Cladonia symphycarpa Can Not be Identified by Spot Tests

Cadonia symphycarpa is a rare, normally sterile, Cladonia forming squamule mats in open vegetation on calcareous soils from the coast to montane habitats. It has been characterised in Britain by a K+ yellow to red spot test with crystals forming under the microscope (norstictic acid), although many other chemotypes occur elsewhere. Burgaz et al (2019) lists seven! of which four have norstictic acid and atranorin along with other chemicals while three others have atranorin with an assortment of other lichen acids, so giving a K+ yellow spot test that is also K(UV) dry+ bright yellow. So the presence of a norstictic acid spot test can not be relied upon.

I have a specimen I collected from limestone soil, CG1 by the coast, Broad Haven, Stackpole, VC45, SR980 942, 31/8/1995, K+ yellow, K/UV (dry)+ bright yellow and Pd+ orange-red, which was determined by Peter James as Cladonia firma (which has these spot tests), but the specimen has largely white squamule undersides and other typical features of C. symphycarpa.

Recently doing some management advice work on The Lizard more generous specimens were found in coastal serpentine rock heath, which appeared to be Cladonia symphycarpa but were K+ yellow in the field. I comparing the three specimens collected with typical K+ yellow to red C. symphycarpa and Cladonia firma specimens (the latter from a location where C. firma had been confirmed by sequencing).This comparison confirmed these were not C. firma but another chemotype of C. symphycarpa.

The spot tests match chemotype V of Burgaz et al (2019) (Atranorin,fumarprotocetraric and rangiformic acids, and zeorin (inconstant)). As Burgaz et al (2019) and Association Française de Lichénologie describe C. firma as preferring substrates with an acid or subneutral pH and non-calcarious soils, it is possible that K+ yellow and Pd+ orange-red C. symphycarpa has been collected in Britain previously from coastal limestone and calcareous dunes but misidentified as C. firma. At the Lizard heaths, true C. firma did occur, but further inland on more acidic heaths.

Cladonia firma https://britishlichensociety.org.uk/resources/species-accounts/cladonia-firma” class=”bbcode_url”>https://britishlichensociety.org.uk/resources/species-accounts/cladonia-firma has darker brown (dry) to darker green (wet) squamules which are less lanceolate, with the undersides strongly grey-brown at the base and much more strongly tomentose. In contrast, C. symphycarpa https://britishlichensociety.org.uk/resources/species-accounts/cladonia-symphycarpa” class=”bbcode_url”>https://britishlichensociety.org.uk/resources/species-accounts/cladonia-symphycarpa has often more elongated squamules with pale grey-green upper surface, with the lower surface starkly white but the edges sometimes darkened with violet tones but white at the base and are more weekly tomentose underside giving a flocked effect.

Cladonia symphycarpa from The Lizard:

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A scan of K+ yellow, K/UV (dry)+ bright yellow and Pd+ orange-red Cladonia symphycarpa specimen from the Lizard.

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A close up of a Cladonia symphycarpa squamule underside showing the lightly flocked underside and violet-brown tinges at the upper edges.

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A close up of a Cladonia symphycarpa squamule upper surface showing brown pruinose tips.

Cladonia firma:

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Cladonia firma with podetia, Beaulieu Heath, New Forest

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Cladonia firma, showing the tometose underside of squamules coloured grey brown tinged with violet, on ironstone exposed in hollow way, heath, Rock Hills, New Forest

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Cladonia firma, underside of squamule, Beaulieu Heath, New Forest

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Cladonia firma, showing the distinctive pruina on the squamule tips, characteristic of this species, Cladonia symphycarpa and Cladonia subcervicornis, White Moor, New Forest © Andy M Cross

Other possible C. symphycarpa K+ yellow chemotypes are Chemotype III: Pd+ yellow, K+ yellow, C–, KC–, UV–. Atranorin and psoromic acid or Chemotype IV: Pd–, K+ yellow, C–, KC–, UV–. Atranorin, rangiformic acid and zeorin (inconstant).

Neil

Reference

Burgaz, A.R., Ahti, T. & Pino-Bodas, R. (2020) Mediterranean Cladoniaceae. Madrid: Spanish Lichen Society.