• Category
  • Length Range
    62-107 µm µm
  • Width Range
    20-29 µm µm
  • Striae in 10 µm
  • Reported As
    Anomoeoneis sphaerophora f. costata (Krammer and Lange-Bertalot 1986, p. 252, plate 92, fig. 5; plate 93, figs 1-3)
    Navicula bohemica (Schmidt 1874-1959, Tafel 49, figs 43, 44)
    Anomoeoneis polygramma (Cleve 1895, p. 6)



Valves are rhombic-lanceolate with broadly rounded apices. The axial area is wide and bordered on each side by a curved longitudinal column of areolae. The central area is asymmetric, the wider side reaching the valve margin. Ghost striae are often visible in the central area. Raphe branches are lateral and straight, becoming filiform towards the distal ends. Distal raphe fissures are hooked sharply to one side. Proximal raphe ends have tear-drop shaped pores. Striae are weakly radiate, becoming parallel then weakly convergent at apices. Areolae are irregularly spaced, except at the valve margins.

Four forms of A. costata have been recorded from Montana waters (see Autecology section below). These may be ecomorphs or, more likely, they are neoendemic species that evolved independently in isolated bodies of water. (To an aquatic organism, a lake is an island in a sea of land and a place where island biogeography applies.) Here we describe the most common and most typical form of A. costata, the one with rhombic-lanceolate valves.

This taxon has also been reported as a form and as a variety of Anomoeoneis sphaerophora. Based on culture experiments, Schmid (1979) claimed that both A. sphaerophora f. costata and A. sphaerophora f. sculpta are intermediate stages in the life cycle of A. sphaerophora. However, photographic evidence of these transition stages is lacking and until these life cycle intermediates can be replicated in other laboratories from pure cultures of A. sphaerophora, we elect to report A. costata here as a species.


Anomoeoneis costata is common in shallow lakes and wetlands with higher concentrations of dissolved salts. In Montana, A. costata sensu lato has been collected from waters with conductivity values ranging from 1430 to 87000 µS/cm and pH values ranging from 8.7 to 10.0 (Montana Diatom Database). Four different forms of A. costata have been recorded from Montana (see plates below). Except for the more common and widespread rhombic-lanceolate form, these forms appear to be endemic to individual lakes and wetlands. Anomoeoneis costata has also been recorded from the Great Salt Lake in Utah (Sylvia Lee, personal communication).

Anomoeoneis Plate 1 Costata
Credit: Loren Bahls
Anomoeoneis taxa from western North America. Forms (species?) identified as A. costata are shown in figs 9-12.
Anomoeoneis Costata Sensulato 2
Credit: Loren Bahls
Two forms of A. costata sensu lato from Montana. The elliptic form with evenly spaced areolae in figs 1-5 was collected from Brush Lake, Sheridan County (MDC 074601). The typical rhombic-lanceolate form in figs 6-11 was collected from Alkali Lake, Lincoln County (MDC 123101) and White Lake, Sheridan County (MDC 141901).
Anomoeoneis Costata Sensulato 1
Credit: Loren Bahls
Two additional forms of A. costata sensu lato from Montana. The narrow lanceolate form (figs 1-7) was collected from North Widgeon Slough, Sheridan County (MDC 124701). The larger lanceolate form with wedge-shaped apices (figs 8-12) was collected from Black Lake, a meromictic lake in Lake County (MDC 125801).
Anomoeoneis Costata internal valve
Credit: Loren Bahls
Internal valve of Anomoeoneis costata from Black Lake, Lake County, Montana.
Anomoeoneis Costata Normal 284802
Credit: Loren Bahls
Opposing normal valve of A. costata from Black Lake, Lake County, Montana.

Original Description

(4f0 ). N. major, turgida, latere secundario oblongoelliptica
obtusa, longitudinallter punctato- costata,
apice rotundato, latere prlmario oblongo, apiclbus
late rotundatls; apertura media majori, terminalibus
minutis. - Long. n - n'"·
Im Bergmehl von St. Flore.

  • Basionym
    Navicula costata
  • Author
    Kützing 1844

Original Images

Navicula Costata Kutzing 1844

Citations & Links


  • Index Nominum Algarum
  • GenBank
  • North American Diatom Ecological Database
    NADED ID: 8020

Cite This Page

Bahls, L., Bishop, I. (2018). Anomoeoneis costata. In Diatoms of North America. Retrieved July 15, 2024, from https://diatoms.org/species/anomoeoneis-costata


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