Abrothallus etayoi Pérez-Ortega & Suija, 2015

Suija, Ave, Ríos, Asunción De Los & Pérez-Ortega, Sergio, 2015, A molecular reappraisal of Abrothallus species growing on lichens of the order Peltigerales, Phytotaxa 195 (3), pp. 201-226 : 212-213

Abrothallus etayoi Pérez-Ortega & Suija , sp. nov.

Mycobank MB#809370; Fig. 7

Diagnosis:—Lichenicolous fungus on Sticta sp. known only by its asexual morph that differs from rest of the Abrothallus species by the barrel-shaped to subglobose pycnidia, and by one-celled, obpyriform conidia with dimensions of 11– (14.1)–17.5 × 7–(8.9)–11 μm.

Type:— MEXICO. Michoacán, Angahuan, Pinus - Quercus forest, elev. 2470 m a.s.l. (19º33’26”N 102º12’65”W), on Sticta sp. on Quercus sp. , 23 August 2010, S. Pérez-Ortega 2003 & M. Arróniz-Crespo (holotype MA)

Mycelium immersed in the host thallus, branched, septate, pale to dark brown, composed of hyphae 2–3 μm thick, K/I–. Conidiomata pycnidial, arising singly, scattered, superficial, barrel-shaped to subglobose, sometimes with the area around the ostiole depressed and constricted at the base giving a saddle-like shape in transversal sections; dark brown to black, with a yellowish pruina covering the surface, especially towards the base, unilocular, 220–350 × 190–220 μm. Walls of conidiomata 30–45 μm thick, composed of 7–12 layers of medium to dark brown to dark green thick-walled pseudoparenchymatous cells, 6–11 × 3–7 μm (textura angularis), K+ intense yellowish green, N+ (brown pigment of the cells becomes lighter); lower part of the pycnidium wall lighter, usually light brown to hyaline. Ostiole irregular. Conidiophores absent. Conidiogenous cells ampulliform to lageniform, lining the pycnidial cavity, percurrently proliferating, aseptate, hyaline, smooth-walled, 10–16 × 7–12 μm. Conidia holoblastic, obpyriform, with the base abruptly truncated, hyaline, bound by mucilage outside the ostiole, simple, with 1–2 guttules, smooth walled, 11–(14.1 ±1.67)–17.5 × 7–(8.9 ±0.95)–11 μm (n=30). Teleomorph not found.

Etymology:—The name is dedicated to Spanish lichenologist Javier Etayo, a keen collector of lichenicolous fungi and lichens. His contribution to the knowledge of lichenicolous fungi from the Iberian Peninsula and South America has been outstanding, with more than 250 new species described to date.

Notes:—The new species was found growing on an unidentified Sticta species on Quercus sp. in a Pinus - Quercus forest. This ecosystem extends over wide regions in Mexico, so we expect the new species might be present in other areas in the country.

Abrothallus etayoi is a clearly pathogenic species as blackish areas (ca. 1 mm diam.) around the well-developed pycnidia are formed on the host thallus. In transversal sections, areas of the host thallus below the pycnidia show a light to dark brown color. In this area the cyanobiont of lichen is absent and both upper cortex and medulla are almost lacking. Differences from the similar A. doliiformis are provided in the notes section of that species.

Figures

FIGURE 7. Abrothallus etayoi (holotype). a: conidiomata on thallus of Sticta; b: cross-section of pycnidium. Note the collapsed photobionts at the pycnidium; c: detail of pycnidial wall; d: conidiogenous cells and conidia; e–f: conidium. Scale bars: a = 0.5 mm; b = 100 μm; c = 25 μm; d–f = 5 μm