Plectocarpon ramalinae Etayo & Flakus, 2018

Etayo, Javier, Flakus, Adam & Kukwa, Martin, 2018, Three new lichenicolous species of the genus Plectocarpon (Ascomycota: Lecanographaceae) discovered in the Bolivian Andes, Phytotaxa 357 (4), pp. 275-283 : 280-281

Plectocarpon ramalinae Etayo & Flakus sp. nov. MycoBank MB 824897

Diagnosis: Differs from Plectocarpon usneae in having black ascomata, smaller 3-septate ascospores, and a different host selection ( Ramalina celastri ).

Type:— BOLIVIA. DEPT. TARIJA: Prov. Burnet O’Connor, 60 km from Tarija, new road between Tarija and Entreríos, 21º28’52”S, 64º17’41”W, 1837 m, Boliviano-Tucumano forest with Podocarpus , on corticolous Ramalina celastri , 28 July 2015, J. Etayo 30679 (holotype LPB!, isotype herb. Etayo!). ( Fig. 3 )

Ascomata stromatic, developing on the upper and lower surface of the host thallus, single, elongate, superficial, emarginate, ellipsoidal with caudate black ends, convex, 0.7–1.5 mm long, 0.3–0.4 mm broad and 0.2–0.3 mm high, surface smooth, matt; not visibly damaging the host thallus; not inducing gall formation, but the host thallus is hollow in place where the stroma are forming. Stroma multilocular, sterile stromatic tissue brown, well developed between the loculi, wall 20–30 μm, K– (or slightly darker), N– (Atra-brown pigment according Ertz et al. 2005); loculi 75–125 μm broad; base of the stroma 25–125 μm thick, hyaline, I+ blue, with many oil guttules. Hymenium hyaline, I+ blue turning quickly red, K/I+ blue, 80–90 μm high. Paraphyses septate, branched and anastomosing, 1.5–3 μm wide, apically slightly enlarged up to 4 μm and covered by brown granular pigment. Asci clavate, Opegrapha - type, wall apically thickened with only a K/I+ blue apical ring, 8-spored, 50–65 × 13–16 μm. Ascospores hyaline (brown when overmature), smooth, oblong with obtuse ends, straight, not or slightly constricted at the septa, 3-septate, with cells more or less equal in length, (12–)13–14(–15) × (4.5–)5–5.5(–6) μm (n=43), covered by a 1–1.5 μm thick gelatinous coat; granular perispore rarely observed in overmature ascospores. Pycnidia immersed, intermixed with the ascomatal loculi. Conidia bacilliform, hyaline, aseptate, 5–6.5 × 1 μm.

Host: The species inhabits the upper and lower surface of the thallus of corticolous Ramalina celastri without causing evident damages to the host (not developing necrosis).

Distribution and habitat: The species is known only from the type locality in the Bolivian Andes, where it grows in the Tucumano-Boliviano montane forests. Some samples shared infections with Lichenoconium cargillianum (Linds.) D. Hawksw. , reported previously from Hypotrachyna pluriformis ( Flakus & Kukwa 2012b) , and with Protounguicularia fasciculata , here reported as new to Bolivia.

Notes: Plectocarpon ramalinae has a similar habit to P. usneae Diederich & Etayo (1994: 598) described from Usnea exasperata in Rwanda ( Diederich & Etayo 1994), but clearly differs by a black stroma with a smooth surface, an olivaceous stromatic pigment, and shorter, 3-septate ascospores [in P. usneae ascospores are (5–)6(–7)-septate, 26–30 x 4–5 μm].

The new species is the first member of the genus known to parasite Ramalina . However, Mixtoconidium nashii (Hafellner in Hafellner et al. 2002: 312) Etayo & van den Boom in van den Boom & Etayo (2017: 127) growing on Niebla (genus closely related to Ramalina ) was originally described as a Plectocarpon ( Hafellner 2002) and sporadically mentioned from Ramalina farinacea ( Brackel 2011 as P. aff nashii ). The genus Mixtoconidium Etayo (1995: 425) can easily be separated from Plectocarpon by several characters, such as the ascoma type, the presence of an orange, K+ purple pruina, and the production of two types of conidia ( Etayo 1995; Ertz et al. 2005; van den Boom & Etayo 2017).

Figures

FIGURE 3. Plectocarpon ramalinae (holotype). A, two ascomata on the thallus of Ramalina; B–C, asci with ascospores (mounted in water); D, cross section through part of stroma; E, paraphyses; F–G, 3-septate ascospores with a thick gelatinous coat. Scales:A=500 μm, B–C=10 μm, D=100 μm, E–G =10 μm.