Heterodermia fragmentata Weerakoon & Aptroot, 2016

Weerakoon, Gothamie & Aptroot, André, 2016, Nine new lichen species and 64 new records from Sri Lanka, Phytotaxa 280 (2), pp. 152-162 : 153-155

Heterodermia fragmentata Weerakoon & Aptroot , sp. nov. ( Fig. 1C–E )

Mycobank No.: MB 817609

Heterodermia with thallus foliose, forming tufts up to 7 cm diam., divided into linear, grey lobes up to 1 cm long and 0.7–2.2 mm wide, at tips tapering, slightly recurved; tips often spotted with white pruina; margins often with a thin dark grey line; lower surface without cortex or rhizines, arachnoid, white, often blackening towards the centre of the thallus; cilia black, shiny, marginal, mostly simple, 0.1 mm thick and up to 3 mm long; soredia, isidia and lobules absent, but the whole non-peripheral part of the thallus becomes dissected into small lobes that originate as marginal, often upright, lobules of up to c. 1.2 mm long, with similar cilia; atranorin in the cortex, zeorin in the medulla.

Type: — SRI LANKA. Nuwaraeliya, on bark of tree, 8 March 2015, G.Weerakoon & A.Aptroot Ne293 (holotype PD, isotypes ABL & F).

Thallus foliose, forming tufts up to 7 cm diam.; lobes linear, grey, up to 1 cm long and 0.7–2.2 mm wide, mostly dichotomously branched every c. 2 mm; tips tapering, slightly recurved; upper surface smooth, not shiny, flat; tips often spotted with white pruina; margins often with a thin dark grey line; lower surface without cortex or rhizines, arachnoid, white, often blackening towards the centre of the thallus. Cilia black, shiny, marginal, mostly simple, 0.1 mm thick and up to 3 mm long; soredia, isidia and lobules absent, but the whole non-peripheral part of the thallus becomes dissected into small lobes that originate as marginal, often upright, lobules of up to c. 1.2 mm long, with similar cilia. Apothecia rare, 1–4 mm diam., stipitate, laminal on the upper surface of the thallus lobes, developing tapering lobes around their margins, similar to the normal thallus lobes in morphology; these lobes up to 1 mm wide and up to 2 mm long, much incised, grey, disc 1–3 mm diam., brown with pale brown pruina; lower surface of the apothecia corticate and yellowish brown. Hymenium c. 120–160 μm high, not inspersed; epihymenium fuscous brown, granular; hypothecium hyaline, c. 30 μm high. Ascospores 8 per ascus, brown, 1-septate, constricted at the septum, with 0–3 sporoblastidia at each apex, 30–35 × 15–17.5 μm. Pycnidia not seen. Chemistry: cortex K+ yellow, medulla K+ faintly yellow; TLC: atranorin in the cortex, zeorin in the medulla.

Distribution and habitat: —On trees and shrubs, mostly in submontane forest, especially abundant on thin twigs of low scrubs in open mountainous areas. Only known from Sri Lanka, but widespread and locally abundant.

Discussion: —This species was striking in the field as a dissected species somewhat resembling H. leucomelos (L.) Poelt (1965: 31) and H. leucomela (Ach.) Trevisan. This species has recently been reclassified in a different segregate genus as Leucodermia leucomelos (L.) Kalb in Mongkolsuk et al. (2015: 35). The lobules are relatively large, and resemble malformed lobes. Specimens with this morphology were common all over Sri Lanka, but not reported outsied Sri Lanka. Sri Lanka is relatively rich in Heterodermia species; together with the species reported here, 34 Heterodermia species are now known from Sri Lanka, including three endemics ( Weerakoon & Aptroot 2013, 2014 & 2016).

Additional specimens seen: — SRI LANKA. Imbulpitiya, Im 137, Im140, Im101, Im96; Gallwaysland, Ga59, Ga56A, Ga50, Ga60A; Monaragala, Mn03; Horton Plains, Ho59, Ho2-3A; Nuwaraeliya, Ne03, Ne490, Ne145, Ne357, Ne351, Ne337, Ne215, Ne107; all 2015, G.Weerakoon (PD & F).

Figures

FIGURE 1. A–B, Astrothelium conjugatum, A, habitus, B, ascospores; C–E, Heterodermia fragmentata, C, apothecium, D–E, thallus; F–G, Lecanactis minutissima, F, apothecia, G, ascospores; H–I, Megalotremis cylindrica, H, conidiomata, I, conidia and conidiophores. Scale:A, H = 0.5 mm, B = 25 μm, C = 2 mm, D–E = 1 mm; F = 0.2 mm, G = 20 μm, I = 10 μm.