''Microsphaeropsis olivacea'' is a fungal species belonging to the family

Didymosphaeriaceae The Didymosphaeriaceae are a family of fungi in the order Pleosporales. The family was erected by Anders Munk in 1953. Taxa have a cosmopolitan distribution, and are saprobic in both woody and herbaceous plants. Some species are parasitic on ot ...

. It is recognized for its diverse ecological roles, ranging from saprobic activities on dead organic matter to pathogenic interactions with various hosts, including plants and occasionally humans.

Etymology

The genus name ''Microsphaeropsis'' comes from the Greek 'micros', meaning small, and 'sphaera', meaning sphere. This naming reflects the small, spherical shape of the microscopic features that are characteristic of this

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 ...

. The species name ''olivacea'' comes from Latin, meaning olive-colored, which describes the typical appearance of the fungus. Additionally, this fungus has been associated with olive leaf die back, among many other endophytic ascomycetes whose earliest records have origin in the Mediterranean, where olive trees, ''Olea europaea'', are abundant.

Taxonomy & history

''Microsphaeropsis'' was first described by Höhnel in 1917, with ''M. olivacea'' (Bonord.) Höhn. designated as the type species. This genus is characterized by pycnidia that are either immersed or erumpent, subglobose in shape, and occur either singly or in clusters. These pycnidia have ostioles and are composed of a wall made of angular cells. The conidiogenous cells within are phialidic, hyaline, and shaped like ampullae, dolia, or slightly cylindrical structures. The conidia are thin-walled, smooth or finely roughened, and may possess zero to one septa. Hönel described this species in 1917 from the former, ''Coniothyrium olivaceum'', described by Bonord in 1869. M. olivacea remains as the officially recognized name, with molecular studies confirming its phylogenetic placement.

Description

''Microsphaeropsis olivacea'' produces small, dark-colored fruiting bodies known as

pycnidia A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inve ...

. These pycnidia harbor conidia—hyaline, asexual

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s—that are instrumental in the dispersal of the fungus. These spores are primarily dispersed through water and air currents. ''M. olivacea'' is without notable diagnostic macro morphological features. ''Microsphaeropsis'' fungi are referred to as coniothyrium-like fungi, often being distinguished from other coelomycetes (a form-class of fungi), via their respective host symbionts. The type specimen of this species is held at the Kew Botanical Garden's Fungarium.

Distribution

''Microsphaeropsis olivacea'' is a ubiquitous species with a wide variety of habitats and symbionts. The species has a worldwide distribution, with frequent occurrences in environmental samples.

Habitat and ecology

This species is adaptable to both terrestrial and aquatic environments. On land, it predominantly affects woody plants, causing diseases such as dieback and cankers, notably in agricultural settings. In aquatic environments, ''M. olivacea'' has been isolated from a marine sponge, an indication of its diversity of hosts, whether terrestrial or aquatic.

Pathogenicity

In terrestrial environments, ''M. olivacea'' poses a significant threat to agricultural productivity by infecting crops and causing woody plant diseases, leading to economic impacts. The species has also been identified as a

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

in humans, causing skin infections. This ability to infect humans suggests potential for medical relevance, particularly in

dermatology Dermatology is the branch of medicine dealing with the Human skin, skin.''Random House Webster's Unabridged Dictionary.'' Random House, Inc. 2001. Page 537. . It is a speciality with both medical and surgical aspects. A List of dermatologists, ...

Research

Research on ''M. olivacea'' includes studies on its molecular identification and pathogenic mechanisms.Additionally, biochemical investigations have identified secondary metabolites such as cerebrosides, which may play roles in the

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

's survival and pathogenicity.