Parmotrema intonsum 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 : 50-54

Parmotrema intonsum D.M. Masson, Magain & Sérus. , sp. nov. MycoBank no. 853869

Diagnosis. Differs from P. melanothrix (Mont.) Hale by the presence of granular isidia and/or laciniae, the larger ascospores and shorter conidia, and by the presence of protolichesterinic and lichesterinic acids in the medulla.

Holotype:— FRANCE. Réunion: Saint-Denis, Roche Écrite trail, elev. 1240 m, 20°57’14”S, 55°26’15”E, at the edge of a windward montane rainforest and a Cryptomeria japonica plantation, in an overall NW orientation, on the bark of an old Erica reunionensis trunk, 20 August 2015, D. Masson 974.4745 (MNHN-PC-PC0088072; isotype: LG).

GenBank accession numbers: ITS ( PP 840423), mtSSU ( PP 842559), EF1-α ( PP 852822).

( Fig. 21 )

Thallus foliose, loosely to moderately adnate, membranaceous, up to 12 × 20 cm. Lobes irregular, imbricate, 3–15 mm wide, irregularly wrinkled, often concave, with margins undulated, dentate or lacerate to laciniate, rarely lobulate, ciliate ( Fig. 21E ). Cilia conspicuous, black, rarely with coppery glints (pigments), dense and ± evenly distributed at the lobe margins, also present at the margin of lobules and phyllidia and at the tip of isidia, sometimes laminal, simple, rarely 1–2(3) times branched, ca. 0.03–0.08 mm in diameter at the base, up to 7 mm long. Upper surface pale yellowish grey centrally, more greenish towards the periphery, mat, glossier towards lobe tips, ± distinctly punctiform white-maculate, maculae more conspicuous on the laciniae and near apothecia, smooth to rugose, sometimes slightly granulate, very rarely cracked, generally isidiate, lacking schizidia, pustules, dactyls, soralia. Isidia mainly marginal and submarginal, occasionally also laminal, very often apically ciliate ( Fig. 21C ); mainly granular, more rarely cylindrical, sometimes developing into phyllidia, up to 3.5 × 4 mm, or into irregular coralloid-branched outgrowths, up to 3 mm high; occasionally lacking in highly laciniate thalli. Laciniae occasional, but may be abundant in some thalli, marginal, often repeatedly branched and brittle when developed, ciliate, up to 8 mm long and 1 mm wide ( Fig. 21D ). Lobules occasional, marginal, rarely laminal, up to 3.5 × 4 mm. Medulla white throughout. Lower surface rugulose, rarely smooth, exceptionally reticulate, rather dull in the central part, shiny in the periphery, black to the margin, or with a buff or chestnut brown erhizinate marginal zone (ca. 1–9 mm wide) at main lobe tips, the margin of the isidiate lobes is most often ivory or ivory-mottled over a width of 0.5–5 mm, underside of the laciniae ivory or ivory-mottled. Rhizines in ± scattered clusters, concolor to the lower surface, simple, rarely 1–2 times branched, heterogeneous in size, up to 4 mm long. Apothecia rather rare (fertile thalli found in six localities out of twenty), submarginal, stipitate on swollen stipes (up to 3 mm in diameter), up to 13 mm in diameter; disc imperforate, orange brown, ± glossy, concave and smooth at first ( Fig. 21D ), flattening and ± rugose with age; margin crenate, generally early isidiate and ciliate, and developing irregular, ± branched and ciliate outgrowths with age ( Fig. 21C ); amphithecium maculate, rugose-striate; hymenium s. lat. (105)– 121.1 –(140) µm high, proper exciple with hyaline layer (6)– 9.4 –(12) µm high, intermediate layer (6)– 8.8 –(13) µm high, cortex-like basal layer (12)– 18.1 –(26) µm high. Ascospores 8 per ascus, simple, colourless, broadly ellipsoidal to ellipsoidal, (21)23– 27.0 –31(33) × (12)13.5– 15.6 –17.5(18) µm, Q = (1.33)1.42– 1.74 –2.06(2.20), epispore (2)– 3.0 –(4) µm thick, n = 120, from 4 thalli, mean values for each thallus: 25.6 × 15.6, 27.2 × 15.6, 27.2 × 16.0, 28.0 × 15.2 µm. Pycnidia frequent, submarginal towards lobe apices, black. Conidia subbacilliform 5–6 × ca. 1 µm. Upper cortex palisade plectenchymatous, not fragile, (11)– 15.8 –(22) µm thick. Algal layer continuous, (10)– 17.6 –(24) µm thick. Medulla (90)– 102.9 –(115) µm thick. Lower cortex prosoplectenchymatous, (11)– 15.2– (18) µm thick.

