Parmotrema orarium D.M. Masson, Magain & Sérus., 2024

Masson, Didier, Magain, Nicolas & Sérusiaux, Emmanuël, 2024, 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, Phytotaxa 657 (1), pp. 1-138 : 83-85

Parmotrema orarium D.M. Masson, Magain & Sérus. , sp. nov. MycoBank no. 853876

Diagnosis. Characterized by a medium-sized, adnate thallus, the sublinear to subirregular narrow lobes (1–4 mm wide) with margins generally eciliate, the maculate upper surface with isidia and/or soredia, the medium-sized ascospores (16–24 × 7–10.5 µm), the short (4–5 µm) bacilliform conidia, and the presence of succinprotocetraric and fumarprotocetraric acids in the medulla.

Holotype:— FRANCE. Réunion: Sainte-Rose, les Cascades, elev. 30 m, 21°11’07”S, 55°49’57”E, in coastal Pandanus thicket, on cliff top, on bark of branch of Pandanus utilis , 13 August 2013, D. Masson 974.4219 (MNHN-PC-PC0088079; isotype: LG).

GenBank accession numbers: ITS ( PP 840561), mtSSU ( PP 842533), LSU ( PP 836528)

( Fig. 32 )

Thallus foliose, adnate to tightly adnate ( Fig. 32D ), membranaceous, up to 6.5 × 11 cm. Lobes sublinear to subirregular, contiguous to imbricate, 1–4 mm wide, plane to ± concave; margins crenate, isidiate-dentate to shortly laciniate, occasionally lobulate, sometimes with a narrow brown or black rim, eciliate to weakly ciliate ( Fig. 32D ). Cilia black, generally absent, occasionally present at lobe margins, mostly in lobe axils, or on some isidia, very rarely laminal, simple, ca. 0.03–0.05 mm in diameter at the base, up to 0.7 mm long. Upper surface pale greenish grey, shiny towards lobe apices, duller centrally, ± distinctly effigurate white-maculate, smooth to rugose, ± cracked, especially in old parts; isidiate, sorediate, pustulate, lacking schizidia, true dactyls. Isidia present in all thalli examined but sometimes only in the early stages of development, at the margin of lobes and apices of laciniae, often also submarginal and ± laminal; granular or subcylindrical, sometimes ± tapering, very rarely dactyliform (one thallus), rarely ciliate, simple or ± branched; usually quickly sorediate ( Fig. 32E ), very rarely developing into phyllidia; up to 1 mm high. Soralia present in 34 of the 37 thalli examined, marginal, submarginal and ± laminal, often originating from rapid decay of young isidia, more rarely from pustules, occasionally orbicular or subcapitate. Soredia subgranulose to granulose, (35)– 51.0 –(80) µm in diameter (n = 90, from 3 specimens, SD = 9.4 µm). Pustules submarginal, or subapical on lateral lobes, soon bursting into soredia ( Fig. 32F ). Laciniae occasional, marginal, short, unbranched or sparsely branched, up to 1.5 mm long, 0.3–0.6 mm wide, apices often isidiate or sorediate. Lobules occasional, marginal, up to 2 × 2.5 mm. Medulla white throughout. Lower surface smooth to rugulose, shiny, black to the margin, or with a buff or chestnut brown, erhizinate marginal zone (ca. 0.5–2 mm wide) at main lobe tips. Rhizines numerous, ± evenly distributed, black, simple, rarely once branched, up to 0.8 mm long. Apothecia rare (fertile thalli found in 2 localities out of 18), laminal and submarginal, cupuliform, up to 1.6 mm in diameter, sessile; disc imperforate, orange brown, concave, shiny, smooth; margin crenate-isidiate, amphithecium early isidiate; hymenium s. lat. (54)– 65.6 –(80) µm high, hyaline layer (6)– 6.4 –(7) µm high, intermediate layer (7)– 10.0 –(12) µm high, cortex-like basal layer (12)– 15.4 –(18) µm high. Ascospores 8 per ascus, simple, colourless, ellipsoidal, sometimes slightly reniform, 16– 19.7 –24 × 7– 8.7 –10.5 µm, Q = (1.78)– 2.29 –(2.67), epispore (1)– 1.4 –(2) µm thick, n = 30, from 1 thallus. Pycnidia fairly rare, mostly submarginal on lobes, but sometimes also on isidia, black. Conidia bacilliform (3)4–5(6) × ca. 1 µm. Upper cortex palisade plectenchymatous, (12)– 15.8 –(19) µm thick. Algal layer ± continuous, (12)– 15.9 –(20) µm thick. Medulla (59)– 69.4 –(78) µm thick. Lower cortex prosoplectenchymatous, (10)– 10.9– (13) µm thick.

