Phaeosaccion cf. multiseriatum R.A.Andersen, L.Graf & H.S.Yoon (BC)

Thalli are gooey, golden tubes, 2-5 cm tall by 1-5 mm wide, which tend to tear open distally (Image A). Tube walls are only a single cell layer thick. In surface view the cells are small, 5-12 µm in dimensions, and irregularly arranged (loosely in packets at times) and relatively compact (Image B & C). Each cell has a parietal plastid with a single pyrenoid, which is best viewed in fresh material.

We have two collections from Tahsis, Princesa Channel, BC, subtidal at 5 m depth, with a gross morphology consistent with Phaeosaccion collinsii Farlow, but the COI-5P we generated for one of these collections (GWS006547) is significantly different from sequences generated for NW Atlantic collections (n = 4) assignable to this morphospecies (one from near the type locality in MA). This situation is further confounded by the fact that neither COI-5P type has a close match in BOLD or GenBank, which makes it difficult to determine if one or both COI-5P types are actually contaminant sequences. However, whereas the cells in Phaeosaccion collinsii Farlow are regularly distributed in packets of 2-4 and separated by thick walls in surface view, those for our BC collections are more compact, larger and less regularly distributed (Images B & C) consistent with separate species. It could be that bona fide Phaeosaccion collinsii Farlow is not found in the BC flora and that all records assigned to this species in that region belong to this genetic/anatomical group. Further work is needed in our flora, however, as Phaeosaccion multiseriatum with a type locality just south of BC is only known from culture, and lacks COI-5P data, our collection may represent the full manifestation of this species in situ (Image A). This name assignment is highly speculative and awaits genetic verification; more of a strong suspicion at this time. Regardless, despite gross morphology, this entity is not assignable to Phaeosaccion collinsii Farlow as recognized on this site.

Image A. Pressed specimen from subtidal (5 m) on rock, Tahsis, Princesa Channel, BC (GWS006549).

Image B. Cells irregularly arranged and relatively compact, which is easily viewed in whole mount (GWS006549; rehydrated from press).

Image C. Cells only loosely in packets and relatively compact (subtidal (5 m) on rock, Tahsis, Princesa Channel, BC; GWS006547; rehydrated from press).