Seanet High Intertidal

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Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Phyllophoraceae

Tetrasporophyte life history phase of Mastocarpus papillatus is a crust 2-2.5 mm thick, dark black-red to olive brown. Formerly thought to be a separate species, Petrocelis.  

Abundant; crusts cover large areas of rock surfaces in high and mid-intertidal zones around bases of erect algae; protected & exposed outer coast.

Geo Range: Alaska to Baja
Synonyms: Petrocelis franciscana
Similar species: other reds (e.g. Mastocarpus jardinii, Pikea) also have crustose phases in their life histories, making field identification to species level difficult.

Image: Corallina(pink erect coralline throughout); blades of Phyllospadix scouleri (surf grass, rt side)