Small island but great diversity: thirty six species of Parmotrema (Parmeliaceae, lichenized Ascomycota), including sixteen new species, on Réunion (Mascarenes), with additional data from the Western Indian Ocean Author Masson, Didier 0000-0002-3340-5472 Vertevoye, 2860 route d’Irieu, F- 40390 Saint-Martin-de-Seignanx, France di. masson @ wanadoo. fr; https: // orcid. org / 0000 - 0002 - 3340 - 5472 di.masson@wanadoo.fr Author Magain, Nicolas 0000-0001-5409-9518 Evolution and Conservation Biology, InBios research centre, Sart Tilman B 22, Quartier Vallée 1, Chemin de la vallée 4, B- 4000 Liège, Belgium nicolas. magain @ uliege. be; https: // orcid. org / 0000 - 0001 - 5409 - 9518 nicolas.magain@uliege.be Author Sérusiaux, Emmanuël 0000-0002-3340-5472 Vertevoye, 2860 route d’Irieu, F- 40390 Saint-Martin-de-Seignanx, France di. masson @ wanadoo. fr; https: // orcid. org / 0000 - 0002 - 3340 - 5472 & Evolution and Conservation Biology, InBios research centre, Sart Tilman B 22, Quartier Vallée 1, Chemin de la vallée 4, B- 4000 Liège, Belgium e. serusiaux @ uliege. be; https: // orcid. org / 0000 - 0002 - 0456 - 0131 * Corresponding author & Vertevoye, 2860 route d’Irieu, F- 40390 Saint-Martin-de-Seignanx, France di. masson @ wanadoo. fr; https: // orcid. org / 0000 - 0002 - 3340 - 5472 di.masson@wanadoo.fr text Phytotaxa 2024 2024-06-27 657 1 1 138 http://dx.doi.org/10.11646/phytotaxa.657.1.1 journal article 10.11646/phytotaxa.657.1.1 1179-3163 13217474 Identification key to the Parmotrema species of Réunion Island 1. Medulla P− or P+ faint yellow ......................................................................................................................................................... 2 - Medulla P+ orange ......................................................................................................................................................................... 18 2. Medulla K−, C−, KC− ...................................................................................................................................................................... 3 - At least one of these 3 tests positive ................................................................................................................................................. 5 3. Without vegetative propagules .......................................................................................................................... [ P. appendiculatum ] (lobe margins and apothecia with corniculate laciniae, apothecial disc imperforate, medulla pigmented yellow near apothecia and containing barbatic acid and secalonic acid A; very rare species not recovered on Réunion since the 19 th century) - With vegetative propagules .............................................................................................................................................................. 4 4. Thallus sorediate, lobes without cilia ................................................................................................................... P. praesorediosum (upper surface emaculate, soralia linear marginal when young, becoming labriform and crescent-shaped [ Fig. 34D ], medulla with fatty acids other than protolichesterinic acid; uncommon species on Réunion , at low elevations) - Thallus isidiate and/or laciniate, cilia numerous ............................................................................................................. P. intonsum (shaggy appearance [ Fig. 21E ], upper surface ± distinctly punctiform white-maculate, esorediate, medulla with protolichesterinic acid as major substance; rather common in Reunionese cloud forests) 5. Medulla K+ yellow, C−, KC− (atranorin, fatty acids) .......................................................................................... P. praesorediosum (chemotype with atranorin, in addition to fatty acids, in the medulla) - Other medullary reactions ................................................................................................................................................................ 6 6. Medulla K+ slowly pinkish brick red, C−, KC+ fleeting violet then brick red (lividic acid chemosyndrome) ......... P. reunionicum (lobe margins with conspicuous cilia, upper surface emaculate or faintly punctiform white-maculate, soralia mainly marginal and forming ± rounded clusters with age [ Fig. 36C ]; rare species, only known from a single locality) - Medulla K−, C+ and/or KC+ pink, red, orange, or purple (lividic acid chemosyndrome absent) ................................................... 7 7. Medulla C+ and KC+ pink, red or orange ........................................................................................................................................ 8 - Medulla C−, KC+ purple, pinkish or orange .................................................................................................................................. 