Mazosia lueckingii is a species of foliicolous (leaf-dwelling) lichen in the family Roccellaceae. It is found in India. This lichen forms thin, greyish-brown to yellowish-brown crusts on dicotyledon leaves, with a surface covered in small brown wart-like bumps filled with colourless crystals and minute black reproductive discs that sit flush with the surface. Described as new to science in 2008, it is distinguished by its crystal-filled , dark , and relatively large spores divided by 4âÂÂ5 cross-walls.
The lichen was formally described as a new species in 2008 by Krishna Pal Singh and Athokpam Pinokiyo. The type specimen was collected by the first author in the Darjeeling district (West Bengal) at an altitude of , where it was found growing on dicotyledon leaves. The lichen has a verrucose (warty) thallus with brown, hairless verrucae, a black hypothallus, and ascospores that measure 34âÂÂ45 by 4âÂÂ7 üm with 4 or five septa. The specific epithet lueckingii honours the German-born lichenologist Robert Lücking, who, according to the authors, "has made remarkable contributions to the taxonomy and ecology of foliicolous lichens".
Mazosia lueckingii forms a thin, leaf-dwelling crust that appears light greyish-brown to yellowish-brown. The thallus spreads in roughly circular or patchy colonies 4âÂÂ8 mm across but is only 18âÂÂ30 üm thick. Its surface is covered in small, brown wart-like bumps () 100âÂÂ135 üm wide; each bump is packed with colourless crystals 8âÂÂ15 üm across and capped by a mat of brown fungal threads. A narrow, dark-brown fringes the colony, and the photosynthetic partner is a Phycopeltis green alga whose rounded or rectangular cells measure 8âÂÂ12 à3âÂÂ4 üm.
The reproductive bodies are minute ascostromata that remain largely buried in the thallus. When mature, only a 0.2âÂÂ0.4 mm black becomes visible, sitting flush with the surface. A thin brown margin surrounds each disc, while the lateral wall (excipuloid tissue) slopes gently downward and is overlain by a colourless crystal layer and a thin sheath of thallus tissue. Internally, a pale to faded-brown layer (8âÂÂ15 üm thick) supports a clear hymenium 70âÂÂ80 üm tall. Club-shaped asci (60âÂÂ70 à19âÂÂ25 üm) contain eight spindle-shaped ascospores. Each spore is colourless, 34âÂÂ45 à4âÂÂ7 üm, divided by three to five cross-walls (septa) that do not cause any narrowing, and the end cells are slightly tapered.
The species is distinguished by the combination of brown crystal-filled verrucae, a dark hypothallus, and partly exposed apothecia producing relatively large 4âÂÂ5-septate spores. These features set it apart from similar foliicolous Mazosia species that have paler warts, fewer septa, or spores that constrict at the septum.
Mazosia lueckingii is known only from its type and paratype collections, both made in the Darjeeling district of West Bengal, India. These specimens were gathered on dicotyledonous leaves at roughly 1,200 m elevation in the subtropical eastern Himalaya. Within that montane setting the lichen is strictly foliicolous, forming minute, brown-verruculose colonies on the living leaves of understory shrubs. It occupies the persistently humid microclimate of subtropical hill forest and is part of a characteristic epiphyllous community that also includes Byssoloma leucoblepharum, Gyalectidium filicinum and Echinoplaca streimannii. Mazosia lueckingii is one seven Mazosia species known to occur in the Eastern Himalayas biodiversity hotspot region.