Viridothelium sinuosogelatinosum

Viridothelium sinuosogelatinosum
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Dothideomycetes
Order:	Trypetheliales
Family:	Trypetheliaceae
Genus:	Viridothelium
Species:	V. sinuosogelatinosum
Binomial name
Viridothelium sinuosogelatinosum Aptroot & M.Cáceres (2022)
Holotype: Adolfo Ducke Forest Reserve, Brazil

Viridothelium sinuosogelatinosum is a species of crustose lichen in the family Trypetheliaceae. ^[1] This corticolous (tree bark-dwelling) lichen is characterised by its pale olivaceous-brown thallus and its unique ascospores , which are surrounded by a wavy gelatinous sheath. It was discovered in the Amazonas state of Brazil, within the Adolfo Ducke Forest Reserve near Manaus. ^[2]

Taxonomy

Viridothelium sinuosogelatinosum was formally described in 2022 by the lichenologists André Aptroot and Marcela Eugenia Cáceres, as part of a broader study aimed at cataloging the lichen biodiversity within a small area of the Amazon rainforest. The species epithet, sinuosogelatinosum, alludes to the distinctive wavy (sinuoso) gelatinous sheath that envelops the ascospores , highlighting one of its most distinguishing features. ^[2]

Description

The thallus of Viridothelium sinuosogelatinosum is crustose (crust-like), corticate , and has a dull pale olivaceous-brown colouration. It does not have a prothallus bordering it. The ascomata (fruiting bodies) are single, either globose or pear-shaped, measuring between 0.4 and 0.6 mm in diameter, and are black in colour. The ostioles are apical or slightly off-centre, dark brown with a pale dot in the centre, and concave. ^[2]

The hamathecium (a tissue composed of filamentous hyphae) lacks any inspersed oil droplets. Ascospores are produced eight per ascus, are hyaline (transparent), and 3(–4)-septate. They measure 33–37 by 8–11  μm, and are long-ellipsoid in shape with rectangular lumina . Each spore is encased in a wavy gelatinous sheath up to 5 μm thick. No pycnidia (asexual fruiting bodies) have been observed to occur in this species. ^[2]

Spot tests performed on the thallus show no reaction to ultraviolet light, and negative results for standard lichen substances reactions (C, K, KC, P). ^[2]

References

1. "Viridothelium sinuosogelatinosum Aptroot & M. Cáceres". Catalogue of Life . Species 2000: Leiden, the Netherlands. Retrieved 3 January 2024.
2. Aptroot, André; de Souza, Maria Fernanda; dos Santos, Lidiane Alves; Junior, Isaias Oliveira; Barbosa, Bruno Micael Cardoso; da Silva, Marcela Eugenia Cáceres (2022). "New species of lichenized fungi from Brazil, with a record report of 492 species in a small area of the Amazon Forest". The Bryologist. 125 (3): 435–467. doi:10.1639/0007-2745-125.3.433.