12 8. Medulla C+ and KC+ orange .............................................................................................................................. P. aurantioreagens (lobe margins ciliate, upper surface faintly to clearly effigurate white-maculate, soralia marginal at the tip of short laciniae [ Fig. 7D ], medulla with barbatic and 4- O -demethylbarbatic acids as major substances; rare species, only known from a single locality) - Medulla C+ and KC+ pink or red ..................................................................................................................................................... 9 9. Thallus sorediate ............................................................................................................................................................................. 10 - Thallus isidiate ................................................................................................................................................................................ 11 10. Lobes with marginal cilia ................................................................................................................................................... P. cooperi (upper surface faintly effigurate white-maculate, soralia marginal at first, then submarginal on revolute lobe apices [ Fig. 13D ], medulla with lecanoric acid; in leeward Acacia montane forests on Réunion ) - Lobes without cilia ................................................................................................................................................... P. austrosinense (upper surface emaculate or faintly effigurate white-maculate, soralia linear and marginal [ Fig. 8D ], medulla with lecanoric acid; uncommon species on Réunion ) 11. Lower surface at main lobe tips with a brown erhizinate marginal zone 1–3 mm wide, lobes 2–9 mm wide, medulla with evernic acid .......................................................................................................................................................................... P. meiospermum (lobe margins eciliate, upper surface faintly to clearly punctiform white-maculate, isidia marginal and laminal, eciliate and coralloid-branched, medulla with evernic and lecanoric acids; rare species) - Lower surface at main lobe tips with a brown erhizinate marginal zone 4–15 mm wide, lobes 5–20 mm wide, medulla without evernic acid ..................................................................................................................................................................... P. tinctorum (lobe margins eciliate, upper surface emaculate to faintly white-maculate, isidia marginal and laminal, eciliate, simple to coralloid-branched, medulla with lecanoric acid; common species on Réunion , from sea level to the upper limit of cloud forests) 12. Thallus without vegetative propagules ........................................................................................................................................... 13 - Thallus with isidia or soralia .......................................................................................................................................................... 14 13. Pycnidia conspicuous, marginal, verruciform ( Fig. 43B ); thalline exciple smooth to rugose .................................... [ P. thomsonii ] (lobe margins ciliate, upper surface distinctly white-maculate, apothecial disc perforate, medulla with alectoronic and α-collatolic acids; very rare species not recovered on Réunion since the 19 th century) - Pycnidia inconspicuous, immersed; thalline exciple with abundant and well-developed isidioid protuberances ( Fig. 26C ) ............ .............................................................................................................................................................................................. P. mirum (lobe margins ciliate but cilia sometimes rare, upper surface emaculate, apothecial disc perforate or imperforate, medulla with alectoronic acid (constant) with or without α-collatolic acid; uncommon species on Réunion ) 14. Thallus sorediate, without isidia ...................................................................................................................... P. cf. negrosorientale (lobe margins ciliate, upper surface faintly to clearly white-maculate, soralia generally terminal at the tip of laciniae [ Fig. 27D ], never laminal, medulla with alectoronic and α-collatolic acids as major substances; uncommon species on Réunion ) - Thallus isidiate, with or without soredia ........................................................................................................................................ 15 15. Medulla with norlobaridone .............................................................................................................................................. P. mezierii (lobe margins ciliate, upper surface ± distinctly punctiform white-maculate, isidia coralloid, often ciliate [ Fig. 25C & 25D ], medulla with norlobaridone and protolichesterinic acid as major substances; uncommon species on Réunion ) - Medulla without norlobaridone ...................................................................................................................................................... 