| Candelariales | |
|---|---|
 | |
| Candelariella coralliza | |
Scientific classification | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Candelariomycetes Voglmayr & Jaklitsch (2018) |
| Order: | Candelariales Miadl., Lutzoni &Lumbsch (2007) |
| Families | |
TheCandelariales are anorder offungi in themonotypic classCandelariomycetes. It contains the familiesCandelariaceae andPycnoraceae.[1] The order wascircumscribed by Jolanta Miadlikowska, François Lutzoni, andHelge Thorsten Lumbsch as part of a comprehensivephylogenetic classification of the kingdom Fungi published in 2007.[2] The class Candelariomycetes was proposed in 2018 by Hermann Voglmayr and Walter Jaklitsch.[3]
The yellow "candle-wax" lichens now grouped in Candelariomycetes were long treated as part of the large classLecanoromycetes. A multigene study of lichen-forming fungi published in 2007 first recognised them as a distinct order, Candelariales – comprising the families Candelariaceae and Pycnoraceae – but still left the group inside Lecanoromycetes.[4] Even earlier, Miądlikowska and co-workers had informally coined the name "Candelariomycetidae" (2006) for thislineage,[5] and Lücking and colleagues later formalised that name at subclass rank (2017).[6]
Subsequent DNA analyses that combined ribosomal (nSSU, nLSU, mtSSU) and protein-coding (RPB1, RPB2) genes from virtually every recognised class ofLeotiomyceta showed that Candelariales never clusters with the lecanoroid core. Instead, it forms an isolated, well-supported branch whose internal topology places Pycnoraceae as thesister family to Candelariaceae. In the best-scoring maximum-likelihood tree the class received 88 % bootstrap support (79 % under parsimony) and a posterior probability of 1.0, values that molecular systematists regard as strong evidence.[3]
Recognising this consistent phylogenetic independence, Voglmayr and Jaklitsch erected the new class Candelariomycetes in 2018 (published 2019), with Candelariales as itstype order andCandelaria as the nomenclaturaltype genus. Although different analyses place the class variously nearEurotiomycetes,Arthoniomycetes orDothideomycetes, none recover it within Lecanoromycetes when a broad taxon sample is used; the lineage is therefore now treated as one of the younger, small classes of filamentous Ascomycota.[3]
Members of the Candelariomycetes are readily recognised in the field by their vivid lemon- to orange-yellow thalli. The vegetative body (thallus) ranges from a paper-thin crust tightly appressed to thesubstrate to small, scale-like lobes (squamules) that may pile up into tiny, leaf-likerosettes. In a few species the thallus is reduced or absent and the fungus grows directly on other lichens. A green, spherical alga (achlorococcoid photobiont) providesphotosynthetic energy, and unlike some other lichen groups nocyanobacterial "cephalodia" are formed. The bright colour comes frompulvinic acid pigments in the Candelariaceae or, in the wood-inhabiting Pycnoraceae, fromdepsidic compounds such asalectorialic acid. Most species colonise bark orsiliceous rock in well-lit, nutrient-enriched habitats; a few grow on mosses, soil, or old timber. Thecosmopolitan speciesCandelaria concolor—common on street trees and fence rails—illustrates the group's tolerance of urban conditions.[3]
Sexual reproduction takes place inapothecia, the tiny, often disc-shaped fruiting bodies that dot the thallus surface. These apothecia usually carry a narrow rim of thallus tissue (lecanorine margin) in Candelariaceae or a blackened rim without algal cells (lecideine) in Pycnoraceae. Inside, unbranchedparaphyses (slender sterile filaments) are imbued with starch-like (amyloid) material that turns blue iniodine-basedstaining—a useful diagnostic character. The spore sacs (asci) are club-shaped, also amyloid, and contain eight to as many as sixty-four colourless, smoothascospores. These ascospores areellipsoid to lemon-shaped and lack cross-walls or show, at most, one to three indistinctsepta. When sexual spores are not being produced, many species form minute flask-shapedpycnidia that exude colourless, single-celledconidia.[3]