Parmotrema brachyblepharum 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 : 24-28

Parmotrema brachyblepharum D.M. Masson, Magain & Sérus. , sp. nov. MycoBank no. 853866

Diagnosis. Species of the P. subarnoldii group, similar to P. subarnoldii (Abbayes) Hale , but differs by the much smaller average length of the marginal cilia and the higher average size of soredia.

Holotype:— FRANCE. Réunion: La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 875 m, 21°07’01”S, 55°39’03”E, in submontane Pandanus wet thicket, in overall NE orientation, on bark of a branch of Pandanus montanus , 23 August 2015, D. Masson 974.4832 (MNHN-PC-PC0088069).

GenBank accession numbers: ITS ( PP 840418), mtSSU ( PP 842554), EF1-α ( PP 852817).

( Fig. 9 )

Morphological description and chemistry based on material whose DNA could be examined (six specimens); additional information from other specimens in square brackets.

Thallus foliose, loosely to moderately adnate, membranaceous, up to 14 × 17 cm. Lobes irregular, contiguous to imbricate, 5–12 mm wide, often broadly concave, with margins undulating, crenate to somewhat shortly laciniate when sorediate, mostly ascendant, ciliate ( Fig. 9E ). Cilia conspicuous, black, some with coppery glints (pigments); numerous and ± evenly distributed at lobe margins, sparse on sorediate lobes in the central part, rarely laminal; simple, rarely 1–(2) times branched, ca. 0.04–0.08 mm in diameter at the base, (0.7)1.1– 2.52 –3.9(5) mm long (n = 180, from 6 specimens, mean values for each specimen: 1.64, 2.29, 2.42, 2.72, 2.96, 3.10 mm, Fig. 10 ). Upper surface pale greenish grey near lobe tips to pale yellowish grey centrally, dull, more shiny 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 marginal, linear discontinuous, then ± labriform ( Fig. 9D ), or subcapitate at the tip of very short laciniae (<1 mm); rarely submarginal subcapitate. Soredia subgranulose, (25)– 42.4 –(70) µm in diameter (n = 180, from 6 thalli, SD = 7,8 µm). Lobules occasional, marginal and laminal, ciliate, up to 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. 1–7 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, up to 3 mm long. Apothecia absent. Pycnidia absent [rare, submarginal towards apices, black]. Conidia [not found (15 pycnidia investigated)]. Upper cortex palisade plectenchymatous, not fragile, (13)– 16.8 –(24) µm thick. Algal layer ± continuous, (8)– 14.0 –(19) µm thick. Medulla (75)– 95.1 –(112) µm thick. Lower cortex prosoplectenchymatous, (15)– 17.6– (20) 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), an unidentified fatty acid (Rf classes: A2-3, B1, C 2; minor), ± unidentified fatty acid (Rf classes:A2-3, B1, C 3); ± 1–2 unidentified ciliary pigments: P1, P2.

Etymology:—The epithet means ‘with short cilia’. It is derived from the Greek brachys (short) and blepharon (eyelash).

Geographical distribution:—The species is only known from one locality on Réunion, on the windward side of the island at 870–875 m elevation ( Fig. 9A ).

Ecology:—This species was only found on smooth bark of trunks and branches of the endemic screw pine Pandanus montanus Bory , in a ± disturbed submontane Pandanus wet thicket ( Fig. 9C ). This habitat, which has a very high heritage value in Réunion ( Lacoste et al. 2011), is characterized in particular by high edaphic and atmospheric humidity.The bioclimatic features of the locality are: bioclimate = pluvial tropical, thermotype belt = lower mesotropical (It = 482), ombrotype belt = ultrahyperhumid (Io = 25.6) ( Fig. 9B ).

