The Requienellaceae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of fungi in the order

Pyrenulales The ''Pyrenulales'' are an order (biology), order of ascomycetous fungi within the class Eurotiomycetes and within the subphylum Pezizomycotina. Taxonomy As of 2022 the order contains one family, 14 genera and around 296 species. *Order Pyrenulal ...

. Species in this family have a widespread distribution, and grow on wood and bark.

Taxonomy

Requienellaceae was circumscribed by Jean Boise in 1986, based on studies conducted during research on the genus '' Trematosphaeria''. The family was established within the order Melanommatales (sensu Barr) or

(sensu Eriksson and Hawksworth). The

type genus In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearin ...

is '' Requienella'', which was originally proposed by

Jean-Henri Fabre Jean-Henri Casimir Fabre (; 21 December 1823 – 11 October 1915) was a French naturalist, entomologist, and author known for the lively style of his popular books on the lives of insects. Biography Fabre was born on 21 December 1823 in Saint- ...

in 1883. The genus name was sometimes mistakenly spelled as "Requinella" in early mycological literature, including ''Ainsworth and Bisby's Dictionary of the Fungi'' (1943). When first describing the family, Boise designated '' Requienella seminuda'' as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of both the genus and family. This species was previously known under various names, including ''Sphaeria seminuda'' and ''Requienella olearum''. A significant taxonomic clarification made in the original 1986 publication was that the common concept of "Sphaeria seminuda" at that time (based on Fuckel's Fungi rhenani 2319) actually referred to a different fungus belonging to the genus '' Melanomma''. The genus ''Trematomyces'' was established for ''R. olearum'' and ''R. lichenopsis'' but was later determined to be

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with ''Requienella''. Similarly, ''Acrocordiella'' was initially described as a separate genus but is now considered part of the Requienellaceae.

Description

Requienellaceae fungi are characterized by several distinctive features of their reproductive structures. They produce dark, spherical fruiting bodies (ascomata) that are typically 0.5–1.25 mm in diameter. These structures are initially embedded within or beneath the bark of their host plants, with the surrounding tissue becoming blackened. Over time, they emerge through the bark's surface. A key characteristic of this family is their unique internal structure. They possess unbranched, sparsely septate pseudoparaphyses (sterile threads between the spore-producing cells) and specialized spore-producing cells called asci. The asci have a distinctive broad cylinder of material at their tips that responds distinctively to certain biological stains. This feature helps distinguish them from related fungi. The spores () produced by these fungi are brown in color and have multiple compartments separated by special cross-walls called . These spores show bilateral symmetry, meaning they are mirror images along their middle. In '' Requienella seminuda'', the

of the family, the spores typically contain 4–8 compartments and measure 20–34

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 ...

in length. Members of ''Requienella'' are typically found growing on the bark of various trees, including olive trees (''

Olea ''Olea'' ( ) is a genus of flowering plants in the family Oleaceae. It includes 12 species native to warm temperate and tropical regions of the Middle East, southern Europe, Africa, southern Asia, and Australasia. They are evergreen trees and s ...

''), ash trees (''

Fraxinus ''Fraxinus'' (), commonly called ash, is a genus of plants in the olive and lilac family, Oleaceae, and comprises 45–65 species of usually medium-to-large trees, most of which are deciduous trees, although some Subtropics, subtropical specie ...

''), and cherry trees (''

Prunus ''Prunus'' is a genus of flowering plant, flowering trees and shrubs from the family (biology), family Rosaceae. The genus includes plums, cherries, peaches, nectarines, apricots and almonds (collectively Drupe, stonefruit). The genus has a cosm ...

''). They are not known to form lichens with algae, existing independently as fungi.

Genera

The 2024 Outline of Fungi include 16 species distributed amongst 4 genera in the Requienellaceae: * '' Acrocordiella'' – 4 spp. * '' Lacrymospora'' – 1 spp. * '' Parapyrenis'' – 8 spp. * '' Requienella'' – 3 spp.

References

{{Taxonbar, from=Q7314869 Pyrenulales Lichen families Taxa described in 1986 Eurotiomycetes genera