Chemistry:— Spot tests and fluorescence: upper cortex K+ yellow, UV−; medulla K+ slowly orange brown, C−, KC−, P+ orange, UV−. Secondary metabolites ( TLC): upper cortex with atranorin and chloroatranorin; medulla with succinprotocetraric acid (major), fumarprotocetraric acid (minor/trace), virensic acid (trace), unidentified substance (grey; Rf classes:A3, B5, C 5; trace), ± gyrophoric acid (trace).

Etymology: From the Latin orarius: of the coast; in reference to the coastal distribution of the species.

Geographical distribution:—Currently known only from Réunion, where it was found at low elevations (10– 590 m) at 18 localities, in 14 UTM 1× 1 km grid cells (or 10 UTM 2× 2 km grid cells, Fig. 32A ). All known occurrences are coastal, or close to the coast, and located in the southeastern part of the island.

Ecology:—This lichen typically grows on smooth bark, especially of Pandanus utilis , more occasionally of P. sylvestris Bory or Ficus sp. , on trunks as well as branches. The main phorophyte (95% of the occurrences), the common screw-pine P. utilis , is a tree native and endemic to the Mascarenes, which is now introduced into many tropical regions ( Bosser & Guého 2003). In Réunion, it forms adlittoral woodlands that are either natural or the result of plantations ( Delbosc et al. 2011). These coastal P. utilis woodlands are the main habitat of Parmotrema orarium ( Fig. 32C ). It was also collected once in a lowland dry forest, 4 km from the coast. Thalli of P. orarium are frequently associated with those of Dirinaria and Pyxine species.

The bioclimate of the localities is pluvial tropical, thermotype belts = lower and upper thermotropical (585 ≤ It ≤ 685), ombrotype belts are variable = from upper subhumid to upper hyperhumid (5.7 ≤ Io ≤ 20.7) ( Fig. 32B ).

Notes:—With its small or medium adnate thallus, sublinear to subirregular and rather narrow lobes, Parmotrema orarium looks more like a Canoparmelia s. lat. than a Parmotrema . Our molecular data ( Fig. 2 ) demonstrate that P. orarium does indeed belong to Parmotrema s. str., and not to the taxa Canoparmelia s. str., Crespoa , or Africanae ( Kirika et al. 2016).

Parmotrema orarium is a rather enigmatic species, with a unique combination of characters within Parmotrema s. str. Some of them are shared with P. adspersum (Vain.) Elix , the most phenotypically similar Parmotrema s. str. This taxon is known from Thailand, Philippines, Papua New Guinea and Christmas Island ( Hale 1976, Aptroot & Sipman 1991, McCarty & Elix 2002), and was previously placed in the genus Canoparmelia ( Elix et al. 1986, 2002). However, P. adspersum has more rounded and wider lobes (3–15 vs 1–4 mm), isidia that do not become sorediate, and fumarprotocetraric acid as major medullary extrolite instead of succinprotocetraric acid ( Vainio 1907, Hale 1976). A thallus of P. orarium with pustular soralia and poorly developed isidia could be misidentified as P. pustulatum Louwhoff & Elix. But this New Caledonian species possess wider lobes (4–6 mm), lacks isidia, and the medulla contains protocetraric acid in addition to succinprotocetraric and fumarprotocetraric acids ( Louwhoff & Elix 2000).

