Navicula trilatera

L.L.Bahls 2013      Category: Symmetrical biraphid

Navicula symmetrica


Navicula tripunctata

LM scalebar = 10 µm = 80 pixels.


Contributor: Loren Bahls - October 2012
Length Range: 18-26 µm
Width Range: 4.5-5.5 µm
Striae in 10 µm: 15-17


Valves are linear-lanceolate with subrostrate apices. The axial area is very narrow and widens into a moderately large, irregular, rhombic to transversely rectangular central area. The raphe is filiform with weakly expanded and widely spaced proximal pores. Distal raphe ends are shaped like question marks and hooked in the same direction. Striae are radiate near the valve center and become convergent towards the apices. Striae in the central area are irregularly shortened or may be missing. Areolae are difficult to resolve in LM and number about 40 in 10 µm.

Original Description

Author: L.L.Bahls 2013
Length Range: 17.6-26.3 µm
Width Range: 4.5-5.5 µm
Striae in 10 µm: 15-17

Original Description

Valves linear-lanceolate with subrostrate apices. Valve length 17.6–26.3 μm; valve width 4.5–5.5 μm. Axial area very narrow, widens into a moderately large but irregular central area. Raphe filiform with weakly expanded and widely spaced proximal ends. Terminal raphe fissures shaped like question marks. Striae radiate near the valve center, convergent toward the apices, 15–17 in 10 μm. Striae in the central area irregularly shortened or missing. Areolae about 40 in 10 μm.

Original Images

Cite This Page:
Bahls, L. (2012). Navicula trilatera. In Diatoms of the United States. Retrieved April 20, 2018, from

Species: Navicula trilatera

Contributor: Loren Bahls

Reviewer: Sarah Spaulding


Bahls, L. (2013). New diatoms (Bacillariophyta) from western North America. Phytotaxa 82(1): 7-28.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

North American Diatom Ecological Database (NADED)


Autecology Discussion

In addition to the type locality, Navicula trilatera has been confirmed from another wetland in Waterton Lakes National Park, from Camas Creek on the west side of Glacier National Park, and from Horseman Flat Lake in the Beartooth Mountains of southern Montana. These waters drain three sides of the Continental Divide: north to the Saskatchewan River, west to the Columbia River, and east to the Missouri River, respectively, hence the specific epithet. This species prefers cool waters with somewhat alkaline pH and low conductivity at higher elevations. At the type locality, N. trilatera is found in association with N. seibigiana.


Beaver Ponds on Blakiston Creek, Waterton Lakes National Park, Alberta: type locality for Navicula trilatera.

Credit/Source: Barb Johnston, Parks Canada