16 16. Apothecia present, usually numerous; thalline exciple with abundant and well-developed isidioid protuberances .......... P. mirum (morphotype with laminal isidia [ Fig. 26D ]) - Apothecia absent ............................................................................................................................................................................ 17 17. Isidia only present, upper cortex not fragile, medulla without α-collatolic acid ........................................................... P. crossotum (lobe margins conspicuously ciliate, upper surface emaculate or faintly white-maculate, isidia mainly marginal, often ciliate [ Fig. 17C & 17D ], medulla with alectoronic acid; uncommon species on Réunion , in montane rainforests) - Isidia and soredia present, upper cortex fragile, medulla with α-collatolic acid .............................................................. P. mellissii (lobe margins conspicuously ciliate, upper surface emaculate or faintly white-maculate, isidia mainly marginal, often ciliate, soon becoming sorediate [ Fig. 24D ], medulla with alectoronic and α-collatolic acids; rare species on Réunion , in cloud forests) 18. Thallus without vegetative propagules ........................................................................................................................................... 19 - Thallus with vegetative propagules ................................................................................................................................................ 21 19. Medulla K+ yellow then dark red, lower surface often with rhizines to the margins, mean ascospore length <16 µm .................... ........................................................................................................................................................................................... P. cetratum (lobe margins ciliate, upper surface reticulate white-maculate, apothecial disc perforate, medulla with salazinic and consalazinic acids; very rare species on Réunion ) - Medulla K−, lower surface with a broad erhizinate marginal zone, mean ascospore length> 16 µm .......................................... 20 20. Lobes ciliate, medulla UV+ blue-white, KC+ fleeting purple pink, then pink-orange, mean ascospore length> 22 µm .................. .......................................................................................................................................................................................... P. nemorum (upper surface emaculate, rarely faintly white-maculate, medulla white, sometimes tinged with a reddish purple pigment, apothecial disc imperforate, amphithecium and stipe with ± prominent veins and coarse isidioid protuberances [ Fig. 28C ], medulla with alectoronic, protocetraric and protolichesterinic acids as major substances; uncommon in secondary lowland rainforests) - Lobes eciliate, medulla UV−, KC+ pink, mean ascospore length <20 µm .................................................................. P. odontatum (upper surface faintly to clearly effigurate white-maculate, medulla white throughout, apothecial disc imperforate, amphithecium smooth [ Fig. 31D ], medulla with protocetraric acid; uncommon at low elevations) 21. Thallus with isidia, without soredia ................................................................................................................................................ 22 - Thallus with soralia, with or without isidia .................................................................................................................................... 29 22. Medulla K+ yellow persistent, KC− (with stictic acid) .................................................................................................................. 23 - Other medullary reactions (stictic acid absent) .............................................................................................................................. 25 23. With conspicuous laciniae (up to 10 mm long), branched and easily shed ............................................................... P. nephophilum (lobe margins ciliate but cilia sometimes rare, upper surface faintly to clearly white-maculate, marginal and submarginal isidia that mostly develop early into phyllidia and branched laciniae [ Fig. 29E ]; fairly common species on Réunion , in montane and submontane rainforests) - Without or with occasional short (up to 1.5 mm long) laciniae ..................................................................................................... 