Nov 162016
 
Telaranea tetradactyla, photographed by David Long (Long 37778)

Telaranea tetradactyla at Benmore, photographed by David Long (Long 37778)

Murphy’s threadwort (Telaranea murphyae) has had a singular position in the British flora. The species was described by renowned bryologist Jean Paton in 1965, from plants collected in the south of England. It’s a tiny leafy liverwort that is found in only four locations, at Tresco and St Mary’s on the Isles of Scilly, Branksome Chine, Poole in Dorset and Alum Chine, Bournemouth. Murphy’s threadwort has always been known to be an alien species in our flora, and yet because it’s never been found elsewhere, the sole responsibility for conserving the species lay with the UK. Being non-native, however, it was not considered a priority for UK Biodiversity Action Plans.

Telaranea tetradactyla from the RBGE fern house, photographed by Lynsey Wilson

Telaranea tetradactyla from the RBGE fern house, growing with Conocephalum conicum; photographed by Lynsey Wilson

Using DNA sequence data from the plant, and comparing it to sequences from other related species, we showed that genetically, the English plants are the same species as a New Zealand plant, Long’s threadwort (Telaranea tetradactyla, synonmy Telaranea longii). Long’s threadwort was already known from several locations in the UK, including inside the fernhouse at RBG Edinburgh, and near the fernery in Benmore. These habitats are not entirely coincidental – the Victorian craze for ferns saw many gardens import living tree ferns from countries such as Australia and New Zealand, with many smaller plants hitching a ride along on their trunks. Today, conscious of plant health issues and the potential transport of pathogens, new plant living collections have to spend time in quarantine before being planted out; past gardeners were less careful, and some of these hitchhikers have subsequently escaped into the local landscape.

Telaranea tetradactyla from the RBGE fern house, photographed by Lynsey Wilson

Telaranea tetradactyla from the RBGE fern house, photographed by Lynsey Wilson

Sinking our UK Murphy’s threadwort plants into the New Zealand species means that any conservation requirements now rest instead with New Zealand, although we can continue to enjoy seeing this diminutive mat-forming liverwort in its select few UK locations.

 

 

Key reference: Porley, R.D., 2013, England’s Rare Mosses and Liverworts. Princeton University Press.

 

 

Villarreal et al. 2014, Journal of Bryology 36(3): 191-199

Villarreal et al. 2014, Journal of Bryology 36(3): 191-199

 

Sep 062016
 

University of Edinburgh/RBGE student David Bell, studying for the Masters degree in the Biodiversity and Taxonomy of Plants; thesis submitted August 2009.

Supervisors: Dr David Long and Dr Michelle Hart.

 

David used plastid DNA barcode markers rbcL (from 34 accessions) and psbA-trnH (from 36 accessions) to look at the four species of Herbertus in Europe, H. aduncus subsp hutchinsiae (British Isles, Norway and Faroes), H. stramineus (British Isles, Norway and Faroes), H. borealis (Scotland and Norway) and H. sendtneri (European Alps).

In addition to the four recognised taxa, David’s study identified a fifth species, later named as H. norenus, that occurs in Norway and the Shetland Isles.

A paper based on David’s MSc thesis work was published in Molecular Ecology Resources in 2012.

Herbertus norenus, photographed by David Long

Mixed sward including Herbertus norenus, photographed in Shetland by David Long

 

Bell et al. 2012, MER

 

 

Other student projects at the Gardens:

Student projects at RBGE: DNA barcoding British liverworts: Lophocolea

Student projects at RBGE: Barcoding British Liverworts: Plagiochila (Dumort.) Dumort.

Student projects at RBGE: Barcoding British Liverworts: Metzgeria

Aug 122016
 

University of Edinburgh/RBGE student Lucy Reed, studying for the Masters degree in the Biodiversity and Taxonomy of Plants; thesis submitted August 2011.

Supervisors: Dr David Long, Dr Michelle Hart and David Bell.

The leafy liverwort genus Plagiochila is known for high levels of infraspecific morphological variation and blurred species boundaries. To address this, Lucy sequenced the plastid rbcL and matK plant barcode loci, along with the plastid psbA-trnH spacer, and the nuclear ITS region, assessing the genetic distinctiveness of four British taxa of Plagiochila sect. Plagiochila (Plagiochilaceae), as part of our wider project to DNA barcode the British bryophyte flora. The molecular matrix consisted of sequences from 14 accessions of P. asplenioides, 15 accessions of P. britannica, 3 accessions of P. norvegica, 7 accessions of P. porelloides, and two accessions that were not confidently identified to any species. Most of the samples came from across the UK, although plants from Ireland, Italy, Norway, Sweden and Switzerland were also included. Several outgroups were also available – 5 accessions of P. carringtonii, 3 accessions of P. heterophylla, 3 accessions of P. bifaria, 4 accessions of P. punctata, 5 accessions of P. spinulosa, and 2 accessions of P. exigua.

Lucy also undertook a herbarium study, to revise morphological characters for the taxa and correlate them with the molecular results. She scored a range of non-reproductive characters, using 13 of these for Principal Component Analysis (PCA). Because the plants are dioicous, using reproductive characters would have required male and female plants; furthermore, sporophytes are rarely collected, and not known at all for P. norvegica.