Within our material here assigned to P. orarium , two different ITS sequences have been detected ( Table 3). The other two loci studied (mtSSU and EF1-α) do not show any variation. No other characters, either morpho-anatomical, chemical or ecological, could be found to support the recognition of two entities. The rather large variation in the soralia and isidia developed within the populations of this species does not correlate with the two ITS sequences. Further neither of the two species discovery methods used for species delimitation (bPP and Stacey) supported the recognition of two different species ( Fig. 3 ). We therefore assign this variation to the presence of two different ITS within the populations of this species.

According to our phylogenetic tree based on 3-locus data ( Fig. 3 ), P. orarium belongs to a well-supported clade comprising four other species, all of them potentially endemic to the Mascarenes.

Additional specimens examined (paratypes): — FRANCE. Réunion: Saint-Philippe, Basse Vallée, Cap Mascarin, elev. 15 m, 21°22’35–36”S, 55°42’06–10”E, in coastal Pandanus thicket, on bark of Pandanus utilis , 26 August 2017, D. Masson 974.5130 (REU), 974.5132, 974.5135 (Hb. DM), 974.5131, 974.5134 (LG); ibid., Cap Méchant, elev. 20 m, 21°22’30”S, 55°42’39”E, in coastal landscaped picnic area, on bark of a trunk of Pandanus utilis , 14 August 2015, D. Masson 974.4646 (LG); ibid., near Pointe de la Mare d’Arzule, elev. 10 m, 21°21’52–53”S, 55°46’25–26”E, in coastal Pandanus thicket, on bark of trunks of Pandanus utilis , 14 August 2015, D. Masson 974.4640 (REU), 974.4645 (Hb. DM); ibid., near la Petite Vache, elev. 15 m, 21°21’43”S, 55°46’40”E, in disturbed coastal thicket, on bark of a trunk of Pandanus utilis , 14 August 2015, D. Masson 974.4642 (Hb. DM); ibid., Ravine Angot, elev. 25 m, 21°21’02”S, 55°47’38”E, in secondary coastal thicket with Casuarina , Pandanus , Psidium , etc., on bark of a branch of Ficus sp. , 17 August 2013, D. Masson 974.4288 (Hb. DM); Saint-Pierre, Piton de Mont Vert, elev. 590 m, 21°19’40”S, 55°32’33”E, in lowland dry forest, on bark of a branch of Pandanus sylvestris , 19 August 2017, D. Masson 974.5016 (LG); Sainte-Rose, le Port, elev. 9 m, 21°07’32”S, 55°47’21”E, in coastal landscaped picnic area, on bark of a trunk of Pandanus utilis , 12 April 2003, D. Masson 974.0291 (Hb. DM); ibid., la Marine, elev. 10 m, 21°07’31”S, 55°47’26– 32”E, in secondary coastal thicket, on bark of trunks of Pandanus utilis , 15 August 2013, D. Masson 974.4242 (REU), 974.4245, 974.4246 (Hb. DM); ibid., near Pointe de Sainte-Rose, elev. 15 m, 21°07’36”S, 55°47’50”E, in coastal Pandanus thicket on cliff top, on bark of a trunk of Pandanus utilis , 14 August 2015, D. Masson 974.4639 (LG); ibid., between Pointe de Sainte-Rose and Bassin des Harengs, elev. 10 m, 21°07’41”S, 55°48’02”E, in coastal Pandanus thicket on cliff top, on bark of a branch of Pandanus utilis , 14 August 2015, D. Masson 974.4638 (Hb. DM); ibid., La Cayenne, elev. 10 m, 21°07’59”S, 55°48’23”E, in coastal landscaped picnic area, on bark of a trunk of Pandanus utilis , 14 August 2015, D. Masson 974.4636 (Hb. DM); ibid., Bois Blanc, SW of Quai au Bois, elev. 20–30 m, 21°12’33– 34”S, 55°49’03–05”E, in coastal Pandanus thicket on cliff top, on bark of trunks and adventitious root of Pandanus utilis , 13 August 2015, D. Masson 974.4610 (LG), 974.4611–13 (Hb. DM); ibid., Bois Blanc, between Quai au Bois and Quai de l’Église, elev. 25 m, 21°12’26–29”S, 55°49’15–18”E, in coastal Pandanus thicket on cliff top, on bark of trunks of Pandanus utilis , 13 August 2015, D. Masson 974.4616 (LG), 974.4617 (REU), 974.4618 (Hb. DM); ibid., Bois Blanc, near Quai de Tigo, elev. 25 m, 21°12’15–18”S, 55°49’24–25”E, in coastal Pandanus thicket on cliff top, on bark of trunks of Pandanus utilis , 13 August 2015, D. Masson 974.4619 (LG), 974.4622 (Hb. DM); ibid., Bois Blanc, between Quai de Tigo and Roche du Pas de Cabri, elev. 20 m, 21°12’11”S, 55°49’29”E, in coastal Pandanus thicket on cliff top, on bark of a trunk of Pandanus utilis , 13 August 2015, D. Masson 974.4623 (Hb. DM); ibid., Bois Blanc, near Pointe de Bois Blanc, elev. 20 m, 21°11’54”S, 55°49’30”E, in coastal Pandanus thicket on cliff top, on bark of a trunk of Pandanus utilis , 13 August 2015, D. Masson 974.4625 (Hb. DM); ibid., les Cascades, elev. 30 m, 21°11’07”S, 55°49’57–58”E, in secondary coastal thicket with Pandanus and Casuarina , on cliff top, on bark of branches of Pandanus utilis , 13 August 2013, D. Masson 974.4221 (LG), 974.4222 (REU), 974.4247, 974.4248 (Hb. DM); ibid., between Pointe des Cascades and Pointe des Bambous, elev. 20 m, 21°10’51”S, 55°50’06”E, in secondary coastal thicket with Pandanus and Casuarina , on cliff top, on bark of branch of Pandanus utilis , 13 August 2013, D. Masson 974.4225 (Hb. DM).

