Sep 092016
 
Sphaeropcaros texanus photographed by David Long (Long 33162)

European material of Sphaerocarpos texanus, photographed by David Long (Long 33162)

The Sphaerocarpales (or “Bottle Liverworts”) form a very distinct group in the complex thalloid liverworts, with ca. 30 species in five genera: originally the group just included Geothallus (monospecific), Sphaerocarpos (8-9 species) and Riella (ca. 20 species), with two more monospecific genera, Austroriella and Monocarpus, added within the last few years. All five genera have very unusual, and highly reduced, thallus morphologies. With the exception of Monocarpus, they also all enclose their sex organs (or gametangia – the antheridia and archegonia) in inflated flask-shaped bottles (as can be seen in the accompanying photograph). This feature sets them apart from all other liverworts. All of them are adapted to extreme habitats, including arable fields, hot arid regions, seasonal lakes and pools, and salt pans.

A worldwide revision of the second largest genus of the group, Sphaerocarpos, is over 100 years old (Haynes 1910); other revisional work focuses on individual geographic areas, including South Africa (Proskauer 1955), North America (Haynes & Howe 1923, Frye & Clark 1937, Schuster 1992, Timme 2003), California (Howe 1899), Europe (Reimers 1936, Müller 1954), and France (Douin 1907). No revisions have been made for large areas including Australia, Asia and South America, and most of the work predates any DNA-based concepts of plant identification or species relationships. Bringing the taxonomy of Sphaerocarpos into the 21st century, Dr Daniela Schill spent 18 months (2007-2009) at RBGE on a Sibbald Trust-funded project to compile a world-wide taxonomic revision of the genus. Two field expeditions fed into the project, with Dr David Long collecting European species in Portugal in April 2007, and Daniela collecting North American species in California in March 2008 (funded by the Peter Davis Expedition Fund).

Spore SEMs of Sphaerocarpus drewiae, taken by Daniela Schill

Spore tetrads of Sphaerocarpos drewiae, SEMs taken by, and plate prepared by, Daniela Schill

Daniela’s work is based on morphological and anatomical characters, including spore characters that she observed using Scanning Electron Microscopy (SEM). Her aim has been to produce identification keys to the species, species descriptions, species lists, synonyms, botanical drawings, distribution maps, and ecological, nomenclatural and taxonomical notes. Although the study is not yet published, much of it, including SEM plates for spores from the ca. 9 different species (as seen on the right), is complete.

In parallel, RBGE staff have also been sequencing multiple accessions of all available Sphaerocarpos species, producing data that has helped inform some of Daniela’s taxonomic decisions, and that also allow us to generate a stand-alone phylogeny for the genus.

This research will lead to some taxonomic changes. For example, European Sphaerocarpos texanus plants differ from American S. texanus, both in their DNA sequences and in their spore characters, and so they are likely to be considered a separate species. Furthermore, European Sphaerocarpos michelii material includes three different forms based on spore characters; these are also confirmed by molecular research, and may be recognised at or below the rank of species.

 

References:

Cargill, D.C. & J. Milne. 2013. A new terrestrial genus and species within the aquatic liverwort family Riellaceae (Sphaerocarpales) from Australia. Polish Botanical Journal 58(1): 71-80.

Douin R. 1907. Les Sphaerocarpus français. Revue Bryologique 34(6): 105-112.

Frye T.C. & L. Clark. 1937. Hepaticae of North America. University of Washington Publications in Biology 6: 105-113.

Haynes C.C. 1910. Sphaerocarpos hians sp. nov., with a revision of the genus and illustrations of the species. Bulletin of the Torrey Botanical Club 37(5): 215-230.

Haynes C.C. & M.A. Howe. 1923. Sphaerocarpales. North American Flora 14: 1-8.

Howe  M.A. 1899. The hepaticae and anthocerotes of California. Memoirs of the Torrey Botanical Club 7: 64-70.

Müller K. 1954. Die Lebermoose Europas. In: Rabenhorst’s Kryptogamenflora von Deutschland, Österreich und der Schweiz. 3. Auflage. Volume VI. Part 1. Leipzig, Akademische Verlagsgesellschaft Geest & Portig K.-G., Johnson Reprint Corporation (1971), New York, London.

Proskauer J. 1955. The Sphaerocarpales of South Africa. The Journal of South African Botany 21: 63-75.

Reimers H. 1936. Revision des europäischen Sphaerocarpus-Materials im Berliner Herbar. Hedwigia 76: 153-164.

Schill D.B., L. Miserere & D.G.Long. 2009. Typification of Sphaerocarpos michelii Bellardi, S. terrestris Sm. and Targionia sphaerocarpos Dicks. (Marchantiophyta, Sphaerocarpaceae). Taxon 58(2): 638-640.

Schuster R.M. 1992. Sphaerocarpales. In: The hepaticae and anthocerotae of North America V. Field Museum of Natural History, Chicago: 799-827.

Timme S.L. 2003. Sphaerocarpaceae. In: Bryophyte Flora of North America, Provisional Publication.

