Pinnularia parvulissima

Krammer 2000      Category: Symmetrical biraphid

Pinnularia nodosa var. percapitata


Pinnularia polyonca

LM scalebar = 10 µm = 40 pixels.


Contributor: Aneliya Sakaeva - June 2013
Length Range: 40-88 µm
Width Range: 9-12 µm
Striae in 10 µm: 9-10


Valves are linear with slightly convex sides. The ends are broadly rostrate, to subcapitate and rounded. The central area is large, with a rhombic fascia extending to the valve margin. The width of the fascia is variable among specimens. Four large, shallow depressions are present on the internal surface of the valve, containing ghost striae. The axial area continuously widens from the ends to form the large central area. Striae are radiate in the middle and become slightly convergent toward the ends. Longitudinal lines are absent. The raphe is lateral, with the outer fissure weakly undulate. The proximal raphe ends are small and placed relatively closely to one another. The length-to-width ratio is 4.5-6.5.

Original Description

Author: Krammer 2000
Length Range: 34-70 µm
Width Range: 10-12 µm
Striae in 10 µm: 8-10

Original Description

Outline linear, sides slightly convex, ends very broadly rostrate to subcapitate and broadly rounded, length 34-70 µm, breadth 10-12 µm, length-to-breadth ratio about 5.5 in medium size valves. Raphe lateral, the outer fissure very weakly undulate and proximally curved to the ventral side, central pores small, drop-like, close standing, terminal fissures large, ?-shaped. Axial area 1/4-1/3 the valve breadth, continuously widened from the ends to the rhombic central area which is differentiated, in the valve middle with a moderately broad assymentrical fascia. Striae 8-10/10 µm, radiate in the middle, slightly convergent towards the ends, longitudinal lines absent. The central area is accompanied by four large markings, the larger in the ventral side.

In the outline this taxon has some resemblance with the rhombarea group, whereas the broad axial area and the markings combine the taxon with the gibba group. Navicula parva sensu Grunow has a similar outline, however the axial area is much smaller.

Original Images

Cite This Page:
Sakaeva, A. (2013). Pinnularia parvulissima. In Diatoms of the United States. Retrieved April 25, 2018, from

Species: Pinnularia parvulissima

Contributor: Aneliya Sakaeva

Reviewer: Sam Rushforth, Kalina Manoylov, Rex Lowe


Krammer, K. (2000). The genus Pinnularia. The Diatoms of Europe. Diatoms of Inland Waters and Comparable Habitats 1: 1-703.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Pinnularia parvulissima CAS

NCBI Genbank Taxonomy

Pinnularia parvulissima NCBI

North American Diatom Ecological Database (NADED)


Autecology Discussion

The specimens shown were collected from two sites: Beck’s Canal in Little Miller’s Bay, with water temperature 15 C, pH 8.37 and conductivity 436 µS. The pond on Highway 9 had a water temperature of 13.2 C, pH 7.97 and conductivity of 1022 µS. Both sites were near roads and high human disturbance.