Phlyctis psoromica Elix & Kantvilas
Mycobank MB 517805
Thallus crustose, 40–80 µm thick, whitish to very pale blue-grey to greenish grey, rimose, scurfy or furfuraceous, lacking isidia and soredia but often becoming ulcerous, eroded and rather granular in the vicinity of the apothecia, forming extensive, irregularly spreading patches 3–10 cm wide; prothallus white, arachnoid, sometimes forming a narrow, ± byssoid margin; photobiont chlorococcoid, with cells globose to subglobose, 6–12(–15) µm wide. Apothecia 0.1–0.4 mm wide, usually aggregated in clusters of 2–6(–10), rarely solitary, immersed to adnate; thalline margin slightly raised, at first entire, soon becoming abraded and at length reduced to white, granular blotches on the surface of the thallus; disc irregularly roundish, plane to concave, pale grey to grey-brown, densely covered with a fine, white pruina; proper exciple grey to grey-black, in section cupular, 10–40 µm, brownish, composed of interwoven, short-celled, branched and anastomosing hyphae 2–4 µm thick. Hypothecium brownish, ca. 25–40 µm thick, poorly differentiated from the excipulum. Hymenium colourless, separating readily in K, 75–120 µm thick, overlain by a brownish, K± olive-brown, granular epihymenial layer that partially dissolves in K; paraphyses simple in the lower part, sparsely branched towards the apices, septate, 1.5–2.5 µm wide, with apices slightly thickened to 2–4 µm wide; asci (4–)8–spored, cylindrical-clavate, 70–100 x 10–12 µm, with wall 1.5–2 µm thick, weakly amyloid but with a thin, more intensely amyloid outer coat, especially near the ascus apex. Ascospores hyaline, fusiform, transversely (3–)7-septate, coiled in the ascus, straight or sigmoid-curved, 30–39.3–50(–52) x 4–5.2–6 µm. Pycnidia not seen. Spot tests: cortex K–, KC–, C– P+ intense yellow. Secondary chemistry: psoromic acid; thallus C–, K–, P+ yellow.
Morphologically, Phlyctis psoromica closely resembles several other species of Phlyctis that share a whitish, often scurfy thallus, ± immersed, often clustered apothecia, 8-spored asci, and fusiform, transversely septate ascospores. It differs from these taxa mainly by its chemical composition. Phlyctis subuncinata Stirt., which is widespread in Australasia, differs in containing stictic, constictic and cryptostictic acids, as well as having somewhat larger ascospores, 40–72 x 5–7 µm (Galloway, 2007). Other related species, also with larger ascospores, include: P. uncinata Stirt., containing norstictic acid but currently unrecorded for Australia; and P. sordida C. Knight, which contains hypostictic acid and is here recorded from Australia for the first time (New South Wales: Gloucester Tops; 32°04’S, 151°34’E, Kantvilas 406/88A, HO). Psoromic acid is known from at least two other species of the genus. Phlyctis megalospora (P. James) D. J. Galloway & G. Guzmán occurs in New Zealand, also contains conpsoromic acid and has ascospores 285–390 x 75–95 µm occurring singly in the ascus. There is also a closely related, similarly large-spored and as yet unidentified species in alpine areas of Tasmania.
This new species is known at present only from several localities in New South Wales. It occurs on smooth bark in shaded habitats on the trunks of understorey trees in wet upland forests from 680 to 1500 m elevation. Frequent hosts include Doryphora sassafras, Atherosperma moschatum and species of Elaeocarpus and Pomaderris.
Type: —AUSTRALIA: New South Wales: Cottan-Bimbang National Park, Stockyard Creek Rest Area, ca. 83 km E of Walcha; 31°24’S, 152°07’E, 685 m; on Acacia in wet Eucalyptus forest; Aug 2008, Elix 43095 (holotype CANB; isotypes HO, NSW).
Additional specimens examined (paratypes):—AUSTRALIA: New South Wales: Mt William; Kantvilas 328/88 (HO, NSW). New England National Park, ca. 3 km W of Point Lookout; Kantvilas 661/88 (HO, NSW). Mount Hyland Nature Reserve, 20 km N of Hernani; Elix 36611, 36652, 36658 (CANB, HO).
Phlyctidi subuncinatae, P. sordidae P. uncinataeque similis sed acidum psoromicum continens et ascosporis minoribus, 30–52 µm longis, 4–6 µm latis.