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.

 

Jun 302016
 

The genus Aitchisoniella contains a single species, A. himalayensis, which was described by Pakistani botanist Professor Shiv Ram Kashyap from plants that he collected in Mussoorie, Uttarakhand, India (1914). Subsequently (1929) he also found the species in Shimla and Kullu in Himachal Pradesh. Although reports of new locations followed (Kanwal, 1977, Pant et al., 1992, Bischler et al., 1994), near Nainital in Uttarakhand, the species was only known from the north-west Himalayas of India until 2010, when its range was extended by RBGE bryologist Dr David Long, on the ‘Kunming/Edinburgh Expedition to Sichuan’. David found Aitchisoniella at two localities in China, in Litang and Daocheng counties of south-west Sichuan Province.

Athalamia pinguis, Sichuan, photographed by David Long (Long # 40305)

Fig. 1. Athalamia pinguis in Sichuan, showing stalked sexual branches (carpocephala), photographed by David Long (Long # 40305)

Aitchisoniella looks quite different to other complex thalloid liverworts: it doesn’t have the stalked sexual branches (carpocephala) that are present in most complex thalloid species like Marchantia, or Athalamia (as can be seen in the photograph, Fig. 1). Instead, the female sex organs (archegonia), and therefore the sporophytes, grow on the lower (ventral) side of a short receptacle (as can be seen in the photograph, Fig. 2). The receptacle is part of the main thallus, with air chambers and air pores, and a groove on the underside of the thallus from which characteristicly complex-thalloid pegged rhizoids grow.

 Aitchisoniella himalayensis in Sichuan showing terminal sporophyte-bearing receptacles, from Long 39886

Fig. 2. Aitchisoniella himalayensis in Sichuan, showing terminal sporophyte-bearing receptacles, photographed by David Long (Long # 39886)

Originally, Aitchisoniella was thought to belong to the Exormothecaceae family of complex thalloid liverworts, along with Exormotheca and Stephensoniella. Earlier this year, we transferred all the plants in Exormothecaeae into another family, Corsiniaceae, where they joined Corsinia and Cronisia (Long et al. 2016a).

Complex thalloid phylogeny reconstructed by Villarreal, J.C., B.J. Crandall-Stotler, M.L. Hart, D.G. Long, L.L. Forrest. 2015. Divergence times and the evolution of morphological complexity in an early land plant lineage (Marchantiopsida) with a slow molecular rate. New Phytologist. DOI: 10.1111/nph.13716

Fig. 3. The phylogenetic position of Aitchisoniella, from the complex thalloid phylogeny reconstructed by Villarreal et al. (2015)

However, having fresh material of the plant meant that we were able to extract DNA from it, and add it into our molecular phylogeny for the group (Villarreal et al. 2015). The results were unexpected, with Aitchisoniella grouping with species from a different complex thalloid family, Cleveaceae (Fig. 3). The growth forms are quite different, as all the species in Cleveaceae have got stalked carpocephala. However, once we started to think more about the evolution of these plants, and look more objectively at differences and similarities, one thing struck us: the spores of Aitchisoniella (see Fig. 4) look more like the spores of plants in Cleveaceae (e.g. Athalamia, Fig. 5) than they do like spores of plants in Exormothecaceae (e.g. Fig. 6).

Spores of Aitchisoniella himalayensis. (A) Distal view; (B) proximal view; (C) lateral view; (D) detail of distal view. (A and C) from Long 39886. (B and D) from Long 40020. Scale bars: (A–C) = 5 μm, (D) = 2 μm.

Fig. 4. Spores of Aitchisoniella himalayensis from Long et al. 2016: (A) Distal view; (B) proximal view; (C) lateral view; (D) detail of distal view. (A & C) from Long 39886. (B & D) from Long 40020. Scale bars: (A–C) = 5 μm, (D) = 2 μm.

