Parmotrema eleonomum 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 : 48-50

Parmotrema eleonomum D.M. Masson, Magain & Sérus. , sp. nov. MycoBank no. 853868

Diagnosis. Species of the P. subarnoldii group similar to P. brachyblepharum , but differs by having marginal cilia of greater mean length (ca. 4–5 mm) and by the ITS sequence ( Table 3).

Holotype:— FRANCE. Réunion: La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 870 m, 21°07’03”S, 55°39’05”E, in disturbed submontane Pandanus wet thicket, in an overall NE orientation, on bark of a branch of Pandanus montanus , 24 August 2013, D. Masson 974.4448 (MNHN-PC-PC0088071).

GenBank accession numbers: ITS ( PP 840574), mtSSU ( PP 842541), EF1-α ( PP 852802).

( Fig. 20 )

Morphological description and chemistry based on accessions whose molecular data are available (four specimens).

Thallus foliose, loosely to moderately adnate, membranaceous, up to 11 × 14 cm. Lobes irregular, imbricate, 4–11 mm wide, frequently broadly concave or irregularly crumpled, sorediate lobes often ± involute; margins wavy, crenate to somewhat shortly laciniate when sorediate, mostly ascendant, ciliate ( Fig. 20E ). Cilia conspicuous ( Fig. 20D ), black, some with coppery-red glints (pigment), numerous and ± evenly distributed at lobe margins, simple, occasionally forked, ca. 0.04–0.09 mm in diameter at the base, (2)2.9– 4.54 –6.2(6.3) mm long (n = 120, from 4 specimens, mean values for each specimen: 4.11, 4.48, 4.78, 4.80 mm, Fig. 10 ). Upper surface pale greenish grey, dull, somewhat shinier towards the periphery, emaculate or faintly ± punctiform white-maculate, smooth, rugulose to ± rugose and cracked in the older parts; sorediate, lacking schizidia, pustules, dactyls, phyllidia and isidia. Soralia most often terminal ± subcapitate on marginal teeth or very short laciniae (<1 mm), also linear discontinuous on lobe margins ( Fig. 20C & 20D ). Soredia subgranulose, (30)– 41.6 –(60) µm in diameter (n = 120, from 4 thalli, SD = 6.9 µm). Lobules rare, marginal, ciliate or not, up to 2.5 × 2.5 mm. Medulla white throughout. Lower surface rugulose, dull, shinier towards the lobe tips, black to the margin, or with a chestnut brown erhizinate marginal zone (ca. 2–7 mm wide) at main lobe tips. Rhizines moderately dense, ± in scattered groups, concolor to the lower surface, sometimes with lighter tip when young, simple, rarely 1–2 times branched or fasciculate, rather short and thick centrally but more slender and looking like cilia near margins, then up to 5 mm long. Apothecia absent. Pycnidia rare, submarginal towards lobe apices; only primordia seen. Conidia not found. Upper cortex palisade plectenchymatous, not fragile, (15)– 20.8 –(30) µm thick. Algal layer ± continuous, (13)– 18.0 –(22) µm thick. Medulla (65)– 89.4 –(100) µm thick. Lower cortex prosoplectenchymatous, (13)– 14.5– (16) µm thick.

Chemistry:— Spot tests and fluorescence: upper cortex K+ yellow, UV−; medulla K−, C−, KC + pink, P+ orange, UV−. Secondary metabolites ( TLC): upper cortex with atranorin and chloroatranorin; medulla with protocetraric acid (major), protolichesterinic acid (major), lichesterinic acid (minor/trace), ± unidentified fatty acid (Rf classes:A2-3, B1, C 2; minor); it was not possible to extract the pigment(s) that give the coppery glint to some cilia.

Etymology:— From the Greek eleionomos: marsh-dwelling. Eleionomae were marshland naiads in ancient Greek mythology. It is said that these nymphs deceived travellers with their illusions. The epithet refers to the habitat of the species in the type locality (wet thicket of Pandanus ) as well as the deceptive morphological and chemical similarities with the sympatric P. brachyblepharum .

Geographical distribution:— So far only known from Réunion. It seems to be a rare species, collected on the windward side of the island at 870 m elevation (type locality) and, possibly, at 1230 m ( Fig. 20A ) .