Figures

FIGURE 2. Phylogenetic relationships of the two new species Parmotrema orarium and P. intonsum among selected representatives of parmelioid taxa, resulted from a RaxML analysis on three loci (ITS, nuLSU, mtSSU) and 71 specimens. Bootstrap values are represented near the branches when ≥ 70.

FIGURE 3. Phylogeny of the Parmotrema species studied. Best ML tree resulted from a RaxML analysis of three loci (EF1-α, ITS, mtSSU) and 102 specimens. Punctelia toxodes was selected as the outgroup. Bootstrap values are represented above the branches, and thick branches have bootstrap support value ≥ 70. Results of the species delimitation analyses are summarized to the right of the terminal labels of the tree. The first column corresponds to the results of the Stacey analysis, while the second column corresponds to the results of the bPP analysis. Specimens attributed the same colour were reconstructed as part of the same putative species by the species delimitation analysis. Major medullary extrolites are also shown for each specimen.

FIGURE 32. Parmotrema orarium. A: Distribution on Réunion (UTM 2×2 km grid system); B: Bioclimatic characteristics of collection sites (abbreviations and threshold values for thermotype and ombrotype horizons from Rivas-Martínez et al. 2011:17–18); C: Coastal stand of Pandanus utilis, a typical habitat for P. orarium on Réunion Island (Sainte-Rose, Bois Blanc, 13August 2015); D: Gross morphology of thallus (holotype); E: Sorediate isidia (Masson 974.4646); F: Submarginal pustules, bursting into soredia (Masson 974.4221). Scale bars: A = 10 km; D = 20 mm; E = 1 mm; F = 2 mm.