This species presents as gooey, golden tubes, 2-5 (20) 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, 3-6 µm in dimensions, and arranged in packets of 2 or 4 (Image B). Each cell has a parietal plastid with a single pyrenoid, which is best viewed in fresh material.
We have four records from the NW Atlantic, including three from a trip to QC and one from near the type locality in MA. We also have two collections from Tahsis, Princesa Channel, BC consistent with this morphospecies (gross morphology only), but the COI-5P is significantly different from those for the NW Atlantic species (n = 4). 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 types are actually contaminant sequences. The QC collections are from the mid intertidal, while both BC collections and the one from MA are from the subtidal (~5 m depth for all three). Further work is needed in our flora, however, the BC collections may represent Phaeosaccion multiseriatum R.A.Andersen, L.Graf & H.S.Yoon (visit that page for discussion) and bona fide Phaeosaccion collinsii may be absent from the BC flora.
Image A. Pressed specimen from mid intertidal on cobble and mussels, Escoumins (east of town across from Rue aux Bouchets), QC (GWS009319).
Image B. Cells form in packets of 2-4, which is easily viewed in whole mount (GWS009319; rehydrated from press).