''Diromma'' is a

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 "unisp ...

fungal

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

in the family

Roccellaceae The Roccellaceae are a family (biology), family of mostly lichen-forming fungi in the order Arthoniales, established by the French botanist François Fulgis Chevallier in 1826. Species in the family exhibit various lichen growth forms, growth ...

. It contains the single species ''Diromma dirinellum'', a rare

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 ...

that grows as a

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

on the lichen ''

Dirina ceratoniae ''Dirina ceratoniae'' is a species of crustose lichen in the family Roccellaceae. It is found in Europe, where it grows on both bark and on calcium-rich rock. The lichen was species description, formally described as a new species in 1810 by Swe ...

''. It has a distribution restricted to the Mediterranean Basin.

Taxonomy

This species was first described in 1882 by Finnish lichenologist

William Nylander William Andrew Michael Junior Nylander Altelius (born 1 May 1996) is a Swedish professional ice hockey Forward (ice hockey), forward for the Toronto Maple Leafs of the National Hockey League (NHL). Nylander was selected by the Maple Leafs in t ...

as ''Platygrapha dirinella'', from specimens collected in

Sardinia Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...

, Italy. It was transferred to '' Schismatomma'' in 1923 by

Alexander Zahlbruckner Alexander Zahlbruckner (31 May 1860, Svätý Jur – 1938, Vienna) was an Austrian- Hungarian botanist who specialized in the study of lichens. Johann Babtist Zahlbruckner, an earlier Austrian botanist, was his grandfather. From 1878 to 1883 ...

, and considered a member of that genus for nearly a century. The genus ''Diromma'' was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

in 2014 by Anders Tehler and Damien Ernst, following

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

analysis and revision of the Roccellaceae. This analysis showed that the species was a quite distinct lineage in the Roccellaceae. The genus name alludes to both its

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

closeness to ''

Dirina ''Dirina'' is a genus of lichen-forming fungi in the family Roccellaceae. All ''Dirina'' species are crustose lichens with a whitish to greyish brown thallus, and live either on rock or on bark–some species can live on both. The partner is ...

'', and its morphological similarity with ''Schismatomma''.

Description

''Diromma dirinellum'' has a crustose thallus with a

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

. Its

ascomata An ascocarp, or ascoma (: ascomata), is the fruiting body (sporocarp (fungi), sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded ascus, asci, each of which typically contains four to ...

, which are immersed (or partly so) in the thallus, measure 0.2–0.6 mm in diameter, and have a more or less circular to irregular outline.

Ascospore In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse Division (botany), division of fungi. After two parental cell nucleus, nuclei fuse, the ascu ...

s are

hyaline A hyaline substance is one with a glassy appearance. The word is derived from , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

with 3

septa SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

, and measure 20–30.5 by 4.5–5.5

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

; they are not enclosed in a gelatinous sheath. The

photobiont A lichen ( , ) is a hybrid colony of algae or cyanobacteria living symbiotically among filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualistic relationship.

partner is trentepholioid –

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

e from genus '' Trentepohlia''. The lichen contains roccellic acid, but does not react with any of the standard chemical spot tests (K−, C−, P−).

References

{{Taxonbar, from=Q47498356, from2=Q47499840 Roccellaceae Lichen genera Taxa described in 2014 Arthoniomycetes genera Lichenicolous lichens Taxa named by Damien Ertz Taxa named by Anders Tehler