Porinaceae

Clathroporina Flabelloporina Gallaicolichen Myeloconis Porina Pseudosagedia Saxiloba Segestria Trichothelium Porinaceae is a family of lichen-forming fungi in the order Gyalectales.

Most members of this family typically have a crust-like appearance and grow on a variety of surfaces, including tree bark, leaves, and rocks.

Porinaceae is known for its diverse morphology, ranging from simple crust-like forms to more complex structures with distinct lobes or fan-shaped scales.

Originally based on Pertusaria pertusa, which was later considered a nomenclatural synonym of Pertusaria—an unrelated genus—Porina has historically been applied to species around Porina nucula following the work of Ferdinand von Mueller in 1883.

A pivotal study in 2004 by Grube, Baloch, and Lumbsch used molecular data to place Porinaceae within the Lecanoromycetes, specifically in a group later recognised as Ostropomycetidae.

This research suggested close relationships between Porinaceae and families such as Graphidaceae, Gyalectaceae, and Stictidaceae,[16] a finding largely corroborated by subsequent studies.

[16] The current consensus among lichenologists maintains Porinaceae as the valid name for this fungal family, which is now placed in the order Gyalectales within the subclass Ostropomycetidae of the Lecanoromycetes.

[17] A significant development came from a 2014 study by Nelsen et al., which conclusively demonstrated that Myeloconidaceae, previously considered a separate family, is nested within Porinaceae.

Despite its unique features, particularly its yellow to orange medullary pigments, Myeloconis was retained as a separate genus within Porinaceae due to its distinct morphology and strongly supported monophyly.

For instance, the genus Saxiloba, described in 2020, forms a strongly supported lineage on a long branch within the family, separate from other genera such as Phragmopeltheca and Segestria.

[19] Similarly, the recently studied genus Gallaicolichen, with its unique reproductive structures, has been firmly placed within Porinaceae, closely related to certain Porina species.

As a result of these complexities, some researchers have opted to retain a broader concept of Porina while awaiting more comprehensive sampling and additional genetic markers to resolve the family's internal relationships.

These lichens form a symbiotic relationship with green algae, typically from the genera Phycopeltis or Trentepohlia, which provide photosynthetic energy for the partnership.

For instance, the genus Flabelloporina is characterised by a thallus bearing flabelliform (fan-shaped) squamules, a feature that expands the known morphological range of the family.

[16] The asci are typically thin-walled compared to other Ostropomycetidae, often featuring a faint chitinoid (resembling chitin) ring-structure around the ascus apex.

These produce disc-shaped diaspores known as peltidia, which consist of dichotomously branched algal cells arranged around a central foot, encapsulating a layer of fungal hyphae.

They vary in shape, from ellipsoid to cylindrical or spindle-shaped (fusiform), and are divided by thin cross-walls (septate), which can range from simple transverse divisions to a more complex, brick-like pattern (muriform).

[2] The family also produces asexual reproductive structures (conidiomata), which release tiny, non-septate (undivided) spores (conidia) that are either ellipsoid or thread-like (filiform) in shape.

This diversity makes it challenging for scientists to classify these lichens based on appearance alone, emphasizing why both physical features and DNA evidence are needed to fully understand how different species are related to each other.

Species in this family grow primarily as epiphytes on bark and leaves, but are also found on rocks, demonstrating their ability to adapt to different habitats.

[22] In terms of substrate preferences, approximately 45% of Porinaceae species are primarily corticolous (bark-dwelling), 35% are mainly foliicolous (leaf-dwelling), and 20% are saxicolous (rock-dwelling).

[23] According to a 2022 survey of fungal classification, Porinaceae (as Trichotheliaceae) contains eight genera and about 365 species,[25] but this total does not account for the most recent genus addition to the family, Flabelloporina.

The leaf-dwelling lichen Porina leptosperma , photographed in Brazil