Orcularia placodiomorpha (Vainio) Kalb & Giralt

Kalb, Klaus & Giralt, Mireia, 2011, Orcularia, a segregate from the lichen genera Buellia and Rinodina (Lecanoromycetes, Caliciaceae), Phytotaxa 38, pp. 53-60 : 58

Orcularia placodiomorpha (Vainio) Kalb & Giralt , comb. nov. Mycobank MB 563561

Bas.: Buellia placodiomorpha Vainio. Étude lich. Brésil 1: 172 (1890).

Type:— Brazil. Rio de Janeiro: Sepitiba in civ . Rio de Janeiro. 1885; E. A. Vainio: Lichenes Brasilienses Exsiccati 473 (TUR-Vain. 9519!— lectotype, selected here; KIEL!, M!—isolectotypes) .

Thallus corticolous, ca. 2 cm diam., whitish to grey or greenish grey, continuous to cracked, smooth or slightly warty. Apothecia small, 0.3-0.4 mm diam., surrounded by a rather persistent pseudothalline margin; disc brownish black to black, not pruinose, flat to slightly convex; proper margin very thin, persistent or not. Proper exciple poorly developed, 20–30(–40) µm thick, KOH-. Hypothecium (50–) 60–80 µm high, dark brownish. Hymenium 60–80(–100) µm high, not inspersed. Epihymenium brown. Paraphyses 1.8–2.0 µm thick, end cells 3–4 µm broad, with a brown cap, unbranched or with a few branches towards the tip. Asci 8- spored, ascospores 1-septate, 15–19 × 7–8.5(–9.5) µm, olive, later pale brown, spore wall smooth; at first lumina only apical, connected by a long isthmus, later with two additional septal lumina. Pycnidia black, 50– 60 µm diam., conidia filiform, 14–25 × 0.7–0.8 µm. Chemistry: Spot tests (thallus): KOH- or KOH+ slightly yellowish, UV-; myeloconon D1 (cf. Kalb & Elix 1998).

Ecology:— Orcularia placodiomorpha is a rare species. It seems to be confined to mangroves or forests near the sea. It was found in the West Indies and Bermuda ( Imshaug 1955), SE Brazil, and is reported for North America ( Esslinger 2011). Here it is newly reported from Réunion.

Notes:—The species is characterized by a greyish or greyish green, thin thallus, small apothecia (up to 0.4 mm diam.) with a rather persistent pseudothalline margin, a clear hymenium and polarilocular, 1-septate ascospores 15–19 × 7–9.5 µ m with four locules when mature and with a smooth spore wall. Orcularia placodiomorpha is very similar to O. insperata but differs in having additional septal spore lumina in mature ascospores. O. placodiomorphoides is also similar, but this species has ascospores more than 20 µm long.

Specimens examined:— BRAZIL. São Paulo: Ilha de São Sebastião; ca. 130 km E of São Paulo, Baía dos Castelhanos, K. Kalb & G. Plöbst (hb kalb 17790); Ilha de Santo Amaro , a few km outside of Bertioga, K. Kalb & G. Plöbst (K. Kalb: Lich. Neotrop. 86 as Buellia placodiomorpha ) . — RÉUNION. Bras Panon, S of mouth of Rivière des Roches, A.M. Brand-59615 (hb. Brand); SE coast, St. Philippe, Puits Arabe, A.M. Brand-58562 (hb. Brand); NW St. Benoît , Pointe Bourbier, P. & B. v.d. Boom-40995 (hb. v.d. Boom) .