This species forms clumps to localized turfs of green tubes that are 3-5 cm tall and up to 2(3) mm wide, which can be compressed and slightly contorted in their upper regions (Image A). Branching and the production of spine-like proliferations are rare and are typically confined to low on the tubes (Image B). Tubes arise from a parenchymatous cushion (Image C) with the cells clearly elongate (up to 28 µm long) and at times rhizoid-like low on the tube and into the upper cushion (Image D). Near the base of the tubes cells are irregular in shape, 3-8 µm, and are irregularly distributed (Image E), whereas at the base of narrower branches they are in meandering rows (Image F) raising the possibility of meandering rows for cells at the base of narrower tubes. Cells near the tops of the tubes are irregular in distribution and slightly larger, 4-10 µm, and separated by moderately thick walls (Image G). In section, our specimen from the mid intertidal at a more exposed location had thin but variable cell walls, overall thickness 14-22 µm (Image H). Our specimen from the low intertidal at a slightly less exposed site had sections with thick inner walls, overall thickness 28-36 µm, with striations evident (Image I). In both cases the actual cells are palisade, 4.5-6 µm wide and 8-12 µm long (Images H & I). Distromatic regions were common in both collections regardless to the production of thin (Image J) or thick (Image K) inner walls.
We only have two collections of this species, both from Haida Gwaii, one each in the low and mid intertidal on rock and cobble respectively. This is unusual as species in this genus tend to grow in the upper intertidal. Using the standard identification keys (e.g. Gabrielson & Lindstrom 2018), this genetic group would likely be assigned to Blidingia chadefaudii (Feldmann) Bliding or Blidingia minima (Nägeli ex Kützing) Kylin depending on whether the individual examined revealed a thick (Image I) or thin (Image H) inner wall, respectively, and specifically to the latter for growing in the lower zone. The current genetic group has a stronger propensity to manifest as distromatic blades than either of those two species as assigned here, although admittedly observations are based on a low number of specimens. Taxonomic work is needed, but this genetic group is sister to Blidingia minima (Nägeli ex Kützing) Kylin and Blidingia minima (Nägeli ex Kützing) Kylin sensu lato BoF (also collected in the low intertidal) in a tight species complex in our preliminary phylogenetic analyses. There are multiple tufA matches for this genetic group in GenBank from Korea, which may indicate an introduction.
Image A. Individuals growing mid intertidal on cobble, Blackburn Point, Gwaii Haanas; BC (GWS030369).
Image B. Branching and spine-like proliferations occurred low on some tubes (low intertidal on rock, exposed, Alder Island, Gwaii Haanas, BC; GWS019747).
Image C. Erect tubes arise from a parenchymatous base (GWS030369).
Image D. Cells at the base of tubes are elongate (GWS019747).
Image E. Cells low on a tube, irregular in shape and distribution (GWS030369).
Image F. Cells low on a narrow branch, irregular in shape but distributed in meandering rows (GWS030369).
Image G. Cells near the top of a tube, irregular in shape and distribution (GWS030369).
Image H. Section revealing thin but variable thickness of the inner wall for our specimen from the mid intertidal at a more exposed location (GWS030369).
Image I. Section with thick inner walls and clear striations for our specimen from the low intertidal at a less exposed location (GWS019747).
Image J. Distromatic region of a thallus where the tube has thin inner walls (GWS030369).
Image K. Distromatic region of a thallus where the tube has thick inner walls (GWS019747).