Chemistry:— Spot tests and fluorescence: upper cortex K+ yellow, UV−; medulla K−, C−, KC−, P−, UV−. Secondary metabolites ( TLC): upper cortex with atranorin and chloroatranorin; medulla with protolichesterinic acid (major) and lichesterinic acid (minor); ± 2 undetermined ciliary pigments: PV, P2.

Etymology:—From the Latin intonsus: unshaven. The name refers to the shaggy appearance of the thalli due to the abundance of cilia.

Geographical distribution:—So far only known from Réunion and Madagascar. The oldest collections from Réunion date to the nineteenth century. Since then, Parmotrema intonsum has been found on this island at least in 21 localities in 18 UTM 1× 1 km grid cells (or 16 UTM 2× 2 km grid cells, Fig. 21A ). These localities are distributed between 1240 and 1980 m elev., mainly on the northern and eastern slopes of the Piton des Neiges massif. The specimen (belonging to the laciniate morphotype) collected in Madagascar was cited by des Abbayes (1961) under the name Parmelia melanothrix .

Ecology:— Parmotrema intonsum is a corticolous species, growing on various phorophytes ( Acacia , Aphloia , Dombeya , Erica , Hypericum , Monimia , Nuxia , Phylica , Weinmannia , etc.). On Réunion, it was collected significantly more frequently on branches than on trunks (15 collections on branches, five on trunks, χ² = 5, P = 0.025). This lichen typically grows in cloud forests [‘forêt mésotherme’, Cadet (1980)], in four habitats: windward montane rainforest (52% of the localities), leeward montane rainforest (29%), Acacia montane forest (10%) and Erica montane thicket (5%). It was also found once in subalpine shrubland. The bioclimate of the Reunionese localities is pluvial tropical; thermotype belts are mainly mesotropical = from upper thermotropical to upper mesotropical (360 ≤ It ≤ 497), ombrotype belts are variable = from lower humid to ultrahyperhumid (8.8 ≤ Io ≤ 28.9) ( Fig. 21B ). The bioclimate of the Malagasy locality is also pluvial tropical, with thermotype belt = upper thermotropical (It = 498), ombrotype belt = lower humid (Io = 7.5).

Notes:—This taxon has been known from Réunion since the 19 th century. It was reported there under the name Parmelia perlata var. ciliata (DC.) Duby by Nylander (1859), then as Parmelia melanothrix var. lacinulata Müll. Arg. by Hue (1899). Since Hale (1965a), it has been identified as Parmotrema melanothrix , a species described from Brazil. In the western Indian Ocean, P. melanothrix was also reported from Madagascar ( Vainio 1898, Hue 1899, des Abbayes 1956, 1961) and Mohéli Island in Comoros ( des Abbayes 1956). We had the opportunity to examine several Brazilian specimens of P. melanothrix , including the holotype. Compared to the specimens of P. intonsum, Brazilian P. melanothrix lack vegetative propagules, have smaller ascospores (mean values for 3 thalli, including holotype collection in italics: 23.7 × 12.7, 22.7 × 11.6, 21.3 × 11.3 µm; epispore 1.5–3 µm thick), longer conidia [6–8(11) µm long], and contain 1–2 undetermined fatty acids (Rf A 20; Rf B 26, 31; Rf C 24, 29) in the medulla [and not protolichesterinic acid as reported by Hale (1965a)]. Both taxa share negative medullary chemical spot tests, imperforate apothecial discs, and abundant marginal cilia containing the same ciliary pigments (PV, P2). Des Abbayes (1956) cited two collections made in Madagascar and on the island of Mohéli (Comoro Archipelago) under the name of Parmelia melanothrix . These specimens are now in REN, and were examined: they do not belong to Parmotrema melanothrix , or to P. intonsum . The Malagasy collection (REN 000049) is a mixture of three taxa without vegetative propagules. Two of them react KC+; the third contains protolichesterinic and lichesterinic acids in the medulla, but also an undetermined yellow pigment not reacting with K. The Comoran collection (REN 000048) belongs to a new species, P. mwaliense , described in this paper below.

