Blidingia dawsonii (Hollenberg & I.A.Abbott) S.C.Lindstrom, L.A.Hanic & L.Golden (BC)

Green filaments and thin tubes(?) forming a sparse turf on various invertebrate hosts (Featured Image above). Numerous uniseriate, biseriate and pluriseriate filaments arise from a parenchymatous base (Image A). Cells near the base of the erect axes and those extending into the basal cushion can appear elongate (Image B) and in some axes are clearly rhizoidal (Image C). Development proceeds from uniseriate (Image D) through biseriate (Images E & F) and eventually, especially in the upper regions of the axes, pluriseriate filaments (Image G). The final tubular stage was not clearly observed in our collection. A particular characteristic of this species is the sub-opposite and offset nature of the two cell rows when the filaments are biseriate (Images B & C). In fresh material chloroplasts are stellate and lobed with a single central pyrenoid.

Our single record is from the upper intertidal on gooseneck barnacles, from Soberanes Point, CA. We currently have only tufA data for this species; there were no matches in GenBank.

We have uncovered nine genetic groups assignable to Blidingia in the Canadian flora. Interestingly Blidingia dawsonii was not one of them, although our not finding this species in BC is likely a sampling artifact. Unlike other species of Blidingia in our flora, this one is easily matched to the original description and is morphologically distinct. This species is closely allied to a second species, Blidingia dawsonii (Hollenberg & I.A.Abbott) S.C.Lindstrom, L.A.Hanic & L.Golden Species2, for which we have collections from BC and CA. The latter recalls better the morphospecies concepts of Blidingia minima (Nägeli ex Kützing) Kylin (and allied morphospecies), but has cells in rows near the base of the axes more typical of Blidingia marginata (J.Agardh) P.J.L.Dangeard ex Bliding.

Image A. Basal cushion bearing numerous erect axes, which are uniseriate to pluriseriate filaments (upper intertidal on gooseneck barnacles, Soberanes Point, CA; GWS021598; rehydrated from silica vial).

Image B. Cells near the base can become elongate and rhizoidal (arrows); note the cells are offset (not opposite) in the biseriate regions of the erect axes (GWS021598; rehydrated from silica vial).

Image C. Cells near the base distinctly rhizoidal in habit (arrow); note the cells are offset in the biseriate regions of the erect axes (GWS021598; rehydrated from silica vial).

Image D. Erect axes start off as uniseriate filaments (GWS021598; rehydrated from silica vial).

Image E. Uniseriate filaments transition to biseriate (arrows) following longitudinal divisions (GWS021598; rehydrated from silica vial).

Image F. Mix of uniseriate and biseriate filaments, which are initially uniseriate at their base and eventually biseriate throughout, arising from a basal cushion (GWS021598; rehydrated from silica vial).

Image G. Upper axes become pluriseriate and reportedly tubular, which was not evident in our collection but nonetheless possible (GWS021598; rehydrated from silica vial).