Sagenidiopsis atroalba Jagadeesh, 2014

Jagadeesh Ram, T. A. M., 2014, New species and new records in Roccellaceae (Arthoniales) from the Andaman Islands, India, Phytotaxa 177 (3), pp. 155-162 : 160

Sagenidiopsis atroalba Jagadeesh , sp. nov. (Figs 1E–F & 2J) MycoBank no.: MB809896

Sagenidiopsis with pale green to mineral grey byssoid thallus, white prothallus, dark brown to blackish hypothallus; black, lecideine, 0.2– 0.4(–0.5) mm diam. ascomata covered with dense whitish tomentum; 8-spored, hemiamyloid asci; hyaline, 3(–5)-septate, fusiform, (13–)15–20(–25) × 3–4.5 μm ascospores and lacking lichen substances.

Type: — INDIA. Andaman Islands : South Andaman , Mount Harriet National Park, Evergreen forest, 11°43’83·8”N, 92°43’ 94·6”N, elev. 35 m, 2 Mar. 2013, T. A. M . Jagadeesh Ram 2728 (Holotype CAL, Isotype PBL) .

Thallus corticolous, epiphloeodal, firmly to loosely attached, suborbicular to irregular, 4–12 cm diam., pale green to mineral grey, byssoid, minutely felty, thin, not flaking off, 45–110 μm thick, lacking calcium oxalate crystals. Photobiont layer thin, 8–20 μm thick; photobiont Trentepohlia , cells in short, irregular threads, 7–15 × 5–10 μm. Hypothallus dark brown to blackish, below the entire thallus, 8–22 μm thick; hyphae brownish to dark brown, thickwalled, 2.5–3.5 μm wide. Medulla white, 30–65 μm thick, medullary hyphae 1.5–2 μm wide. Prothallus with outer up to 0.5 mm wide dark brown to blackish layer and inner up to 1.5 mm wide white layer, byssoid, composed of thin ± spiny radiating hyphae. Isidia and soredia not seen. Ascomata lecideine, solitary, initially spherical, ± rounded, initially sessile and constricted at base, becoming raised and sometimes with a short stalk, up to 0.2–0.4(–0.5) mm diam.; disc black, covered with dense whitish tomentum; proper excipulum brown to dark brown, laterally covered with dense hyaline hyphae (tomentum), continuing below the subhymenium, K + olive-green. Epihymenium greenish brown, 12–20 μm thick, pigments dissolving in K, becoming dark brown and carbonized, I + orange-red, KI+ blue. Hymenium hyaline, 36–50 μm high, I + orange-red, KI+ blue, becoming dark brown and carbonized. Subhymenium hyaline, 12–24 μm thick, I + orange-red, KI+ blue, becoming dark brown and carbonized. Hypothecium brown to dark brown, carbonized, extending to the medulla or substrate, K + olive-green, up to 150 μm thick. Paraphysoids branched and anastomosing, 1–1.5 μm wide; tips thickened, 2–3 μm wide, greenish brown pigmented, richly branched and anastomosing. Tomentum hyphae arising from the epihymenium and excipulum, dichotomously to irregularly branched, septate and constricted at septa, up to 40 μm tall, 2.5–4 μm wide, I + pale orange, KI+ pale blue. Asci clavate to broadly clavate with a short stipe, 8-spored, 30–45 × 10–15 μm; walls hemiamyloid ( I + red, KI+ blue) with a poorly developed ring structure. Ascospores biseriate to irregularly arranged, hyaline, 3(–5)-septate, fusiform, thin-walled, usually with slightly large middle cells, (13–)15–20(–25) × 3–4.5 μm. Pycnidia few, dark brown; conidia not observed. Chemistry. Thallus K –, C –, P –, UV –; I –, KI– or KI + pale blue (section); no lichen substances detected.

Notes: — Sagenidiopsis atroalba is characterized by the byssoid thallus with white prothallus, dark brown to blackish hypothallus; black, lecideine, 0.2–0.4(–0.5) mm diam. ascomata covered with dense whitish tomentum; hyaline, 3(–5)-septate, fusiform, (13–)15–20(–25) × 3–4.5 μm ascospores and lacking lichen substances. Further, it has been observed that the subhymenium, hymenium and epihymenium are gradually carbonized from the hypothecium. It is distinct from the other two non-isidiate species viz. Sagenidiopsis merrotsii R. W. Rogers & Hafellner and S. undulata (Fée) Egea et al. by the smaller ascomata, asci and ascospores, lacking lower medullary or hypothalline reddish brown pigment and the absence of lichen substances. Sagenidiopsis merrotsii has 1 mm diam. ascomata, 50–60 × 12–15 μm asci and 24–29 × 2.5–3.5 μm ascospores and protocetraric acid as major lichen substance whereas Sagenidiopsis undulata has 0.5–2(–3) mm ascomata, 60–80 × 17–21 μm asci, 33–46 × (3–)3.5–4 μm ascospores and lecanoric acid as lichen substance. Sagenidiopsis isidiata G. Thor et al. and S. subconfluentica Elix are the other two species, but both are isidiate. Sagenidiopsis isidiata is the only other species lacking reddish brown pigment in hypothallus similar to the new species which is sterile and having up to 0.8 × 0.5 mm pseudoisidia, and diploschistesic and lecanoric acids as lichen substances ( Rogers & Hafellner 1987, Egea et al. 1995, Elix 2009, Lumbsch et al. 2011).

Distribution and habitat: — Sagenidiopsis atroalba is known only from the type locality in a lowland evergreen forest in the South Andaman.

Etymology: —The specific epithet refers to the black apothecia with the whitish tomentum.