• Category
  • Length Range
    31.4-48.1 µm
  • Width Range
    8.0-9.6 µm
  • Striae in 10 µm



Valves are linear to linear-lanceolate with narrowly rounded apices. Striae are weakly radiate at the center to parallel at the apices. The central area is small and asymmetrically rounded. The axial area is narrow and straight to weakly lanceolate. Striae on one, or both sides, of the central area are irregularly spaced. The raphe is lateral and straight. The distal fissures are scythe shaped and the proximal fissures curve, forming expanded ends. Areolae are lineate with a narrow interstria space. Girdle bands are not yet described.

Note that the original publication shows the name as Navicula walkeri Patrick and Freese. An errata sheet indicates that the name Navicula walkeri is replaced with Navicula perotii.


Original Description

Navicula walkeri sp. nov. Pl. 2, Fig. 12

Valva lineari ad lineari-lanceolata, angustiore ad apices rotundatos. Area axiali angusta. Area media rotundata, asimili. Striis translineatis, radiatis leniter per partem maximam valvae, parallelis aut convenientibus leniter ad apices. Striis sepositis latius circum nodulem mediam. Striis, 10-12 in 10 µ. Longitudo 30-74 µ. Latitudo 6-11 µ.

Valve linear to linear-lanceolate, slightly narrower toward the rounded apices. Axial area narrow. Central area rounded, asymmetrical. Striae cross-lineate, slightly radiate throughout most of the valve, at the apices parallel or very slightly convergent. Striae more widely spaced about the central nodule. Striae 10-12 in 10 µ except at the central area. Length, 30-74 µ. Breadth, 6-11 µ.

This species resembles N. cincta. (Ehr.) Rails var. cincta in the shape of the valve, shape of the axial area, and the more distantly placed striae about the central area. It differs in the angle of the striae which are parallel to slightly convergent at the ends. The striae are also coarser throughout most of the valve. The striae about the central area are regular. This species is also characterized by the slightly asymmetrical central area. Occurrence in collection fairly numerous.

This species is named in honor of E. Perot Walker, who wrote the Latin descriptions of new taxa.

Specimen illustrated.—Station 72 (A-G.C. 8188A). Holotype.

Type locality.—Alaska, Sec. Jud. Div., Saltwater Lake, Pt. Barrow Camp. Coll. L. R. Freese, 14 July 1951.

Distribution.—GEOGRAPHICAL—In addition to the type locality, found also at Station 73, Coll. L. R. Freese, 14 July 1951 (A-G.C. 8189A). ECOLOGICAL-Fresh to brackish water. Holotype from algal scum on gravel-bottom pool. pH, 7.8; temp., 6° C. Other specimens from moss squeezings in nearby pool, but both close to edge of Saltwater Lake. pH, 7.5; temp., 5° C.

  • Basionym
    Navicula walkeri
  • Author
    R.M.Patrick and Freese 1961
  • Length Range
    30–74 µm
  • Width
    6–11 µm
  • Striae in 10µm

Original Images

Nperotii  Orig Ill
Nperotii  Orig Descr Sm

Cite This Page

Hamilton, P. (2011). Navicula perotii. In Diatoms of North America. Retrieved May 30, 2024, from https://diatoms.org/species/navicula_perotii


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Navicula perotii 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.