Using the three plastid markers rbcL, matK and psbA-trnH, Lucy resolved two species groups – a P. asplenioides-P. brittanica group, and a P. porelloides-P. norvegica group. The branch lengths for tree produced from the regions that she sequenced were, however, short and statistical support was absent, so the markers could not reliably be used to distinguish P. asplenioides from P. britannica, or P. porelloides from P. norvegica. On the other hand, only one of the 7 P. britannica accessions that was successfully sequenced for ITS resolved with P. asplenioides; the rest resolved with P. porelloides. Again, branch lengths within clades were too short to confidently distinguish species.

Species summaries:

  1. Plagiochila asplenioides: Lucy considered this species to be relatively easy to distinguish, because of its larger and more robust habit and larger leaves. There was, however, potential for confusion when dealing with smaller plants. However, in combination with DNA sequence data from the four loci, most individuals could be identified.
  2. Plagiochila porelloides: Lucy found that molecular sequence data could clearly separate this species from P. asplenioides and P. britannica. However, P. norvegica, which is separated from P. porelloides mainly by leaf apex shape and leaf margin tooth size, was not distinguishable using molecular data, and may be better either sunk, or reduced to a variety of P. porelloides, which already contains a lot of morphological variability.
  3. Plagiochila britannica: Lucy proposed that discrepancies between the plastid and nuclear gene topologies could be down to a hybrid origin for this species, fitting the diploid (n=18) status of the plant, as opposed to the haploid (n=9) status of both P. asplenioides and P. porelloides (key references: Paton, 1979; Newton, 1986).
  4. Plagiochila norvegica: originally described from Norway, this species has subsequently been found in Sweden and in England. Lucy included samples from England and Norway, but found no molecular evidence that they were distinct from P. porelloides, while the morphological differences that separate the taxa could be related to environmental conditions (Paton 1999).
Plagiochila asplenioides vice county 79 Long 8476

Plagiochila asplenioides vice county 79, Long 8476; photographed by David Long

Plagiochila britannica vice county 50, Long 37707

Plagiochila britannica vice county 50, Long 37707; photographed by David Long

 

Related Posts

Student projects at RBGE: DNA barcoding British liverworts: Lophocolea

Student projects at RBGE: Barcoding British Liverworts: Plagiochila (Dumort.) Dumort.

Student projects at RBGE: Barcoding British Liverworts: Metzgeria

Student projects at RBGE: DNA barcoding of the leafy liverwort genus Herbertus Gray in Europe and a review of the taxonomic status of Herbertus borealis Crundw.

Aug 122016
 

University of Edinburgh Biotechnology student Kenneth McKinlay’s 4th year honours project, 2013. Supervisors: Dr David Long, Dr Laura Forrest

David Long and Kenneth checking out the Lophocolea on a decaying log in the Scottish Borders

David Long and Kenneth check out Lophocolea on a decaying log in the Scottish Borders

Kenneth barcoded all six species of British Lophocolea, L. bidentata, L. bispinosa, L. brookwoodiana, L. fragrans, L. heterophylla and L. semiteres, attempting to get data from three plastid regions (rbcL, matK, psbA-trnH) and one nuclear region (ITS2). The data generated from the rbcL and psbA-trnH regions was effective in discriminating between all the species sampled; however useful data were not obtained from matK or ITS2.

Genetic markers:

1. rbcL: bidirectional sequence data was generated for 38 accessions.

2. matK: amplification was not successful with the primer sets used (LivF1A, LivR1A).

3. psbA-trnH: bidirectional sequence data was generated for 40 accessions.

4. ITS2: although PCR amplification was successful for 35 accessions, the low quality of many of the sequences generated, and the presence of clear heterozygous positions in sequence data from some accessions, made this data set problematic to analyse, so it was excluded from the study.

Lophocolea bispinosa vice county 98 Long 4725

Lophocolea bispinosa vice county 98, Long 4725; photographed by David Long

Lophocolea semiteres vice county 98, Long 0578

Lophocolea semiteres vice county 98, Long 0578; photographed by David Long

 

 

 

 

 

 

 

 

Species and trees:

Distance tree generated using rbcL barcode sequence data for UK Lophocolea accessions

Distance tree generated using rbcL barcode sequence data for Lophocolea accessions, rooted on Chiloscyphus

L. fragrans – all accessions were genetically uniform, forming a monophyletic group.

L. heterophylla – although there was a little genetic variation, again, accessions of this species formed a distinct clade for both rbcL and psbA-trnH.

L. semiteres & L. brookwoodiana – these formed a single clade. All the accessions of L. semiteres (including material from the UK and Belgium) were genetically uniform, while two different genotypes were observed for L. brookwoodiana. While L. semiteres is known to be an introduced species in the UK, it’s possible that the three different genotypes in this clade represent separate introductions.

L. bispinosa – species formed a single genetically uniform group; this nests within a L. bidentata grade.

L. bidentata – accessions of this widespread and common species formed a grade, with three genetically distinct groups. One of these groups may represent L. cuspidata, a species that was sunk into L. bidentata by Bates and Walby in 1991, due to a lack of consistently distinguishing morphological characters. The results of this study suggest that a recircumscription of L. bidentata, “probably the commonest leafy liverwort in the British Isles” (Hodgetts, 2010), is required.

 

Related Posts

Student projects at RBGE: DNA barcoding British liverworts: Lophocolea

Student projects at RBGE: Barcoding British Liverworts: Plagiochila (Dumort.) Dumort.

Student projects at RBGE: Barcoding British Liverworts: Metzgeria

Student projects at RBGE: DNA barcoding of the leafy liverwort genus Herbertus Gray in Europe and a review of the taxonomic status of Herbertus borealis Crundw.