Labrocarpon Etayo & Pérez-Ortega, gen. nov

MycoBank No: MB 515228

Ascomata lirelliformia, nigra, latiora in medio et stricta in lateralibus, labri forma, sulco angustato; excipulum atrobrunneum ad carbonaceum, pseudoparenchymaticum, continuum et basi inmersa in lichen hospedanti; periphysoides valde ampliphicatae; paraphyses ramosae, septatae; asci late clavati, bitunicati; ascosporae ellipsoideae, 1-septatae, leviter constrictae, brunneae ubi maturitatae, laeves.

Typus: Labrocarpon canariensis (D. Hawksw.) Etayo & Pérez-Ortega.

Etymology. ‘Labrum’ refers to the shape of the ascomatal margin, typically thickened in the centre forming a lip shape.

Labrocarpon canariensis (D. Hawksw.) Etayo & Pérez-Ortega comb. nov

MycoBank No: MB 515229

Melaspilea canariensis D. Hawksw., Lichenologist 14: 84 (1982); type: Canary Islands, Tenerife, S. Juan de Reparo, Mirador de Garachico, 1978, P. B. Topham (IMI 259313–holotype, not seen).

(Fig. 1 A & B)

Fig. 1.

Labrocarpon canariensis (Pérez-Ortega 706). A & B, details of periphysoids in the excipule.

With the exception of the periphysoids documented here, Labrocarpon canariensis has been described and drawn in detail by Hawksworth (Reference Hawksworth1982); for this reason we omit repetition of a full description.

Remarks. Melaspilea Nyl. is a genus with c. 80 species described worldwide (Ryan & Nimis Reference Ryan, Nimis, Nash, Ryan, Diederich, Gries and Bungartz2004), which includes lichenized, saprotrophic and lichenicolous taxa. The systematic position of the genus is uncertain; it is currently placed within the family Melaspileaceae W. Watson together with Encephalographa A. Massal. and placed provisionally in the order Arthoniales (Lumbsch & Huhndorf Reference Lumbsch and Huhndorf2007), although previous authors included Melaspileaceae within the Graphidales (Poelt Reference Poelt, Ahmadjian and Hale1974), Patellariaceae (von Arx & Müller Reference von Arx and Müller1975) or Buelliaceae (Eriksson Reference Eriksson1981). Numerous authors have pointed to the need of a thorough revision of Melaspilea as it seems to be heterogeneous (Hawksworth Reference Hawksworth1982; Hawksworth Reference Hawksworth, Purvis, Coppins, Hawksworth, James and Moore1992; Ryan & Nimis Reference Ryan, Nimis, Nash, Ryan, Diederich, Gries and Bungartz2004). Eriksson (Reference Eriksson1981) and Hawksworth (Reference Hawksworth, Purvis, Coppins, Hawksworth, James and Moore1992) remarked that the type species of Melaspilea, M. arthoniodes (Fée) Nyl., appears to be close to Buellia. Later, Matzer (Reference Matzer1996) studied the type species and pointed out that it differs from some Opegrapha species with 1-septate ascospores in having a non-amyloid hymenium and laterally thin and apically strongly thickened ascus wall. Nograsek & Matzer (Reference Nograsek and Matzer1991) observed a distinct Congo red-reaction in the tholus of the species and that old spores exhibited a brown pigment on the surface and in the cell wall.

The newly segregated genus Labrocarpon differs mainly from Melaspilea s. str. by the periphysoids covering the inner part of the excipulum (Fig. 1A & B), a feature lacking in Melaspilea. The genus Poeltinula Hafellner has some similarities to Labrocarpon, but the absence of a periphysoid layer, the asci with an I+ blue tholus, and the halonate ascospores separate it from the new genus and suggest a closer relationship to members of the Rhizocarpaceae (Hafellner Reference Hafellner1984; Ihlen & Ekman Reference Ihlen and Ekman2002). The genus Odontotrema (Ostropales), with several lichenicolous species (Diederich et al. Reference Diederich, Zhurbenko and Etayo2002), also has a periphysoid layer covering the upper inner part of exciple, but the apothecia are not lirellate, its asci are functionally unitunicate and normally I and KI+ blue, and the hyaline ascospores are completely different from those in L. canariensis.

Distribution and host. So far, L. canariensis is known from the Canary Islands, from where it was first described by Hawksworth (Reference Hawksworth1982), Madeira (Hafellner Reference Hafellner1995), Italy (Nimis Reference Nimis1993), mainland Spain (Calatayud et al. Reference Calatayud, Atienza and Barreno1995) and Brazil (Diederich Reference Diederich2003). It is here reported as new to Portugal. Labrocarpon canariensis lives on an unidentified saxicolous whitish yellow crust that probably belongs to the genus Pertusaria.