Athalamia hyalina spore images from M. P. Steinkamp and W. T. Doyle American Journal of Botany Vol. 68, No. 3 (Mar., 1981), pp. 395-401

Fig. 5. Spores of Athalamia hyalina (Cleveaceae) from Steinkamp & Doyle (1981): 1. distal view (x 1,100); 2. proximal view (x 1,100); 3. equatorial view (x 1,100); 4. close-up of pore (x 6,000); 5. distal face (x 3,000).

 

Exormotheca spores: E. bulbigena - A, distal view, B, proximal view. E. holstii - C, distal view, D, proximal view, E, distal view, F, proximal view. From Bornefeld et al., 1996.

Fig. 6. Spores of Exormotheca from Bornefeld et al. (1996): E. bulbigena – A, distal view, B, proximal view. E. holstii – C, distal view, D, proximal view, E, distal view, F, proximal view.

Characters like spore shape used to be considered to be quite neutral in bryophyte evolution, features that were not really acted on by natural selection. Following this theory, spore characters were thought to be indicative of true and ancient relationships, changing very little across huge amounts of time. We have since moved away from this view, with, for example, small changes in the shape and size of spores known to have drastic effects on their aerodynamics. However, within the complex thalloids, it does seem that characters like the presence or absence of carpocephalum branches are quite variable within families, while spore morphology can be indicative of deeper relationships.

As a result of this work, based on both molecular and morphological evidence, we have transferred the genus Aitchisoniella to the family Cleveaceae (Long et al. 2016b), where it joins the four genera accepted by Rubasinghe et al. (2011): Athalamia, Clevea, Peltolepis and Sauteria.

 

REFERENCES

Bischler, H., Boisselier-Dubayle, M.C. & Pant, G. 1994. On Aitchisoniella Kash. (Marchantiales). Cryptogamie. Bryologie-Lichénologie, 15: 103–10.

Borenfeld, T., O.H. Volk & R. Wolf. 1996. Exormotheca bulbigena sp. nov. (Hepaticae, Marchantiales) and its relation to E. holstii in southern Africa. Bothalia 26,2: 159–165.

Kanwal, H.S. 1977. Marchantiales of district Naini Tal (Kumaun Hills) U.P., India. Revue Bryologique et Lichénologique, 43: 327–38.

Kashyap, S.R. 1914. Morphological and biological notes on new and little known West-Himalayan Liverworts. I. New Phytologist, 13: 206–26. doi: 10.1111/j.1469-8137.1914.tb05751.x.

Kashyap, S.R. 1929. Liverworts of the Western Himalayas and the Panjab Plain. Part 1. Lahore: The University of the Panjab.

Long, D.G., L.L. Forrest, J.C. Villarreal & B.J. Crandall-Stotler. 2016a. Taxonomic changes in Marchantiaceae, Corsiniaceae and Cleveaceae (Marchantiidae, Marchantiophyta). Phytotaxa, 252: 77–80.

Long, D.G., L.L. Forrest, J.C. Villarreal & B.J. Crandall-Stotler. 2016b. The genus Aitchisoniella Kashyap (Marchantiopsida, Cleveaceae) new to China, and its taxonomic placement. Journal of Bryology.

Pant, G., S.D. Tewari & S. Joshi. 1992. An assessment of vanishing rare bryophytes in Kumaun Himalaya – thalloid liverworts. Bryological Times, 68/69: 8–10.

Rubasinghe, S.C.K., D.G. Long, R. Milne & L.L. Forrest. 2011. Realignment of the genera of Cleveaceae (Marchantiopsida, Marchantiidae). The Bryologist 114: 116-127. http://dx.doi.org/10.1639/0007-2745-114.1.116.

Steinkamp, M.P. & W.J. Doyle. 1981. Spore wall ultrastucture in the liverwort Athalamia hyalina. American Journal of Botany 68: 395-401.

 

Villarreal, J.C., B.J. Crandall-Stotler, M.L. Hart, D.G. Long & L.L. Forrest. 2015. Divergence times and the evolution of morphological complexity in an early land plant lineage (Marchantiopsida) with a slow molecular rate. New Phytologist. 209: 1734–46, doi: 10.1111/nph.13716.

