''Lempholemma polycarpum'' is a little-known species of

saxicolous A saxicolous lichen is a lichen that grows on rock. The prefix "sax" from the Latin means "rock" or "stone". Characteristics Saxicolous lichens exhibit very slow growth rates. They may develop on rock substrates for long periods of time, give ...

(rock-dwelling) lichen in the family

Lichinaceae The Lichinaceae are a family of ascomycete fungi. Most species are lichenized with cyanobacteria, and have a distribution largely in temperate regions. Taxonomy The family was circumscribed in 1854 by Finnish lichenologist William Nylander. H ...

. It was first described from

Yemen Yemen (; ar, ٱلْيَمَن, al-Yaman), officially the Republic of Yemen,, ) is a country in Western Asia. It is situated on the southern end of the Arabian Peninsula, and borders Saudi Arabia to the Saudi Arabia–Yemen border, north and ...

and is characterised by its blackish

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 ...

, abundant small

apothecia An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...

(fruiting bodies), and

cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...

from the genus ''

Nostoc ''Nostoc'', also known as star jelly, troll’s butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch’s jelly, is the most common genus of cyanobacteria found in vari ...

'' as its . The lichen is found on inclined

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

boulders in sun-exposed habitats with open forest vegetation. It also occurs in

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

and in

Aldabra Aldabra is the world's second-largest coral atoll, lying south-east of the continent of Africa. It is part of the Aldabra Group of islands in the Indian Ocean that are part of the Outer Islands of the Seychelles, with a distance of 1,120 k ...

Taxonomy

The lichen was first formally described by the German lichenologist Matthias Schultz. 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 ...

of ''Lempholemma polycarpum'' was collected in Shah-ot, Damkaur,

Al Mahrah Governorate Al Mahrah ( ar, ٱلْمَهْرَة '), or simply Mahra, is a governorate (''muhafazah'') of Yemen in the southern part of the Arabian Peninsula. Situated in the area of the former Mahra Sultanate, its capital is Al Ghaydah, and it has internat ...

, Yemen, on small inclined

boulders at an elevation of . The species epithet ''polycarpum'' refers to the abundantly produced, small

Description

The

of ''Lempholemma polycarpum'' is blackish, dull, and rarely slightly , with a gelatinous texture when wet. Thalli consist of individual, regular, - rosettes measuring 3–6 mm in size. are radiating, free, tongue-shaped, and convex, with short lengths of 1.5–2.5 mm, widths of 0.5–0.6 mm, and thicknesses of 0.25–0.45 mm. The surface of the lobes is smooth but becomes when numerous small apothecia are produced. Microscopically, the forms a loose network of elongated

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e that becomes denser towards the lobe margins, with cells measuring 10–17.5 by 1.5–2 (up to 5)

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. The is ''

'', which forms twisted and bent, bead-like chains of 5–20 spherical to

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

cells. Photobiont cells are 3–5 μm wide without the sheath, and 10–12.5 μm wide with the sheath. The gelatinous sheath is

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 ...

in the thallus centre and yellowish-brown towards the upper surface.

Apothecia An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...

are usually abundant, with 1–10 per lobe, and are very small, measuring 200 (up to 250) μm wide. They are immersed to partially immersed in the thallus with a low , and have a reddish-black apothecial when dry, which turns dark red when moist. number eight per

ascus An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

, are ,

, and broadly

, measuring 12.4–6.5 μm; their spore wall thickens with age, reaching up to 1.5 μm wide.

Similar species

''Lempholemma polycarpum'' is similar to '' Lempholemma socotranum'', but the latter has an umbilicate-squamulose thallus with to short-lobed margins, larger apothecia with wider, open , and smaller . '' Lempholemma radiatum'' has elongated, radiating lobes that are longitudinally ridged and , and it differs in the presence of isidia, the type of ascoma ontogeny, and a more or less arctic distribution. '' Lempholemma lingulatum'' is another lobate member of the genus, but its lobes are unbranched, distinctly tongue-shaped, and widened at the tips. ''Lempholemma polycarpum'' is also similar to '' Collema multipartitum'' and '' C. fragile'', both of which occur in similar habitats on Socotra. The former species differs in the presence of eventually

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

apothecia, septate ascospores,

amyloid Amyloids are aggregates of proteins characterised by a Fibril, fibrillar morphology of 7–13 Nanometer, nm in diameter, a beta sheet (β-sheet) Secondary structure of proteins, secondary structure (known as cross-β) and ability to be Staining, ...

ascus tips, and finely striate lobes, while the latter differs mainly in the presence of laminal isidia on more stunted, shortly forked lobes with usually pruinose tips.

Habitat and distribution

''Lempholemma polycarpum'' grows on inclined limestone boulders in sun-exposed habitats on rocky slopes with open forest vegetation. It is known from two localities in southeast Yemen. The species is found growing alongside '' Paulia aldabrensis'', '' P. perforata'', '' Lempholemma botryosum'', and a species of '' Psorotichia''. Three other species of ''

Lempholemma ''Lempholemma'' is a genus of fungi within the family Lichinaceae. The genus contains about 33 species. Species *''Lempholemma botryosum'' *''Lempholemma chalazanum'' *''Lempholemma cladodes'' *''Lempholemma compactum'' *''Lempholemma corticola ...

'' are known to occur in the Arabian Peninsula and Socotra: '' Lempholemma socotranum'', '' L. intricatum'', and ''L. botryosum''. ''Lempholemma polycarpum'' has also been recorded in Madagascar, and in

References

{{Taxonbar, from=Q17388107 Lichinomycetes Lichen species Lichens described in 2005 Lichens of Western Asia Lichens of Madagascar Lichens of the Western Indian Ocean