Further material studied. Portugal: Lisboa: Sintra, granitic boulders in Pinus halepensis forest, on Pertusaria sp., c. 250 m, 38° 45′ 37″ N, 9° 25′ 57″ W, 22 viii 2006, S. Pérez-Ortega & A. Álvarez Lafuente (hb. Pérez-Ortega 706).—Spain: material from the Canary Islands studied here is listed in Etayo (Reference Etayo1996, Reference Etayo2000) and Boom & Etayo (Reference van den Boom and Etayo2006).

Buelliella protoparmeliopsis Etayo & Pérez-Ortega sp. nov

MycoBank No: MB 515230

Ascomata lirelliformia ad disciformia, nigra, 250–540 × 180–530 μm; excipulum atrobrunneum ad carbonaceum, pseudoparenchymaticum, continuum et base inmersum. Paraphyses ramosae, septatae. Asci subclavati ad subglobosi, bitunicati, 48–66 × 8–16 μm, 8-spori. Ascosporae late ellipsoidae, 1-septatae, constrictae, cellulis plus minusve differibus, brunneae ubi maturitatae, (14–)18 ± 1·7 (–21) × (4–)6 ± 1·2 (–10)[cellulae infera]–(5–)8 ± 1·5 (–12)[cellulae supera].

Typus: Chile, [VII Region, Maule] Valle central, carretera de Rancagua a Termas de Cauquenes, cerros con acacias y cactus, sobre Protoparmeliopsis sp., c. 400 m, 31 January 2008, J. Etayo 24468 (MAF—holotypus).

(Fig. 2 A–G)

Fig. 2.

Buelliella protoparmeliopsis (holotype). A, habit; B, young ascomata with slit-like opening; C, mature ascomata with roundish exposed disc; D, longitudinal section of excipulum showing the dark matrix which confers the carbonaceous aspect; E, mature asci with eight ascospores; F, young asci showing two layers; G, paraphyses and their apical apices surrounded by the dark pigmented matrix; H, young hyaline ascospore; I, mature brown ascospores. All photographs taken of material mounted in water. Scale bars: A = 500 μm; B & C = 100 μm; D–F = 15 μm; G–I = 10 μm.

Ascomata elongate, lirelliform when young, broadly fusiform or ± roundish when mature, unbranched, arising singly or more or less crowded, confluent, black, disc sometimes slit-like, although usually roundish, margin usually convex and uneven, 250–540 × 180–530 μm. Excipulum carbonaceous, dark brown to black depending on the thickness of section (Fig. 2D), well-developed, continuous and penetrating up to 120 μm into the host thallus, giving the appearance of a short stalk (Fig. 2B), 30–45 μm thick in the upper part, pseudoparenchymatous throughout, formed by 8–14 rows of angular cells, mostly 5–8 μm, interspersed with dark brown granules that turn black in K (Fig. 2D), cells in the outer layers with thicker walls, up to 3 μm wide. Subhymenium hyaline, c. 30–50 μm tall. Hymenium hyaline, c. 65–100 μm tall, I−. Epihymenium comprising the tips of the paraphyses, immersed in a dark brown matrix (Fig. 1G), up to 14 μm thick, K−, N− or orangish brown. Hamathecium of cellular paraphyses, branched and anastomosed, especially towards their bases, hyaline, thick-walled, 2–4 μm wide, with clear apical thickenings to 5 μm (Fig. 2G). Asci bitunicate in structure, fissitunicate, clavate to subclavate, often with a short stalk, thickened at the apex, often with a distinct apical beak when young, I−, 48–66 × 8–16 μm (n = 12), 8-spored. Ascopores broadly ellipsoid, 1-septate, visibly constricted at the septum, cells of unequal size, lower cell narrower than upper cell (Fig. 2H), with rounded apices, hyaline when young, becoming light brown at maturity, smooth-walled, (14–)18 ± 1·7 (–21) × (4–)6 ± 1·2 (–10) [lower cell]–(5–)8 ± 1·5 (–12) [upper cell] (n = 35), usually with one or two guttules inside each cell, surrounded by an irregular gelatinous sheath when very young.

Pycnidia not known.

Etymology. The epithet ‘protoparmeliopsis’ refers to its lichenicolous habit on Protoparmeliopsis M. Choisy, a genus resurrected by Hafellner & Türk (Reference Hafellner and Türk2001) for the Lecanora muralis group.