Ecology:—At its type locality, Parmotrema eleonomum was found on the smooth bark of branches of the endemic screw pine Pandanus montanus , in a ± disturbed submontane Pandanus wet thicket. A specimen, which could belong to this species on the basis of its morphological and chemical features (but without molecular data), was also collected on the bark of a trunk of Weinmannia sp. in a windward montane rainforest. The bioclimates of the two locations are similar: pluvial tropical in the lower mesotropical belt (It = 482 and 425) and the ultrahyperhumid ombrotype belt (Io = 25.6 and 28.3) ( Fig. 20B ).

Notes:— Parmotrema eleonomum is phenotypically very similar to P. brachyblepharum with which it co-occurs in the type locality. The only character discriminating the two species seems to be the mean length of cilia fringing the lobes ( Table 5, Fig. 10 ). In the specimens studied, the average length of the cilia is greater than 3.5 mm in P. eleonomum , whereas it is less than this value in P. brachyblepharum . On the other hand, comparison of ITS sequences strongly support the separation of two taxa ( Fig. 4 , Table 3). Further, phylogenetic analysis based on a 3-locus dataset confirm they are indeed different, the isidiate P. subcorallinum being the closer sister species to P. eleonomum and the clade formed by both of them being strongly supported as sister to P. brachyblepharum ( Fig. 3 ). Lastly, Stacey and bPP analyses clearly separate P. eleonomum from P. brachyblepharum .

Morphological characteristics clearly distinguish P. eleonomum from P. udisilvestre ( Table 5). Parmotrema eleonomum (as well as P. brachyblepharum ) has a non-fragile upper cortex (versus fragile and flaking in P. udisilvestre ), its soralia have a different location and development, and the soredia produced have a smaller mean size (subgranular versus granular).

Additional specimens examined (paratypes):

Genetically analysed specimens:— FRANCE. Réunion: La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 870 m, 21°07’03”S, 55°39’05”E, in submontane Pandanus wet thicket, in an overall NE orientation, on bark of branches of Pandanus montanus , 18 August 2017, D. Masson 974.4993, 974.4995, 974.4997 (LG).

Non-genetically analysed specimens:— FRANCE. Réunion: La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 870 m, 21°07’03”S, 55°39’05”E, in submontane Pandanus wet thicket, in an overall NE orientation, on bark of branches of Pandanus montanus , 24 August 2013, D. Masson 974.4449 (REU), 18 August 2017, D. Masson 974.4996 (Hb. DM); Saint-Benoît, forêt de Bébour, trail to Takamaka, elev. 1230 m, 21°05’52”S, 55°34’46”E, in windward montane rainforest, on bark of a trunk of Weinmannia sp. , 29 July 2005, D. Masson 974.1854 (Hb. DM).

Figures

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 4. Global tree (best scoring maximum likelihood tree) of Parmotrema based on the fungal ITS barcoding marker. Figure can be enlarged for a better reading of labels. Accessions in black are those retrieved from GenBank on June 2023. Those in red are those produced by the authors for this study. Bootstrap support is indicated on branch when ≥ 70%.

FIGURE 10. Comparison of the mean lengths (± SE) of the marginal cilia of 4 species of the P. subarnoldii group: P. subarnoldii (lectotype from Madagascar, 1 specimen from Rwanda), P. eleonomum (7 specimens from Réunion), P. brachyblepharum (8 specimens from Réunion), and P. udisilvestre (14 specimens from Réunion, 1 from Madagascar). Soralia of type A: marginal, linear or ± subcapitate or labriform; soralia of type B: submarginal, arising from pustule-like swellings, or forming from disintegration of the upper cortex.

FIGURE 20. Parmotrema eleonomum. A: Distribution on Réunion (UTM 2×2 km grid system), lemon-yellow cell = specimens with molecular data, pale yellow cell with a cross = specimen without molecular data; B: Bioclimatic characteristics of collection sites (abbreviations and threshold values for thermotype and ombrotype horizons from Rivas-Martínez et al. 2011: 17–18); C & D: Sorediate lobes with conspicuous long cilia, and soralia terminal ± subcapitate on marginal teeth or very short laciniae, or linear discontinuous on lobe margins (C: holotype, D: Masson 974.4997); E: Gross morphology of thallus (holotype). Scale bars: A = 10 km; C = 1 mm; D = 4 mm; E = 10 mm.