• Category
  • Length Range
    10.5-14.1 µm
  • Width Range
    4.8-5.6 µm
  • Striae in 10 µm
  • Synonyms
    Navicula schadei Krasske 1929



Valves are small (< 20 µm), with a broadly elliptic valve outline. The apices are distinctly capitate. The striae are radiate across the entire valve face. The central area is small and shaped as an irregular oval. The raphe is threadlike with simple terminal raphe ends that are deflected unilaterally. The axial area is very narrow, expanding slightly near the central area. Areolae are too fine to resolve using light microscopy.

In SEM, the external proximal raphe ends are slightly inflated. A conopeum is present. Areolae are round and vary somewhat in size.


Illustrated specimens are from mesotrophic inland lakes located in Isle Royale National Park, Michigan where Sellaphora schadei is reported as rare (<1% relative abundance) in sediment collections from Ahmik, Richie, and Wallace lakes. Other Great Lakes National Parks where S. schadei has been recorded in sediment cores include Grand Sable Lake, in Pictured Rocks National Lakeshore and Peary Lake, Voyageurs National Park.

Cumming et al. (1995) reported the taxon as present but rare (<2% relative abundance) in six lakes in British Columbia; Sellaphora schadei (as Navicula schadei) had a total phosphorus optima of 11.7 µg/L and occurred over a range of 5.6 to 24.7 µg/L. Reavie and Smol (1998) reported the taxon as absent in modern collections but rare (<1% relative abundance) in sediment core material from the St. Lawrence River, Ontario-New York. Fallu et al. (2000) reported a few individuals of Navicula schadei from two lakes along coastal plain of eastern Hudson Bay, in the Jamésie-Hudsonie region (Quebec, Canada).

This taxon has been reported from lakes and streams of the Rocky Mountains (Bahls 2023). In cool, alkaline waters with low nutrients and conductivity.

Krammer and Lange-Bertalot (1986) report it as fairly rare in Europe, but locally common in oligosaprobic ponds near Zürich and southern Sweden.

Original Description

Protolog: Navicula Schadei Krasske, nov. spec. Fig. 11 a - b. Rundlich bis elliptisch mit vorgezogenen kopfigen Enden, Streifen strahlend, an den Enden konvergierend, 22 in 10 um, in der Mitte etwas weiter stehend und verkürzt, so daß sich hier die enge Längsarea zu einer breiten rundlichen Zentralarea erweitert. Länge 14 m, Breite 5 - 6 um.

Vorkommen: Fossil in dem Kieselgurlager in den Seewiesen bei Dresden-Kaditz (33) Doch ist als sicher anzunehmen, daß die Art wie alle anderen Arten des Lagers noch heute in Sachsen sich lebend finden wird.

Lectotypus: A VII 63 (Sachsen), mehrere Exemplare.

Weitere Belege: Sachsen: A VII 62, 64, 65 (Paralectotypen), Alpen: B II 121, 122.

Bemerkungen: Krasske und Hustedt waren nur fossile Vorkommen der Art bekannt.
KRAMMER & LANGE-BERTALOT (1986) berichten auch von rezenten Funden, z. B. aus Südschweden,
HUSTEDT (1961 - 1966, p. 222, 223) weist ausdrücklich darauf hin, daß die Transapi-kalstreifen von Navicula schade an den Enden nicht konvergent, sondern wenig radial bis fast senkrecht zur Mittellinie verlaufen. Demgegenüber bemerken KRAMMER & LANGE-BERTALOT (1986, p. 200), daß die Anordnung der Streifen an den Enden von schwach radial bis schwach konvergent variieren kann. Diese Auffassung wird durch Fig. 18: 6-7 bestätigt. KRAMMER & LANGE-BERTALOT (1986, p. 200) ziehen das Taxon Navicula globosa Meister als Syonym zu Navicula schadei ein und schlagen vor, die sehr ähnliche Navicula glomus Carter (1981, p. 578, 579) zur Varietät von Navicula schadei herabzustufen.

  • Basionym
    Navicula schadei
  • Author
    Krasske 1929
  • Length Range
    14 µm
  • Width
    5-6 µm
  • Striae in 10µm

Original Images

Navicula schadei description

Citations & Links



  • Index Nominum Algarum
  • DiatomBase
  • The Academy of Natural Sciences, Drexel University

Cite This Page

Jackson, J., Allen, L., Edlund, M., Bishop, I., Spaulding, S. (2023). Sellaphora schadei. In Diatoms of North America. Retrieved July 24, 2024, from https://diatoms.org/species/sellaphora-schadei


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