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Anomobryum apiculatum (Schwägr.) D.Bell & Holyoak is a widespread moss from tropical and subtropical areas of the world. It has been also reported from Europe. However, the recent re-evaluation of those records indicate they have been mistaken with unrelated Bryum Hedw. species and thus, its actual presence in Europe is doubtful. During independent bryological surveys, samples from two distant Mediterranean localities in Spain and Israel were collected. These samples differed from any other Bryaceae Rchb. species reported to date but matched the morphological traits described for A. apiculatum, which is here newly reported for Spain and Israel. A detailed morphological study of specimens from the two localities revealed conspicuous variation at vegetative traits related to leaf arrangement and shape. This variation in vegetative traits contrasted with the similarity of tubers. Plants from both populations showed rhizoidal and axillary tubers of the distinctive features described for A. apiculatum s.l., including their large size (166-359 µm), brown to dark-brown colour and strongly protuberant cells. Tuber traits make A. apiculatum readily distinguishable from all other tuberous species of Bryum s.l. in the Mediterranean, including Ptychostomum rubens (Mitt.) Holyoak & N.Pedersen. This latter species also occurs on disturbed soil, and has axillary and rhizoidal tubers with protuberant cells, but with distinctive red colouration. Its leaves have a conspicuous limbidium, and are dentate in the upper part, contrasting with the entire margin and absence of limbidium in those of A. apiculatum. These traits allow a clear differentiation between both species. [ABSTRACT FROM AUTHOR]

Riella Mont. is unusual among bryophyte genera because its species have an ephemeral habit and grow submerged in fresh or brackish waters. Most species show fragmented distribution areas and have few known populations and are thus of conservation concern. The flagship Mediterranean species R. helicophylla (Bory & Mont.) Mont. has recently been taxonomically reassessed, and most populations have been placed in a new species, R. macrocarpa (P.Allorge) Puche, Segarra-Moragues, Sabovlj., M.Infante & Heras. Here we describe the development of nuclear microsatellite markers for R. macrocarpa with the aim of characterising the population genetic dynamics of this species of conservation concern, and we report their potential use in other species of the genus. Nuclear microsatellite markers were isolated from 454 genomic libraries and amplification parameters optimised for the set of loci finally selected. Nine microsatellite loci were characterised and amplified a total of 53 alleles in a sample of 120 individuals from four populations, having a mean of 5.89 alleles per locus. Unbiased genetic diversity for the polymorphic loci within populations ranged from 0.067 to 0.791. Cross-species transferability assayed in six other species of Riella covering reproductive and taxonomic diversity in the genus showed transferability success rates ranging from 77.8% to 100%, with 33.3% to 57.1% of the successfully transferred loci being polymorphic within species. These markers will be useful for studying population genetic diversity and structure and will contribute towards better conservation management of populations of R. macrocarpa and other species of Riella. [ABSTRACT FROM AUTHOR]

A new population of the Argentinian endemic Riella choconensis Hässel (Riellaceae, Marchantiophyta) was discovered from a culture of sediments from the Laguna de los Juncos (Río Negro province, Argentina). This species was known previously from two nearby collections, made in 1984, in the type locality at the Ramos Mexía reservoir (Neuquén province) and was not recorded since. Fresh material from the new population enabled detailed morphological analyses, which are extensively described here, illustrated and compared to type material of the species. Based on the smooth female involucre, the species belongs to subgenus Riella Mont. However, cross-sections of this structure showed that R. choconensis has bistratose involucre walls, contrasting with the unistratose female involucres of all other species in the genus. The updated morphological data are integrated into a new key to the identification of the American species of Riella. [ABSTRACT FROM AUTHOR]

Riella (Riellaceae, Sphaerocarpales) is a genus of aquatic liverworts with a disjunct worldwide distribution in areas of seasonal Mediterranean-type climates. Its centre of diversity is located in the Mediterranean basin, where about half the species number of the genus is concentrated. In the course of a worldwide revision of the genus Riella, plants from a monoicous species with wingless, not papillose and smooth involucres were found in two distant Iberian localities. These plants showed a geminate dorsal wing, unlike the single wing occurring in the remaining species of the genus. This character unambiguously assigns these populations to R. bialata, a species known to date from a single collection in its Algerian type locality. Riella bialata is thus reported as new to Europe. Fresh materials enabled detailed morphological analyses, and the Iberian materials are extensively described and illustrated herein [ABSTRACT FROM AUTHOR]