Streams are important ecosystems that harbor a high diversity of plant species including bryophytes. Studies suggest streams can function as refugia and/or corridors that buffer against the effects of disturbances. In this study, we sampled five sites along a second-order tropical stream in the Luquillo Experimental Forest. We described the riparian bryophyte community composition in conjunction with the physical structure of the stream to understand what environmental factors influence bryophyte composition in the stream. We identified 56 bryophytes, 33 liverworts and 23 mosses; and we recorded cyanobacteria associated with over half of the species of bryophytes. Rocks were the most frequent and important substrate which supported the highest bryophyte richness. Community composition and species diversity were similar among sites. Ceratolejeunea cornuta (Lindenb.) Steph. and Taxithelium planum (Brid.) Mitt. were the most frequent species, recorded in all sites. Although stream width varied between sites, all the other environmental variables measured (canopy cover, temperature, humidity, and elevation) were similar. Across plots, species richness increased with bryophyte cover, whereas canopy cover, location in the stream, substrate, site, temperature, and relative humidity showed no clear associations with richness. Bryophyte community composition seems to be shaped by the substrates occupied. We found that similar types of substrates such as branches, trunks, logs and vines, shared more species in common. This is one of the first studies to describe the bryophyte community of a tropical stream and can provide a baseline for future research on the response of bryophytes to increased disturbances and a changing climate.
Fumaroles generate steep microclimatic and edaphic gradients that allow bryophyte communities to persist where the surrounding landscape is too dry or extreme. To explore this phenomenon, we surveyed bryophytes across the Khaybar White Volcano Geopark (north-western Saudi Arabia) during two field campaigns in 2024 and 2025, using a systematic 5 & times; 5 km grid to reduce spatial bias. Within fumarolic habitats, we counted vents by diameter class (0-2, 2-10, 10-50, >50 cm) in GPS-referenced plots and recorded bryophyte presence and abundance following the Braun-Blanquet scale. Across 188 relev & eacute;s distributed among 11 fumarolic sites, we collected 1806 records representing 37 bryophyte taxa - about 72% of the 51 species known from the entire Geopark. Thirteen species were found exclusively in fumarolic microhabitats, and seven showed tropical or paleotropical affinities. Statistical analyses (Spearman correlations, n = 188) revealed that both species richness and cumulative abundance were highest in plots containing more medium-sized vents. These values declined near larger vents (>50 cm) and showed no clear relationship for smaller ones (<= 10 cm). The association between medium vent abundance and bryophyte richness remained consistent across sites. Tropical species richness did not vary systematically with vent size but was clearly structured by orientation, with northerly and north-easterly slopes hosting most tropical taxa. Even so, the results suggest that clusters of medium-sized fumaroles create locally buffered conditions that support bryophyte establishment in this hyper-arid volcanic setting. We propose a preliminary Bryothermal Index (BTI) that integrates community-level indicators - species richness, abundance, and the proportion and fertility of hygrophilous or tropical-affinity taxa - to estimate geothermal influence. Future research should include high-frequency temperature and humidity logging, gas and substrate analyses, and replicated transects around vents to clarify mechanisms and validate the BTI. Despite their small extent (<1 ha), the Khaybar fumaroles stand out as microrefugia and should be considered for targeted micro-reserve protection and long-term ecological monitoring.
Macromitrium sulcatum (Hook.) Brid. is widely distributed in sub-Saharan Africa, South Asia, Indochina, Southeast Asia and Yunnan province of China. Our examination of its type and ordinary specimens showed that the species highly varied in the outline, basal cells, apical cells and upper margins of its branch leaves. On the phylogenetic tree based on trnL-F, trnG and ITS2, seventeen samples formed a strongly supported clade, which were morphologically associated with the types of M. sulcatum and its previous synonyms including M. seriatum Paris & Broth., M. ceylanicum Mitt., M. belangeri M & uuml;ll. Hal. and M. bequaertii Th & eacute;r. & Naveau, as well as those of M. lorifolium Paris & Broth., M. muellerianum Mitt., M. pseudoramentosum Herzog and M. turgidum Dixon. In this study, we compared the types and ordinary specimens of these species and found that the variations of the later four species fall within the morphological variation range of M. sulcatum. Therefore, we treated them as new synonyms of M. sulcatum.
The first checklist of bryophytes from R & eacute;union, published in 2005, recorded 621 species for the island. Nearly 20 years later, the total number of bryophyte species reported has increased to 822. This significant growth in knowledge results from ongoing floristic exploration, and ecological studies examining diversity across elevational gradients. We here report 500 species of mosses, 313 species of liverworts, and nine species of hornworts, including 16 moss, 20 liverwort, and three hornwort taxa that are newly recorded for R & eacute;union. Unsurprisingly, endemism levels have decreased with increased knowledge of the local and regional flora. Forty-nine bryophyte species are endemic (6 %), comprising 36 mosses and 13 liverworts. We also indicate taxa described based on type material from either R & eacute;union or the wider Madagascar region, and provide references linking each name to its first published report on the island. Future research on the flora should focus on clarifying the taxonomy of poorly known taxa. Additionally, targeted collecting efforts and inventories will help improve our understanding of species distributions, which is essential for informed conservation planning.
The genus Ignatovia U.B.Deshmukh comprises the sole species Ignatovia microphylla (Ignatov & Ignatova) U.B.Deshmukh, which has been thus far known only from Russia. During our recent expeditions to Shangfangshan National Forest Park in Beijing, China, we encountered an interesting moss that can be assignable to I. microphylla, characterized by small leaves, round to oblate and thick-walled lamina cells that are somewhat bulging abaxially, nearly homogeneous thick-walled cells in the cross-section of the stem, a cross-section of the costa without stereids, and triangular inner perichaetial leaves. Molecular phylogenetic analyses based on nrITS1-5.8S-ITS2 and trnL-F further support the morphological identification. Our finding represents the first report of I. microphylla outside Russia, a new generic record for China. Additionally, we assembled and annotated its organelle genomes. The results showed that the complete chloroplast genome is 124 918 base pairs (bp) in length with 29.2% GC content, consisting of 82 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The complete mitogenome is 103 161 bp in length with a GC content of 41.0%, comprising 40 protein-coding genes, 24 tRNA genes, and three rRNA genes. The discovery of I. microphylla could lay the foundation for investigating biogeographical patterns and species evolution in further studies.