 

Long, D.G., L.L. Forrest, J.C. Villarreal, B.J. Crandall-Stotler. 2016. The genus Aitchisoniella Kashyap (Marchantiopsida, Cleveaceae) new to China, and its taxonomic placement. Journal of Bryology.

Nov 042015
 

The complex thalloid liverwort Monocarpus sphaerocarpus has been found on two continents, Australia and Africa, separated by around 8,000 km of mostly ocean. The green plants themselves are not particularly easy to compare, as the plants are small and the material that we have to work with has been squashed down and dried to form crumbly herbarium specimens. However, there are differences between the morphological descriptions of plants growing in Australia (Carr 1956; Proskauer 1961) and South Africa (Perold 1999). The characteristics of the plant’s spores are rather easier to observe (using scanning electron microscopy); this shows that spores from collections from Australia and South Africa are quite distinct – although there are also differences between spores from plants from Western Australia and Victoria.

Monocarpus spores: a,d: Victoria, Australia, b,e: Western Australia, c,f: Cape Province, South Africa

From Forrest et al. Fig. 4: Scanning electron micrographs of Monocarpus spores: a,d: Victoria, Australia, b,e: Western Australia, c,f: Cape Province, South Africa.

Although the distances between the three regions in which Monocarpus has been found are huge, it is possible that populations of Monocarpus are more widespread than we might expect. Dust storms could lift spores into the atmosphere, and the dark coloration of the spores suggests some ultraviolet resistance. Proskauer (1961) was able to grow sporelings from four-year-old herbarium collections, showing that they can survive drying out, so may be able to travel a long way in the air currents. However, we would expect genetic isolation over the thousands of kilometres that separate the known populations of these plants.

Given both factors – that there are morphological differences between the plants, and that we expect there to be genetic isolation – we have considered naming the South African material as a separate species, after South African bryologist Sarie Perold, whose publication “Studies in the Sphaerocarpales (Hepaticae) from southern Africa. 1. The genus Monocarpus and its only member, M. sphaerocarpus” is a meticulously detailed piece of work.

However, in order to really understand Monocarpus in South Africa, and decide whether it represents a new species or not, we need to get hold of a bit more material and try some other investigations, including DNA analyses. Perold (1999) got the plant’s South African location from Australian botanist Hellmut Tölken, who had originally found it, and made several trips trying to recollect it; bryologist Terry Hedderson has also been keeping an eye open for samples. But no further material has been forthcoming: the site from which it is known has been developed, and now contains a hotel. And, unfortunately, the Monocarpus specimen from South Africa is scanty. Most of the collection, which was sent out as a loan from the Bolus Herbarium in Cape Town to the National Herbarium, Pretoria (PRE), has, according to T. Trinder-Smith, been lost. All that remains are some fragments of the original collection that were gifted to the National Herbarium of Victoria (MEL), and that we currently have on loan here in Edinburgh:

Monocarpus sphaerocarpus herbarium specimen, photograph by Tiina Sarkinen

Monocarpus sphaerocarpus herbarium specimen, photograph by Tiina Sarkinen

Unless the plant is rediscovered in South Africa, further study of the taxon there is impossible, given the size and fragility of the dust-like remaining specimen (shown in its entirity in the photograph above), as is molecular work to look for genetic differences between Australian and South African material.

It would be unfortunate, though, if the eradication of its only known site caused the extinction of a distinct South African species even prior to its formal description, which in itself is rendered impractical by the loss of nearly all of the existing plant material.

 

Monocarpus heading

 

 

References

Proskauer J (1961) On Carrpos I. Phytomorphology 11, 359-378.

On Monocarpus – http://stories.rbge.org.uk/archives/17112

Finding Monocarpus, in the Herbarium – http://stories.rbge.org.uk/archives/17146

Finding Monocarpus, in the field – http://stories.rbge.org.uk/archives/17272

Sep 112015
 

At the Royal Botanic Garden Edinburgh we’ve been working on the phylogeny of the complex thalloid liverworts for rather a while now. David Long presented a poster on it in 2004 at the International Botanical Congress in Vienna, with data that were included in a collaborative study published in 2006 (Forrest et al., see below).

