Acanthothecis nivalis
Acanthothecis nivalis is a species of corticolous script lichen in the family Graphidaceae. It was formally described as a new species in 2003 by Urmila Makhija and Bharanti Adawadkar. The species epithet nivalis refers to the distinctive snow-white appearance of its fruiting bodies. It occurs in the Andaman Islands in the northeastern Indian Ocean, where it grows on tree trunks in moist forests.
Description
The thallus is corticolous, brownish in colour, and has an irregularly cracked, texture. It typically measures 3–3.5 cm across and is. The thallus features a distinctive black zone at its periphery, which is studded with numerous colourless crystals.The ascocarps are conspicuously white with a form, raised above the thallus surface. These structures range from to branched, appear slender, and measure approximately 2–8 mm in length and 0.25 mm in width. They have acute ends, though the is not readily visible until it appears brown, very narrow, and slit-like when mature.
The is non-, pale orange-brown, entire to striate, and convergent. The hymenium measures about 58–63 μm in height and is clear. Chemical spot tests are K−, C−, KC−, P+, and UV−; psoromic acid is a secondary metabolite made by A. nivalis.
Acanthothecis kalbii is a related species that shares certain taxonomic features with A. nivalis. This Brazilian species is characterized by oblong lirellae with grey-white discs, spiny paraphyses-tips and, an uncarbonized excipulum, and hyaline ascospores that are transversely 3–5-septate measuring 9–15 by 4–5 μm. While both species have similar ascospore dimensions and septation patterns, as well as the distinctive spiny structures on both paraphyses tips and periphysoids, several key differences exist. A. nivalis can be readily distinguished by its more prominent and considerably longer lirellae, discs that remain largely concealed rather than exposed, and different chemistry, containing psoromic acid instead of the norstictic acid found in A. kalbii.