Biology:Lapismalleus

Lapismalleus is a monospecific genus of lichen-forming ascomycetes in the family Porocyphaceae. It was circumscribed in 2024 as part of a molecular phylogenetics-informed reclassification of the class Lichinomycetes; the genus was created to accommodate a single species, Lapismalleus lugubris. The species has had a complicated taxonomic history, having been placed in at least nine different genera since its original description in the mid-19th century. It forms distinctive dark crusts with thick, cracked patches that often reveal a pale cottony base layer as they age.

Taxonomy

Lapismalleus was introduced by Matthias Schultz and María Prieto in 2024 during a broad revision of Lichinomycetes based on a multilocus molecular phylogenetics analysis. Within the revised framework it is placed in the family Porocyphaceae. The type and only species is Lapismalleus lugubris, proposed as a new combination for Stenhammara lugubris, which was originally described by Abramo Bartolommeo Massalongo in 1856. The species has also been known as Psorotichia lugubris (A.Massal.) Arnold (1885), with infraspecific names including Stenhammara lugubris f. atrata Arnold (1860). The generic name, from lapis and malleus, deliberately echoes Christian Stenhammar's name and the tangled 19th-century usage of Stenhammara.

Description

Lapismalleus has a black to dark olive-brown, crustose thallus that breaks into thick [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]; older parts often erode to reveal a pale, cottony basal layer. The thallus is [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] and [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] (a dense, brick-like tissue), with robust hyphae arranged more or less vertically. The [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] is a cyanobacterium present as single cells in a yellow-brown gelatinous sheath. Apothecia are [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] in form (with both a [[Glossary of lichen terms#{{biology:{1}}}|thalline]] and a [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]]); the proper margin is dark and distinctly thickened toward the rim, and the [[Glossary of lichen terms#{{biology:{1}}}|{{Biology:{1}}}]] are dark reddish-brown to nearly black. The asci are of the Lichina type and eight-spored; ascospores are simple, hyaline and broadly ellipsoid. Pycnidia are present and produce short bacilliform conidia. No secondary metabolites have been reported in Lapismalleus by thin-layer chromatography.

Habitat and distribution

Lapismalleus lugubris grows on inclined, well-lit, seeping calcareous rock; it also occurs seasonally in shallow rock pools in alvar landscapes. As currently known it is restricted to Central and Northern Europe.

References

Wikidata ☰ Q136435382 entry