Parmotrema udisilvestre 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 : 114-116

Parmotrema udisilvestre D.M. Masson, Magain & Sérus. , sp. nov. MycoBank no. 853880

Diagnosis. Species of the P. subarnoldii group, characterized by the fragile upper cortex often flaking, the submarginal soralia frequently arising from pustules, the granular soredia, and the marginal cilia of moderate average size (ca. 2.5–4 mm).

Holotype:— FRANCE. Réunion: La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 875 m, 21°06’59”S, 55°39’00”E, in submontane Pandanus wet thicket, in an overall NE orientation, on bark of a branch of Pandanus montanus , 23 August 2015, D. Masson 974.4815 (MNHN-PC-PC0088083).

GenBank accession numbers: ITS ( PP 840415), mtSSU ( PP 842552), EF1-α ( PP 852814).

( Fig. 42 )

Morphological description and chemistry based on molecularly analysed material (14 specimens).

Thallus foliose, loosely to moderately adnate, membranaceous to subcoriaceous, up to 12 × 22 cm. Lobes irregular, contiguous to imbricate, 3–18 mm wide, plane to ± concave, apices rounded, lateral sorediate lobes sometimes ± convolute; margins undulate, sinuate, crenate to dentate, rarely shortly laciniate when sorediate, mostly ascendant, ciliate ( Fig. 42E ). Cilia conspicuous, black, some with coppery glints (pigments); numerous and ± evenly distributed at lobe margins, occasionally laminal; simple, rarely 1–2 times branched, ca. 0.04–0.09 mm in diameter at the base, (1.5)2.2– 3.46 –4.7(5.5) mm long (n = 420, from 14 specimens, mean values for each specimen: 2.82, 3.03, 3.25, 3.27, 3.34, 3.42, 3.46, 3.49, 3.66, 3.67, 3.68, 3.71, 3.76, 3.82 mm, Fig. 10 ). Upper surface pale greenish grey near lobe tips to pale yellowish grey centrally, dull, shinier towards the periphery, emaculate or faintly ± punctiform white-maculate, smooth or rugulose to ± rugose, upper cortex fragile, here and there cracking and flaking ( Fig. 42D ); sorediate or pustulate-sorediate, lacking dactyls, phyllidia and isidia. Soralia mostly submarginal, arising from pustule-like swellings, or forming from disintegration of the upper cortex of ± revolute lobes ( Fig. 42C ) or very short marginal laciniae, then developing into ± erect, capitate clusters; very rarely laminal punctiform. Soredia granulose, (30)– 55.4 –(80) µm in diameter (n = 420, from 14 thalli, SD = 9.0 µm). Lobules occasional, mostly regenerative in older parts, marginal and laminal, up to 5 × 5.5 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. 0.5–10 mm wide) at main lobe tips, sorediate lobes sometimes with a mottled or fully ivory erhizinate marginal zone (ca. 1–2 mm wide). Rhizines in small scattered groups, concolor to the lower surface, sometimes with lighter tip when young, simple or fasciculate, more rarely 1–2 times branched, up to 4 mm long. Apothecia absent. Pycnidia rare, submarginal towards apices; only primordia seen. Conidia not found. Upper cortex palisade plectenchymatous, fragile, (14)– 18.7 –(22) µm thick. Algal layer ± continuous, (14)– 18.6 –(22) µm thick. Medulla (80)– 95.6 –(108) µm thick. Lower cortex prosoplectenchymatous, (13)– 14.6– (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); ± 1–2 unidentified ciliary pigments: P1, PV.

Etymology:—The specific epithet is derived from the Latin udus (wet, humid, damp) and silvestris (of woods), in reference to the habitat of the species.

Geographical distribution:—Among the three taxa of the Parmotrema subarnoldii group occurring on Réunion, P. udisilvestre appears to be the most frequent. It was found at four localities, in four UTM 1× 1 km grid cells (or four UTM 2× 2 km grid cells, Fig. 42A ), on the windward side of the island at elevations between 685 and 875 m. The species also occurs in the northeast of Madagascar, in mountain massif of Marojejy, between 966 and 1326 m elevation.