24 24. Average thickness of the cupular proper exciple <50 µm ( Fig. 30C ) ............................................................................. P. crinitum (lobe margins ciliate, upper surface faintly to clearly white-maculate, isidia marginal and laminal, granular to coralloid, often ciliate [ Fig. 14E ]; common species on Réunion , from submontane to subalpine belts) - Average thickness of the cupular proper exciple> 55 µm .............................................................................................. P. occultum (phenotypically similar to P. crinitum , but differs by the greater thickness of the cupular proper exciple [ Fig. 30C ] and the ITS sequence; rare species on Réunion , in cloud forests) 25. Medulla K+ yellow then red (with salazinic acid) .................................................................................................... P. subisidiosum (lobe margins ciliate but cilia sometimes rare, upper surface conspicuously reticulate white-maculate [ Fig. 40D ], isidia mainly marginal and submarginal, coralloid; uncommon species on Réunion , in submontane and montane rainforests) - Other medullary reactions (salazinic acid absent) .......................................................................................................................... 26 26. Medulla UV+ blue-white, KC+ fleeting purple pink, then pink-orange (with alectoronic acid) .................................... P. nemorum (morphotype with some laminal or submarginal isidia [ Fig. 28D ]) - Medulla UV–, KC– or KC+ pinkish (alectoronic acid absent) ...................................................................................................... 27 27. Medulla K−, KC+ pinkish (with protocetraric acid) ............................................................................................... P. subcorallinum (lobe margins ciliate, upper surface emaculate or faintly white-maculate, isidia mainly marginal and submarginal, coralloid or arbuscular, very often ciliate [ Fig. 38D ], medulla with protocetraric and protolichesterinic acids; uncommon in the windward part of Réunion , in the submontane belt) - Medulla K+ slowly orange brown, KC− (with succinprotocetraric acid) ...................................................................................... 28 28. Thallus moderately adnate, lobes 2–13 mm wide ................................................................................................... P. mascarenense (lobe margins eciliate or irregularly ciliate, upper surface effigurate white-maculate, isidia marginal to laminal, simple to coralloid, occasionally ciliate [ Fig. 22C ], medulla with succinprotocetraric and fumarprotocetraric acids; fairly common on Réunion ) - Thallus adnate to tightly adnate, lobes 1–4 mm wide ....................................................................................................... P. orarium (looks more like a Canoparmelia s. lat. than a Parmotrema [ Fig. 32D ], lobe margins eciliate to weakly ciliate, upper surface effigurate white-maculate, isidia marginal to laminal, simple or ± branched, rarely ciliate, usually quickly sorediate [ Fig. 32E ], medulla with succinprotocetraric and fumarprotocetraric acids; in the southeastern part of Réunion , near the coast) 29. Medulla K+ yellow persistent, KC− (with stictic acid) ............................................................................................. P. nephophilum (sorediate morphotype, Fig. 29F ) - Other medullary reactions (stictic acid absent) .............................................................................................................................. 30 30. Medulla K+ yellow then red (with salazinic acid) ......................................................................................................................... 31 - Other medullary reactions (salazinic acid absent) .......................................................................................................................... 33 31. Upper surface emaculate, rarely faintly punctiform maculate; lower surface with a broad erhizinate marginal zone ....................... ....................................................................................................................................................................................... P. cristiferum (lobe margins eciliate to clearly ciliate, soralia mainly marginal, linear to labriform [ Fig. 16D ]; uncommon in the windward part of Réunion , at low elevation) - Upper surface reticulate maculate; lower surface often with rhizines and papillae to the margins ............................................... 32 32. Marginal zone of the lower surface of sorediate lobes dark brown or black ....................................................... P. reticulatum aggr. (lobe margins ciliate, soralia mainly capitate at the tips of laciniae or submarginal ± linear at the apex of revolute lobes [ Fig. 35F ]; common and widespread on Réunion ) - Marginal zone of the lower surface of sorediate lobes often white or white mottled .......................................... P. cf. clavuliferum (lobe margins ciliate, soralia mainly capitate at the tips of laciniae [ Fig. 12D ]; uncommon species on Réunion ) 33. Medulla K+ slowly orange brown, KC− (with succinprotocetraric acid) ...................................................................................... 34 - Medulla K− or K± yellowish, KC+ pinkish (with protocetraric acid) ........................................................................................... 35 34. Thallus adnate to tightly adnate, lobes 1–4 mm wide, isidia present (at least in the early stages of development) ........ P . orarium (looks more like a Canoparmelia s. lat. than a Parmotrema [ Fig. 32D ], lobe margins eciliate to weakly ciliate, upper surface effigurate white-maculate, isidia marginal to laminal, soralia marginal to laminal [ Fig. 32F ], often originating from rapid decay of young isidia, more rarely from pustules, occasionally orbicular or subcapitate, medulla with succinprotocetraric and fumarprotocetraric acids; in the southeastern part of Réunion , near the coast) - Thallus moderately adnate, lobes 3–8 mm wide, isidia totally absent ............................................................. P. paramascarenense (lobe margins eciliate to irregularly ciliate, upper surface effigurate white-maculate, soralia terminal at the apex of tiny laciniae when young, then labriform or subcapitate, finally spreading submarginally on revolute lobes [ Fig. 33D ], medulla with succinprotocetraric and fumarprotocetraric acids; rare species on Réunion ) 35. Medulla with echinocarpic acid ...................................................................................................................................... P. dilatatum (lobe margins eciliate or very sparsely ciliate, upper surface emaculate or faintly punctiform white-maculate, soralia marginal, linear to labriform when young, then subcapitate and ± coalescing on arbuscular rising structures [ Fig. 19D ], medulla with protocetraric and echinocarpic acids as major substances; very rare species on Réunion ) - Medulla without echinocarpic acid ................................................................................................................................................ 36 36. Medulla without protolichesterinic acid ......................................................................................................................................... 37 - Medulla with protolichesterinic acid .............................................................................................................................................. 38 37. Medulla UV+, with alectoronic acid ......................................................................................................................... P. cf. deflectens (lobe margins conspicuously ciliate, upper surface emaculate or faintly punctiform white-maculate, upper cortex fragile, flaking, soralia mainly marginal, linear to labriform [ Fig. 18C ], medulla with protocetraric and alectoronic acids as major substances; very rare species on Réunion ) - Medulla UV−, alectoronic acid absent ............................................................................................................................ P. robustum (lobe margins eciliate to ± irregularly ciliate, upper surface emaculate to punctiform white-maculate, soralia marginal at the apex of laciniae when young, then labriform or subcapitate and ± coalescing [ Fig. 37D ], medulla with protocetraric acid as major substance; common species on Réunion , mainly in montane rainforests) 38. Medulla UV+, with alectoronic acid ........................................................................................................................ P. subdeflectens (lobe margins conspicuously ciliate, upper surface emaculate or faintly punctiform white-maculate, soralia either terminal labriform or subcapitate on very short laciniae [ Fig. 39C ], or marginal and ± labriform [ Fig. 39D ], medulla with protocetraric, alectoronic and protolichesterinic acids as major substances; rare species on Réunion , in leeward submontane forests) - Medulla UV−, without alectoronic acid ......................................................................................................................................... 39 39. Soralia submarginal, often pustulate ( Fig. 42C ), never marginal linear; upper cortex fragile, here and there flaking ( Fig. 42D ); soredia granulose (mean diameter> 50 µm) ............................................................................................................... P. udisilvestre (species of the P. subarnoldii group, lobe margins conspicuously ciliate, upper surface emaculate or faintly punctiform white-maculate, medulla with protocetraric and protolichesterinic acids as major substances; uncommon in the windward part of Réunion , in the submontane belt) - Soralia marginal, linear discontinuous, then ± labriform ( Fig. 9D & 20D ), or subcapitate at the tip of very short laciniae ( Fig. 20C ), never pustulate; upper cortex not fragile; soredia subgranulose (mean diameter <45 µm) .......................................................... 40 40. Marginal cilia short (mean length < 3.5 mm ) .................................................................................................... P. brachyblepharum - Marginal cilia long (mean length> 3.5 mm ) ............................................................................................................... P. eleonomum (two species of the P. subarnoldii group, lobe margins conspicuously ciliate, upper surface emaculate or faintly punctiform white-maculate, medulla with protocetraric and protolichesterinic acids as major substances; rare species on Réunion )