Macroskyttea parmotrematis Etayo, Flakus & Kukwa, 2015

Etayo, Javier, Flakus, Adam, Suija, Ave & Kukwa, Martin, 2015, Macroskyttea parmotrematis gen. et sp. nov. (Helotiales, Leotiomycetes, Ascomycota), a new lichenicolous fungus from Bolivia, Phytotaxa 224 (3), pp. 247-257 : 252

Macroskyttea parmotrematis Etayo, Flakus & Kukwa sp. nov. MycoBank no MB 812781

Diagnosis: Differs from all similar species of the genera Skyttea and Diplolaeviopsis in having large apothecia with long excipular hairs, with greenish pigment in exciple of young apothecia (reacting K+ olive) and brownish orange pigment in mature exciple (reacting K+ purple), large, fusiform ascospores and the host selection.

Type:— BOLIVIA. DEPT. TARIJA: Prov. Burnet O’Connor, Lomas de la Soledad , road between Entre Ríos and Chiquiacá, 21°39’38”S, 64°07’31”W, 1670 m, Tucumano-Boliviano altimontano forest, on Parmotrema aberrans , 10 August 2012, M. Kukwa 11316 (holotype UGDA!, isotype LPB!; sequences accession numbers: rDNA nuSSU KP984790, nuLSU KP984788, ITS KP984784) .

( Figs 2–3 )

Ascomata apothecioid, developing directly on healthy thallus or on small, black dots, dispersed on the host thallus (single) or in groups of 3–4(–8), immersed at first, soon superficial to stipitate, black with upper part of exciple greyish due to the presence of hyaline hairs, (200–)400–800 μm in diam.; disc black, obscured by the margin when young, but widely exposed when mature; exciple c. 60 μm wide laterally, 90–100 μm wide basally, para- to prosoplectenchymatous, consisting of thick-walled cells (1–2 μm thick), ellipsoid to subsphaerical 5–9 μm diam.; inner exciple composed by thin-walled cells (structura angularis or in part structura intricata), hyaline to greenish (K+ olive), but in open disk (mature) specimens brownish orange (K+ purple); when very young, apical part near hymenium sometimes with additional yellowish green pigment (K–); ectal exciple composed of thick-walled cells (structura globosa or structura angularis), 20–25 μm wide, greenish grey when young (K+ olive) to dark brown when mature (K+ purple); excipular hairs simple, aseptate or rarely septate, smooth-walled, hyaline to greenish grey or brownish, cylindrical or tapering towards the apex with an obtuse apex, thin-walled (near the hymenium) or thick-walled (external hairs), specially thick near the apex where the wall can be solid along the length of 5–25 μm, 48–80 × 3–4 μm; hairs are covered by gelatine outer-layer which after application of K becomes evidently thick and undulated; hymenium 45–65 μm high, I–, K/I–; paraphyses hyaline, covered by a hyaline gel, septate, not constricted at the septa, 2–2.5 μm wide, not or only slightly (up to 3 μm) widened and pigmented in the upper part; hypothecium hyaline to pale brownish orange, 10–15 μm, of small, 2–3 μm wide, roundish to elongate cells, in mature ascomata sometimes K+ purple; epihymenium, greenish grey (K+ olive) to dark brown (K+ purple); asci 8-spored, cylindrical to narrowly clavate, apically thickened into a tholus with a narrow ocular chamber with a characteristic widening on top (more evident in younger asci and in Congo Red solution), I–, K/I– (epiplasm orange), 40–53 × 6–7 μm; ascospores hyaline, without perispore, narrowly ellipsoidal to fusiform, sometimes slightly curved, thin- and smooth-walled, usually with 4 small oil guttules, 12–17 × 2–3 μm; conidiomata not observed.

Host: Macroskyttea parmotrematis inhabits the upper thallus surface of corticolous and saxicolous specimens of Parmotrema aberrans and P. ultralucens . As many ascomata appear on healthy parts of the thalli, we assume it is biotrophic mycoparasite.

Distribution and habitat: So far the new species is known only from three localities in Bolivian Andes, where it grows in Yungas and Tucumano-Boliviano forests at elevation 1600–2000 m. The type locality is very diverse in terms of lichenicolous fungi; other species will be treated elsewhere.

Additional specimens examined (paratypes). BOLIVIA. DEPT. COCHABAMBA: Prov. Ayopaya, 20 km de Cocapata hacia Cotacajes, 16°46’S, 66°44’W, 2000 m, bosque secundario disturbado en una quebrada, on Parmotrema ultralucens , on bark, 27 May 1996, K. Bach 97A, M. Kessler, J. Gonzales, A. Acebey ( LPB). DEPT. TARIJA: Prov. O’Connor, near Soledad, 21°40’49”S, 64°07’33”W, 1600 m, Tucumano-Boliviano montano forest, on P. aberrans on exposed rock near the road, 11 August 2012, J. Etayo 28402 ( LPB, hb. Etayo).

Figures

FIGURE 2. Macroskyttea parmotrematis. A, habit of a ascomata:A, young almost close ascomata (Kukwa 11316), B, mature ascoma with strongly exposed dark pigmented disc (Bach et al. 97a); C, cross section of mature ascoma (Bach et al.97a); D, cross section of young ascoma showing excipular hairs (Kukwa 11316); E, ascospores (Kukwa 11316). Scale bars:A–B—250 μm, C—50 μm, D—25 μm, E—10 μm.

FIGURE 3. Macroskyttea parmotrematis. A, cross section of mature ascoma mounted in LPCB (Bach et al. 97a); B, cross section of young ascoma mounted in LPCB (Etayo 28402); C, cross section of young ascoma mounted in LPCB showing inner (left) and ectal (right) exciple (Etayo 28402); D, inner exciple mounted in LPCB showing thin-walled cells (structura angularis) (Etayo 28402); E, ectal exciple mounted in LPCB showing thick-walled cells (structura globosa) (Etayo 28402); F, asci in different development stages mounted in Congo Red showing apically thickened tholus with a narrow ocular chamber with a characteristic widening on top, two right-hand asci with 4-guttulate ascospores (Etayo 28402). Scale bars: A–B—25 μm, C–F—10 μm.