Conchocelis

Conchocelis is a filamentous sporophyte stage found in some red algae, most notably within the Bangiales, including Porphyra (now often placed in Pyropia). The name derives from concha, meaning shell, because this stage commonly grows inside mollusk shells or in crevices of calcareous substrates. The conchocelis phase is diploid and forms a branching filament that produces conchosporangia. Each conchosporangium releases conchospores, which settle and develop into the leafy, haploid gametophytic thallus that is typically recognized as Porphyra/Pyropia.

Life cycle context is important for understanding conchocelis. In Florideophyte red algae, the life cycle is triphasic, consisting of a gametophyte (male and female), a carposporophyte that develops on the female gametophyte after fertilization, and a tetrasporophyte. The conchocelis stage represents the sporophyte phase that generates conchospores rather than carpospores. In Porphyra, conchospores germinate to form the coastal, blade-like gametophyte thallus, which can then participate in sexual reproduction leading to the next stages of the cycle.

Habitat and significance: Conchocelis stages occur in temperate marine environments and are often associated with shells and other calcareous substrata. Historically, recognition of the conchocelis phase helped scientists understand the complex life cycle of edible red algae in the group that includes nori. In modern taxonomy, many Porphyra species are placed in Pyropia, but the conchocelis phase remains a key feature of their life cycle.

Distribution and taxonomy: Conchocelis occurs worldwide in suitable temperate coastal habitats, within the Bangiales. The term appears mainly in historical and developmental literature on red algal life cycles, though it remains a useful concept for describing the sporophyte phase of these taxa.