Upretia

''Upretia'' is a genus of lichen in the family Teloschistaceae. It has three species of saxicolous (rock-dwelling), crustose lichens. ''Upretia'' is characterised by its small and narrow, rod-shaped . The distribution of the genus ranges from mid-altitude rocky terrains in India to both arid and higher altitudinal environments in China.

Taxonomy

''Upretia'' was circumscribed by lichenologists Sergey Kondratyuk, Arne Thell, and Jae-Seoun Hur in 2017, with ''Upretia amarkantakana'' assigned as the type species. ''Upretia'' is a member of the subfamily Caloplacoideae of the Teloschistaceae. The genus is named in honour of the Indian lichenologist Dalip Kumar Upreti, recognising his contributions to the study of Indian lichens.

Its closest relative, the monotypic genus '' Ioplaca'' from the eastern Himalayas, is differentiated by its thallus colour, areolae structure, and apothecia.

Description

The genus ''Upretia'' is characterized by a crustose thallus that is typically orbicular in shape and ranges from to somewhat in form. The central part of the thallus often has a subsquamulose appearance but can sometimes be to . Its colour varies from olive-grey to brownish grey or ash-grey. The thalline lobes of ''Upretia'' are generally narrow to wide, branched, and have a flat to slightly convex surface, often covered with a fine dusting known as .

The outermost layer of the thallus, or layer, is thin and made of tightly interwoven cells (). The uppermost cells in this layer are typically brownish, but there is no distinct . The inner layer of the thallus, or medulla, is white. Both a prothallus and are usually present and are characterized by their black colour.

The apothecia of ''Upretia'' are in form, meaning they have a that is the same colour as the thallus. They start as immersed structures in their young stage and become as they mature. The of the apothecia ranges in colour from orange to brownish and can be either concave or flat. The , the layer beneath the thalline margin, also has a paraplectenchymatous structure. The paraphyses, or sterile filaments within the apothecia, contain oil droplets. Each ascus typically contains eight spores. These are clear (hyaline) and , meaning they are divided into two components () separated by a central septum with a hole. The , or asexual spores, are narrowly (rod-shaped) and small.

''Upretia'' shows no colour change when exposed to potassium hydroxide (K−), bleach (C−), or para-phenylenediamine (Pd−) chemical spot tests. However, the apothecium disc and react with potassium hydroxide to turn purple, while not reacting to bleach or para-phenylenediamine. The presence of parietin and an olive spot at RF class 4 has been noted in the apothecial disc, based on previous research.

Habitat and distribution

''Upretia'' species grow on rocks in varying environmental conditions and altitudes. ''Upretia amarkantakana'' thrives on sun-exposed bauxite rocks. It is found in the Madhya Pradesh region of India, specifically in the Anuppur, Dindori, and Shahdol districts around the Amarkantak area. This species is typically found at altitudes ranging from . It is often found in the company of species from the genera '' Buellia'' and ''Staurothele''. ''Upretia hueana'' is located in Madhya Pradesh as well, but it is found at a higher altitude, around . ''Upretia squamulosa'' is known to grow in arid environments and has a broader elevation range, from . Its distribution is limited to Yunnan province in China, marking a significant geographical distinction from its congenera in India.

Species

* '' Upretia amarkantakana''
* '' Upretia hueana''
* '' Upretia squamulosa''

References

{{Taxonbar, from=Q55280210

Teloschistales
Teloschistales genera
Taxa described in 2017
Taxa named by Sergey Kondratyuk
Taxa named by Arne Thell
Taxa named by Jae-Seoun Hur
Lichen genera