Genetically verified records for this group in the NW Atlantic flora are limited to three specimens collected subtidally (8-9 m) in the lower Bay of Fundy growing on cobble, commonly overgrowing Phymatolithon spp. Crusts range from 0.5-3 cm in diameter, are smooth, pink to greyish pink and obviously thick at the margins (Image A).
Taxonomic Note: this identification is highly tentative, but vegetatively this genetic group is a good match to the details provided in Irvine & Chamberlain (1994) for Lithophyllum crouaniorum. Notably there is a 4-5 celled epidermal layer and the cells of the erect filaments are typically cuboidal and strongly aligned in horizon rows with secondary pit connections rampant. See Sears (2002) for comments.
Image A. Closeup of a specimen from Meadow Cove, NB (GWS013996), displaying the thick margin.