Parmotrema subdeflectens 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 : 104-107

Parmotrema subdeflectens D.M. Masson, Magain & Sérus. , sp. nov. MycoBank no. 853879

Diagnosis. Similar to Parmotrema deflectens (Kurok.) Streimann , but differs by the presence in the medulla of protolichesterinic acid in addition to alectoronic and protocetraric acids and the marginal cilia often branched.

Holotype:— FRANCE. Réunion: Cilaos, Ravine des Calumets , elev. 1220 m, 21°09’16”S, 55°29’31”E, in disturbed leeward montane rainforest, in a ravine in an overall SSW orientation, on bark of a trunk of Erica reunionensis , 21 August 2012, D. Masson 974.3943 (MNHN-PC-PC0088082).

GenBank accession numbers: ITS ( PP 840404), mtSSU ( PP 842523), EF1-α ( PP 852793).

( Fig. 39 )

Thallus foliose, loosely to moderately adnate, membranaceous to subcoriaceous, up to 8 × 17 cm. Lobes irregular, imbricate, 4–16 mm wide, broadly concave, sometimes convolute when sorediate, with margins undulated, crenate to somewhat shortly laciniate when sorediate, mostly ascendant, ciliate ( Fig. 39E ). Cilia conspicuous, black, some with coppery glints (pigment), numerous and ± evenly distributed, simple or 1–3 times branched, ca. 0.05–0.09 mm in diameter at the base, up to 7 mm long. Upper surface pale greenish grey, dull, emaculate or faintly punctiform white-maculate, distinctly punctiform white-maculate near primordia of apothecia, smooth, often slightly wrinkled and finely cracked in the older parts, sorediate, lacking schizidia, pustules, dactyls, phyllidia and isidia. Soralia either terminal labriform or subcapitate on very short laciniae (up to 1 mm long) ( Fig. 39C ), or marginal and ± linear labriform ( Fig. 39D ); rarely submarginal, and then subcapitate. Soredia subgranulose, (30)– 41.3 –(60) µm in diameter (n = 180, from 6 thalli, SD = 6.4 µm), sometimes tinged with orange. Medulla white, at times orange-tinged in soralia and in patches near the lower cortex. Lower surface smooth or slightly rugulose, moderately shiny, black to the margin, or with a chestnut brown or buff erhizinate marginal zone (ca. 1–8 mm wide) at main lobe tips, frequently mottled or fully ivory at the tip of sorediate lobes. Rhizines in scattered groups, concolor to the lower surface, sometimes with whitish tip when young, mostly simple and short, but in places 1–2 times branched and elongated (up to 3.5 mm long). Apothecia rare, submarginal, only primordia seen (Madagascan specimen). Pycnidia very rare, submarginal towards apices, black. Conidia not found (3 pycnidia investigated). Upper cortex palisade plectenchymatous, not fragile, (13)– 18.7 –(25) µm thick. Algal layer ± continuous, (10)– 19.5 –(26) µm thick. Medulla (60)– 93.0 –(120) µm thick. Lower cortex prosoplectenchymatous, (13)– 15.4– (20) µm thick.

Chemistry:— Spot tests and fluorescence: upper cortex K+ yellow, UV−; medulla K−, C−, KC + pink, P+ orange, UV+ white; pigmented medulla and soredia K+ purple. Secondary metabolites ( TLC): upper cortex with atranorin and chloroatranorin; medulla with protocetraric acid (major), alectoronic acid (major), protolichesterinic acid (major), lichesterinic acid (trace), ± skyrin, ± parietin; ± an undetermined ciliary pigment: P1.

Etymology:—The specific epithet refers to the phenotypically similar Parmotrema deflectens .

Geographical distribution:—So far Parmotrema subdeflectens seems to be a localized and rare species in Réunion. It has been found at three localities, in three UTM 1× 1 km grid cells (or three UTM 2× 2 km grid cells, Fig. 39A ), on the southern flank of the Piton des Neiges massif, in or near the Cirque de Cilaos, at elevations of between 1050 and 1220 m. In addition to Réunion, the species has been collected on the Montagne d’Ambre, in the north of Madagascar, at an elevation of 1000 m.

