Acaulon muticum
WORK IN PROGRESS
WORK IN PROGRESS
Common Name: Rounded Pygmy Moss, Conservation Status - Near Threatened (Baudraz, et. al., 2019)
Historically, Acaulon muticum was considered a singular species with two subspecies, var. muticum and var. mediterraneum, but in 2006 var. mediterraneum was upgraded to full species status and given the name A. mediterraneum. The species were separated based on differences in spore shape (BBS, n.d.). Both species can be found in the UK, although A. mediterraneum is significantly rarer, and it can only be found in southern England (Blockeel, 2014a; Callaghan, 2022).
Appearance and Identification
A. muticum is a tiny acrocarpous moss, which stands at just 1-2mm tall, with highly concave, ovate leaves of a similar length. The upper (perichaetial) leaves are generally larger than the lower leaves, with a slightly excurrent nerve and blunt teeth along the upper edge (may require a magnification to be visible. The perichaetial leaves are so curved that they form a bud-like structure which often obscures their capsules from view (BBS, n.d.; Lawley, 2010). The capsules themselves are cleistocarpous, meaning they have no operculcum, and contain fine, granulose spores which are between 30-50µm in size (BBS, n.d.; Hill et al., 2017). In A. muticum capsules are very common and can be seen in all seasons except summer, with the number of mature capsules peaking during the winter months (Blockeel, 2014b; Lawley, 2010).
Similar looking species: