Lange-Bertalot and Metzeltin 1999      Category: Symmetrical biraphid
TYPE SPECIES: Neidiopsis vekhovii (Lange-Bertalot and Genkal) Lange-Bertalot in Lange-Bertalot and Genkal




Image Credit: Ditmar Metzelin

CLASS: Bacillariophyceae
  ORDER: Naviculales
    FAMILY: Neidiaceae (?)

  1. Longitudinal lines present
  2. Proximal raphe ends straight or unilaterally deflected
  3. Distal raphe ends simply curved
  4. Striae may be uniseriate or biseriate

Valves are linear, linear-lanceolate, or linear-elliptic with variously protracted and obtusely rounded apices. A longitudinal, hyaline line runs from apex to apex along each side of the valve, interrupting the striae. Outer raphe branches are filiform. The proximal raphe ends are either straight or deflected to the same side. The proximal raphe ends are not expanded. Distal raphe ends are simply curved, rather than bifurcate. In some taxa, striae near the axial area are biseriate. The girdle is composed of a few perforated bands.

Neidiopsis contains the former Navicula levanderi Hustedt and its allies. Species within the genus are found in oligotrophic and low-conductivity lakes and ponds in northern and alpine regions. Representative species have been reported from the Northern Rocky Mountains, the Great Lakes, and the northeastern United States, as well as Arctic Canada, Greenland, and Siberia.

Neidiopsis differs from Neidium in the absence of longitudinal canals. Other features of Neidiopsis not shared by species of Neidium are simply curved (not bifurcate) terminal raphe fissures, unilaterally deflected proximal raphe ends and biseriate striae.

Cite This Page:
Bahls, L., and Metzeltin, D. (2012). Neidiopsis. In Diatoms of the United States. Retrieved April 26, 2018, from

Contributor: Loren Bahls | Ditmar Metzeltin - January 2012


January 31st, 2012 - Genus description

The original Neidiopsis page was posted in 2009 by Spaulding and Edlund, with Metzeltin added at a later date. Bahls clarified the diagnostic features and expanded on the genus description in the text for this update. There were no taxonomic or nomenclatural changes involved in the update. - S. Spaulding