Pilularia minuta 

Scope: Global & Mediterranean
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Polypodiopsida Salviniales Marsileaceae

Scientific Name: Pilularia minuta Durieu
Regional Assessments:
Common Name(s):
English Dwarf Pillwort
French Pilulaire Délicate, Pilulaire menue
Pilularia globulifera L. subsp. minuta (Durieu) Bonnier & Layens
Pilularia globulifera L. subsp. minuta (Durieu) Bonnier & Layens
Taxonomic Source(s): Christenhusz, M. and Raab-Straube, E. von. 2013. Polypodiopsida. Euro+Med Plantbase - the information resource for Euro-Mediterranean plant diversity. (Accessed: 2015).

Assessment Information [top]

Red List Category & Criteria: Endangered B2ab(i,ii,iii,iv,v) ver 3.1
Year Published: 2010
Date Assessed: 2007-09-19
Needs updating
Assessor(s): Rhazi, L., Grillas, P. & Rhazi, M.
Reviewer(s): Grillas, P., Ali, M.M., de Bélair, G. & Alves, P.
Pilularia minuta has a very small and severely fragmented area of occupancy. It is declining as a result of many anthropogenic threats on its habitat, temporary pools.

Geographic Range [top]

Range Description:Pilularia minuta is a steno-Mediterranean plant. It is found in France, in the regions of Hérault and Alpes-Maritimes as well as in Corsica in Bonifacio, Lecci, and in the vicinity of Aleria and Ghisonnaccia. In Portugal, it is present in the Algarve, and in Spain, in the regions of Andalusia, Castilla y Leon, and Menorca (Anthos 2009). In Italy, it occurs in the region of Rome, Sardinia and Sicily. It has been found in Greece, in the west and northern islands of the Aegean Sea, as well as in Cyprus. In Croatia, it is present at the Dalmatian coast. Turkey has a subpopulation close to Izmir. In Morocco, it occurs southeast of Tiflet, west of Benslimane, and in Rommani. It is probably extinct in Algeria, but there are old records from Kabylie, Castiglione-Bou Ismaïl, Djebel Santo, Mudjardjo, Les Issers, Msabia. In Tunisia, it has been discovered lately in 2006 in Garâa Sejenane.

It is considered as vulnerable in Italy, Greece, France and Spain, Endangered in the Balearic Islands and very rare in Morocco, Algeria and Tunisia.
In the Mediterranean region, the extent of occurrence of P. minuta is about 2,300,000 km² within which the occupied area is very small, but nevertheless exceeds 10 km² when measured using a 1 km² grid.
Countries occurrence:
Algeria; Croatia; Cyprus; France (Corsica, France (mainland)); Greece (East Aegean Is.); Italy (Italy (mainland), Sardegna, Sicilia); Morocco; Portugal (Portugal (mainland)); Spain (Baleares, Spain (mainland)); Tunisia; Turkey (Turkey-in-Asia)
Additional data:
Estimated area of occupancy (AOO) - km2:20-500
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:In spite of its large distribution along the Mediterranean basin, the number of sites as well as the real area occupied by Pilularia minuta remains very small resulting from the scattered distribution and the small size of the temporary pools. It is present in:
- Morocco: about 12 sites, last observation in 2006 (Benslimane, Tiflet),
- Algeria: six sites (last observation 1952)
- Tunisia: 10 sites (last observation 2007)
- Spain: three sites (last observation 2003 in Andalusia) on the mainland and three sites in Menorca (Anthos 2009)
- Croatia: two sites (on islands),
- France: on the continent at least three sites (last observation Roque-Haute 2001); Corsica: 12 sites
- Greece: three sites,
- Portugal: three sites, (last observation 2010)
- Italy: at least three sites (last observation 2007 in Sardinia, 1982 in Sicily)
- Turkey: one site (last observation 1998)
- Cyprus: one site (last observation 1998)

The population sizes at all sites are very variable from one year to the next according to rainfall conditions. This makes the assessment of the status of the populations difficult, however they seem to be globally in decline following the destruction of the sites (pool of Biot in France destroyed in 1975, pools close to Alger destroyed by urbanization and agriculture). At the remaining sites, the populations are vulnerable and threatened notably by the increasing pressure from anthropogenic activities, especially in North Africa. The populations are classed as being severely fragmented.
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:The perennial species is found in temporary pools at low elevation in diverse landscapes such as forests, matorrals or agricultural lands. It is a small amphibious fern of small stature, with a threadlike rhizome (Geophyte with rhizome). The germination of the spores requires very humid (water saturated) or flooded conditions; the maturation of the sporocarpes only takes place after complete exposure to air at the end of the spring.

Threats [top]

Major Threat(s): The habitat of P. minuta is submitted to numerous anthropogenic threats, such as drainage, filling in, agriculture, overgrazing and urbanization. It is also exposed to natural threats bound to the encroachment of perennial competitive plants following the abandonment of previous extensive uses (e.g. pools of Roque-Haute in the Hérault, France).

Conservation Actions [top]

Conservation Actions: The following conservation measures are in place:
- Protected in Europe (Convention of Bern, Annex I)
- Protected in France (decree of August 31, 1995) and classed as Vulnerable on the Red List (Olivier et al. 1995)
- Red list in Spain (Vulnerable) (Moreno 2008)
- Red list in Italy (Vulnerable)
- Red list in Greece (Vulnerable)
- Croatia: classified as Critically Endangered (Nikolić and Topić 2005)
- Natural reserve for the pools of Roque-Haute (France)
- Natural reserve for the pools of Tre Padule of Suartone (Corsica)
- Harvest and ex situ conservation of the spores by the National Botanical Conservatory of Porquerolles (France)

In North Africa, there are no conservation measures in place but the following actions are recommended:
- Legal protection of the species in the Maghreb countries (list of protected species in Morocco, Algeria and Tunisia)
- Surveillance of the existing sites and search for new sites
- To assure a mastery of the urbanization and to enforce legal protection measures in Morocco (Law on the protection and the enhancement of the environment, Law on the studies of impact)
- To maintain an extensive grazing in order to limit the development of a dense plant setting in the pools (France)
- Monitoring of the population dynamics
- Raising public awareness

Citation: Rhazi, L., Grillas, P. & Rhazi, M. 2010. Pilularia minuta. The IUCN Red List of Threatened Species 2010: e.T164187A5768625. . Downloaded on 21 September 2018.
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