Lichens of Wales

Heterodermia leucomela

synonyms

Heterodermia leucomelos

Common Name(s)

Cilate Strap-lichen / Y cen Rhuban Blewog

Description & Identification

Heterodermia leucomela is a rather inconspicuous fruticose lichen which forms loose tufts up to 10cm across.  The grey-white thallus is highly dichotomously branched, the branches being between 3-5mm in width. The margins of the branches are lined with many black  cilia or "whiskers" up to 5mm long. The lower surface ihas a broad, white, slightly sunken channel along the centre, which appears slightly rough under a lens due to the lack of a cortex here. This is in contrast to the smooth raised margins on each side. Apothecia have not been observed in British material.

Photo: Alan Hale

Similar Species

H. leucomela can superficially appear similar to several of the shrubby Cladonia species, and to some species of Physcia that are similar in colour and have dark cilia. However, on closer inspection these are all quite distinct. It is hard to confuse this species with any other British taxon.

Habitats

Amost exclusively found on exposed coastal cliffs in short turf on thin soil, or more rarely on low rock outcrops. It is usually associated with other lichens, and bryophytes, which it often uses to attach itself to. It has rarely in the past been found on trees (the Flora says wayside trees, Bryan Edwards says "trees in ancient woodland or parkland").

Distribution

Heterodermia leucomela is widespread in tropics and sub-tropics, reaching it's northern limit in Britain. It has a southern-oceanic distribution in Britain and Ireland, being restricted to south-west England, West Wales and south-west Ireland.

H. leucomela is currently known from 5 sites in Wales, in 5 different hectads. Historically it was first recorded in Wales in 1895 by J.E. Griffiths who found it near Rhoscolyn on the west coast of Anglesey. In more recent times there are records from Bardsey and near Aberdaron on the Lleyn Peninsula. A survey in 2001 rediscovered the species on Anglesey and found healthy populations on the tip of the Lleyn Peninsula (Edwards, 2002). The Bardsey populations are part of a long term monitoring project. In 2004 the species was recorded for the first time in Pembrokeshire at St David’s Head, and in 2005 it was found in some quantity further south at Stackpole Head. It's Anglesey sites are the northenmost in Europe.

Records from Wales
Location Grid Reference Year Last Rec Recorder SSSI
Anglesey: Rhoscolyn Head SH 2574 7552 2002 B. Edwards Yes
Anglesey: Penrhosfeilw Common, Penrhyn Mawr SH 2118 7959 2002 B. Edwards Yes
Caernarfon: St Mary's Well, Lleyn SH 1387 2521 2003 A.D. Hale & T. Dines Yes
Caernarfon: Trwyn y Gwyddel SH 1399 2506 2003 A.D. Hale & T. Dines Yes
Caernarfon: Slopes of Mynydd y Gwyddel SH 1413 2490 2003 A.D. Hale & T. Dines Yes
Caernarfon: Ynys Enlli, above Pen Cristin SH 1218 2122 1992 A. Fletcher Yes
Caernarfon: Ynys Enlli, southern tip, western side SH 110 204 2001 A. Fletcher Yes
Caernarfon: Ynys Enlli, southern tip, eastern side SH 114 207 2001 A. Fletcher Yes
Caernarfon: Ynys Enlli, southern tip, western side SH 12 21 2001 A. Fletcher Yes
Pembroke: St. David's Head SM 724 280 2005 A.D. Hale & R.G. Woods Yes
Pembroke: Saddle Point, Broadhaven SR 981 940 2005 R.G. Woods Yes
 

 

Threats and Status

 H. leucomela has always been a rare species in Britain. Numbers of populations in Wales have actually increase in recent years, probably due to increased awareness of the species and effort focused on looking for populations. It is listed on Scheduel 8 of the Wildlife and Countryside Act 1981 as being in need of special protection, and is on both the UKBap and Wales Section 42 lists.

Proposed Actions
  UKBAP Signposting Actions:
1.

 

Monitor the habitat and species (along with Pseudocyphellaria aurata with which it grows*), at a sub-set of extant sites, at least every 6 years, to ensure that grazing and shrub control management maintains open nature of maritime heathland and grassland and modify accordingly.
2. Encourage survey for this species and incorporate new sites into the monitoring and management framework.

* Not in Wales.

Hectad Distribution in Wales/Link to NBN Gateway Map

NBN Taxon Key
NHMSYS0001484074
References

Edwards, B. (2002). The current status of Heterodermia leucomela (L.) Poelt in Wales. Plantlife Report
Hale, A.D. (2003). Heterodermia leucomela sites on the Lleyn Peninsula. CCW internal note (with location photographs).
Hale, A.D., Sutton, M. & Woods, R.G. (2005). Heterodermia leucomela (Ciliate strap lichen) at St. David's Head, Pembrokeshire. CCW Staff Report.
Rose, F. (1998) Heterodermia leucomelos. Species account 558/1998 in the third fascicle of the Lichen Atlas of the British Isles produced by the British Lichen Society, London.