Neidium rugosum

This taxon appears to have a circumboreal distribution. In North America, it has been reported with light micrographs from Alaska (Foged 1981, pg. 238, Pl. 25, Fig 2, as N. iridis), the Canadian Arctic Archipelago (Antoniades et al. 2008, pg. 592, Pl. 121, Figs 1-2,6, as N. ampliatum s.l.), the Great Lakes (Reavie 2022, pg. 387, Fig 392, as N. c.f. fossum), and Nunavut (Bahls 2023, pg. 293, Pl. 109, Figs 6-8). Due to confusion surrounding the identity of this taxon, as well as its low relative abundance in counts, the ecological preferences of this taxon are poorly understood.

In the Great Lakes National Parks (Edlund et al. 2011, 2012, 2013), this taxon is a minor component of the diatom community in the sediment of Shell Lake, and a trace component of the diatom community in the sediment of Bass Lake. Both lakes are within Sleeping Bear Dunes National Lakeshore, Michigan.

Large specimens belonging to the genus Neidium were historically associated with Neidium iridis, however examination of type material has resolved the identity of that taxon allowing many other large taxa to be described (Lefebvre and Hamilton 2015, Hamilton et al. 2019). Like many large taxa, it typically occurs in low abundance relative to smaller taxa in the community. Large taxa are typically underestimated using traditional counting techniques (Snoeijs et al. 2002). As originally suggested by Hustedt (1957), traditional counting techniques are likely insufficient for understanding large-celled diatoms. Because the importance of taxa with larger cell volumes is usually greater in communities (Snoeijs et al. 2002) more effort should be devoted to understanding the diversity, ecology and biogeography of large celled diatom taxa.