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SOUTHWARD RANGE EXTENSION of Riccia frostii Austin (Ricciaceae) to THE ARABIAN PENINSULA

AuthorsVincent Hugonnot¹, Florine Pépin¹, Jean-Baptiste Gibout² & Tom Coupeau³

Published 30 December 2025 Volume 3:2 Pages 252-259

Checked for plagiarism Yes

Peer reviewer comments 2

³¹25, Impasse des Oponces, 43380 Blassac, France

²54, boulevard Pommery, F-51100 Reims, France

³32, bis avenue Colbert, F-58000 Nevers, France

*Correspondence: hugonnot.vincent@orange.fr

Abstract

Riccia frostii Austin is reported for the first time from the Arabian Peninsula, based on material collected in southwestern Saudi Arabia (western Sarawat Mountains, near Al Makhwah). The species was found on recently exposed sandy-clayey substrates along the fluctuating margins of a reservoir, occupying shallow, moisture-retaining microdepressions within pioneer hygrophilous vegetation. Identification was based on diagnostic thallus and spore characters consistent with the current circumscription of the species. This record represents a southward extension of the known distribution of R. frostii and highlights the ecological importance of transient drawdown habitats in arid regions. Such unstable, moisture-buffered environments may act as overlooked refugia for hygrophilous bryophytes and therefore warrant targeted survey efforts and conservation attention.

Keywords Reservoir drawdown zones, Hydrological instability, Pioneer vegetation, Hygrophilous annuals, Trampling disturbance, Cyperus michelianus subsp. Pygmaeus