Dictyonema metallicum Lücking, Dal-Forno & Lawrey, 2013

Lücking, Robert, Dal-Forno, Manuela, Lawrey, James D., Bungartz, Frank, Holgado Rojas, María E., Hernández, Jesús E., Marcelli, Marcelo P., Moncada, Bibiana, Morales, Eduardo A., Nelsen, Matthew P., Paz, Elias, Salcedo, Luis, Spielmann, Adriano A., Wilk, Karina, Will-Wolf, Susan & Yánez-Ayabaca, Alba, 2013, Ten new species of lichenized Basidiomycota in the genera Dictyonema and Cora (Agaricales: Hygrophoraceae), with a key to all accepted genera and species in the Dictyonema clade, Phytotaxa 139 (1), pp. 1-38 : 22-24

Dictyonema metallicum Lücking, Dal-Forno & Lawrey , sp. nov. ( Fig. 11 )

Mycobank #805385

Genbank ITS barcoding sequence: KF443222

Differing from the morphologically similar and related Dictyonema hernandezii in the thin, completely appressed thallus and the dark blue color, with a metallic shimmer when dry.

Holotype: — ECUADOR. Pichincha: Río Guajalito Protected Forest ; 0°09’S, 78°39’W, 1800 m; montane rainforest, on tree trunk; September 2008, Lücking 26255 ( QCNE; isotype: F).

Thallus epiphytic on tree trunks and overgrowing nearby bryophytes, appressed filamentous, in irregular, dispersed to confluent patches, each 1–5 cm across and entire thallus eventually covering larger areas of the substrate, forming a strongly compressed mat of horizontal, loosely interwoven, dark blue fibrils completely embedded in a gelatinous, silvery prothallus with strongly metallic shimmer. Thallus in section 25–50 µm thick, composed of an irregular photobiont layer but lacking a discernible medulla; photobiont layer composed of numerous cyanobacterial filaments wrapped in a closed hyphal sheath formed by jigsaw puzzleshaped cells; cyanobacterial filaments composed of 10–13 µm wide and 4–6 µm high, dark aeruginous blue cells penetrated by tubular fungal hyphae; heterocytes sparse, hyaline, 8–12 µm wide and 4–6 µm high; cells of hyphal sheath wavy in lateral outline, 3–4 µm thick; hyphae associated with hyphal sheath straight, 4–6 µm thick, lacking clamp connections; compacted prothallus mostly found by densely arranged empty hyphal sheaths admixed with straight hyphae.

Hymenophore not observed.

Chemistry: no substances detected by TLC.

Distribution and Ecology: —This species is thus far known from montane rain forest in Ecuador, forming dispersed mats on the trunks of shaded trees in the rain forest understory, also overgrowing nearby epiphytic bryophytes.

Etymology: —The epithet refers to the metallic shimmer of the thallus when dry.

Remarks: — Dictyonema metallicum is similar to the recently described D. hernandezii Lücking, Lawrey & Dal-Forno ( Lumbsch et al. 2011: 46) in having the fibrils embedded in a gelatinous matrix formed by the fungal prothallus and hypothallus. The latter differs in the much thicker thallus which forms a thick, bulging, zonate marginal prothallus, and the more greenish color of the cyanobacterial photobiont. The tiny fibrils of D. metallicum are reminiscent of those of Cyphellostereum phyllogenum (Müll. Arg.) Lücking, Dal-Forno & Lawrey , comb. nov. [Mycobank #805396; bas.: Dichonema phyllogenum Müll. Arg. , Flora 66: 352 (1883); syn.: Dictyonema phyllogenum (Müll. Arg.) Zahlbr., Cat. Lich. Univ. 7: 746 (1931); lectotype ( Parmasto 1978: 124): Malaysia (Borneo: Sarawak), Beccari 1624 (G!)] and C. nitidum (Lücking) Lücking ( Lücking 2008; Yánez et al. 2012), but those two species have a Cyphellostereum -type thallus lacking a distinct hyphal sheath and also lacking haustoria.

Additional specimens examined: — ECUADOR. Pichincha: Río Guajalito Protected Forest ; 0°09’S, 78°39’W, 1800 m; montane rainforest, on tree trunk; September 2008, Lücking 26255 (F) .

Figures

FIGURE 11. Dictyonema metallicum (Ecuador, Lücking 26203). A–B. Specimen in the field. C. Thallus surface enlarged showing filaments. Scale = 1 mm.