Asterina lopi A.L. Firmino & O.L. Pereira, sp. nov.

Index Fungorum number: IF 900067; MycoBank number: MB 900067; Facesoffungi number: FoF 13384; Fig. 1

Etymology – The name refers to the mountain range, where the fungus was collected, Serra do Lopo.

Holotype – VIC 44219

Sexual morph: Colonies epiphyllous, circular to irregular, single to confluent, black, 1–6 mm diam. Hyphae straight to flexuous, branching unilaterally or irregularly, brown, septate, hyphal cells cylindrical, 4–4.5 μm diam., smooth. Appressoria numerous, entire to irregularly lobate, sessile, lateral, alternate to unilateral, never opposed, cylindrical to globose, unicellular, straight to angular, 5–7.5 × 5–6 μm, brown, penetration peg central on the appressorial cell. Ascomata superficial, thyriothecia, scutiform, on top of mycelial mat, circular to ellipsoid, single to confluent, fringed at margins, randomly distributed in the colony, 112–212.5 μm diam., opening by a central star-shaped fissure, dark brown; wall of textura radiate to irregulata, cells isodiametric to cylindrical to irregular. Pseudoparaphyses cylindrical, filiform, septate, unbranched, hyaline, up to 2.5 μm wide. Asci bitunicate in structure, fissitunicate, disposed as an upright palisade layer, ovoid to subclavate, 8-spored, and hyaline, 35–55×20–25 μm. Ascospores cylindrical to oblong, ends broadly rounded, straight, 1-septate, constricted at the median septum, hyaline, becoming pale brown to brown at
maturity, verruculose, 12.5–15×6–7 μm. Asexual morph: Not observed.

Material examined – Brazil, Minas Gerais, Extrema, on living leaves of Miconia sp. (Melastomataceae), 24 December 2014, A.L. Firmino & S.R. Pacheco (VIC 44219, holotype).

GenBank numbers – MZ475299 (LSU)

Notes – Twenty-seven species of Asterina have been reported previously in association with living leaves of melastomataceous hosts. Asterina guianensis on Miconia guianensis from Costa Rica and Miconia mirabilis from Puerto Rico and Virgin Islands, A. racemosae on Miconia racemose from Puerto Rico, and A. tetrazygiae on Tetrazygia sp., and Tetrazygia elaeagnoides from Puerto Rico and Virgin Islands, were described by Ryan (1924) and not used in the comparisons for having an ostiolar opening, a characteristic that does not belong to Asterina.

Figure 1 – Asterina lopi (VIC 44219, holotype) a Colony with open thyriothecia and surface mycelium. b Ascoma opened by a central star-shaped fissure. c Cross section of the ascoma. d Cylindrical to globose unicelular appressoria. e Immature ascus. f Mature ascus. g Immature ascospores. h Mature brown ascospores. Scale bars: a=200 µm, b=50 µm, c–f=20 µm, d–e=10 µm, g–h=5 µm