Cephaloziella marionensis: The Tiny Moss with a Big Story

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2020-08-04-16-19-39.jpg from: https://www.britishbryologicalsociety.org.uk/learning/species-finder/cephaloziella-divaricata/

Cephaloziella marionensis: A Tiny Moss with a Big Story


In the vast world of mosses, Cephaloziella marionensis S.W.Arnell is a diminutive but fascinating species. This tiny moss, also known simply as Cephaloziella, belongs to the Lophoziaceae family. Despite its small size, C. marionensis has a unique story to tell. In this blog post, we’ll dive into the details of this intriguing moss species.


cepspi_pgd9447_web4.jpg from: https://www.southernappalachianbryophytes.org/cephaloziellaspinicaulis.html


Cephaloziella marionensis was first described by the Swedish botanist Sigfrid Wilhelm Arnell in 1953 based on specimens collected from Marion Island, a remote volcanic island in the sub-Antarctic Indian Ocean. The species epithet “marionensis” refers to the island where it was discovered.


medium.jpeg from: https://uk.inaturalist.org/taxa/56495-Cephaloziella-divaricata

C. marionensis is classified in the liverwort class Jungermanniopsida


2020-08-04-16-17-15-800×600.jpg from: https://www.britishbryologicalsociety.org.uk/learning/species-finder/cephaloziella-hampeana/

and the division Marchantiophyta. Jungermanniopsida includes over 5,000 species of leafy liverworts found worldwide.


Cephaloziella_dentata_009C.JPG from: https://cisfbr.org.uk/Bryo/Cornish_Bryophytes_Cephaloziella_dentata.html

Morphology and Identification

Cephaloziella marionensis is one of the smallest mosses, with shoots typically less than 5 mm tall. The leaves are minuscule, only 0.2-0.4 mm long, and are divided into two unequal lobes. Leaf cells have thick walls and are covered in tiny papillae.
The underleaves (modified leaves on the underside of the stem) are small or absent. Rhizoids (root-like structures) are scarce. The species is dioicous


large.jpeg from: https://www.inaturalist.org/observations/109553779

, meaning male and female reproductive structures are on separate plants.
Identifying C. marionensis requires careful microscopic examination due to its extremely small size. It can be distinguished from related species by its thick-walled leaf cells with papillae and lack of underleaves.

Global Distribution and Habitat

Cephaloziella marionensis has a restricted distribution, found mainly in the sub-Antarctic region. In addition to Marion Island, it has been recorded from Prince Edward Island, Îles Crozet, and Îles Kerguelen. The species grows on damp, peaty soil or rotting wood in sheltered habitats.

Ecological Roles and Adaptations

As a pioneer species, C. marionensis plays an important role in the sub-Antarctic ecosystem by helping to establish vegetation on bare ground. Its small size and tolerance of harsh conditions allow it to colonize exposed areas.


CephaloziellaDivaricata5862Habit.jpg from: https://lichens.twinferntech.net/pnw/species/Moss_or_liverwort_species.shtml

The thick cell walls and papillae on the leaves help the moss conserve moisture in the cold, windy sub-Antarctic environment. The lack of underleaves reduces water loss. These adaptations enable C. marionensis to survive in its challenging habitat.


Cephaloziella marionensis may be tiny, but it has a fascinating story to tell. From its unique morphology to its restricted sub-Antarctic distribution, this diminutive moss is a testament to the incredible diversity of bryophytes. The next time you find yourself in the sub-Antarctic, keep an eye out for this pint-sized pioneer. Who knows what other secrets it may reveal upon closer inspection?

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