Abrothallus doliiformis 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 : 209-210

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

Mycobank MB#809367; Fig. 4

Diagnosis:—Lichenicolous fungus on Sticta sp. that differs from the rest of Abrothallus species by the superficial, doliiform pycnidia with one-celled, hyaline, obpyriform conidia 9.5–(11.9)–14.5 × 6–(7.5)–9.5 μm in size.

Type:— PERU. Cusco, Aguas Calientes, Machu Picchu, Subida al Huayna Picchu, elev. 2484 m a.s.l (13º9’27”S 72º32’17”W), on Sticta sp. , 14 October 2010, S. Pérez-Ortega 2004 & A. de los Ríos (holotype MA, isotype ibid. S. Pérez-Ortega 2005 & A. de los Ríos, 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 or more often in groups of 4–6, superficial, doliiform, blackish, occasionally with a yellowish pruina covering the surface especially towards the base in mature specimens, unilocular, 250–450 × 200–290 μm. Walls of conidiomata 40–55 μm thick, composed of 5–8 layers of dark green thick-walled pseudoparenchymatous cells, 6–10 × 3–7 μm in size (textura angularis), K+ intense emerald green, N+ brown (dark green pigment turns dark brown and finally light brown), the lower part of the wall is lighter, even hyaline. Ostiole rather wide, irregular. Conidiophores absent. Conidiogenous cells ampulliform to lageniform, lining the pycnidial cavity, percurrently proliferating, aseptate, hyaline, smooth-walled, 10–18 × 5–8 μm (n=15). Conidia holoblastic, obpyriform, with the base abruptly truncated, hyaline, bound by mucilage mass outside the ostiole, simple, with 1–2 guttules, smooth-walled, 9.5–(11.9 ±1.09)–14.5 × 6–(7.5 ±0.68)–9.5 μm (n=44). Teleomorph not seen.

Etymology:—The name refers the characteristic barrel-shaped (doliiform) pycnidia.

Notes:—The new species is known only from the type locality ( Peru) where it grew on an unidentified Sticta species. Abrothallus doliiformis is clearly a pathogenic species causing host damage, easily seen in transverse sections. Cortical areas around the conidiomata are usually black, the area below the thallus surface has a brownish tinge, the photobiont cells have disappeared and thallus seems to be collapsed.

Another anamorphic species on Sticta sp. , Abrothallus etayoi (described here) differs in the shape of pycnidia, that are more subglobose in A. etayoi , and in the size of conidia, 11–(14.1)–17.5 × 7–(8.9)–11 μm in A. etayoi and 9.5–(11.9)–14.5 × 6–(7.5)–9.5 μm in A. doliiformis . Abrothallus kamchatica differs from both species by the colour (pale brown when mature) and size of conidia (7.5–(8.85)–10.5 × 4.5–(5.6)–6.5 μm).

Figures

FIGURE 4. Abrothallus doliiformis (holotype). a–b: pycnidia; c: cross section of pycnidium; d: detail of the base of the pycnidium; e–f: conidium (DIC). Scale bars: a–b: 0.5 mm; c–d = 100 μm; e–f = 5 μm