Pyrenula gigaspora Soto-Medina, Aptroot & Lücking, sp. nov.

(Fig. 3)

A new Pyrenula similar to P. montocensis Lücking, but differing by its larger ascospores of 125-140 ×40-45 µm.

HOLOTYPE. — Colombia. Valle del Cauca, Municipio Bugalagrande, Hacienda la Venta, 4°11’56.2”N, 76°03’56.2”W, 1166 m, bosque seco tropical, 23-27.IX.2020, Soto Medina s.n. (holo-, TULV).

ETYMOLOGY. — The epithet refers to the giant ascospores.

ECOLOGY. — The species grows on branches in the interior of the tropical dry forest.

CHEMISTRY. — Thallus UV–, K–, C–; medulla C–, K–, KC–.

MYCOBANK. — MB 849071.

DESCRIPTION

Thallus crustose, corticate, olive-green, with abundant spots with crystals (pseudocyphellae). Photobiont of a species of Trentepohlia. Perithecia solitary, dispersed, hemispherical but mostly immersed and only upper portion erumpent from the thallus, basally and in part laterally covered by thallus, c. 0.9-2 mm diam. Ostioles apical, flat, black. Hamathecium not inspersed. Asci 2-spored. Ascospores becoming dark brown, 3-septate, narrowly ellipsoid to almost fusiform, 125-140× 40-45 µm, ends rounded, lumina more or less diamond-shaped, separated from the walls by a thickened endospore layer. Pycnidia not observed.

NOTES

This new species is characterized by unusually large ascospores occurring singly in the asci. Thus far, the largest 3-septate ascospores in the genus known were those of Pyrenula montocensis Lücking, which are up to 90 ×30 µm in size, and P. subpraelucida Müll. Arg., which are up to 75 ×30 µm in size and with small terminal lumina. Some Pyrenula species with muriform ascospores have much larger ascospores, in the order of 200 µm. The latter also differs in thallus morphology, whereas P.montocensis agrees with the new species in the pseudocyphellate thallus and both species are undoubtedly closely related. This thallus morphology is also found in the common P. quassiicola Fée which, however, has much smaller ascospores (25-40 × 8-15 µm) (Aptroot et al. 2008). The new species would key out in the recent world key to the family (Aptroot 2021) in couplet B72 with: ascospores 125-140×40-45 µm.