• Category
  • Length Range
    70-144 µm
  • Width Range
    32-44 µm
  • Striae in 10 µm
  • Reported As
    Anomoeoneis sphaerophora var. sculpta (Patrick and Reimer 1966, p. 375, plate 32, fig. 2)
    Anomoeoneis sphaerophora f. sculpta (Krammer and Lange-Bertalot 1986, p. 253, Figs 92: 3, 4)
    Navicula sculpta (Schmidt 1874-1959, Taf. 49, Figs 46-48)



Valves are broadly elliptic, with apiculate apices. The axial area is narrow and bordered on each side by an isolated column of areolae. The central area is large, symmetric and shaped like a lyre. The central area is covered with surficial spots of various shapes and sizes. The central area does not reach to the valve margin. The central nodule is transversely elliptic and largely void of spots. Raphe branches are lateral, becoming filiform near the terminal fissures, which are deflected to one side. Proximal raphe ends are bent gently to the same side and terminate in large, bulbous pores. Striae are weakly radiate at the valve center, becoming more radiate near the apices, then parallel at the apices. Lateral spacing of areolae is variable except near the valve margins, where the areolae number 9-13 in 10 µm.

Two distinct morphotypes have been reported as Anomoeoneis sculpta in North America. The one described here is the most common and widespread of the two. The other one is pictured, without description, in the Autecology section below. Both of these taxa differ from the type of this taxon in valve shape, end shape and/or shape of the central area. Therefore, future work may find that these morphotypes are deserving of description as distinct taxa. Other specimens that have been recorded from Europe (see Krammer and Lange-Bertalot 1986 and Schmidt 1874-1959) also have different morphologies compared to North American specimens. The specimen that Patrick and Reimer (1966) used to illustrate this taxon was collected in Bohemia and apparently lacks spots in the central area (Plate 32, Fig. 2).

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. sculpta and A. sphaerophora f. costata are intermediate morphological 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 repeated, we elect to display A. sculpta at the species rank.


Anomoeoneis sculpta was collected with a 20 µm-mesh plankton net at Beck’s Canal in West Lake Okoboji, Dickinson County, Iowa. This taxon was also present in Lakeside Lab Reimer Herbarium samples from a fish hatchery and Three-Corner Pond in Dickinson County, Iowa. Plankton samples in which the species was found were collected from shallow, turbid waters frequented by boaters and swimmers. Another sample in which this species was found was collected from a canal in the Central Valley of California.

Anomoeoneis sculpta is the largest North American species of Anomoeoneis. Like other species in this genus, it has a large, highly lobed plastid. As a genus, Anomoeoneis is considered to be euryhaline and epipelic (Round et al. 1990).

Another morphotype, but also reported as A. sculpta, was collected from Brush Lake, a deep, clear, glacially-scoured lake in northeastern Montana. This taxon is distinguished from the one described above by lanceolate valves, subrostrate apices and asymmetric central area that reaches to the valve margin on one side (see photos below). It also lacks prominent spots in the central area. In these respects, it more closely resembles the type illustrations of Ehrenberg. It is likely a separate species from the one described above.

At the time of collection, Brush Lake had the following water quality characteristics: conductivity = 5760 µS/cm; pH = 9.30; total alkalinity = 1350 mg/L CaCO3; total hardness = 1168 mg/L equivalent CaCO3; Kjeldahl nitrogen = 1.3 mg/L; total phosphorus = 0.018 mg/L; dissolved oxygen = 7.50 mg/L; temperature = 18 C; CO3 = 1070 mg/l; SO4 = 2210 mg/L; Cl = 72.3 mg/L. In Brush Lake, this taxon was part of a remarkable diatom association that included Scoliopleura peisonis, Staurophora amphioxys, Surirella crumena and other brackish-water species typical of coastal waters.

Lakeside Micrographs 2 063  Anom Sph  Sandspit  Mbay
Credit: Steve Main
Live cell of Anomoeoneis sculpta from a sand-spit in Little Miller's Bay, West Lake Okoboji
Lakeside Micrographs 2 065  Anom Sph  Sandspit  Mbay
Credit: Steve Main
Live cell of Anomoeoneis sculpta from a sand-spit in Little Miller's Bay, West Lake Okoboji
Anomoeoneis Sculpta 074601
Credit: Loren Bahls
Anomoeoneis sculpta morphotype (?) from Brush Lake, Sheridan County, Montana.
Anomoeoneis Plate 1 Sculpta
Credit: Loren Bahls
Anomoeoneis taxa from western North America. Taxa reported as Anomoeoneis sculpta are shown in Figs 1 and 2.

Original Description

The basionym, Navicula sculpta, was established by Ehrenberg (1840) without a description. His later (1854) illustrations show rostrate to subrostrate apices and an asymmetric central area that reaches the valve margin on one side.

  • Basionym
    Navicula sculpta
  • Author
    Ehrenberg 1840

Original Images

Navicula Sculpta 3
Navicula Sculpta 5Ab

Citations & Links



Cite This Page

Thrash, T., Bahls, L., Bishop, I. (2018). Anomoeoneis sculpta. In Diatoms of North America. Retrieved July 18, 2019, from https://diatoms.org/species/anomoeoneis-sculpta


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