Notes:—Molecular-based phylogeny of Parmotrema specimens from Réunion with marginal cilia, soralia, and whose medulla contains protocetraric acid, protolichesterinic acid, lichesterinic acid and ± an undetermined fatty acid, shows that they are resolved into three distinct clades ( Fig. 3 ), here proposed as new species: P. brachyblepharum , P. eleonomum and P. udisilvestre . These three taxa share a similar range on the island and even co-occur in the same locality (La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, Fig. 9C ). Only two previously described species have the same combination of characters as those shared by the three taxa cited above: P. rubromarginatum and P. subarnoldii . Parmotrema rubromarginatum is characterized by a unique mixture of four undetermined pigments [two red (R1 & R2), one pink (P1) and one purple (PV)], present on the surface of the cilia and lobe margins ( Pooprang et al. 1999, first author’s observation). Pigments P1 and PV can be found on the cilia of the three Reunionese taxa, but not R1 or R2. Furthermore, comparison of the ITS sequences of a Thai sample of P. rubromarginatum (GenBank accession MK722224) and of the three taxa from Réunion ( Fig. 4 ) supports that none belong to P. rubromarginatum . The case of P. subarnoldii , a species described from Madagascar ( des Abbayes 1961), must also be considered. We were able to examine the lectotype, designed by Hale (1965a), and kept in REN. The specimen is in good condition but, unfortunately, has neither apothecia nor pycnidia. The medulla contains protocetraric acid (major), protolichesterinic acid (major), and lichesterinic acid (minor/trace), apparently without any other fatty acid. The marginal cilia are very long [(5.0)5.2– 6.56 –7.9(8.0) mm, n = 30], and we did not detect the presence of pigment(s). The soralia are similar to those of P. brachyblepharum and P. eleonomum , but the soredia are farinose [(25)– 38.0 –(50) µm in diameter, n = 30, SD = 6.4 µm]. Examination of the other specimens cited in the protologue ( des Abbayes 1961: 113) revealed a mixture of different taxa ( Table 4), none of which share the same combination of characters as the lectotype. On the other hand, we found two collections in LG that could be attributed to P. subarnoldii , because of their phenotypic traits matching those of the lectotype (i.e., long cilia, marginal soralia linear or becoming subcapitate, farinose soredia, and protocetraric and protolichesterinic acids as major medullary substances). One collection originates from Rwanda, the other from a Malagasy locality, about 65 km away from the type locality of P. subarnoldii . Unfortunately, we were unable to generate molecular data from the relatively recent Malagasy sample. The comparison of the morphological characters of P. subarnoldii , P. brachyblepharum , P. eleonomum and P. udisilvestre ( Table 5) suggest, however, that none of the last three taxa found on Réunion correspond to P. subarnoldii s. str. Further the three samples of P. subarnoldii s. str. were collected at higher elevations (1770–2000 m) than the other three taxa (685–1230 m), suggesting differences in ecological niches.

Amongst the four species of the P. subarnoldii group studied here, P. brachyblepharum and P. eleonomum are the most phenotypically similar ( Table 5), the only discriminating character between these two taxa being the average length of the cilia present at the lobe margins. There seems to be a gap between the two taxa around the mean value 3.5 mm ( Fig. 10 ), but this will have to be confirmed with more specimens.

As demonstrated by phylogenetic analysis of a 3-locus data matrix ( Fig. 3 ), P. brachyblepharum belongs to a strongly supported radiation, comprising ten species, including this one, either described as new in this paper or already described. Five of them are possibly endemic to Réunion or the Mascarenes, three also occur on Madagascar, and two also occur in the Paleotropics. In our ITS phylogeny ( Fig. 4 ), P. rubromarginatum , so far only known from Thailand, belongs to the same clade.

Additional specimens examined (paratypes):

Specimens with DNA data:— FRANCE. Réunion: La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 870–875 m, 21°07’00–03”S, 55°39’00–06”E, in submontane Pandanus wet thicket, in an overall NE orientation, on bark of trunk and branches of Pandanus montanus , 24 August 2013, D. Masson 974.4443 ( LG) , 23 August 2015, D. Masson 974.4814 ( LG) , 18 August 2017, D. Masson 974.4990, 974.4992, 974.4999 ( LG) .

Specimens without DNA data:— FRANCE. Réunion: La Plaine-des-Palmistes, Ligne Deux Mille en Dessous, elev. 870 m, 21°07’00–03”S, 55°39’03–06”E, in submontane Pandanus wet thicket, in overall NE orientation, on bark of trunk and branch of Pandanus montanus , 24 August 2013, D. Masson 974.4444 (REU), 23 August 2015, D. Masson 974.4828 (Hb. DM).

Specimens studied for comparison:

Parmotrema rubromarginatum .— THAILAND. Nakhon Ratchasima Province: Khao Yai National Park , along the trail from the entrance to the old golf course, elev. 829 m, 14°25’07.29”N, 101°22’18.52”E, on Mangifera indica , secondary forest, 28 November 2003, W. Polyiam 22779 ( RAMK) .

Parmotrema subarnoldii .— MADAGASCAR. Analamanga: Angavokely Forest Station , E of Antananarivo, elev. 1770–1780 m, 18°55’37.9”S, 47°44’15.2”E, summit with degraded ericaceous shrub, montane forest and granitic rocks with Vaccinium madagascariense , on branches, 14 October 2008, E. Sérusiaux 18 ( LG); Vakinankaratra: forêt de Manjakatompo, massif de l’Ankaratra, elev. 2000 m, tronc d’arbre en lisière, 30 July 1956, H. des Abbayes 2357 ( REN 000061 , lectotype; US [image!], isolectotype) .

RWANDA. Forêt de Rugege , entre Garamba et la plantation de Gisakura, elev. ca. 1900 m, petites lianes mortes (cf. Embelia ), fond de vallon dans un défrichement de la forêt de montagne, 01 September 1974, J. Lambinon 74/1038 ( LG) .

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 9. Parmotrema brachyblepharum. A: Distribution on Réunion (UTM 2×2 km grid system); B: Bioclimatic characteristics of collection site (abbreviations and threshold values for thermotype and ombrotype horizons from Rivas-Martínez et al. 2011: 17–18); C: Type locality, a disturbed submontane Pandanus wet thicket crossed by a track; D: Sorediate lobe with marginal, linear discontinuous soralia and subgranulose soredia (Masson 974.4443); E: Gross morphology of thallus (holotype). Scale bars: A = 10 km; D = 1 mm; E = 10 mm.

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.