Anisomeridium macaronesicum van den Boom, 2015

Boom, P. P. G. Van Den, 2015, Notes on the genus Anisomeridium (lichenized Ascomycotina) from Madeira and the Azores (Macaronesia), Phytotaxa 205 (1), pp. 65-70 : 65-67

Anisomeridium macaronesicum van den Boom sp. nov. ( Fig. 1 ) Mycobank: MB 811451

Thallus corticolous on bark, whitish, pale greyish to grey, very thin, continuous. Ascomata dispersed, rarely aggregated, ca. 0.1–0.25 mm diameter. Perithecium black, subglobose to mostly globose. Asci cylindrical-clavate, 60‒75 × 25‒30 μm. Ascospores colourless, (15‒)17‒22(‒25) × 7‒9(‒10) μm, 1-septate, cells unequal, the distal cell enlarged. Macropycnidia conical, up to 0.3 mm high. Macroconidia 0(‒1)-septate, 5‒6 × 2.8‒3.5 μm. Mesopycnidia conical, up to 0.3 mm high. Mesoconidia bacilliform, simple, (3.5‒)4‒6 × 0.9‒1.1 μm.

Type:― PORTUGAL. Madeira: NE of Funchal, W of Portela, trail to the west, along levada, in laurisilva area with mature Acer trees along the trail, 665 m, 28 April 2012, P. & B. van den Boom 47672 (holotype B!, isotype hb. v.d. Boom!).

Thallus corticolous on bark of Acer and Juniperus , whitish, pale grey to grey, immersed to very thin, 20–40 μm thick, continuous, UV ‒. Photobiont Trentepohlia , cells globose, yellowish green. Ascomata perithecioid, 0.1–0.25 mm diam., solitary or sometimes 2 or 3 grouped, subglobose to mostly globose, immersed to semi-immersed, black, matt, usually with an apical ostiole with a brownish tinge. Perithecial wall lacking cellular hyphae, black above and 50‒70 μm thick, at base medium brown and 40‒50 μm thick. Hamathecium 120–150 μm high, colourless, not inspersed with oil droplets. Paraphyses unbranched near the base, branched and anastomosed above, septate, 1‒1.5 μm wide. Asci 8-spored, ellipsoid to widely clavate, 60‒75 × 25‒30 μm, apical dome with distinct, broad ocular chamber, I ‒, spores biseriate or irregularly arranged in the ascus. Ascospores colourless, (15‒)17‒22(‒25) × 7‒9(‒10) μm, 1-septate, cells unequal, distal cell much enlarged, without a perispore, sometimes broken at the septum. Macropycnidia sparsely present, black, superficial, conical, up to 0.3 mm high, 0.1–0.2 mm diam., with a white blob at the top. Macroconidia slightly to clearly ovoid, 0(‒1)-septate, 5‒6 × 2.8‒3.5 μm. Mesopycnidia sparsely present, black, immersed to superficial, conical, up to 0.3 mm high, 0.1–0.15 mm diam., with a white blob at the top. Mesoconidia bacilliform, simple, (3.5‒)4‒6 × 0.9‒1.1 μm. Micropycnida not found.

Chemistry:— Thallus K-, C-, KC-, Pd-, no compounds detected.

Etymology:— The epithet refers to the occurrence in Macaronesia.

Distribution and ecology:— Known from two collections from Madeira. At the type locality it has been found on a trunk of a medium size Acer tree along a levada trail with a rather rich lichen community. Lichens growing nearby on the same trunk are Bacidia canariensis Erichsen , Bactrospora patellaroides (Nyl.) Almq. , Byssoloma leucoblepharum (Nyl.) Vain. , Caloplaca aegatica Giralt, Nimis & Poelt , Catinaria atropurpurea (Schaer.) Vězda & Poelt , Collema subflaccidum Degel. , Helocarpon corticolum (Zahlbr.) Breuss and Hypotrachyna laevigata (Sm.) Hale.

Remarks: — The new species is characterized by a corticolous habitat, relatively small, immersed perithecia, up to 0.25 mm diam., and ascospores of (15‒)17‒22(‒25) × 7‒9(‒10) μm. In the world-wide key for Anisomeridium ( Harris 1995) it comes out as A. throwerae R.C. Harris , so far known from SE Asia ( Sipman 2010). However, that species has narrower ascospores, 5‒6 μm wide, a submedian septum, oblong to ovoid macroconidia of 8‒10 × 4‒5 μm, and in particular long-beaked, bristle-like pycnidia. In the most recent keys of Anisomeridium ( Aptroot et al. 2008, Smith et al. 2009) none of the species fits the examined material. Among the four known foliicolous Anisomeridium species, only A. musaesporoides Etayo & Lücking has comparable characters, but the perithecia are lens-shaped and much bigger, 0.4–0.7 mm diam. ( Lücking 2008).

Additional specimen examined: ― Portugal, Madeira, N of Funchal, Ribeiro Frio, trail (PR10) to Portelo, Levada do Furado, some dead or living mature Acer trees, shrubs and Erica , on Juniperus , 950 m, 1 May 2012, P. & B. van den Boom 47891 (hb. v.d. Boom).

Figures

FIGURE 1A-B: Anisomeridium macaronesicum, holotype. A) Thallus and perithecia. Scale: 0.5 mm. B) Ascospores in an ascus. Scale: 20 μm.