Carneothele sphagnicola Fryday, M. Svenss. & Holien sp. nov.

MycoBank number: MB 830095; Index Fungorum number: IF 830095; Facesoffungi number: FoF;

Thallus biofilm-like, coating Sphagnum mosses; ascomata red- brown, perithecioid, the wall pigment forming magenta crystals in 10% KOH, attenuating to a narrow ostiole, with asci 220– 250 × 30–35 μm, polysporous, containing ellipsoid ascospores.

Type: USA, Alaska, Petersburg Borough, Mitkof Island, ‘Towers muskeg’, 56.672750°N, 132.918500°W, 10 m, Sphagnum bog (muskeg) with Oxycoccus oxycoccos, 1 September 2014, Fryday 10667, K. Dillman & Spribille (MSC—holotype, E— isotype). (Fig. 14)

Thallus biofilm-like. Photobiont present as scattered bundles of green algal cells, 20–60 μm across, present around the base of the perithecia; individual cells orbicular, 5–9 μm diam. Ascomata perithecioid, scattered, brick red, occasionally with light yellow pruina around the ostiole, becoming pale brown in the herbarium, flask-shaped, 0.20–0.25–0.30 mm diam., 0.4–0.5 mm tall, ½ to ⅔ immersed in substratum. Ascomatal wall hyaline (blue in 10% HCl), composed of longitudinally arranged hyphae 2–2.5 μm thick but with numerous, minute, golden brown crystals that dissolve in KOH to give a fleeting magenta solution followed by the formation of ± rectangular or dendroid magenta crystals, mostly c. 10–18 μm across but up to 30 × 10 μm, crystals not dis- solving in 10% HCl or 50% HNO3, but becoming golden brown. Hamathecium composed of numerous, slender (c. 1 μm thick), lax, unbranched filaments, I−. Asci 220–250 × 30–35 μm, slightly clavate at base, gradually tapering to a narrow apex, wall I+ blue, tholus I+ blue with a narrow, I− ocular chamber; ascospores uni- cellular, numerous (>200) per ascus, broadly ellipsoid with pointed ends, 9–10 × 4–5 μm, amyloid (IKI+ blue).

Chemistry. Thallus spot tests negative, ascomatal wall with KOH + magenta crystals (see below), HNO3− (50% solution), HCl− (15% solution). No substances detected by TLC.

Etymology. A reference to the apparently obligate occurrence on the tops of Sphagnum hummocks.

Habitat. Found only on the dry tops of Sphagnum hummocks, apparently most frequent on S. fuscum (Schimp.) Klinggr. At the type locality it occurs in a distinctive community with Absconditella sphagnorum Vězda & Poelt, as well as an undescribed ascomycete superficially resembling Geltingia associata (Th. Fr.) Alstrup & D. Hawksw. and Epibryon sp.

Notes. Carneothele sphagnicola is a highly distinctive species that defied placement in any known genera. It is apparently close to Thelocarpon, with which it shares the minute ascomata on organic substrata with the occasional presence of a yellow pruina, plus the multi-spored asci that gradually taper to a narrow apex. However, it differs from that genus in the more robust red-brown ascomata with the wall pigment forming magenta crystals in 10% KOH.

Fig. 14. Carneothele sphagnicola (A & B from Spribille 40821; C–F from Spribille 40824). A & B, habitus; C, section through ascoma; D, ascomatal section in Lugol’s solution, showing deeply amyloid hymenial region and adjacent non-amyloid zone; E, ascoma in K, demonstrating dendritic crystals; F, ascospores in Lugol’s solu- tion, showing characteristic amyloid reaction. Scales: A & B = 0.5 mm; C–E= 50 μm; F= 10 μm.