Besides P. intonsum , four other species of Parmotrema have ciliate lobe margins, contain protolichesterinic acid as the only major medullary substance and are esorediate. The Malagasy P. glaucocarpoides (Zahlbr.) Hale lacks isidia, its apothecia have an eciliate margin and a perforate and somewhat pruinose disc, and its ascospores are narrower with a thinner epispore ( Müller 1884, Dodge 1959, Krog & Swinscow 1981). The Chinese P. laeve (Zhao) J.B. Chen & Elix lacks isidia and laciniae, the apothecial margins are smooth and eciliate, and the ascospores are smaller ( Zhao 1964, Chen et al. 2005). The underside of the African P. leonis (Krog & Swinscow) Krog & Swinscow is predominantly white, the upper surface is strongly maculate, isidia and laciniae are lacking, the apothecial disc is perforate, the apothecial margins are smooth and eciliate, the ascospores are much smaller and the conidia much longer ( Krog & Swinscow 1981). The protolichesterinic acid chemotype of P. abessinicum (Nyl. ex Krempelh.) Hale lacks isidia and laciniae, the apothecial disc is perforate, and the ascospores are much smaller ( Krog & Swinscow 1981).

The development of isidia and laciniae seems to be rather variable in P. intonsum , at least in Réunion. Most thalli produce granular isidia and no laciniae. However, specimens with numerous, branched and ciliate laciniae, but totally devoid of isidia, are sometimes encountered. They include, in particular, the samples cited by Hue (1899) as Parmelia melanothrix var. lacinulata and, later, by Hale (1965a) as P. melanothrix . These laciniae are fragile and easily detached; it is likely that they function as propagules. Apart from the type of propagules, specimens of the isidiate morphotype and those of the laciniate morphotype are morphologically, anatomically and chemically identical. It was also not possible to find any differences in the ecology or distribution of these two morphs in Réunion. Thalli with both isidia and laciniae were also found (e.g. the Malagasy collection REN 000052). For these reasons, we provisionally consider that both morphotypes belong to the same species. Unfortunately, we could not compare the two morphotypes molecularly, as sequences were only obtained from the isidiate specimens.

In the ITS and 3-locus phylogenetic trees produced for this study ( Fig. 3 & 4 ), these isidiate specimens were recovered in two strongly supported sister clades corresponding to two different ITS sequences ( Table 3). No variation in the sequences of the other two loci (mtSSU and EF1-α) was detected. The Stacey and bPP species delimitation analyses gave contradictory results, the former supporting the separation of Parmotrema intonsum into two distinct species, while the latter merged all specimens into a single species ( Fig. 3 ). As there is no phenotypic, ecological or chorological data to support the recognition of two different cryptic taxa, we assume that two ITS variants are present in the populations of a single species.

