''Megalospora austropacifica'' is a species of corticolous (bark-dwelling),

crustose lichen Crustose lichens are lichens that form a crust which strongly adheres to the Substrate (biology), substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichen ...

in the family

Megalosporaceae The Megalosporaceae are a family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Division or divider may refer to: Mathematics *Division (mathematics), the inverse of multiplication *Division algorithm, a ...

. It is found on the islands of Taveuni and Viti Levu in

Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists ...

. It has a yellowish grey to whitish grey, glossy

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

that is thick and may appear slightly wrinkled or smooth, often with irregular cracks and small containing , but lacking

isidia An isidium is a vegetative reproductive structure present in some lichens. Isidia are outgrowths of the thallus surface, and are corticated (i.e., containing the outermost layer of the thallus), usually with a columnar structure, and consisting o ...

and soredia. Its apothecia (fruiting bodies) are circular, up to 4.5 mm in diameter, with the evolving from concave to slightly convex and coloured from orange-brown to red-brown, surrounded by a thick, prominent margin.

Taxonomy

The lichen was described as new to science in 2011 by the lichenologists

Helge Thorsten Lumbsch Helge Thorsten Lumbsch (born 1964) is a German-born lichenologist living in the United States. His research interests include the phylogeny, taxonomy, and phylogeography of lichen-forming fungi; lichen diversity; lichen chemistry and chemotaxon ...

, Alifereti Naikatini, and

Robert Lücking Robert Lücking (born 1964) is a German lichenologist. He is a leading expert on foliicolous lichens–lichens that live on leaves. Life and career Born in Ulm in 1964, Lücking earned both his master's (1990) and PhD degree (1994) at the Univer ...

. The

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

was collected in Fiji, specifically along the access road to the summit of Devo Peak on Taveuni. The specimen was found in a mountainous relict forest adjacent to the roadside. The species epithet alludes to its

South Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

distribution.

Description

''Megalospora austropacifica'' is distinguished by its yellowish grey to whitish grey

, which has a glossy surface. The thallus is thick and may have a slightly wrinkled () appearance or be smooth and continuous. Often, it shows irregular cracks and may have small , which contain (asexual reproductive structures). Unlike some lichens, it lacks

and soredia, which are vegetative

propagule In biology, a propagule is any material that functions in propagating an organism to the next stage in its life cycle, such as by dispersal. The propagule is usually distinct in form from the parent organism. Propagules are produced by organisms ...

s related to reproduction. The apothecia (fruiting bodies) of ''Megalospora austropacifica'' are a common feature and are circular in shape. They can reach up to 4.5 mm in diameter and up to 1 mm in height. When young, the of the apothecium is concave, but as it matures, it flattens or becomes slightly convex. The colour of the disc ranges from orange-brown to red-brown, turning blackish near the margins. These discs are glossy and lack a powdery coating (). The margin of the apothecium is thick and prominent. Its inner part, known as the , is yellowish brown to pale brown and has a , non-powdery appearance. The outer part, the , matches the colour of the thallus and is glossy and epruinose. The exciple itself has an orange-brown inner part and a translucent part that is unreactive to potassium hydroxide (K−). The , the topmost layer of the apothecium, is orange-brown and measures 20–35 μm in thickness. The , the tissue layer beneath the

hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some ...

, varies from clear to orange in colour. The hymenium is 200–250 μm high, clear (

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

), with particles, and has an amyloid reaction. The

asci ASCI or Asci may refer to: * Advertising Standards Council of India * Asci, the plural of ascus, in fungal anatomy * Accelerated Strategic Computing Initiative * American Society for Clinical Investigation * Argus Sour Crude Index * Association of ...

typically contain eight spores each. Individual of ''Megalospora austropacifica'' are clear and two-celled, with a slight curve reminiscent of the ''sulphurata''-type spores. They measure 60–85 by 22–26 μm, with spore walls that are 2–3 μm thick and have a thin, smooth outer layer (). In terms of chemistry, this lichen produces

usnic acid Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933-1937 by Curd and Robertson. Usnic a ...

and

zeorin Zeorin is a triterpene with the molecular formula C30H52O2 which occurs in many lichens A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among hypha, filaments of multiple fungus, fungi species in a mutu ...

Similar species

''Megalospora austropacifica'' is part of the '' Megalospora sulphurata'' species complex, a group known for asci containing multiple two-celled, usually curved ascospores. Initially, ''Megalospora sulphurata'' was broadly defined by Sipman in 1983, but subsequent studies by Ludmilla Untari in 2006 led to the differentiation of additional species within this complex. ''Megalospora austropacifica'' sets itself apart from other species in this group through several distinct features. Unlike '' M. flavoexcipulata'' and ''M. sulphurata'', it has a hypothecium that ranges from hyaline (clear) to orange in colour. Compared to '' M. javanica'', ''M. austropacifica'' is identified by its lighter apothecial margins, consistently zeorine apothecia (with the apothecial margin not incorporated into the thallus), a paler hypothecium, a hyaline ectal exciple, and ascospores that are longer and narrower. These characteristics help in distinguishing ''Megalospora austropacifica'' from closely related species within the complex.

Habitat and distribution

At the time of its original publication, ''Megalospora austropacifica'' had been identified exclusively on the Fijian islands of Taveuni and Viti Levu. In these locations, it typically grows in montane forests, both relict and

secondary Secondary may refer to: Science and nature * Secondary emission, of particles ** Secondary electrons, electrons generated as ionization products * The secondary winding, or the electrical or electronic circuit connected to the secondary winding i ...

, where it is found on tree bark.

References

{{Taxonbar, from=Q21323135 Teloschistales Lichens described in 2011 Lichens of Oceania Lichen species Taxa named by Helge Thorsten Lumbsch Taxa named by Robert Lücking