Melanelia stygia (L.) Essl.

Szczepanska, Katarzyna, Guzow-Krzeminska, Beata & Urbaniak, Jacek, 2021, Infraspecific variation of some brown Parmeliae (in Poland) - a comparison of ITS rDNA and non-molecular characters, MycoKeys 85, pp. 127-160 : 127

Melanelia stygia (L.) Essl.

Lichen stygius Mycotaxon 7:47 (1978) ≡ Lichen stygius L., Species Plantarum 2:1143 (1753).

Description.

M. stygia has foliose thallus, composed of 0.25-1.5 mm broad, smooth and usually distinctly convex lobes ( Szczepańska and Kossowska 2017). The upper surface is glossy, dark brown to almost black. The lower surface is dark brown to black, paler near the margins, with single, dark rhizines. Pseudocyphellae in this species are numerous, rounded or slightly elongated and laminal - clearly visible on the upper surface of the lobes. Pycnidia are also common, globose, laminal and immersed with hyaline, bacilliform conidia (3.5-5 × 1 µm). Apothecia are laminal, constricted at the base and 0.5-6 mm in diameter. Ascospores are hyaline, ellipsoid to oblong-ellipsoid, 6-8 × 4-6 μm in size.

Chemistry.

Protocetraric and fumarprotocetraric acids (Race 1) or no substances detected (Race 6).

Distribution.

M. stygia is a circumpolar and arctic-alpine species occurring mainly on siliceous rocks in upper mountain areas in North America and Europe ( Otte et al. 2005). Available molecular data concern only a few samples collected in North America (Greenland) and North (Iceland, Finland, Norway) and West (Italy) Europe.

Haplotypes differentiation.

Amongst five identified haplotypes in Melanelia stygia (n = 19), all newly-sequenced specimens (five from Poland, one from Austria and one from the Czech Republic) have the same haplotype, previously reported from Austria, Finland, Italy and Norway (Fig. 5 , Table 2 ). It differs from the haplotype identified in another Finnish specimen in two positions. Two Greenlandic specimens have the same haplotype that differs from the most common one in five positions. Four Icelandic samples have an identical haplotype that differs from the Norwegian sample in five positions; however, these samples differ in at least 13 positions from other haplotypes of M. stygia . Moreover, these Icelandic and one Norwegian samples form a separate clade shown in Fig. 1 , in contrast to the remaining specimens of M. stygia . These molecular data suggest that these lineages may represent phenotypically indistinguishable cryptic species.

Figures

Figure 1. Phylogenetic relationships of Melanelia spp., based on Bayesian analysis of the ITS rDNA dataset. Posterior probabilities and Maximum Likelihood bootstrap values are shown near the internal branches. Newly-generated sequences are additionally described with isolate numbers following the species names and are marked in bold. GenBank accession numbers of sequences downloaded from GenBank are listed on the tree with species names.

Figure 5. Haplotype network, based on ITS rDNA sequences from specimens of Melanelia stygia. Newly-generated sequences are described with isolate numbers preceding the species names. Sequences downloaded from GenBank are described with their accession numbers. Mutational changes are presented as numbers in brackets near lines between haplotypes.