• Category
  • Length Range
    68-102 µm
  • Width Range
    5.5-6.5 µm
  • Striae in 10 µm
  • Synonyms
    Bacillaria paradoxa Gmelin



Valves are narrow and linear. The raphe is located within a keel, within the in the center of the valve. Keel puncta are rectangular, but not regular in shape and number about 6-10 in 10 µm. Striae are distinct and coarse. Striae are parallel and perpendicular to the keel. Living cells are joined in colonies, which are joined by hooks along the keel.

The taxon was originally described as Vibrio paxillifer (Müller, 1786). Later, Gmelin (1788) established the genus Bacillaria and referred to Müller’s Stäbgenthier, naming the species B. paradoxa. It appears that Gmelin was unaware that Müller had formally named the taxon. As a result, the name B. paradoxa is illegitmate. Hendey (1951) corrected the name by the rules of priority, and established Bacillaria paxillifera (O.F.Müll.) N.I.Hendey. The name B. paradoxa has been widespread in its incorrect use, but it is homotypic; it refers to the same type.

This diatom is the first diatom observed - as Vibrio paxillifer by Müller (1786). Müller observed, and illustrated colonies of this diatom in its variety of cell arrangement. In a fascinating twist, this diatom was first placed in the genus Vibrio, which is the genus that includes the cholera bacteria, V. cholerae. Shortly after its initial description, Gemlin (1788) considered Bacillaria to be sufficiently distinctive to place it in its own genus. With the designation of Bacillaria, the first genus of diatoms was formally described. The name Bacillaria thus became the name of the class to which all other diatoms now belong. Furthermore, in taxonomic literature, diatoms are referred to as Bacillariophyceae or Bacillariophyta.

The genus Bacillaria was revised (Jahn and Schmid 2007), with recognition of additional species. Bacillaria paxillifera var. czarneckii was described from material from the Mississippi, but also documented in Europe. Bacillaria kuseliae and B. urve-millerae were described from Germany and Australia, respectively. These taxa differ in the structure of the raphe flanges, valve shape and plastid shape and number.

It is likely that these species and varieties are not being recognized by most surveys. In North America, these taxa have been considered as Bacillaria paradoxa by most authors. The actual species diversity of the genus has yet to be uncovered.


Bacillaria grows in colonies in benthic, epipelic or planktonic habitats, from freshwater to brackish waters (Jahn and Schmid 2007). Colonies have a wonderful coordinated movement of cells, with the entire colony expanding into a line of cells and contracting to bring cells together. The movement occurs by the raphe system, as each cell slides across the neighboring cell.

This diatom is able to tolerate fluctuations in salinity. Consequently, Bacillaria is found rivers with higher salt content, as the result of human influence or of influx of marine waters. In freshwaters, it is considered to be indicative of human induced pollution.

In North America, Bacillaria paxillifera (as B. paradoxa) was common in the western EMAP survey (2000-2004), particularly in the slow moving, sandy, high specific conductance of rivers in Montana and North Dakota. It was also common in rivers of California, influenced by agriculture and sea salts.

Original Description

1) Das Stäbgenthier gerade ausgestreckt, dem Faden einer Conferve nicht unähnlich, von oben gesehen.
2) Dasselbe in gleicher Streckung, von der Seite gesehen.
3) Dasselbe in einem länglichen Viereck zusammengezogen mit aufrechts stehenden Stäbgen und eingebogenen Enden, gleich einem Hobelspan.
4) In einem rechtwinckligen Viereck, davon sich das unterste Stück zu entfernen scheinet.
5) Wie die äussersten Stäbgen das Fortschreiten nach einer Seite angefangen haben, und ein wenig auszuruhen scheinen.
6) Zwei kleinere durch eine Communications Linie verbundene Vierecke; an der einen ist das äusserste Stä bgen schräg gestellet.
7) Das Stäbgenthier im Zickzack.
8) Dasselbe in der Gestalt eines Wetterstrahls.

  • Basionym
    Vibrio paxillifer
  • Author
    O.F.Müll. 1786

Original Images

Vibrio Paxillifer


Jul 27, 2018 - Jul 27, 2018 - Update of taxon name from Bacillaria paradoxa to Bacillaria paxillifera

From July 2008 until July 2018, the images on this page were presented as Bacillaria paradoxa. In July 2018, the page was revised to B. paxillifera. The change is now implemented on Diatoms of North America. The previous version of the page is available upon request. - S. Spaulding

Cite This Page

Spaulding, S. (2018). Bacillaria paxillifera. In Diatoms of North America. Retrieved September 18, 2021, from https://diatoms.org/species/bacillaria_paxillifera


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Bacillaria paxillifera from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.