The enigmatic moss Fissidens jansenii Sérgio & Pursell recorded on Plateau de Millevaches (Limousin, France) with comments on its morphological variability

Abstract

<jats:p>The rare<jats:italic> Fissidens jansenii</jats:italic> Sérgio &amp; Pursell is reported on plateau de Millevaches, Limousin (France), nearly 1000 km north of the nearest known population. As a result,<jats:italic> F. jansenii</jats:italic> is known from the Iberian Peninsula and now from western France. An updated distribution map of the species in Europe is provided. The new material is fully described and illustrated and the ecology in France is outlined. Gametophytically, French specimens of<jats:italic> F. jansenii</jats:italic> do not deviate significantly from Portuguese material and the variability of characters is discussed. In France, on plateau de Millevaches,<jats:italic> F. jansenii</jats:italic> is relatively frequent but constitutes rather small populations, with a low number of individuals. Sporophytes were regularly encountered and reproduction is most likely to be by spore dispersal. On plateau de Millevaches,<jats:italic> F. pusillus</jats:italic> (Wilson) Milde shares a comparable habitat but is easily distinguished from<jats:italic> F. jansenii</jats:italic>. Morphologically similar species occurring in Western Europe and that could potentially be confused with<jats:italic> F. jansenii</jats:italic> (<jats:italic>F. rivularis</jats:italic> and<jats:italic> F. rufulus</jats:italic> Bruch &amp; Schimp.) are compared.</jats:p>

New records of Fissidens jansenii Sérgio & Pursell (Fissidentaceae, Bryophyta) from the Iberian Peninsula

“…Hugonnot & Chavoutier (2020) compared the new French populations of F. jansenii with F. rivularis and F. rufulus . These authors expanded on the differences with F. rivularis , regarding the size of the plants, the shape of the leaves and their apices, the structure of the limbidium at the apex, the excurrence of the costa, the width of the limbidium in the dorsal laminae, sexuality, and spore size.…”

“…1). In the light of these new findings, the status of the species, assessed as Critically Endangered in Europe ( Hodgetts et al 2019), should be reevaluated as suggested by Hugonnot & Chavoutier (2020). This highlights the importance that plant collecting still has today in the Iberian Peninsula; it has led in recent years to the addition of numerous novelties ( Guerra & Cano 2022).…”

“…Hal.) Broth., this taxon is a diminutive species belonging to section Fissidens subgenus Fissidens ( Pursell & Bruggeman-Nannenga 2004) (=section Pachylomidium Müll.Hal., sensu Bruggeman-Nannenga 1985, Hugonnot & Chavoutier 2020). The species in this section are perhaps the most difficult to identify, as there are few stable characters and considerable variation within a given species ( Pursell 2007).…”

“…Both species belong to subgenus Fissidens. Fissidens jansenii was described from a single locality in Portugal (Beira Alta, Poço do Inferno, Serra da Estrela), and recently it was reported from four new localities in France (plateau de Millevaches) by Hugonnot & Chavoutier (2020). Fissidens eremicus has a wide distribution in southeastern Spain, southern Portugal and northern Africa.…”