Coenogonium pineti (Schrad. ex Ach.) Lücking & Lumbsch, Mycologia

Kalb, Jutarat, Boonpragob, Kansri & Kalb, Klaus, 2016, New Coenogonium species (Ostropales: Coenogoniaceae) from Thailand, new reports and a revised key to the species occurring in the country, Phytotaxa 283 (2), pp. 101-122 : 116-117

Coenogonium pineti (Schrad. ex Ach.) Lücking & Lumbsch, Mycologia 96 (2): 290 (2004). ( Fig. 8B )

Lecidea pineti Ach., Lich. Univ. 195: (1810); Dimerella pineti (Ach.) Vězda, Lichenes Selecti Exsiccati : no. 1279 (1975: 2); Dimerella diluta (Pers.) Trevis, Rend. Reale Ist. Lomb. Sci. , ser. 2, 13 (3): 66 (1880).

Thallus crustose, mostly corticolous, but also occurs on wood and mosses, continuous, ± thin, sometimes barely visible, smooth, greyish green to greenish black, 5–20 mm diam., without a distinct corticiform layer; prothallus absent. Photobiont Trentepohlia , cells angular to rounded, mostly in irregular filaments, cells 5–13 × 4–12 μm. Apothecia sessile, rounded, 0.2–0.5 mm diam., 140–160 μm high; disc plane to concave, white to pinkish white, very rarely with an orange tinge; margin prominent, relatively thick, whitish to cream-colored. Excipulum paraplectenchymatous with irregularly arranged cells, 60–75 μm broad, outer part I+ yellow-brown, inner part I–; cells globose to elongate, thin- or partly thick-walled, 3–7 × 4–5 μm. Hypothecium 15–20 μm high, colorless to pale yellowish. Hymenium 80–90 μm high, colorless, I+ blue, then quickly reddish brown then greyish brown. Asci 65–75 × 9–11 μm. Ascospores (irregularly) uniseriate, ellipsoid, 1-septate, 9–14 × 2.3–4.5 μm, 2.5–3.5 times as long as broad. Pycnidia wart-shaped, 0.1–0.2 mm diam., whitish. Conidia oblong, non-septate, ± centrally constricted, ca. 6–8 × 1.8–2.6 μm. Chemistry: no substances detected by TLC.

Distribution and habitat:—Cosmopolitan with a preference for temperate regions, rare in the tropics.

Remarks:—This species is distinguished by its small, pale apothecia with a broad margin and relative large, ± broadly ellipsoid ascospores. It is similar to Coenogonium stramineum (Aptroot & Seaward) Lücking, Aptroot & Sipman from the Seychelles, but differs in having apothecia with a smooth margin (denticulate in C. stramineum ) and asci with uniseriate ascospores (biseriately arranged in C. stramineum ). Actually, C. pineti looks more similar to Absconditella species, especially A. delutula (Nyl.) Coppins & Kilias , than to any other Coenogonium species, but C. pineti is mostly growing on bark, while Absconditella species have a chlorococcoid photobiont and are growing over mosses, soil or rocks.

Material from Thailand examined:— Trat Province: Laem Ngob District; Black sand beach near Tambon Laem Ngob, in an old ± disturbed mangrove forests with dominant Rhizophora apiculata , Rh. mucronata , Lumnitzera racemosa and Avicennia marina , ± 3 m, 12°10’11’’ N, 102°24’27’’ E, 25 February 2011, K. Kalb & P. Mongkolsuk (hb. Kalb 38905).

Figures

FIGURE 8. Habitus photographs of Coenogonium species. A. Coenogonium nepalense (KK 35180), scale 1 mm. B. Coenogonium pineti (KK 38905), scale 0.3 mm. C. Coenogonium queenslandicum (KK 41131), scale 0.5 mm. D. Coenogonium subborinquense (KK 38820) thallus with apothecia and pycnidia (arrow), scale 1 mm. E. Coenogonium subluteum (KK 39803), scale 0.5 mm. F. Coenogonium verrucimarginatum (KJ 41288), scale 0.25 mm.