Neopetractis

Neopetractis is a small genus of rock-dwelling, crustose lichens in the family Gyalectaceae.^[1] It was established in 2021 to accommodate two species formerly assigned to Petractis, on the basis of molecular data and photobiont differences.

Neopetractis
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Gyalectales
Family:	Gyalectaceae
Genus:	Neopetractis Ertz (2021)
Type species
Neopetractis luetkemuelleri (Zahlbr.) Ertz (2021)
Species
N. luetkemuelleri N. nodispora

Taxonomy

Neopetractis was circumscribed by Damien Ertz as a segregate of Petractis. It differs from Petractis in the strict sense (whose type species associates with a cyanobacterium) in having a trentepohlioid green-algal partner, and it also differs from Gyalecta sensu lato in having ascospores surrounded by a thick gelatinous sheath. The new combinations Neopetractis luetkemuelleri and N. nodispora were made in the protologue. In multi-locus phylogenies, Neopetractis forms a lineage close to Ramonia and the taxon often cited as "Gyalidea praetermissa"; deeper family-level relationships are unresolved and the broader family Gyalectaceae may not be monophyletic in those analyses.^[2]

Description

The thallus of Neopetractis forms a thin crust on rock, either endolithic (inside the rock) or semi-epilithic (partly on the surface). It is continuous, smooth to finely wrinkled, whitish grey to pale pink, and lacks a distinct cortex. The photobiont is trentepohlioid, i.e. a filamentous green alga. Apothecia (sexual fruiting bodies) are at first immersed and perithecioid (flask-like), later opening to expose a small disc up to about 0.5 mm across with a slightly raised, often paler margin; the disc is beige-pink to pale brown and flat to shallowly concave. The exciple is thin and pale; the hymenium is colourless and stains I− or faintly I+, KI+ blue. Asci are 8-spored and the paraphyses are simple. Ascospores are hyaline, ellipsoid, 3–5-septate to submuriform (occasionally with longitudinal septa). They have dimensions of roughly 16–25 × 5.5–10 μm, and are each surrounded by a distinct gelatinous sheath about 2–4 μm thick. Pycnidia are immersed in the thallus; conidia are colourless and either simple or forming irregular multicellular clusters. No lichen substances were detected by thin-layer chromatography.^[2]

Habitat and distribution

Species of Neopetractis occur on calcareous rocks. The type of N. luetkemuelleri was collected on limestone on the island of Hvar (Croatia), while the type of N. nodispora is from a northwest-facing limestone wall in Glamorgan, Wales.^[2]