Ecology:—At all its Reunionese localities, Parmotrema udisilvestre was curiously only found on branches and trunks of the screw pine Pandanus montanus where it grows directly on the bark, more rarely on epiphytic mosses. Two habitats were reported in Réunion, Pandanus submontane wet thickets and windward submontane rainforests. In Madagascar, it was also corticolous, thriving on branchlets of an undetermined phorophyte in a dense humid montane forest. The species appears to be ombrophilous and moderately thermophilous, as shown by the bioclimatic indices of the localities: bioclimate pluvial tropical, thermotype belts = from upper thermotropical to lower mesotropical (482 ≤ It ≤ 531) in Réunion ( Fig. 42B ), upper thermotropical (It = 543) in Madagascar, ombrotype belts = from lower hyperhumid to ultrahyperhumid (17.5 ≤ Io ≤ 25.6) in Réunion, lower humid (Io = 7.8) in Madagascar (climate data for Madagascar from Anonymous 2014).

Notes:—Of the three taxa phenotypically similar to Parmotrema subarnoldii that we describe as new species here, P. udisilvestre has the most distinctive morphology. The combination of a fragile upper cortex, the submarginal and often pustular soralia, and the granulose soredia is characteristic of this species ( Table 5). The Reunionese and Malagasy specimens studied form a distinct and well-supported clade in the phylogenetic tree constructed from ITS sequences ( Fig. 4 ) as well in that using three loci ( Fig. 3 ). Two slightly different ITS sequences were found ( Table 3), but neither of the two methods used for species delimitation (bPP and Stacey) supported the recognition of two different taxa ( Fig. 3 ).

Just like the other representatives of the P. subarnoldii group studied here, P. udisilvestre is part of a strongly supported radiation of ten species ( Fig. 3 ), five of them (including P. udisilvestre ) possible Mascarene endemics, three also occurring on Madagascar, and two being more widespread in the Paleotropics ( Table 1).

Additional specimens examined (paratypes):

Genetically analysed specimens:— FRANCE. Réunion: Bras-Panon, sentier de la Caroline, elev. 730–735 m, 21°01’41”S, 55°37’10–11”E, in disturbed windward submontane rainforest with patches of Pandanus wet thickets, on bark of trunks and a dead branch of Pandanus montanus , 15 August 2017, D. Masson 974.4957–59 (LG); La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 875 m, 21°07’00–01”S, 55°39’00–03”E, in submontane Pandanus wet thicket, in an overall NE orientation, on bark of branches of Pandanus montanus , 23 August 2015, D. Masson 974.4813, 974.4833 (LG); Saint-André, forêt de Dioré, elev. 825 m, 20°59’35”S, 55°34’55”E, in windward submontane rainforest, on bark of branches of Pandanus montanus , 21 August 2017, D. Masson 974.5062–65 (LG); Saint-Benoît, Saint-François les Hauts, sentier Sainte-Marguerite, elev. 685 m, 21°06’57” to 21°07’00”S, 55°40’42– 43”E, in submontane Pandanus wet thicket, in an overall NE orientation, on bark of trunks and branches of Pandanus montanus , 28 August 2012, D. Masson 974.4104, 974.4109 (LG), 23 August 2015, D. Masson 974.4840 (LG).

MADAGASCAR. Sava : W of Sambava , Marojejy National Park , along trail from camp Marojejia to camp Simpona, from 14°26’20.1”S, 49°45’38.2”E, elev. 966 m to 14°26’11.7”S, 49°44’35.8”E, elev. 1326 m, rather dense humid montane forest, October 2014, E. Sérusiaux M6-16 ( LG) .

Non-genetically analysed specimen:— FRANCE. Réunion: Saint-Benoît, Saint-François les Hauts, sentier Sainte-Marguerite, elev. 685 m, 21°06’57”S, 55°40’42”E, in submontane Pandanus wet thicket, in an overall NE orientation, on bark of a branch of Pandanus montanus , 28 August 2012, D. Masson 974.4101 (Hb. DM).

Erroneous, doubtful and problematic reports

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 42. Parmotrema udisilvestre. 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: Submarginal soralia arising from pustule-like swellings or forming from disintegration of the upper cortex of ± revolute lobe (holotype); D: Sorediate lobe with fragile, cracking and flaking upper cortex (Masson 974.4959); E: Gross morphology of thallus (Masson 974.4833). Scale bars:A = 10 km; C = 2 mm; D = 3 mm; E = 8 mm.