Pyrenula subvariabilis
| Pyrenula subvariabilis | |
|---|---|
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Eurotiomycetes |
| Order: | Pyrenulales |
| Family: | Pyrenulaceae |
| Genus: | Pyrenula |
| Species: | P. subvariabilis
|
| Binomial name | |
| Pyrenula subvariabilis Aptroot & Sipman (2018)
| |
| |
| Holotype: Potaro-Siparuni Region, Guyana[1] | |
Pyrenula subvariabilis is a rare species of corticolous (bark-dwelling) crustose lichen in the family Pyrenulaceae.[2] Found in Guyana, it was formally described as a new species in 2018 by the lichenologists André Aptroot and Harrie Sipman. This lichen forms a thin, smooth, yellowish-brown crust on tree bark and is distinguished by its clustered black flask-shaped fruiting bodies that are partially fused together with off-centre openings. It is known only from a single location in the Pakaraima Mountains of Guyana, where it grows on smooth bark of canopy trees in savanna woodland at around 800 metres elevation.
Taxonomy
[edit]Pyrenula subvariabilis was described as a new species in 2018 by the Dutch lichenologists André Aptroot and Harrie Sipman, based on collections made in the Pakaraima Mountains of Guyana. It is distinguished by its combination of fused ascomata with lateral ostioles and relatively small, submuriform ascospores. While a few species in Pyrenula have submuriform spores, P. subvariabilis is the only known species in the genus that combines this spore type with grouped, fused ascomata and ascospores of this specific size range.[1]
Description
[edit]This crustose lichen has a smooth, continuous, ochraceous thallus that is thin and lacks any pseudocyphellae or visible crystal inclusions. The photobiont is a green alga from the genus Trentepohlia, commonly associated with tropical lichens.[1]
The ascomata are perithecioid (flask-shaped), grouped in clusters of 2–8, and pyriform (pear-shaped). These are emergent—partially protruding from the bark surface—and black, measuring 0.4–0.7 mm in diameter. Most are partly covered by the surrounding thallus. The ostioles are pale brown, fused laterally, and off-centre (eccentric), about 0.2 mm wide. The wall is about 50 micrometres (μm) thick and uniformly carbonised.[1]
The hamathecium is hyaline and not inspersed. Each ascus contains eight brown ascospores, which are submuriform—meaning they have both transverse and longitudinal septa, but not in a regular pattern. The spores have 6–12 lumina, are fusiform in shape, and measure 17–20 (occasionally up to 25) × 6–9 μm. The ends are pointed, and the internal chambers are mostly rounded or triangular. The terminal lumina are separated from the outer spore wall by an internal endospore layer. Pycnidia (asexual fruiting bodies) were not observed. No secondary metabolites were detected by standard chemical tests.[1]
Habitat and distribution
[edit]Pyrenula subvariabilis is known only from a single locality in Guyana. It was found growing on smooth bark of canopy tree branches in savanna woodland near Pakaraima Village in the Potaro-Siparuni Region, at an elevation of roughly 800 metres. It appears to be a rare and narrowly distributed species, adapted to seasonally dry tropical conditions.[1]
See also
[edit]References
[edit]- ^ a b c d e f Aptroot, André; Sipman, Harrie J.M.; Mercado Diaz, Joel Alejandro; Mendonça, Cléverton de Oliveira; Feuerstein, Shirley Cunha; Cunha-Dias, Iane Paula Rego; Pereira, Thamires Almeida; Cáceres, Marcela Eugenia da Silva (2018). "Eight new species of Pyrenulaceae from the Neotropics, with a key to 3-septate Pyrgillus species". The Lichenologist. 50 (1): 77–87. doi:10.1017/s0024282917000573.
- ^ "Pyrenula subvariabilis Aptroot & Sipman". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 18 June 2025.