Vahliella isidioidea Pérez-Vargas, C. Hdez.

Pérez-Vargas, Israel, Hernández-Padrón, Consuelo, Pérez De Paz, P. L., Van Den Boom, P. P. G. & Jørgensen, P. M., 2014, A new species in the lichen genus Vahliella from the Canary Islands, including a key to Vahliellaceae, Pannariaceae, and Coccocarpiaceae in Macaronesia, Phytotaxa 167 (2), pp. 183-188 : 184-185

Vahliella isidioidea Pérez-Vargas, C. Hdez. -Padr., van den Boom & P. M. Jørg. sp. nov. MycoBank MB 807634 ( Fig. 1 )

Similar to Vahliella atlantica but with a squamulose thallus, smaller and ovoid-fusiform ascospores with oil droplets inside and a different ecology.

Type:— SPAIN. Canary Islands: Tenerife Island, La Esperanza , “Pista de El Acebiñal”, UTM: 364871/ 3145558, 1200 m, on consolidated soil with bryophytes, March 2008, A. Dorta 7164 (holotype TFC Lich!; isotype BG!) .

Thallus terricolous, minute squamulose, partly granular-isidioid, greyish, spreading irregularly, up to 10 cm diam.; medulla loose containing clusters of Nostoc , gradually merging into rhizohyphae below, lower cortex lacking.Apothecia laminal, numerous, occurring in clusters, often merged, to 1.5 mm diam.; disc orange-brown, finally convex and with a granulose thalline margin quickly excluded. Proper margin variably developed but always present. Hymenium up to 125 μm high, upper part brownish, the remainder colorless, reacting I+ blue changing to red-brown (hemiamyloid) with inspersed oil droplets. Paraphyses unbranched, septate, c. 3 μm thick with clavate, pigmented and expanded apices up to 5 μm. Subhymenium to 125 μm, yellowish-brownish with interwoven hyphae. Asci clavate, to 85–100 μm high with sheet-like apical structures persistently I+ blue. Ascospores 8 per ascus, non-septate, colorless, ovoid to fusiform, smooth-walled, lacking perispore and with numerous internal oil droplets (16–)18.1–19.3(–22) × (6–)6.8–7.5(–9) μm (n = 30). Pycnidia not seen.

Chemistry:— All reactions negative; only zeorine (traces) was detected by TLC.

Etymology:— The specific epithet isidioidea refers to the isidioid thallus appearance.

Distribution and ecology:— The new species grows on consolidated soil in the laurel forest, a relic of the subtropical North Thetian forest from the end of the Tertiary era. The laurel forest shifted to the south because of Pleistocene glaciations and found refuge in the Macaronesian islands. It is characterized by perennial broadleaf laurifolious tress, although at the top of the ridges ericoid species can dominate ( Del Arco et al. 2010). It shows a high biodiversity, a high degree of endemism, and relatively stable and mild temperatures with high humidity due to the trade winds (alisios). So far, the new taxon is only known from the Canary Islands. In spite of the intensive sampling carried out by us in most of the Macaronesian islands, we have not found this species in other archipelagoes, but we do not discard its occurrence.

Discussion:— Vahliella isidioidea bears a superficial similarity to Moelleropsis nebulosa . That species however, has a darker blue-grey and leprarioid thallus and it has no isidia-like structures. Fertile material can best be distinguished by larger and guttulate ascospores of this new species (10–15 × 5–8 μm in M. nebulosa ) and different ascus tips ( Jørgensen 2000); also M. nebulosa is a lowland species that grows mainly on sand. Gregorella humida (Kullh.) Lumbsch is another similar species with granulate thallus, with squamules occasionally present, but it has no isidia-like structures. Also, the ascospores (occasionally 1-septate) are smaller (8.5–)12.4–16.1(–19.0) × (5.0–)7.1–9.8(–15.0) μm in G. humida and it has different apical ascus structures ( Lumbsch 2005, Vondrák et al. 2013). The new species resembles also the western European Vahliella atlantica , which is also isidiate but that species has ellipsoid and larger ascospores [15–25(–30) × 6–8 μm] without oil droplets, a more crustose thallus and it occurs on stabilized maritime soil ( Jørgensen 2005; Jørgensen & Johnsen 2006).

Additional specimens examined:— SPAIN. Canary Islands: Tenerife: La Esperanza, “Pista de El Acebiñal”, UTM: 364871/ 3145558, 1200 m alt., C. Hernández, I. Pérez-Vargas & P.L. Pérez de Paz 9330 (TFC Lich); Santiago del Teide, Barranco de Cuevas Negras, 590 m alt., P. van den Boom 38009, 38019 (herb. v.d. Boom); Erjos, hacia Las Portelas, 1000 m alt, P. van den Boom 37689, 37889 (herb. v.d. Boom); La Palma: W of Lomadas, Fayal Brezal, 700 m alt, P. & B. van den Boom 48535, 48550 (TFC Lich, herb. v.d. Boom); La Gomera: Mirador de Agulo, 705 m alt., P. & B. van den Boom 46180 (herb. v.d. Boom); Gran Canaria: E of Moya, 500 m alt., P. & B. van den Boom 49020 (TFC Lich, herb. v.d. Boom).

Figures

FIGURE 1. Vahliella isidioidea, part of holotype. Habit showing thallus and apothecia. Scale bar: 0.5 mm.