Figure 5. Marchantiopsida - from Forrest et al. 2006.

Figure 5. Marchantiopsida – from Forrest et al. 2006, The Bryologist

However, several genera were not available at that time. For many of these missing genera, the phylogenetic placement was not really controversial – while we had not sampled Bucegia, for example, morphologically we expect it to fit in a lineage with Marchantia and Preissia. Oxymitra, likewise, is expected to fit near Riccia. The placement of Monocarpus, on the other hand, remained controversial; several authors, including Denis Carr (1956) and Sarie Perold (1999) placing it with Sphaerocarpos (Sphaerocarpales), while the most up to date liverwort classification, from Barbara Crandall-Stotler, Ray Stotler and David Long (2009), put it in the Marchantiales.

One of the people that we contacted to try to get hold of Monocarpus material for DNA extraction, back in July 2006, was Chris Cargill, from the Australian National Herbarium, who promised to keep a lookout for us. In January 2008 she sent us an excited email – a few weeks previously she had picked up 15 boxes of bryophytes from Denis Carr and been slowly going through them. They were collections made over 50 years ago, still wrapped in their original newspaper packets, many with quite a lot of loose dirt. Collection details for many had been lost, rendering them as good as useless.

Monocarpus specimens collected by Carr

Monocarpus specimens collected by Carr, photographed by Chris Cargill

However, when Chris grabbed her first box of 2008 to go through, she found  a box within the main box, written on which was “New Victorian localities for Monocarpus“.  In her words, it was “absolutely full of shovel loads of Monocarpus, collected by Carr.

Her email was to ask us if we were interested in receiving any of this plant material for DNA work. Our answer was a very resounding yes. Although the age of the material meant we were not sure we would be able to recover amplifiable DNA from it, the quantity of plants in the collection, and the number of large brown spores that were visible, gave us some hope of success.

Monocarpus specimen collected by Carr, photographed by Chris Cargill

Monocarpus specimen collected by Carr, photographed by Chris Cargill

The plants arrived in Edinburgh, our first actual sighting of the genus, in February 2008. Sadly, by the end of the month the extracted DNA had not amplified in PCR reactions for a wide range of DNA regions, meaning that we remained unable to place the genus in an evolutionary context – although postdoctoral researcher Daniela Schill, then studying Sphaerocarpos here at the Botanics (supported by a Sibbald fellowship), did manage to obtain some new scanning electron micrographs (SEMs) to show the morphology of the plant’s spores.

Monocarpus specimen collected by Carr, photographed by Chris Cargill

Monocarpus specimen collected by Carr, photographed by Chris Cargill

 

Monocarpus sphaerocarpus spores. D.J.Carr s.n., Australia. A distal view; B proximal view; C fine distal ornamentation; D fine proximal ornamentation at centre; E side view; F fine proximal ornamentation at margin. Scale bars: A, B, E, 10 µm; scale bars: C, D, F, 1 µm. Equatorial diameter of spores between 41.9-51.7 µm.

Monocarpus sphaerocarpus spores. D.J.Carr s.n., Australia. A distal view; B proximal view; C fine distal ornamentation; D fine proximal ornamentation at centre; E side view; F fine proximal ornamentation at margin. Scale bars: A, B, E, 10 µm; scale bars: C, D, F, 1 µm. Equatorial diameter of spores between 41.9-51.7 µm. Images taken by Daniela Schill.

 

Monocarpus heading

 

On Monocarpus – http://stories.rbge.org.uk/archives/17112

Finding Monocarpus, in the Herbarium – http://stories.rbge.org.uk/archives/17146

Finding Monocarpus, in the field – http://stories.rbge.org.uk/archives/17272

Lost before found: Was there more than one species in Monocarpus? – http://stories.rbge.org.uk/archives/17904