Halecania athallina

Halecania athallina
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Leprocaulales
Family:	Leprocaulaceae
Genus:	Halecania
Species:	H. athallina
Binomial name
Halecania athallina Fryday (2020)

Halecania athallina is a species of lichen in the family Leprocaulaceae. ^[1] Found in Alaska, it was described as new to science in 2020 by British lichenologist Alan Fryday. The type specimen was discovered in Hoonah-Angoon Census Area in Glacier Bay National Park. There it was found growing on argillite rock on an alpine heath with rock outcrops. ^[2]

The thallus of this lichen is completely immersed in its substrate. The specific epithet athallina refers to this characteristic absence of a thallus. The lichen makes dark reddish-brown lecideine apothecia that are typically 0.3–0.4 mm in diameter. The ascospores are hyaline, have a single septum, and measure about 12 by 5  μm. The most morphologically similar lichen is Halecania rhypodiza , but this species has a dark brown thallus and larger spores measuring 12–15 by 4.5–6 μm. ^[2]

Description

Halecania athallina shows itself only through its fruiting bodies, as it lacks a visible vegetative crust (its epithet literally means "without a thallus"). The tiny, lecideine apothecia—so called because they have a proper margin but no rim formed by the missing thallus—are scattered singly across the substrate. Each disc is dark reddish-brown, roundish to angular, and just 0.3–0.4 mm across, with a persistent, slightly raised edge about 0.05 mm wide. In section the exciple is nearly clear inside, built from slender, interwoven hyphae about 1  micrometres (μm) thick, but its outermost 10 μm turn brown as the hyphae expand into short cortical cells capped by dark pigment, a pattern echoed at the tips of the hymenial filaments. ^[2]

The hymenium rises 35–40 μm and is overlaid by a 5–10 μm brown epihymenium. Straight, unbranched paraphyses thread the spore layer; they start only 1–1.5 μm wide but swell abruptly to 3–4 μm at the apex, where the same brown pigment forms a minute cap. Beneath lies a clear hypothecium about 30 μm tall. The asci follow the Catillaria type: slightly club-shaped, two-walled, and eight-spored, measuring 30–35 × 12–18 μm. Their contents show no color change in iodine solutions (I−, KI−). The mature spores are hyaline, smooth, and divided by a single cross-wall; they are 9.5–14.5 μm long and 3.5–5.5 μm wide, most commonly around 12 × 4.7 μm, giving a length-to-width ratio near 2.5. Each spore is wrapped in a very thin outer envelope (perispore). No asexual reproductive structures (conidiomata) have been observed. ^[2]

Standard spot tests are negative on Halecania athallina: sections placed in potassium hydroxide (K), sodium hypochlorite (C), or para-phenylenediamine (PD) do not change color, and thin-layer chromatography detects no recognizable lichen products, only an unidentified trace compound that runs in various solvent classes. ^[2]

References

1. "Halecania athallina Fryday". Catalogue of Life . Species 2000: Leiden, the Netherlands. Retrieved June 17, 2025.
2. Spribille, Toby; Fryday, Alan M.; Pérez-Ortega, Sergio; Svensson, Måns; Tønsberg, Tor; Ekman, Stefan; Holien, Håkon; Resl, Philipp; Schneider, Kevin; Stabentheiner, Edith; Thüs, Holger; Vondrák, Jan; Sharman, Lewis (2020). "Lichens and associated fungi from Glacier Bay National Park, Alaska". The Lichenologist. 52 (2): 61–181. doi: 10.1017/S0024282920000079 . PMC   7398404 .