Ecology:— Parmotrema subdeflectens is a corticolous lichen, growing on branches and trunks of shrubs (e.g. Erica reunionensis , Turraea sp. ) in disturbed and undisturbed leeward submontane forests on Réunion; on the trunk of Cinchona sp. in a plantation in Madagascar. The bioclimatic features of the Reunionese localities are: bioclimate = pluvial tropical, thermotype belt = lower mesotropical (420 ≤ It ≤ 470), ombrotype belt = upper humid (9.3 ≤ Io ≤ 11.1) ( Fig. 39B ). The bioclimate of the Malagasy locality is also pluvial tropical, with thermotype belt = upper thermotropical (It = 554), ombrotype belt = lower hyperhumid (Io = 16.4).

Notes:— Parmotrema subdeflectens , P. cf. deflectens from Réunion and Madagascar, and P. deflectens are phenotypically similar taxa. However, they differ in several morphological and chemical characteristics ( Table 13). The most salient diagnostic feature is the presence in the medulla of protolichesterinic acid (aliphatic acid) as a major substance together with protocetraric acid (β -orcinol depsidone) and alectoronic acid (orcinol depsidone). To our knowledge, no other Parmotrema has such a combination of secondary metabolites, except for the phylogenetically related P. nemorum . Soredium size has proved to be an important taxonomic character in distinguishing morphologically similar species in some genera of lichenized fungi (e.g. Obermayer & Mayrhofer 2007, Ohmura et al. 2008).Comparison of the average soredium size suggests that P. subdeflectens has slightly, but significantly (Wilcoxon-Mann-Whitney test, U = 0, n 1 = 6, n 2 = 2, P = 0.036, one-tailed), smaller soredia than P. cf. deflectens . Unfortunately, we do not have measurements for P. deflectens .

As is the case with P. deflectens ( Krog & Swinscow 1982) and P. cf. negrosorientale (this work), the yellow anthraquinone parietin (together with the bis-anthraquinone skyrin) was detected in some old soredia of one P. subdeflectens thallus (Masson 974.5160). Interestingly, skyrin was also found as an accessory substance in the soredia of P. cf. deflectens and P. cf. negrosorientale . On the other hand, its occurrence in P. deflectens has not been clearly established (see the entry for P. cf. deflectens ).

Phylogenetic analysis of a 3-locus data matrix showed that the sorediate P. subdeflectens is sister to the fertile P. nemorum in a well-supported clade, both taxa being strongly supported as distinct by Stacey and bPP analyses ( Fig. 3 ). They share the same medullary chemistry, with alectoronic, protocetraric and protolichesterinic acids as major secondary metabolites. Both species further belong to a strongly supported radiation, comprising a total of ten species, either described as new in this paper (eight) or already described (two).

Additional specimens examined (paratypes):— FRANCE. Réunion: Cilaos, Ravine des Calumets, elev. 1200 m, 21°09’20”S, 55°29’31”E, in secondary leeward montane rainforest, in a ravine in an overall South orientation, on bark of a branch of an unidentified shrub, 21 August 2012, D. Masson 974.3946 ( LG); Saint-Louis, Les Makes, Bois Bon Accueil, elev. 1050 m, 21°11’49”S, 55°23’48”E, in leeward submontane rainforest, in an overall South orientation, on bark of a branch of Turraea sp. , 28 August 2017, D. Masson 974.5160 ( LG) .

MADAGASCAR. Diana : Montagne d’Ambre, poste des Roussettes, elev. 1000 m, 12°31’37”S, 49°10’18”E, sur tronc de Quinquina en plantation claire, 31 October 1956, H. des Abbayes 3144 ( REN 000059 ) .

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 39. Parmotrema subdeflectens. 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: Sorediate lobes with marginal and often branched cilia, and terminal labriform or subcapitate soralia on very short laciniae (holotype); D: Sorediate lobes with marginal and ± linear labriform soralia (Masson 974.3946); E: Gross morphology of thallus (Masson 974.3946). Scale bars:A = 10 km; C = 4 mm; D = 3 mm; E = 10 mm.