Polyblastidium fragilissimum (Kurok.) Kalb, 2015

Mongkolsuk, Pachara, Meesim, Sanya, Poengsungnoen, Vasun, Buaruang, Kawinnat, Schumm, Felix & Kalb, Klaus, 2015, The lichen family Physciaceae in Thailand-II. Contributions to the genus Heterodermia sensu lato, Phytotaxa 235 (1), pp. 448-450 : 448-450

3. Polyblastidium fragilissimum (Kurok.) Kalb , comb. nov. ( Fig. 10D )

Mycobank MB 813840

Basionym: Anaptychia fragilissima Kurok., Beih. Nova Hedwigia 6: 60 (1962). Type:— JAPAN. Prov. Kii: Mt. Koya, Nuymaziri 679; (TNS n.v., isotype CANB!); Heterodermia fragilissima (Kurok.) Wei & Jiang, Lich. Xizang 111 (1986).

Thallus foliose, orbicular to irregularly spreading, loosely adnate, 5–12 cm wide. Lobes 1.0– 1.5 mm wide, ca. 2–3 mm wide at the tips, plane to weakly convex or weakly concave, sublinear-elongate, dichotomously to digitately branched, radiating; apices not ascending, contiguous to discrete, eciliate. Upper surface greenish white, whitish gray to cream-colored, epruinose, with marginal dorsiventral phyllidia, very rarely also laminal, usually minutely dissected, often granular near the tips, or entire phyllidia becoming granular and appearing sorediate. Medulla white. Lower surface ecorticate, ± compact, violet-gray in the centre, violet-striate towards the apices; yellow pigments absent. Rhizines marginal, at first simple and concolorous with the lower surface, then black and squarrosely branched, 2–4 mm long. Apothecia laminal, adnate to substipitate, 1–4 mm wide; margin lobulate, the lobules becoming elongate and deeply dissected; disc concave, dark brown to blackish brown, ± thinly gray-pruinose. Ascospores Polyblastidia - type, ellipsoidal, with 2 or 3 sporoblastidia at either ends, 36–50 × 16–20 µm. Pycnidia common, immersed, then becoming emergent, visible as black dots; conidia bacilliform, 4–5 × 1 µm.

Chemistry: Cortex K+ yellow, C–, KC–, P+ yellow; medulla K+ yellow, C–, P+ pale yellow; containing atranorin (major), zeorin (major), japonene (major), anaptychin-5 (minor), anaptychin-1 (trace), 6α-acetoxy- 16β,22-dihydroxyhopane-25-oic acid (trace).

Distribution and habitat:—Occurs on trees in Chiang Mai; also on rocks in Australia, Guatemala, Tanzania, China and Japan.

Remarks: — characterized by the minutely dissected marginal phyllidia, the ecorticate lower surface and the presence of atranorin and triterpenes. This species is very similar to P. violostriatum from which it is distinguished by the longer, Polyblastidia - type ascospores with more numerous sporoblastidia and in containing the japonica - rather than the leucotylin -chemosyndrome of triterpenes ( Elix 2011a: 20). The North American P. squamulosum is similar, but the spores are smaller in that species and laminal phyllidia are much more common than in P. fragilissimum .

Material reported from Thailand:— Chiang Mai: Doi Inthanon National Park (Wolseley & Aguirre-Hudson (1997: 333).

Specimen examined:— MASCARENE ISLANDS. Réunion: between le Dix Septième and Plain d'Affouches , ca. 8 km SSW of St-Denis, in remnants of a rainforest, 1000 m, 20°56' S, 55°24'30'' E, 14 August 1991, K. & A. Kalb (herb. Kalb 33752) .

Figures

FIGURE 10. A. Leucodermia boryi, fertile specimen (scale 5 mm). B. Leucodermia leucomelos, sorediate specimen (scale 5 mm). C. Polyblastidium appendiculatum (scale 5 mm). D. Polyblastidium fragilissimum (scale 5 mm). E. Polyblastidium hypocaesium (scale 5 mm). F. Polyblastidium hypoleucum (scale 5 mm).