Parmotrema aurantioreagens D. M. Masson & Serus., sp. nov.
Creators: name: Masson, Didier
name: Magain, Nicolas
name: Sérusiaux, Emmanuël
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Lecanoromycetes
Lecanorales
Parmeliaceae
Parmotrema
Parmotrema aurantioreagens

description: Parmotrema aurantioreagens D.M. Masson & Sérus., sp. nov. MycoBank no. 853865
Diagnosis. Shares with P. explanatum (Hale) Hale the barbatic acid chemosyndrome, a rare medullary chemistry in the genus Parmotrema, but differs chiefly by the presence of marginal cilia, soralia, a maculate upper surface and the corticolous habit.
Holotype:— FRANCE. Réunion: Sainte-Suzanne, les Hauts de la Perrière, elev. 765 m, 20°58’44”S, 55°33’52”E, in disturbed windward submontane rainforest in overall NE orientation, on roadside, on bark of a branch of an undetermined tree, 11 August 2015, D. Masson 974.4598 (MNHN-PC-PC0088068).
GenBank accession numbers: ITS (PP 840413), mtSSU (PP 842550), EF1-α (PP 852812).
(Fig. 7)
Thallus foliose, loosely adnate, membranaceous, ca. 12 × 8 cm (thallus fragmented). Lobes irregular, imbricate, 5–11 mm wide, irregularly wrinkled, sometimes convolute, with margins undulating, crenate to laciniate when sorediate, rarely lobulate, ciliate (Fig. 7E). Cilia black, unevenly distributed (Fig. 7C), simple, very rarely 1–2 times branched, ca. 0.04–0.05 mm in diameter at the base, up to 3 mm long. Upper surface pale greenish grey, mat or slightly shiny, faintly to clearly effigurate white-maculate, slightly wrinkled, rarely smooth, sometimes cracked in the older parts, sorediate, lacking schizidia, pustules, dactyls, phyllidia and isidia. Soralia marginal at the tip of short laciniae (Fig. 7D), occasionally somewhat labriform. Soredia subgranulose, (30)– 42.3 –(60) µm in diameter (n = 30, from 1 thallus, SD = 7.7 µm). Lobules occasional, marginal, up to 2 × 2.5 mm. Medulla white throughout. Lower surface smooth or granulose, rather dull in the central part, shiny in the periphery, black to the margin, or with an ochraceous-buff erhizinate marginal zone (ca. 1–3.5 mm wide) at main lobe tips; sorediate laciniae often ivory mottled (Fig. 7D). Rhizines ± in clusters, sometimes rather dense, concolor to the lower surface, often with pale tip when young, simple, rarely 1–2 times branched, slender, heterogeneous in size, up to 2.5 mm long. Apothecia not present. Pycnidia not present. Upper cortex palisade plectenchymatous, not fragile, (9)– 14.2 –(25) µm thick. Algal layer discontinuous, (0)– 17.0 –(30) µm thick. Medulla (67)– 77.0 –(83) µm thick. Lower cortex prosoplectenchymatous, (11)– 14.2– (17) µm thick.
Chemistry:— Spot tests and fluorescence: upper cortex K+ yellow, UV−; medulla K−, C + orange, KC + orange, P−, UV± bluish-white. Secondary metabolites (TLC): upper cortex with atranorin and chloroatranorin; medulla with barbatic acid (major), 4- O -demethylbarbatic acid (major), and obtusatic acid (trace).
Etymology:—The specific epithet refers to the orange reaction of the medulla produced by the C and KC spot tests.
Geographical distribution: —So far known from a single locality on Réunion Island, at an elevation of 765 m, on the northern slope of the Piton des Neiges massif (Fig. 7A).
Ecology:—The species was found on the bark of a branch of an undetermined tree, on the side of a road through a degraded windward submontane rainforest covering a northeastern facing slope. Various alien plants invaded this forest, mainly Strawberry Guava (Psidium cattleianum Afzel. ex Sabine). The bioclimate of the locality is pluvial tropical, thermotype belt = upper thermotropical (It = 500), ombrotype belt = lower hyperhumid (Io = 16.2) (Fig. 7B).
Notes:— Parmotrema aurantioreagens is primarily characterized by its medullary chemistry, which is uncommon in the genus Parmotrema. Only one other species, P. explanatum, has both barbatic and 4- O -demethylbarbatic acids as major substances (Hale 1965b, label of the isotype kept in the US herbarium). However, P. explanatum lacks marginal cilia, vegetative propagules, and maculation on the upper surface, and its medulla is twice as thick (Hale 1965b). Parmotrema insuetum (Kurok.) Hale, P. matudae (Kurok.) Hale ex DePriest & B.W. Hale and P. neodiffractaicum R.S. Egan are also sorediate species with barbatic acid in the medulla, but they are eciliate, emaculate, and they all contain diffractaic acid as the major substance, not 4- O -demethylbarbatic acid (Kurokawa 1984, Louwhoff & Elix 1999, Egan et al. 2016).
As demonstrated by our phylogenetic analysis of a 3-locus data matrix (Fig. 3), Parmotrema aurantioreagens belongs to a supported clade, comprising two other species either described as new in this paper (P. mascarenense) or already described (P. meiospermum). All three are possible endemics to the Mascarenes.
description: Published as part of 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, pp. 1-138 in Phytotaxa 657 (1) on pages 20-22, DOI: 10.11646/phytotaxa.657.1.1, http://zenodo.org/record/13217474