Ecology and distribution. Buelliella protoparmeliopsis lives on an unidentified species of Protoparmeliopsis growing on rock in savanna vegetation of Acacia and Cereus, in the VII Region, Maule, central Chile. It seems to be parasymbiotic as no damage has been observed to the host thallus despite the numerous ascomata of the lichenicolous fungi found in some areas of the thallus. So far, the new fungus is known only from the type locality, where it was found growing only on one thallus; an extensive search failed to find more colonized thalli in the same and surrounding localities.

Remarks. Buelliella Fink is a genus of lichenicolous fungi with apothecioid ascomata, initially closed, bitunicate asci with negative or very slightly I+ blue reaction with iodine and with 2-celled ascospores, initially colourless, later becoming brown. Eleven species have been described so far: B. colombiana, B. dirinariae, B. eximia, B. inops, B. lecanorae, B. minimula, B. nuttallii, B. physciicola, B. poetschii, B. pusilla and B. trypethelii (Fink Reference Fink1935; Hafellner Reference Hafellner1979, Reference Hafellner1985; Kalb Reference Kalb1990; Santesson Reference Santesson1994; Aptroot et al. Reference Aptroot, Diederich, Sérusiaux and Sipman1997; Etayo Reference Etayo2002; Hafellner et al. 2002, Reference Hafellner, Herzog and Mayrhofer2008; Suija & Alstrup Reference Suija and Alstrup2004). Buelliella protoparmeliopsis must be compared with the three species of Buelliella, B. lecanorae, B. inops and B. trypethelii, with a brown epihymenium. The other eight taxa do not have this pigment in the epihymenium, remaining instead only hyaline to weakly pigmented (Suija & Alstrup Reference Suija and Alstrup2004). The recently named B. lecanorae (Suija & Alstrup Reference Suija and Alstrup2004) grows on corticolous species of the Lecanora subfusca group [i.e. L. chlarotera Nyl., L. pulicaris (Pers.) Ach., and L. argentata (Ach.) Malme], and is known from Estonia (Suija & Alstrup op. cit.). Apart from the different host and habitat, B. lecanorae possesses much smaller apothecia, < 200 μm diam.; a brown, reddish brown epihymenium reacting N+ slightly red; and a shorter hymenium 60-65 μm tall. Buelliella inops also has smaller apothecia, 150–200 μm wide, and a shorter hymenium (45–55 μm tall) and grows on Caloplaca species. The habitat of the last species may be similar to that of B. protoparmeliopsis, as it lives in Mediterranean regions of Australia, Mexico and the USA. Finally, B. trypethelii, known on Trypethelium spp. in Guyana and the USA., also has smaller apothecia (300–450 μm diam.) but differs in possessing a reddish black, N+ red epihymenium very different from that of the new species.

The new species recalls some lichenicolous species of Melaspilea. Three lichenicolous species of Melaspilea are currently recognized, namely Melaspilea canariensis D. Hawksw. (combined in this paper within the new genus Labrocarpon), on Pertusaria sp., M. leciographoides Vouaux on sterile Verrucaria in England and France (Hawksworth Reference Hawksworth, Purvis, Coppins, Hawksworth, James and Moore1992), and M. lentiginosa (Leight.) Müll.Arg. on Phaeographis dendritica, known from England, France and Ireland (Hawksworth Reference Hawksworth, Purvis, Coppins, Hawksworth, James and Moore1992). Melaspilea gallowayii S. Kondr. on Pseudocyphellaria dissimilis and known from Australia and New Zealand, has been recently transferred to the arthonioid genus Plectocarpon (Ertz et al. Reference Ertz, Christnach, Wedin and Diederich2005).

Buelliella protoparmeliopsis is similar in some respects to Labrocarpon canariensis. While M. canariensis has lirellate ascomata, split-like and to 400 μm long and 150 wide, in B. protoparmeliopsis the ascomata take on the lirellate form only when the apothecia are crowded against each other; when growing singly, the apothecia are disc-like, and individual apothecia can then be up to 500 μm diam. Furthermore, they live on different hosts: L. canariensis occurs on a greyish to yellowish sterile crustose species of Pertusaria, and B. protoparmeliopsis lives on an unidentified species of Protoparmeliopsis. Ascus and ascospore sizes are very similar in the two species, but the exciple of L. canariensis differs by appearing to almost cover the disc, and by possessing a well developed layer of periphysoids in the inner part; these periphysoid filaments are septate, simple and 7–12 × 2–3 μm. Buelliella protoparmeliopsis lacks this character.