 

Apr 262016
 
Setting up PCRs in our laminar flow hood

Setting up Aneura PCRs in our laminar flow hood

Sitting in Edinburgh airport on a Monday morning, waiting for David Long to join me, checked in through to Trondheim via Copenhagen, I felt completely unprepared. The previous week had been a fluster of lab work and reading DNA sequences, trying to get everything ready in time – a stressful Friday evening, trying to copy all the Aneura files into my Dropbox and onto flash drives before the building shut down at 6pm, willing all the file transfers to go faster and faster… but in the end having to leave many of the images that I had planned to take with me behind in the office. Despite a relatively early start on the Monday, we had a 7 hour layover in Copenhagen,

The Lego shop, Copenhagen

The Lego shop, Copenhagen

time for a train ride into the city, lunch, and a meander through the downtown streets, so didn’t get to Trondheim until late. From the airport bus we could make out snow and birch trees, before getting off on a near-deserted icy street. A short walk to the Comfort Hotel Park, an easy check-in, and sleep.

Swedish bryologist Lars Söderström picked us up in the foyer at about 9am. The university is only 20 minutes or so walk away, but the icy pavements made that impractical, so we were taking the bus. Lars had our bus tickets on his phone, cheaper and easier than using cash on the bus. Once purchased, they’re good for an hour and a half, with a spinning bar that gets shorter over the time period until it eventually disappears and the ticket has gone. It was a short ride, across the river and uphill, through mostly painted wooden buildings. Ana Séneca, our Portugese team-Aneura colleague, met us on the bus.

The university building is modern and airy, with open atriums the height of the building, planted with dead bamboo. Ana and I made our way to the Herbarium, a windowless room filled with cupboards of bryophytes that had mostly been collected by herself and by Lars. This was the day that the two of us had put aside for compiling and analysing our Aneura data. I’d begun sending sequences over to Ana on the Friday, so the datasets were already joined together. We had sequences from just over 300 accessions of Aneura, mostly from the British Isles and Norway, but with representatives from Albania, Sweden, Iceland, Portugal, Belgium, Austria, Latvia, the Faroe Islands, China, Fiji, India, the Falklands, Reunion, South Africa, the US, Canada, Panama, Peru…

Building phylogenetic trees in the University Herbarium, Trondheim

Building phylogenetic trees for Aneura in the University Herbarium, Trondheim

We used PAUP to run some quick parsimony analyses, printing out multi-page phylogenetic trees for each of four gene regions that we had been sequencing.

Papering over the table with our Aneura data

Papering over the table with our Aneura data

Clades that were in common between all four trees were marked on using some provisional, and informal, clade names, and after a search for coloured crayons, Ana undertook the serious business of marking geography onto the trees. Although she tracked down a pack of 12 coloured crayons, that wasn’t quite enough to separate the regions we were interested in, so we ended up with a key that combined colour and symbols.

Back to basics - colouring in the trees

Back to basics – colouring in the trees

A little after 5pm, it was time to call it a day, roll up the trees we’d made, and head out into the cold and dark to catch the bus back into town; the four of us headed to the Microbrewery in town for beer and burgers, then a nightcap of whisky at the hotel before Lars and Ana caught the bus out to their home.

Lars, David and Ana pick their way across the least icy route to the Museum

Lars, David and Ana pick their way across the least icy route to the Museum

The next morning, Lars and Ana met us at the hotel again, but this time instead of a bus, we were walking to the Museum, only five minutes or so from where we were staying. The paths were icy, but the views across the river were beautiful in the sunlight. We signed in at the Museum, where our Norwegian friend and colleague, Kristian Hassel, was waiting. First we headed up to the Herbarium, with views out across the city, before going downstairs for coffee, and settling on a sofa in the library to roll out our trees and start the conversation – what are we going to do with this data?

View from the Herbarium, NTNU Museum

View from the Herbarium, NTNU Museum

Luckily, we all agreed on the next actions – we are going to give names to a set of new species, based on molecular characters. We won’t name things that have only been collected and sequenced once, but if there are 4 or more accessions that form a lineage, then they will get named. Because of the focus of our sampling, we will restrict the taxonomy to taxa that occur in Europe. We also have to deal with the species of Aneura that have already been described. Because we are planning to use DNA for taxonomy, then we need to also have sequence data for all the existing names in the genus, even those that were described before anyone know what DNA was. This can be done retrospectively, using epitypification.

Ana and Lars compare names in the Museum library

Ana and Lars compare names in the Museum library

When a species name is published, it is linked to something known as a ‘type’. Usually this is a physical specimen, botanically, a dried out plant sample, although historically, illustrations were also used. The specimens are particularly important, often placed in special red folders, and treated with great respect. Methods like DNA extraction, which involve physically destroying parts of the material, are frowned upon. Given that some of the material can be over a hundred years old, DNA methods can also have very low success.

