucicula, Querstriefen 18-21 in 0,01 mm., die mittelsten etwas weiter. Lange 0,022-0,035 mm., Schalenbrete 0,008-0,010 mm. Häufig in schwach salzigem Wasser und Salinen des Binnenlandes. Taf. II, Fig. 38. 900/1.

Original Images

Cite This Page:
Bishop, I. (2017). Prestauroneis protracta. In Diatoms of the United States. Retrieved April 24, 2018, from

Species: Prestauroneis protracta

Contributor: Ian Bishop

Reviewer: Rosalina Stancheva


Andrejić, J.Z., Krizmanić, J. and Cvijan, M. (2012). Diatom species composition of the Nišava River and its tributaries Jerma and Temska rivers (southern Serbia). Archives of Biological Sciences 64 (3): 1127-1140.

Bishop, I.W., Minerovic, A.D. and Kociolek, J.P. (2017). Validation of Prestauroneis protracta (Grunow) I.W.Bishop, Minerovic, Q.Liu & Kociolek comb. nov. et stat. nov. (Bacillariophyceae). Notulae algarum No. 27: 1-2.

Żelazna-Wieczorek, J. and Ziułkiewicz, M. (2009). Using benthic diatoms in the assessment of spring water quality in suburban areas. Oceanological and Hydrobiological Studies 38: 121-131.

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

Mann, D.G. (1988). Sexual reproduction and systematics of Navicula protracta. Diatom Research 3(2): 227-236. 10.1080/0269249X.1988.9705035

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

Prestauroneis protracta has a broad demonstrated range in North America. US Geological Survey samples collected from western Oregon and North Carolina contain this taxon (Pacific Northwest Regional Survey, 2015). In the Pacific Northwest, P. protracta co-occurs with the smaller but similar P. protractoides. Prestauroneis protracta is also encountered across Europe, from the British Isles (Mann 1988) to Poland (Żelazna-Wieczorek et al. 2009) and Serbia (Andrejić et al. 2012).