''Malmographina'' is a fungal

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

in the family

Graphidaceae The Graphidaceae are a family of lichens in the order Ostropales. Distribution and ecology The vast majority of Graphidaceae species are restricted to the tropics. Most Graphidaceae species are epiphytic (i.e. they grow only on plants). Gener ...

. The genus is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

, containing the single species ''Malmographina plicosa'', a script lichen found in South America. Genus ''Malmographina'' is characterised by its smooth, olive-green

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 ...

, to prominent (fruiting bodies) with orange to cinnabar-red pigment, a clear

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 ...

, and

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 ...

, non-

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, ...

ascospores.

Taxonomy

The genus ''Malmographina'', with its single species ''Malmographina plicosa'', was

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polyg ...

to address

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

discrepancies in the family

. Historically, genera within Graphidaceae with ascomata were classified based on spore pigmentation and septation (internal partitioning), as well as the organisation of the

ascomata 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 mos ...

. This resulted in the recognition of eight genera, including '' Graphis'', '' Phaeographis'', ''

Graphina ''Graphina'' is a genus of script lichens in the family Graphidaceae. It has about 25 species. The genus was circumscribed in 1880 by Swiss lichenologist Johannes Müller Argoviensis. Müller Argoviensis did not indicate a type species for the g ...

'', '' Phaeographina'', '' Glyphis'', '' Medusulina'', '' Sarcographa'', and '' Sarcographina''. However, this classification was highly artificial and was challenged by Bettina Staiger in 2002, who proposed new genus circumscriptions based on a combination of morphological, anatomical, and chemical features, expanding the classification to 22 genera.

Molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

studies conducted by various researchers in the years following were used to further refine the genus circumscriptions. These studies confirmed some of Staiger's taxa but also revealed that certain genera, like ''Graphis'' and ''Hemithecium'', were

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

and contained multiple unrelated lineages. ''Hemithecium plicosum'', a species with uncertain phylogenetic affinities, did not cluster with either ''Graphis'' or '' Hemithecium'' in

analyses. Instead, it fell within the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

containing ''Phaeographis'' and other grey-brown-spored genera, despite having persistently hyaline ascospores. This justified the creation of the new genus ''Malmographina'' to accommodate this

taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

. The genus ''Malmographina'' is characterised by its smooth, olive-green thallus, to prominent (fruiting bodies) with orange to cinnabar-red pigment, a clear

, and

, non-

ascospores. It differs from other genera in Graphidaceae by the combination of Hemithecium-like lirellae and the presence of

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxo ...

pigments in the lirellae. The type species, ''Malmographina plicosa'', shows unique features that support its placement in a separate genus, including the absence of lichen substances in the thallus, the presence of anthraquinones in the lirellae, and the distinctive morphology of its ascomata and ascospores.

Description

''Malmographina plicosa'' is characterised by its smooth, olive-green

, which can turn yellowish when preserved in a

herbarium A herbarium (plural: herbaria) is a collection of preserved plant specimens and associated data used for scientific study. The specimens may be whole plants or plant parts; these will usually be in dried form mounted on a sheet of paper (called ...

. The thallus has a dense outer layer and an irregular interspersed with clusters of

calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydrate ...

crystals. The

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 ...

, known as , are to prominent and have a finely but distinctly striated surface, with an orange to cinnabar-red pigment. The of the apothecia is hidden, and the (the outer rim of the apothecium) is distinctly scalloped and ranges in colour from orange-brown to dark brown or in the inner parts. Over time, the old, compressed layers of hymenia between the excipular striations also turn dark brown to nearly carbonised. The

(spore-producing layer) is clear, while the , the uppermost layer of the hymenium, contains clusters of dark brown to blackish . The are (divided into multiple chambers),

(translucent), and do not

stain A stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. They are caused by the chemical or physical interaction of two dissimilar materials. Accidental staining may make materials app ...

with

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

. No lichen substances have been detected in the thallus of ''Malmographina plicosa'', but the lirellae contain anthraquinones, specifically tetrahydroxyanthraquinone (1,3,6,8) and other pigments.

Habitat and distribution

''Malmographina plicosa'' is primarily found in the

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

. Its known range includes

Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...

, where the type specimen of ''Opegrapha plicosa'' was collected, and various locations in the

Peruvian Amazonia Peruvian Amazonia ( es, Amazonía del Perú) is the area of the Amazon rainforest included within the country of Peru, from east of the Andes to the borders with Ecuador, Colombia, Brazil and Bolivia. This region comprises 60% of the country and ...

, particularly in the

Department of Madre de Dios Madre de Dios (, en, Mother of God) is a department and region in southeastern Peru, bordering Brazil, Bolivia and the Peruvian departments of Puno, Cusco and Ucayali, in the Amazon Basin. Its capital is the city of Puerto Maldonado. It is als ...

. Additionally, it has been recorded in Amazonian Brazil, with several collections from

Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, ...

, and in the adjacent state of

Mato Grosso Mato Grosso ( – lit. "Thick Bush") is one of the states of Brazil, the third largest by area, located in the Central-West region. The state has 1.66% of the Brazilian population and is responsible for 1.9% of the Brazilian GDP. Neighboring ...

, where the type of ''Graphina malmei'' was found. This lichen species grows in partially exposed to sully sun-exposed microsites, predominantly on the bark of large trees. In these habitats, it is commonly associated with other lichens that share similar ecological preferences, such as species of ''Glyphis'', ''Phaeographis'', and other members of the Graphidaceae.

References

{{Taxonbar, from1=Q21293626 , from2=Q17387369 Graphidaceae Graphidales genera Lichen genera Taxa named by Marcela Cáceres Taxa named by Robert Lücking Taxa described in 2011