• Category
  • Length Range
    255-375 µm
  • Width Range
    9-14.5 µm
  • Striae in 10 µm
    24-26
  • Synonyms
    Synedra sigmoidea (Nitzsch) Kütz. 1844

Identification

Description

Valves are sigmoid, both in valve and girdle view. The raphe is eccentric, positioned within a canal at the valve margin. Fibulae are continuous through the middle of the valve. Fibulae are irregularly distributed, numbering 4-6 in 10 µm in the center valve, becoming more dense (7-8 in 10 µm) at the apices. Striae are parallel.

Specimens outside or North America have a greater range in size, as Reichardt (1984) reported valve lengths of 90-500 µm.

Autecology

Nitzschia sigmoidea was found in epipelic samples from two small streams flowing from a restored prairie, through a small forested area and into Little Miller’s Bay on the north side of Iowa Lakeside Lab, Dickinson County, Iowa. The streams had a conductivity of 568-1001 µS, pH of 7.34-8.41 and a temperature of 13.2-18.5°C. In previous collections from the Reimer Herbarium at Iowa Lakeside Lab, Nitzschia sigmoidea was found in plankton tows from West Lake Okoboji and Badger Lake, in homogenized bottom matter (including detrital leaf matter, sediment and silt), in scrapings from a cement tunnelway and in epipelic samples from a deep-water dredge in West Lake Okoboji.

Nitzschia sigmoidea appears to be widely distributed globally, with reports from Denmark (Knattrup et al. 2007), Germany (Krammer and Lange-Bertalot 1997), the United Kingdom (Hartley 1996) and Japan (Mayama et al. 2004). Nitzschia sigmoidea had not been detected in Japan prior to 1993, and as such was a good candidate for studying the transfer of diatoms between aquatic systems (Mayama et al. 2004) .

Nitzschia sigmoidea is typically found in brackish and freshwaters (Hartley, 1996) and is tolerant over a medium to high trophic range (Krammer and Lange-Bertalot 1997). The genus Nitzschia is generally epipelic with some planktic species. Nitzschia sigmoidea, despite being detected in planktic samples, is likely to primarily be a benthic diatom because of its large size and extensive raphe system. It may become suspended in the plankton with the mixing of bottom waters.

N Sigmoidea Live
Credit: Stephanie Robson
Living cells of Nitzschia sigmoidea, in girdle view
Ill Streams
Credit: Stephanie Robson
Two streams contained Nitzschia sigmoidea near Iowa Lakeside Lab. The streams are only a few meters apart and exhibited similar pH, conductivity and temperature.

Original Description

B. compressa, longa, sigmoidea, fulva; an gullis terminalibus acutissimis, albis.

Die Esbazilla rie ist durch ihre Gestalt, Farbe und Größe sehr ausgezeichnet, und von allen übrigen Arten dieser Gattung sehr leicht zu unterscheiden. Zwar ähnelt sie in Länge und Zusammendrückung, oder ungleicher Brei te der Bogen- und Planflächen, der Ellenba zillarie; allein diese hat weder die bestimmte Färbung, noch die seltsame Krümmung der Enden, welche man beider Esbazillarie immer bemerkt. Fast ohne Ausnahme präsentiert sich die Bac. sigmoidea (als eine stets ruhende, bloß vegetabilische Art) mit einer Bogen fläche, und so zeigen sich ihre beiden Enden in entgegengesetzter Richtung sanft nach den.

Planerscheint dann völlig so geformt, wie die El lenbazillarie auf gleichnamiger Fläche, näm lich als eine gerade, an beiden Enden scharf zugespitzte Nadel (Fig. 5. b.)

Die Farbe dieser schönen Art war in allen, von mir beobachteten, Individuen völlig diesel be, nämlich durchaus röthlichgelb, mit Aus nahme der Enden, welche reinweiß, oder viel mehr farbenlos waren.

In Betreff der Größe, bemerkte ich auch fast keine Verschiedenheit. Es ist diese Bazil larie der Masse nach wohl die größeste Art, in dem sie bei größrer Breite eben so lang, wo nicht noch etwas länger, als die Bacillaria U da ist.

Außer den einfachen Stäbchen sah ich nur noch doppelte (Fig. 6.). Bei letzteren sind die Krümmungen völlig parallel. Es versteht sich auch von selbst, dass, insofern diese Art immer esförmig ist, bei der Vervielfältigung der Theilungssprung niemals eine gerade Richtung haben kann, sondern ebenfalls esförmig, und der Biegung der Planseiten parallel sein muß.

Die Esbazillarie fand ich ziemlich häufig unter einem Haufen von Individuen der vori gen Art.

  • Basionym
    Bacillaria sigmoidea
  • Author
    Nitzsch 1817

Original Images

N Sigmoidea Original Image
N Sigmoidea Originaldescription

Cite This Page

Robson, S. (2017). Nitzschia sigmoidea. In Diatoms of North America. Retrieved October 18, 2018, from https://diatoms.org/species/nitzschia_sigmoidea

Responses

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