Blidingia minima (Nägeli ex Kützing) Kylin sensu stricto (BC/A)

This species appears as bright to yellowish green tubes forming turfs on rock (Featured Image above). Thalli are tubular to compressed (blade-like appearance) and slightly contorted in upper regions (Images A & B). In the NW Atlantic this species is typically < 1 cm tall and < 1 mm wide (Image A), whereas our BC collections reach 6 cm tall and 2 mm wide (Image B). Regardless to biogeography, all specimens arise from a pseudoparenchymatous cushion and there is occasional branching lower on the erect tubes (Image C). Although rarer, branching can also occur mid to upper tube in some individuals (Image D). At the base of the erect tube on smaller plants the cells are not modified while some cells on larger thalli become slightly elongate, 3-9 µm wide by 4-20 µm tall (Image E). Low on the tube the cells are irregularly distributed or occur in weak rows, the actual cells being irregular to elongate, 4-8 µm wide by 3-8 µm tall (Image F). Mid (Image G) to upper (Image H) thallus the cells are more typically irregular in distribution and shape, 3-8(9) µm diam., and are typically compact (thin walls between cells). In section, NW Atlantic individuals lack thickened inner walls with an overall thickness of 15-17 µm and the individual cells rectangular, 4-6 µm wide by 10-12 µm long (Image I). In the larger individuals from BC, the walls are thicker, 22-25 µm, owing to an enhanced inner wall, but individual cells are still rectangular and 4-6 µm wide by 11-13 µm long (Image J). Differences in tube thickness are evident in optical section (Images K & L, respectively). Some specimens were noticeably infested with fungal hyphae (Image H) while virtually all specimens hosted the green alga Halochlorococcum moorei (N.L.Gardner) Kornmann & Sahling (Image M).

This genetic group only has five confirmed indivduals to date. They were all collected from the upper intertidal on cobble and rock, at sheltered to exposed locations and can occur in freshwater runoff. Our collections are from BC, NB and NL. Matches in GenBank for rbcL include specimens identified as Blidingia minima from Japan, while tufA matches Blidingia sp. from Germany.

The differences among our collections from the Pacific to the NW Atlantic, both in terms of overall size and inner wall thickness, call into question such features as taxonomically useful (see Burrows 1991). The former locations were typically more sheltered than the latter possibly indicating that habitat played some role in the differences. Ignoring “Blidingia minima (Nägeli ex Kützing) Kylin sensu lato BoF” and “Blidingia minima (Nägeli ex Kützing) Kylin sensu lato Haida Gwaii“, deciding which genetic group is best assigned to Blidingia cf. chadefaudii (Feldmann) Bliding versus Blidingia minima is difficult (assuming these names are even assignable to these genetic groups). Both genetic groups are present in Europe based on matches in GenBank. This genetic group has some individuals with thin as well as thick walls, whereas in the group tentatively assigned to Blidingia cf. chadefaudii (Feldmann) Bliding all individuals have at least some wall thickening, which are in some cases striated (not exclusive to that species, for example see Blidingia subsalsa (Kjellman) Kornmann & Sahling). In addition, cells in the upper regions of tubes for this genetic group are slightly smaller, 3-8(9) µm versus 4-10(12) µm, and more compact (less space between cells) then those observed for the genetic group assigned to Blidingia cf. chadefaudii (Feldmann) Bliding. These features are consistent with the tentative name assignments on these pages (Burrows 1991). Any thoughts on more appropriate name assignments are welcome.

Image A. Pressed specimen from upper intertidal on rock, Harrington Cove exposed biodiversity site, Grand Manan, NB (GWS003770).

Image B. Pressed specimen from upper intertidal on rock, Stephenson Pt., Nanaimo, BC (GWS006463).

Image C. Branching tube arising from a parenchymatous base (upper intertidal rock wall, freshwater seepage, semi-sheltered, Beach Front Cottages, Seal Cove, NB; GWS005954; rehydrated from press).

Image D. Tube branching mid thallus (GWS003770; rehydrated from press).

Image E. Cells at the tube to basal cushion interface on a larger individual (GWS006463; rehydrated from press).

Image F. Cells low on erect tubes (GWS003770; rehydrated from press).

Image G. Cells mid thallus (GWS003770; rehydrated from press).

Image H. Cells upper thallus, which are slightly smaller and more compact than those in Blidingia cf. chadefaudii (Feldmann) Bliding as assigned here. Fungal hyphae are common on this specimen (arrow) (GWS003770; rehydrated from press).

Image I. Section of a specimen from the NW Atlantic (GWS003770; rehydrated from press).

Image J. Section of a specimen from BC (GWS006463; rehydrated from press).

Image K. Walls viewed in optical section for a specimen from NB (GWS003770; rehydrated from press).

Image L. Walls viewed in optical section for a specimen from BC (GWS006463; rehydrated from press).

Image M. Individuals of this species commonly host Halochlorococcum moorei (N.L.Gardner) Kornmann & Sahling (GWS006463; rehydrated from press).