Sticta silverstonii Moncada & Lücking, 2012

Moncada, Bibiana & Lücking, Robert, 2012, Ten new species of Sticta and counting: Colombia as a hot spot for unrecognized diversification in a conspicuous macrolichen genus, Phytotaxa 74 (1), pp. 1-29 : 21-23

Sticta silverstonii Moncada & Lücking , spec. nov. ( Fig. 9 )

MycoBank #801851

Differing from Sticta dilatata in the large, plane, contiguous cyphellae covering the underside towards the margin with numerous papillae on the cells of the basal membrane, and the simple to fasciculate cilia bordering the lobes.

Holotype: — COLOMBIA. Valle del Cauca: Mun. El Cairo, eastern slope of Cerro del Inglés ; 2320 m; 1 Jan 1987, Silverstone et al. 2845 ( CUVC; isotype: UDBC).

Primary photobiont cyanobacterial ( Nostoc ). Stipe present but indistinct, up to 5 mm long. Thallus palmate to irregular in outline, up to 10 cm diam., much branched, with 6–10 branches per 5 cm radius, branching dichotomous to anisotomous; lobes laciniate, adnate to horizontal, interspaced, plane to weakly revolute, their apices obtuse to truncated, plane, their margins entire, weakly thickened; lobe internodes (2–)4–7(–10) mm long, (2–)4–6(–8) mm broad; thallus papyrose to subcoriaceous, fragile. Upper surface with shallow, broad, rounded protuberances that correspond to the position of the large cyphellae in the underside, greenish grey when fresh, pale brown in the herbarium, slightly shiny; surface glabrous, without papillae and pruina, but with scattered, irregular, cream-colored maculae; marginal cilia sparse but extensions from the lower tomentum resembling cilia present, simple to fasciculate, white to brownish, up to 0.5 mm long. Apothecia abundant, principally laminal, dispersed, subpedicellate, with pronounced invagination on lower side, up to 1.5 mm diam.; disc red-brown, matt; margin tomentose, weakly ciliate, cream-colored. Vegetative propagules absent. Lower surface smooth, cream-colored; primary tomentum dense and thick but absent towards the margin, spongy to intertwined, soft, dark brown; secondary tomentum arachnoid, pale. Rhizines absent. Cyphellae 1–20 per cm 2 towards the thallus center and margin, contiguous, rounded, plane, immersed, remaining below the level of the primary tomentum, with the margin thin to thickened, cream-colored to yellowish, without tomentum; pore (2–)2.5(–3) mm diam.; basal membrane pubescent, cream-colored, K –, C –, KC–, P –. Medulla lax, pale yellow, K – to K + yellow, C –, KC–, P –. No substances detected by TLC.

Upper cortex paraplectenchymatous, 20–30 µm thick, forming two different layers: upper layer consisting of 1–2 cell layers with cells 3.5–6 µm diam., their walls 2.5–3.5 µm thick and their lumina rounded to isodiametric, 1.2–2.5 µm diam.; lower layer consisting of 2–3 cell layers; cells 6–10 µm diam., their walls 1–1.5 µm thick and their lumina rounded to isodiametric, 5–8 µm diam. Photobiont layer 25–40 µm thick, its cells 10–15 µm diam. Medulla 50–100 µm thick, its hyphae 2.5 µm broad, without crystals. Lower cortex paraplectenchymatous, 20 µm thick, with 1–2 cell layers; cells 5–13 µm diam., their walls 1–1.5 µm thick. Hairs of lower primary tomentum 140–500 µm long, in fascicles of more than 20, unbranched hyphae, septate with their apices free. Hairs of lower secondary tomentum 10–20 µm long, of single, unbranched hyphae, septate with free apices. Cyphellae cavity 160 µm deep; cells of the basal with numerous (7–10) papillae. Apothecia biatorine, 300–400 µm high, without stipe; excipulum 80 µm broad, with laterally projecting hairs. Hymenium 100 µm high; epihymenium 2.5–5 µm high, orange, without gelatinous layer above. Ascospores 1–3-septate, 25–35 × 7.5–10 µm, fusiform, hyaline.

Distribution and Ecology: —Chocó biogeographic region of Colombia, found bertween 2250 and 2320 m in montane rain forests on the western slopes of the Cordillera Occidental; growing on bark and usually associated with liverworts of the genus Plagiochila .

Etymology: —Named after Philip Arthur Silverstone-Sopkin, for his valuable contributions to the flora of the tropical dry forest of the Cauca river valley, describing many new taxa for this ecosystem (Silverstone- Sopkin & Graham 1986; Meerow & Silverstone-Sopkin 1995; Silverstone-Sopkin 2004).

Remarks: — Sticta silverstonii is another new species in the S. dilatata group, similar to S. dilatata and S. papillata (see above; Vainio 1913) but differing in the very large, plane cyphellae which become contiguous towards the margin and give the underside a characteristic, unique, pitted-stamped appearance with a corresponding upper surface with broad, rounded, shallow protuberances. In addition, the number of papillae per cell of the basal membrane of the cyphellae is the highest known in this group, with up to 10 per cell.

Additional specimens examined (paratypes): — COLOMBIA. Valle del Cauca: Mun. El Cairo, Cerro del Inglés , vertiente oriental; 2250 m; 28 Dec 1986, Silverstone 2741b ( CUVC) .

Figures

FIGURE 9. Sticta silverstonii (holotype collection). A. Thallus in herbarium showing surface structure. B. Lower surface showing large, contiguous cyphellae. C. Upper surface with apothecia. D. Microscopic section through cyphella showing basal membrane with papillose cells. E. Microscopic section of lower surface showing primary and secondary tomentum. Scale in A and B = 10 mm, in C = 0.5 mm, in D = 5 µm, in E = 20 µm.