Instead of trying to get hold of old plant types and grind them up, we intend to use an alternative, which is the designation of new good-quality plant material as ‘epitypes’ – explanatory types that have more characteristics than the original material had, and so allow a better understanding of the correct application of the plant name. The material that we will designate as epitypes will be from large collections, with associated DNA material, and will have been sequenced for the set of four DNA markers in our project.

Trondheim, by the river

Trondheim

Trondheim

Trondheim

Thursday saw us back in the University, continuing discussions about data handling, dealing with mundane tasks like tracking down specimen information and compiling tables of data. More excitingly, bringing together collection details for plants in different evolutionary groups in our trees started to reveal some biology behind our proposed new species, with different ones occurring in different habitats. Although our departure on the Friday morning can only be described as totally uncivilised, with a 6.30 am flight from Trondheim to Oslo, a short stopover then an arrival in Edinburgh at approximately breakfast time, at least we had the satisfaction that the story of Aneura is finally beginning to come together – and an agreement that the next time we meet, it will be somewhere a bit less frozen, like Portugal…

A land of snow and ice - Norway from the plane

A land of snow and ice – Norway from the plane

 

 

Mar 172016
 

One of the most recognisable groups in the bryophytes, the complex thalloid liverwort genus Marchantia, has just become a bit larger. We have sunk Preissia and Bucegia into it, because in molecular phylogenies they are both phylogenetically nested within Marchantia (Villarreal et al. 2015). Although this only adds two species to the genus (Preissia quadrata and Bucegia romanica), taking the total number of species recognised from 36 to 38, it also broadens the range of plant morphologies that occurs in Marchantia.

Marchantia sampling from Villarreal et al. 2015

Maximum likelihood topology for Marchantia from Villarreal et al. 2015; * indicates bootstrap support of 100% and posterior probabilites of 1

Preissia quadrata (Scopoli) Nees returns to an earlier name, Marchantia quadrata Scopoli. This is the name under which it was first described, by Scopoli, in 1772. For Bucegia romanica Rad., first described by Radian (1903), a new combination has been made, Marchantia romanica (Rad.) Long, Crandall-Stotler, Forrest & Villarreal.

A new subgenus, Marchantia subg. Preissia, has been created for these species. A third species that was collected in China by David Long, and was included in the molecular phylogeny, has not yet been named, but will also belong to subgenus Preissia. Morphologically, the new species is most similar to Marchantia quadrata.

bucegia paperMarchantia romanica is known from northern Europe and northern North America (e.g. Evans 1917, Konstantinova et al. 2014). Photographs of fertile plants, and transverse sections showing 2-3 layers of filament-less air chambers, can be seen in Konstantinova et al.’s report. The hollow air chambers they illustrate are one of the clearest features that separated Bucegia from Marchantia and Preissia.

Preissia quadrata carpocephalum, photographed by Des Callaghan

Marchantia quadrata carpocephalum, photographed by Des Callaghan

Marchantia quadrata is also a northern hemisphere species; it is widespread in the British Isles, and a map and photographs are available in the British Bryological Society Field Guide. Like Marchantia romanica, this species lacks gemmae cups. Its two ranks of ventral scales could also be used to separate Preissia from Marchantia, which typically has 4 or more rows of ventral scales. Two subspecies are recognised in Schuster (1992), one more southerly and dioicous (ssp quadrata) and the other northern and monoecious (ssp hyperborea) (Schuster 1985). From our data, using DNA regions from genes that were chosen to show relationships between genera rather than within species, genetic differences can be seen between a collection from the South Ebudes off the west coast of Scotland, and one from Snowbird, Utah in the United States. Molecular sampling from across the range of Marchantia quadrata may reveal a complex of several species. Indeed, this was anticipated by Schuster (1992, p. 366), who described the range of morphological variation within the species as “astonishing”.

Konstantinova et al. 2014: phylogentic variation between accessions of Bucegia and Preissia

Konstantinova et al. 2014: phylogenetic variation between accessions of Bucegia and Preissia

Konstantinova et al. (2014) generated DNA sequences for the nuclear ITS region, and two plastid regions, trnL-F and trnG, for six accessions of Marchantia romanica (“Bucegia”, from Romania, Ukraine and Svalbard), and three accessions of Marchantia quadrata (“Pressia”, from Russia). Unfortunately the regions that they sequenced do not overlap with the sequencing in our study, so we cannot combine the datasets. However, they do rather intriguingly resolve two clades within Marchantia romanica (“Bucegia”), one from mainland Europe, and the other from Svalbard. Again, molecular sampling from across the range of this taxon could reveal several distinct lineages. Adding samples from North America seems a priority.

Thus, although we have only added two species to Marchantia, the number of species is likely to rise with additional molecular sampling, in line with a clearly necessary taxonomic revision of Marchantia subgenus Preissia.

 

David G. Long, Laura L. Forrest, Juan Carlos Villarreal & Barbara J Crandall-Stotler. 2016. Taxonomic changes in Marchantiaceae, Corsiniaceae and Cleveaceae (Marchantiidae, Marchantiophyta). Phytotaxa 252 (1): 077-080.

 

Long et al