Astrothelium rogitamae Simijaca, Lücking & Moncada, 2021

Simijaca, Diego, Lücking, Robert & Moncada, Bibiana, 2021, Two new species of Astrothelium (Trypetheliaceae) with amyloid ascospores inhabiting the canopy of Quercus humboldtii trees in Colombia, Phytotaxa 508 (2), pp. 229-234 : 231-232

Astrothelium rogitamae Simijaca, Lücking & Moncada , sp. nov ( Fig. 2 )

Mycobank IF558500

Differing from Astrothelium flavoduplex in having trypethelioid ascomata without forming pseudostroma, being solitary and with a conspicuous yellow pruina, as well as the IKI+ blue ascospores.

Etymology: The epithet refers to the type locality, the ROGITAMA reserve.

Holotype:— COLOMBIA. Dept. Boyacá: Arcabuco, Vereda Peñas Blancas, Sector Mordoñal , Reserva Natural ROGITAMA, 05º47’47.3”N, 73º26’56.0”W, elev. 2530 m, in oak forest, on bark of Quercus humboldtii , 12 July 2015, Simijaca et al. 2706 ( UDBC, holotype!)

Thallus corticolous, distinctly corticate, light brownish to greenish grey, smooth to uneven. Ascomata solitary, with apical, separate ostioles, 1–1.3 mm diam, immersed-erumpent, covered by thallus except for the protruding ostiolar area, the latter with yellow pigment pruina, darkening when dry. Hamathecium inspersed. Ascospores 4 per ascus, muriform, with 9–11 primary transverse septa (the median cells further divided by secondary transverse septa) and 1–3 longitudinal septa, with the distinct diamond-shaped lumina and with a slight constriction at the median septum, narrowly ellipsoid to fusiform, 100–120 × 27–30 µm, IKI+ blue.

Chemistry: Secondary substances absent except for a yellow pigment around the ostiole; thallus surface UV-, K-, ostiolar pigment K + blood-red, UV-.

This is a second new species with amyloid ascospores, differing from the preceding one mainly in the yellowpigmented, protruding ostiolar area and in the formation of secondary transverse septa in the median cells. Only one other species of Astrothelium is known with a combination of pigments and amyloid, muriform ascospores, namely A. flavoduplex . It deviates by producing lichexanthone ( UV + yellow) and by the strongly pseudostromatic ascomata covered with with yellow-orange pigment, as well as the longer ascospores (110–350 × 20–27 µm). A morphologically similar species but with I-negative ascospores is A. vezdai (Makhija & Patw.) Aptroot & Lücking , which has larger and much broader ascospores (80–175 × 25–50 µm) and the ostiolar pigment is orange rather than yellow ( Aptroot & Lücking 2016).

Additional specimen examined: COLOMBIA. Dept. Boyacá: Arcabuco, Vereda Peñas Blancas, Sector Mordoñal , Reserva Natural ROGITAMA, 05º47’47.3”N, 73º26’56.0”W, elev. 2530 m, in oak forest, on bark of Quercus humboldtii , 12 July 2015, Simijaca et al. 2695, 2713 ( UDBC) .

Figures

FIGURE 2. Astrothelium rogitamae A. Thallus with perithecia; B. Perithecium enlarged showing pigmented ostiolar area. C. Ascospore. D. Ascospore showing IKI + blue reaction. Scale = 1 mm in A–B, 10 µm in C–D.