Megalaria pachaylenophila Phraphuchamnong, Buaruang & Lumbsch, sp. nov.

Phraphuchamnong, Phimpisa, Nelsen, Matthew P., Distefano, Isabel, Mercado-Diaz, Joel A., Parnmen, Sittiporn, Rangsiruji, Achariya, Buaruang, Kawinnat, Luecking, Robert & Lumbsch, H. Thorsten, 2022, A new species of Megalaria (Ramalinaceae, Ascomycota) from Thailand, and recognition of subgenus Catillochroma, MycoKeys 93, pp. 149-163 : 149

Megalaria pachaylenophila Phraphuchamnong, Buaruang & Lumbsch, sp. nov.

Fig. 2

Type.

Thailand. Chumphon province: Pathio District; Tambon Pak Klong , 10°53.255'N, 99°28.649'E, 5 m elev., mangrove forest, on bark of Rhizophora mucronata , 28 March 2019; Kawinnat Buaruang et al., Chum 2771 (RAMK 034555- holotype, F-isotype) .

Diagnosis.

Similar to Megalaria bengalensis , but differs in an ochre to brownish apothecial disc (black in M. bengalensis ) and in lacking isidia and secondary products (atranorin in M. bengalensis ).

Etymology.

The specific epithet refers to the English translation ( Pāchāylen) of the Thai name for mangrove (ป่าชายเลน), and philos (greek) = friend, referring to the ecological preference of the new species.

Description.

Thallus crustose, corticolous, gray to olive-gray or greenish gray, up to 10 cm in diameter, smooth, cracked, without soredia or isidia. Apothecia biatorine, plain and flat, becoming slightly convex with age, circular in outline or becoming deformed, sessile, 0.3-0.8 mm in diameter; margins black, shining, contrasting strongly with the coloration of the discs; discs beige to brownish, epruinose. Epihymenium 2-5 μm thick, not pigmented or light beige, K-, N-. Hymenium 75-100 μm thick, hyaline, not inspersed. Subhymenium 10-20 μm thick, hyaline. Central hypothecium 50-80 μm thick, pigmented red-brown, K+ wine-red, N-; lateral hypothecium blue to blue-black, K-, N+ purple. Excipulum 15-25 μm thick, comprised of thick, gelatinized hyaline to blue hyphae, not inspersed with crystals, K-, N+ purple. Asci cylindrical to clavate, eight-spored; ascospores narrowly ellipsoid, hyaline, one-septate (rarely simple), thin walled, not halonate, (9-)11-15 × 4-5 μm. Pycnidia not seen.

Secondary metabolites. Thallus K-, C-, and KC-, UV-, no lichen substances found using TLC.

Distribution and ecology.

The new species was found in the south-eastern province of Chumphon where it was growing in old mangrove forests on the bark of Excoecaria agallocha , Hibiscus tiliaceus , Rhizophora apiculata , and Rhizophora mucronata .

Notes.

In the phylogenetic tree, Megalaria pachaylenophila and M. bengalensis cluster together, and indeed, their apothecial anatomy is very similar. However, they can easily be separated by the isidiate thallus in the latter. No other species in Megalaria sens. lat. is known to form a beige or brownish apothecial disk. Interestingly, this can be found in some species of Megalaria (Lopezaria) versicolor which is the sister clade to Megalaria pachaylenophila and M. bengalensis . Additional superficially similar species include the North American M. beechingii , which differs in having purple-black to jet black apothecia, a margin that is concolorous with disc, and broadly ellipsoid ascospores, that are often kidney bean-shaped ( Lendemer 2007). Catillochroma phayapipakianum , which was recently described from Thailand ( Kalb 2022) and is transferred to Megalaria below, is readily distinguished from M. pachaylenophila by having larger (16-26 μm long), narrowly ellipsoid to fusiform, ascospores, and containing atranorin, zeorin, and fumarprotocetraric acid.

Additional specimens examined.

Thailand. Chumphon province: Pathio District; Chum Kho sub-district, mangrove forest, on bark of Rhizophora apiculata , 15 Feb 2018; K. Buaruang et al., Chum 2024 (RAMK), 2028 (RAMK), 2072 (RAMK) .

Below we propose new combinations to reflect the broad recognition of Megalaria and the recognition of the Catillochroma clade at subgeneric level:

Figures

Figure 2. Megalaria pachaylenophila (RAMK 36122) A thallus B thallus and ascomata C apothecia cross section D ascospore. Photos by P. Phraphuchamnong. Scale bars: 1 cm (A); 0.5 mm (B); 200 µm (C); 10 µm (D).