Mazosia lueckingii

Mazosia lueckingii
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Arthoniomycetes
Order:	Arthoniales
Family:	Roccellaceae
Genus:	Mazosia
Species:	M. lueckingii
Binomial name
Mazosia lueckingii Kr.P.Singh & Pinokiyo (2008)

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 verrucae, dark hypothallus, and relatively large spores divided by 4–5 cross-walls.

Taxonomy

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 1,200 m (3,900 ft), 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 34–45 by 4–7 μm 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".

Description

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 4–8 mm across but is only 18–30 μm thick. Its surface is covered in small, brown wart-like bumps (verrucae) 100–135 μm wide; each bump is packed with colourless crystals 8–15 μm across and capped by a mat of brown fungal threads. A narrow, dark-brown hypothallus fringes the colony, and the photosynthetic partner is a Phycopeltis green alga whose rounded or rectangular cells measure 8–12 × 3–4 μm.

The reproductive bodies are minute ascostromata that remain largely buried in the thallus. When mature, only a 0.2–0.4 mm black disc 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 hypothecioid layer (8–15 μm thick) supports a clear hymenium 70–80 μm tall. Club-shaped asci (60–70 × 19–25 μm) contain eight spindle-shaped ascospores. Each spore is colourless, 34–45 × 4–7 μm, divided by three to five cross-walls (septa) that do not cause any narrowing, and the end cells are slightly tapered.

The species is distingushed by the combination of brown crystal-filled verrucae, a dark hypothallus, and partly exposed apothecia producing relatively large 4–5-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.