Parmotrema cf. deflectens (Kurok.) Streimann (1986: 93) MycoBank

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 : 44-45

Parmotrema cf. deflectens (Kurok.) Streimann (1986: 93) MycoBank no. 129347

Parmelia deflectens Kurok. (1979: 130) MycoBank no. 115854

Type:— PAPUA NEW GUINEA. Morobe District: Bulolo , 780 m, 12 November 1965, S. Kurokawa 5810 ( TNS!, holotype) .

( Fig. 18 )

Thallus foliose, moderately adnate, membranaceous, ca. 6 × 3.5 cm (thallus fragmented). Lobes imbricate, irregularly branched, up to 10 mm wide; margins entire to crenate, conspicuously ciliate ( Fig. 18C ); apices rounded. Cilia black, some with coppery glint, numerous, simple or rarely once bifurcate, up to 4 mm long. Upper surface pale yellowish grey, emaculate or faintly punctiform white-maculate, smooth or ± rugose and cracked in places, sorediate, lacking pustules, dactyls, phyllidia and isidia; cortex fragile, flaking (schizidia?). Soralia marginal, linear interrupted to somewhat labriform ( Fig. 18C ), rarely submarginal and ± capitiform. Soredia subgranulose, (35)– 45.5 –(60) µm in diameter (n = 30, SD = 7.2 µm), sometimes tinged with orange ( Fig. 18D ). Medulla white, at times orange-tinged in soralia. Lower surface black, rugulose, ± shiny centrally, erhizinate margin duller, chestnut brown, pale tan to ivory, ca. 0.5–6 mm wide. Rhizines concolor to the lower surface, in scattered groups, simple, rarely furcate, short, up to 1 mm long. Apothecia not present. Pycnidia not present.

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), ± skyrin in soralia; it was not possible to extract the pigment(s) that give the coppery glint to some cilia.

Geographical distribution:—According to Louwhoff (2001), Parmotrema deflectens is a broadly paleotropical species. It is known from East Africa (at least in Tanzania; Krog & Swinscow 1981, 1982), Papua New Guinea ( Kurokawa 1979, Louwhoff & Elix 1999) and southern China ( Chen et al. 2005). A unique specimen collected by Krog & Timdal at 1150 m a.s.l. near Cilaos, on Réunion Island ( Fig. 18A ), probably belongs to this species, as well as a specimen collected by des Abbayes in Madagascar (at 920 m a.s.l.) and cited by him under the name Parmelia subarnoldii ( des Abbayes 1961) .

Ecology:—According to the specimen examined, the fragmentary thallus collected on Réunion was corticolous. Unfortunately, the label does not provide any information on the phorophyte or the type of habitat. The bioclimate of the town of Cilaos, nearby the collection site on Réunion, is pluviseasonal tropical, thermotype belt = lower mesotropical (It = 427), ombrotype belt = upper humid (Io = 9.3) ( Fig. 18B ). The bioclimate of the Malagasy locality is pluvial tropical, with thermotype belt = upper thermotropical (It = 498), ombrotype belt = lower humid (Io = 7.5).

In Papua New Guinea, Parmotrema deflectens is a rare corticolous species, occurring in a wide range of elevations between 780 and 2600 m ( Kurokawa 1979, Louwhoff & Elix 1999).

Notes:—The Malagasy specimen is similar to the one from Réunion. In particular, it has the same chemistry, a fragile upper cortex, and soredia sometimes tinged with orange. The marginal cilia are, however, more unevenly distributed, the soralia tend to develop at the tips of short laciniae and are more capitate, and the underside is somewhat brighter. We assigned both collections to Parmotrema deflectens , this taxon being the only one currently described possessing both soralia and the combination of alectoronic and protocetraric acids as major extrolites. Krog & Swinscow (1981, 1988) considered it to be a chemotype of P. subarnoldii . In contrast, Kurokawa (1979), Louwhoff & Elix (1999) and Chen et al. (2005) treated it as a distinct species. However, the two specimens from Réunion and Madagascar differ from the two Papuan specimens of P. deflectens we examined (including the holotype) in having a fragile upper cortex that flakes off and in the presence of skyrin in some soralia. Skyrin is neither cited in the protologue ( Kurokawa 1979) nor present in the holotype. In their monograph on the genus Parmotrema in Papua New Guinea, Louwhoff & Elix (1999) provide contradictory information on the presence of skyrin in P. deflectens . It is either cited as an accessory substance (p. 46) or reported as being constantly lacking (p. 24 and p. 48). Krog & Swinscow (1982) reported a specimen from Tanzania whose soralia were coloured yellow-orange, the pigment involved being parietin, not skyrin. Environmental factors may be responsible for these differences, but we believe that a complex of species sharing the same medullary chemistry (alectoronic and protocetraric acids) and the presence of soralia and marginal cilia should also be considered. In support of this point of view, a specimen from Burundi in LG is ciliate, sorediate, and with medulla containing alectoronic and protocetraric acids, but has linear marginal soralia of the same type as those of P. austrosinense and producing farinose soredia. Another example is one of the syntypes of P. subarnoldii ( Table 4, REN 000 058) with farinose to subgranulose soredia that arise mainly at the tip of short laciniae. Molecular data that could test for the existence of such a group of species are so far unfortunately lacking.

Specimens examined:— FRANCE. Réunion: Cilaos , along trail (GR R2) in canyon just W of Cilaos town, elev. 1150 m, 02 October 1996, H. Krog RE34/2 & E. Timdal (O) .

MADAGASCAR. Alaotra-Mangoro : Andasibe, forêt d’Analamazaotra, elev. 920 m, 18°56’S, 48°25’E, sur tronc d’arbre en forêt, 06 August 1956, H. des Abbayes 250 ( REN 000055 ) .

Specimen studied for comparison:— BURUNDI. Bujumbura Rural: Gakara , elev. 1960 m, tronc d’eucalyptus, bord de route, 05 April 1980, J. Lambinon 80/137 (LG) .

PAPUA NEW GUINEA. Eastern Highlands Province: Mount Gahavisuka Provincial Park , 11 km N of Goroka, along trail to lookout, elev. 2400 m, 6°01’40”S, 145°25’00”E, little disturbed mossy mountain forest, 03 August 1992, P. Diederich 10402 (Hb. P. Diederich) .

Figures

FIGURE 18. Parmotrema cf. deflectens. 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: Ciliate sorediate lobes with marginal, linear interrupted to somewhat labriform soralia (Krog RE34/2 & Timdal); D: small marginal soralia tinged orange by skyrin, and fragile cortex cracking (Krog RE34/2 & Timdal). Scale bars:A = 10 km; C = 5 mm; D = 1 mm.