A working checklist of accepted taxa worldwide is vital in achieving the goal of developing an online flora of all known plants by 2020 as part of the Global Strategy for Plant Conservation. We here present the first-ever worldwide checklist for liverworts (Marchantiophyta) and hornworts (Anthocerotophyta) that includes 7486 species in 398 genera representing 92 families from the two phyla. The checklist has far reaching implications and applications, including providing a valuable tool for taxonomists and systematists, analyzing phytogeographic and diversity patterns, aiding in the assessment of floristic and taxonomic knowledge, and identifying geographical gaps in our understanding of the global liverwort and hornwort flora. The checklist is derived from a working data set centralizing nomenclature, taxonomy and geography on a global scale. Prior to this effort a lack of centralization has been a major impediment for the study and analysis of species richness, conservation and systematic research at both regional and global scales. The success of this checklist, initiated in 2008, has been underpinned by its community approach involving taxonomic specialists working towards a consensus on taxonomy, nomenclature and distribution.

Estimates of extant liverwort species range from 4,500 to 9,000, with estimates in the past decade converging on 5,000 to 6,000. Potential problems and pitfalls of deriving species estimates are addressed, including binomial accumulation, the impact of synonymy, taxonomic inflation, the impact of unrevised species-rich genera, species concepts and cryptic species. We present a revised mean estimate of 7,500 for the number of liverwort species based on estimating rates of synonymy in a sample of recently monographed and revised taxa. This estimate does not include infraspecific names and may underestimate global diversity as a result. We also present a databased estimate of about 8,500 species derived from the Early Land Plants Today data set. We argue higher estimates are supported by: 1) the number of published species has not reached a plateau and new species continue to be discovered; 2) not all regions have been thoroughly explored and with equal intensity, with survey effort being historically biased toward northern temperate regions; 3) synonymy rates are not uniform across taxonomic groups; 4) novel discovery of species outpaces new species derived from elevation in rank (taxonomic inflation); and 5) species numbers are not necessarily distorted by large unrevised genera. A standardized global worldwide liverwort checklist with strong community participation coupled with the critical need for ongoing monographs and revisions, will aid in arriving at a clearer estimates of liverwort diversity. We promote and encourage interest in the topic using an evidence-based approach and quantitative data.

The serpentine-substrate effect is well documented for vascular plants, but the literature for bryophytes is limited. The majority of literature on bryophytes in extreme geoedaphic habitats focuses on the use of species as bioindicators of industrial pollution. Few attempts have been made to characterize bryophyte floras on serpentine soils derived from peridotite and other ultramafic rocks. This paper compares the bryophyte floras of both a peridotite and a granite outcrop from the Deer Isles, Hancock County, Maine, and examines tissue elemental concentrations for select species from both sites. Fifty-five species were found, 43 on serpentine, 26 on granite. Fourteen species were shared in common. Twelve species are reported for the first time from serpentine soils. Tissue analyses indicated significantly higher Mg, Ni, and Cr concentrations and significantly lower Ca:Mg ratios for serpentine mosses compared to those from granite. Soil analyses demonstrated significant differences between the two substrates.

The natural history collections community has made significant strides in the past decade in the digitization of their holdings. Digitization has made the data and corresponding images of collections publicly available to researchers, students, and the public. Data and images are served online by institutions’ local databases, and regional, national, and international aggregators. One challenging aspect in digitizing natural history collections is the presence of offensive language, such as racial slurs in collection and location data. We present findings from a community survey and analysis of data from relevant aggregators to assess the presence of and approach to offensive language in collections data. We also suggest initial guidelines for data warning statements and disclaimers and transcription guidelines to help preserve historical integrity of data while also supporting inclusive and safe workspaces. Please note that in writing about offensive terms found in natural history collections, we use and refer to offensive terms and include images of labels and documents to provide examples.

The liverwort family Acrobolbaceae Hodgson (1962: 117) is primarily distributed in the Southern Hemisphere and is currently described as containing three subfamilies and seven genera with approximately 60 accepted species names. The subfamily Acrobolboideae (or Acrobolbaceae s. str.) has historically contained the genera Acrobolbus Gottsche et al. (1844: 5), Marsupidium Mitt. in Hooker (1867: 751), and Tylimanthus Mitt. in Hooker (1867: 751).

It is clearly evident that the bryophyte flora of the islands of Fiji remains inadequately documented. Here, five liverwort species of Lepidoziaceae are reported as new to the Republic of Fiji: Lepidozia haskarliana, Neolepidozia cuneifolia, N. wallichiana, Telaranea major and Tricholepidozia melanesica.

The liverwort subfamily Acrobolboideae has historically contained the three genera: Acrobolbus, Marspidium, and Tylimanthus. Generic delimitations in this subfamily have been historically inferred from morphological characters, specifically the location of gametangia. Taxonomists have had difficulty separating the genera, with some combining Tylimanthus and Acrobolbus, whereas others merged Marsupidium and Tylimanthus. We used five chloroplast loci to reconstruct a phylogeny of the group, revealing all three genera are polyphyletic as currently described. An assessment of key morphological characters used to separate genera in the subfamily resulted in several observations: characters used to circumscribe Acrobolbus were homoplasious; characters used to circumscribe each genus (e.g., the placement of female reproductive organs) do not reflect phylogenetic relationships; and the evolutionary trajectories of some characters (i.e., the number of antheridia, male reproductive organs, per male bract) correspond directly with previous evolutionary hypotheses for the family, but do not follow historical taxonomic inferences. Irrespective of generic concepts, several well-supported clades within the phylogeny have a strong biogeographic structure. Using these lines of evidence, we recognize Acrobolbus as a single genus in Acrobolboideae.

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