Mazosia, A. MASSAL.

Ertz, Damien & Lebreton, Élise, 2024, A new corticolous species of Mazosia A. Massal. (Roccellaceae, Arthoniales) from Guadeloupe, remarkable by its byssoid thallus, Cryptogamie, Mycologie 20 (1), pp. 1-10 : 9

WORLDWIDE KEY TO CORTICOLOUS SPECIES OF THE GENUS MAZOSIA A. MASSAL. (UPDATED FROM Sakata et al. 2017)

1. Thallus byssoid; ascospores 1-septate; pycnidia stipitate ...................... M. byssoidea Lebreton & Ertz , sp. nov.

— Thallus compact; ascospores 3-septate; pycnidia not stipitate ....................................................................... 2

2. Apothecia prominently elevated above the thallus, sharply to slightly delimited in outline .......................... 3

— Apothecia slightly elevated above the thallus, semi-immersed to immersed, not sharply delimited in outline .. .................................................................................................................................................................... 6

3. Thallus with irregular and partly confluent verrucae; apothecial margin warty and irregular ........................... ...................................................................................................... M. viridescens (Fée) Aptroot & M.Cáceres

— Thallus slightly verrucose or almost smooth; apothecial margin crenulate .................................................... 4

4. Epihymenium with crystals ......................................................................................................................... 5

— Epihymenium lacking crystals ............................................................... M. bruguierae A.Sakata & H.Harada

5. Thallus slightly verrucose; apothecia prominently elevated above the thallus, slightly delimited in outline .................................................................................................... M. carnea (Eckfeldt) Aptroot & M.Cáceres

— Thallus smooth; apothecia prominently elevated above the thallus, sharply delimited in outline ..................... .......................................................................................................................... M. endonigra (Nyl.) Sparrius

6. Ascospores (15-)18-20 × 3-4 µm ............................................................... M. japonica A.Sakata & H.Harada

— Ascospores larger ......................................................................................................................................... 7

7. Ascospores (17-)19-25(-27) × 4-5.5(-6.5) µm; thallus with psoromic acid ..................... M. corticola Kantvilas

— Ascospores (22-)28-35 × 4-7 µm; thallus lacking psoromic acid .......................... M. leptosticta (Nyl.) Sparrius