Thallus muscicolous, whitish, pale grey to grey, continuous. Ascomata dispersed, rarely aggregated, ca. 0.2–0.4 mm diameter. Perithecium black, subglobose to mostly globose. Asci cylindrical-clavate, 70‒95 × 25‒40 μm. Ascospores colourless, 40‒55 × 10‒12 μm, 1-septate, lower cells sometimes somewhat smaller than the upper or cells, or equal. Macropycnidia conical, up to 1 mm high. Macroconidia 0‒1-septate, 4.5‒6 × 1.8‒2.5 μm. Micropycnidia roundish to conical, up to 0.15 mm high. Microconidia roundish, 2.5‒3 μm diameter.

Type:― PORTUGAL. Madeira: W side of island, road (ER 209) from Paul da Serra to Ribeira da Janela, W of Fanal, W side of the road, open area with Laurus trees and Erica shrubs among ferns, 1080 m, 2 May 2012, P. & B. van den Boom 48062 (holotype B!; isotype hb. v.d. Boom!).

Thallus muscicolous over corticolous liverworts, whitish grey to grey, immersed to very thin to filmy, continuous, up to 30 μm thick, UV ‒. Photobiont Trentepohlia, cells globose, yellowish green. Ascomata perithecioid, 0.25–0.4 mm diameter, solitary or sometimes 2–3 confluent, subglobose to mostly globose, strongly constricted at base, black, glossy, shining, usually naked, sometimes covered by a thalline layer at base, young perithecia immersed to semi-immersed, ostiole apical. Perithecial wall lacking cellular hyphae, black, 50‒70 μm thick at upper half, 40‒50 μm thick in lower parts. Hamathecium 140–180 μm high, colourless, not inspersed with oil droplets. Paraphyses branched and anastomosed, septate, 1‒1.5 μm diam. Asci 8-spored, cylindrical-clavate, 70‒95 × 25‒40 μm, apical dome with distinct, broad ocular chamber, I ‒. Ascospores colourless, 40‒55 × 10‒12 μm, 1-septate, cells equal or distal cells sometimes somewhat enlarged, without a perispore, rarely broken at the septum. Macropycnidia abundant, black, elongate, superficial, conical, up to 1 mm high, 0.1–0.2 mm diam., with a white blob of jelly with extruding conidia at the top. Macroconidia ellipsoid to slightly ovoid, 0‒1-septate, 4.5‒6 × 1.8‒2.5 μm. Micropycnida rarely found, semi-immersed, black, roundish to conical, up to 0.15 mm high, 50‒100 μm wide. Microconidia roundish, 2.5‒3 μm diam.

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

Etymology:— The epithet refers to the remarkable long pycnidia.

Distribution and ecology:— Known from the type collection and from two collections on Terceira (Azores). The type collection was found on moss on a trunk of a medium size Laurus tree. The Azores collections were also overgrowing mosses. Associated lichens in the type locality are Cladonia parasitica (Hoffm.) Hoffm., C. ramulosa (With.) J.R. Laundon, Degelia plumbea (Lightf.) P.M. Jørg. & P. James, Parmeliella parvula P.M. Jørg., Pertusaria ophthalmiza (Nyl.) Nyl. and Pyrenula dermatodes (Borrer) Schaer.

Remarks:— The new species is characterized by its muscicolous habitat, relatively large, exposed perithecia up to 0.4 mm diam., large ascospores of 40‒55 × 10‒12 μm and conspicuous, elongate macropycnidia up to 1 mm high. Anisomeridium endobryum (Döbbeler & Poelt) R.C. Harris, known from Brazil, grows on liverworts, and differs in having shorter ascospores of 33‒42 × 10‒12.5 μm and larger macroconidia of 5‒7 × 3.5‒4.5 μm, which are oblong and embedded in gelatine (Harris 1995). A further corticolous species of Anisomeridium with long pycnidia is A. throwerae R.C. Harris, which differs from the new species in having bristle-like beaks on the pycnidia, larger macroconidia of 8‒10 × 4‒5 μm, and smaller ascospores of 12‒17 × 5‒6 μm (Harris 1995). The recently described Anisomeridium robustum Orange, Coppins & Aptroot has macropycnidia up to 0.5 mm high and 0.2‒0.6 mm diam. and its macroconidia are pyriform to ellipsoid and 4.5‒6 × 2.5‒3 μm; the ascomata of this species are unknown (Coppins & Aptroot 2008).

Additional specimens examined: ― Portugal, Azores, Terceira, NW of Angra do Heroismo, W of Pico Gordo, Mistério dos Negros (N), trail from Lagoa do Negro to Juniperus forest, fence posts along fields, some rows of Cryptomeria trees and heathland with young Cryptomeria, on Erica, 570 m, 28 June 2014, P. & B. van den Boom 51411 (hb. v.d. Boom). Ibid., trail from Lagoa do Negro to the west, ± damp Juniperus forest with some young Vaccinium cylindraceum, on Juniperus, 555 m, 28 June 2014, P. & B. van den Boom 51422 (hb. v.d. Boom).