| Biatoropsis | |
|---|---|
 | |
| Biatoropsis usnearum | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Tremellomycetes |
| Order: | Tremellales |
| Genus: | Biatoropsis Räsänen (1934) |
| Type species | |
| Biatoropsis usnearum Räsänen (1934) | |
Biatoropsis is a genus of lichenicolous (lichen-dwelling) fungi of uncertain familial placement in the order Tremellales. [1] It comprises 11 species that parasitise various species in the fruticose lichen genera Usnea and Protousnea .
The genus was circumscribed in 1935 by the Finnish lichenologist Veli Räsänen, who assigned Biatoropsis usnearum as the type species. [2] The genus remained monospecific for several decades, until research, starting in the 1990s, [3] showed that B. usnearum represented a species complex. Since then another ten species have been added to the genus. [4] [5]
Biatoropsis is a genus of fungi that parasitises lichens (making it lichenicolous). The fungus produces reproductive structures called basidiomata that vary in both shape and colour, with a waxy-gelatinous texture similar to jelly. [5]
At a microscopic level, the internal tissue (context) consists of thread-like cells called hyphae that lack specialised connecting structures known as clamps. The fungus penetrates its host using specialised feeding structures called haustoria, which have a distinctive twisted or convoluted form characteristic of the Tremellales order of fungi. The reproductive surface (hymenium) contains numerous immature spore-producing cells called probasidia. These initially develop in a club-shaped form and may or may not have a clamp at their base. Unlike some related fungi, Biatoropsis lacks specialised sterile cells called hyphidia and cystidia in its hymenium. [5]
When fully mature, the spore-producing cells (basidia) are club-shaped to almost cylindrical and divided by cross-walls (septa). These cells develop extensions called epibasidia that are roughly cylindrical in shape. The spores (basidiospores) they produce are nearly spherical to elliptical in shape and have a distinctive side projection called an apiculus. When these spores germinate, they do so by producing a tube-like growth. [5]
The fungus can also reproduce asexually in several ways. It commonly produces chains of spores called catenulate conidia. In one rare observation, crescent-shaped (lunate) conidia were documented. In one species of Biatoropsis, the basidia themselves can function as cells that produce asexual spores – these spores are colourless and lack internal divisions. [5]
All species in the genus parasitise species of the fruticose lichen genera Usnea and Protousnea , causing galls in infected species. [5]
As of December 2024 [update] , Species Fungorum (in the Catalogue of Life) accepts 11 species of Biatoropsis: [6]