Tephromela multireflexa Aptroot & M. F. Souza 2023, sp. nov.

Overview & Synopsis

Tephromela multireflexa Aptroot & M.F.Souza, sp. nov.(Fig. 3A, B)Similar to Tephromela atra, but corticolous and differing in the apothecium thalline margin containing lichexanthone in the cortex and α- collatolic acid in the medulla.HOLOTYPE. — Brazil. Mato Grosso, Cuiabá, Chapada dos Guimarães, Pousada do Parque private area, alt. 700 m, 15°26’50”S, 55°49’50”W, on bark, 12-19.IX.2020, A. Aptroot & M.F. Souza 81950 (holo-, CGMS; iso-, ABL).ETYMOLOGY. — The name refers to the two different UV-reflectant colours.CHEMISTRY. — Thallus UV-, C-, P-, K-, apothecium margin UV+ yellow, apothecium medulla UV+ bluish-green. With lichexanthone (apothecial margins) and α- collatolic acid detected by TLC.ECOLOGY AND DISTRIBUTION. — On exposed tree branch in Cerrado forest; known only from the type collection from Brazil.MYCOBANK. — MB 846314.DESCRIPTIONThallus crustose, mineral to greenish-grey, rimose to areolate, minutely verrucose, somewhat glossy, c. 0.3 mm thick, areoles 0.05-0.2 mm in diam. Prothallus absent. Photobiont an unicellular green alga, arranged in one layer below the cortex. Apothecia present, sessile, roundish to lobate, homogeneously distributed on the thallus. Disk black, 0.5- 2.5 mm in diam., flat to slightly convex, epruinose. Thalline margin concolorous with the thallus, glossy, c. 0.3 mm wide, raised above the level of the disk, minutely crenate. Proper exciple thickest at the base, becoming thinner at the edges, hyaline. Exciple with crystals that after treatment with K partly dissolve. Hymenium c. 90-180 µm thick, blue, colour in K unchanged. Subhymenium 50-70 µm thick, dark blue, in K dark purple. Epihymenium dark purple, pigment in K dissolving leaving the blue of the hymenium. Paraphyses simple, septate, 2-3 µm wide, with 4-6 µm wide hyaline apical cells, surrounded by lilac pigmented gel. Hypothecium 0-80 µm thick, pale yellow, intensifying orange yellow in K. Asci slightly clavate, 70-55 µm tall, 8-spored. Ascospores simple, hyaline, ellipsoid, 14-16×5-6.5 µm, wall 1 µm thick. Pycnidia not observed.DISCUSSIONThe substance α- collatolic acid is commonly occurring in the genus Tephromela, while lichexanthone is so far only reported from T. velloziae. In that species, and in two further species described below, lichexanthone occurs in the thallus and the apothecium margins, not only in the thallus. The new species is the first in the genus that combines both lichexanthone and α- collatolic acid.