Additional specimens examined (paratypes):— FRANCE. Réunion: without locality, 1840, M.E. Mézières de Lépervanche 25 (PC 0009291); without locality, 1890 & 1893, frère Rodriguez (= E.A. Marquet) & Chauvet s.n. (PC 0722516); Cilaos, above Îlet des Salazes, elev. 1730 m, 21°06’33”S, 55°26’47”E, in leeward montane rainforest, in an overall SE orientation, on the bark of a branch of Erica reunionensis , 20 August 2012, D. Masson 974.3916 (Hb. DM); ibid., Ravine des Calumets, elev. 1290 m, 21°09’11”S, 55°29’37”E, in leeward montane rainforest, in a ravine with an overall SW orientation, on the bark of a branch of an old Erica reunionensis , 21 August 2012, D. Masson 974.3942 (LG); La Plaine-des-Palmistes, Col de Bébour, along track towards Plaine des Cafres, elev. 1420 m, 21°07’54”S, 55°34’31”E, 04 October 1996, H. Krog RE40/30 & E. Timdal (O L-231259); La Possession, Dos d’Âne, Piton Grand Bazar, elev. 1330 m, 20°58’25”S, 55°23’25”E, in leeward montane rainforest, in an overall NW orientation, on the bark of the trunk of an undetermined shrub, 19 August 2015, D. Masson 974.4723 (Hb. DM); ibid., la Grande Montagne , sentier des Lataniers, elev. 1330 m, 20°58’11”S, 55°23’40”E, in leeward montane rainforest, in an overall NW orientation, on the bark of a trunk of Nuxia verticillata , 19 August 2015, D. Masson 974.4736 (LG); Le Tampon, Plaine des Cafres, sentier de Bébour, elev. 1600 m, 21°08’39”S, 55°34’17”E, in disturbed Erica montane thicket, on the bark of Erica reunionensis , 26 August 2012, D. Masson 974.4050 (LG); ibid., elev. 1605 m, 21°08’16”S, 55°34’22”E, in leeward montane rainforest, on the bark of Monimia rotundifolia , 26 August 2012, D. Masson 974.4068 (Hb. DM); Saint-Benoît, Piton de Bébour, elev. 1355–1360 m, 21°07’33”S, 55°33’53”E, in windward montane rainforest, on the bark of a branch of Monimia rotundifolia , 07 April 2003, D. Masson 974.0127 (Hb. DM); ibid., elev. 1385 m, 21°07’36”S, 55°33’56”E, in windward montane rainforest, on the bark of branches of Dombeya reclinata and an undetermined tree, 07 April 2003, D. Masson 974.0098 (REU), 974.0166 (Hb. DM); ibid., forêt de Bébour, sentier de la Rivière des Marsouins, elev. 1380 m, 21°06’41”S, 55°33’47”E, in windward montane rainforest, on the bark of the trunk of an undetermined tree, 15 April 2003, D. Masson 974.0416 (Hb. DM); ibid., forêt de Bébour, les Trois Mares, elev. 1400 m, 21°06’33”S, 55°33’43”E, on the edge of a road through a windward montane rainforest, in an overall SE orientation, on the bark of a twig of Weinmannia sp. , 21 August 2015, D. Masson 974.4786 (Hb. DM); ibid., elev. 1440 m, 21°06’11”S, 55°33’23”E, on the edge of a road through a windward montane rainforest, in an overall ESE orientation, on the bark of a dead branch of Hypericum lanceolatum , 21 August 2015, D. Masson 974.4782 (LG); ibid., forêt de Bébour, plateau de Duvernay, elev. 1320 m, 21°07’29”S, 55°34’27”E, in windward montane rainforest, in an overall SE orientation, on the bark of a branch of a young Dombeya sp. , 21 August 2015, D. Masson 974.4774 (Hb. DM), D. Masson 974.4775, 974.4776 (LG); ibid., NW side of forêt de Bébour, trail GR R1 from gîte de Bélouve to Caverne Mussard, elev. 1980 m, 21°05.3’S, 55°31.3’E, rather well-lit area with mixed shrubs, including Erica sp. , on Phylica nitida , 02 June 2008, P. van den Boom 40489 ( Hb. van den Boom); Saint-Denis, Plaine d’Affouches, elev. 1480 m, 20°58’59”S, 55°24’36”E, in leeward montane rainforest, on the bark of a branch of Erica sp. , 04 August 2005, D. Masson 974.1951 (Hb. DM); Saint-Joseph, Grand Coude, elev. 1390 m, 21°16’29”S, 55°37’51”E, in windward montane rainforest, on the bark of a branch of Aphloia theiformis , 24 August 2017, D. Masson 974.5117 (LG); Sainte-Marie, Plaine des Fougères, elev. 1640 m, 20°59’59”S, 55°30’25”E, in Acacia montane rainforest, on the bark of a branch of Acacia heterophylla , 31 August 2012, D. Masson 974.4154 (Hb. DM); ibid., elev. 1445 m, 20°58’49”S, 55°30’05”E, in windward montane rainforest, in an overall NNE orientation, on the bark of a branch of Monimia rotundifolia , 30 August 2012, D. Masson 974.4139 (LG); Salazie, Bélouve, sentier de l’École Normale, elev. 1435 m, 21°03’32”S, 55°33’18”E, in an exploited Acacia heterophylla forest, on the bark of a branch of A. heterophylla , 24 August 2012, D. Masson 974.4013 (LG); ibid., montagnes de Salazie, forêt de Bélouve, February 1893, Chauvet s.n. (PC 0722520); ibid., Piton d’Enchain, elev. 1350 m, 21°02’35”S, 55°29’50”E, in windward montane rainforest, on the bark of the trunk of an undetermined tree, 13 April 2003, D. Masson 974.0359 (Hb. DM).

MADAGASCAR. Alaotra-Mangoro : Périnet, forêt d’Analamazoatra, elev. 920 m, sur tronc d’arbre, 06 August 1956, H. des Abbayes 2507 ( REN 000052 ) .

Specimens studied for comparison:

Parmotrema melanothrix .— BRAZIL. Minas Gerais: Sítio [= Antônio Carlos, Ahti 1998], 1885, E.A. Vainio, Lich. Bras. Exs. 1053 ( PC 0722519 ) ; Rio de Janeiro: Parque Nacional da Serra dos Orgaos, surroundings of Subsede near Barreiro , elev. 400 m, 17–18 October 1952, F. Mattick 446, c (B); ibid ., Rio de Janeiro, 1831, C. Gaudichaud-Beaupré 89 bis (MNHN-PC-PC0722518, holotype; fide Hale 1965a)

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 21. Parmotrema intonsum. 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: Part of thallus with granular or cylindrical ciliate isidia and a mature apothecium with ± branched and ciliate outgrowths on margin (holotype); D: Part of thallus with ciliate phyllidia/laciniae and apothecia of various ages (Masson 974.0359); E: Gross morphology of thallus (holotype). Scale bars:A = 10 km; C = 5 mm; D = 4 mm; E = 10 mm.