# Carassea

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***Carassea*** is a fungal [genus](/source/Genus) in the family [Cladoniaceae](/source/Cladoniaceae).[1][2] The genus was [circumscribed](/source/Circumscription_(taxonomy)) in 2002 by the Finnish lichenologist [Soili Stenroos](/source/Soili_Stenroos).[3] A [monotypic](/source/Monotypic) genus, *Carassea* contains the single species ***Carassea connexa***, a [fruticose lichen](/source/Fruticose_lichen). This species, originally named *Cladonia connexa*, was first documented by [Edvard August Vainio](/source/Edvard_August_Vainio), who collected specimens from [Minas Gerais](/source/Minas_Gerais), Brazil, in 1885, and published a [description](/source/Species_description) of the species in the first of his three-volume *Monographia Cladoniarum universalis*.[4] The Cladoniaceae genera most closely related to *Carassea* include *[Pycnothelia](/source/Pycnothelia)* and *[Metus](/source/Metus_(fungus))*.[3]

## Taxonomy

Stenroos established *Carassea* after large-scale [phylogenetic](/source/Phylogenetic) analyses of nuclear small-subunit rDNA ([SSU rDNA](/source/SSU_rDNA)) across the lichens showed that *[Cladonia](/source/Cladonia)* (as then delimited) was not a natural, single [lineage](/source/Lineage_(evolution)). In those [phylogenetic trees](/source/Phylogenetic_tree), *Cladonia connexa* consistently grouped outside the core *Cladonia* [clade](/source/Clade) and instead formed a clade with *[Pycnothelia](/source/Pycnothelia)* (and, in the SSU analysis, with *[Metus](/source/Metus_(fungus))*) within a recircumscribed [Cladoniaceae](/source/Cladoniaceae). A strict-consensus tree and a simplified [cladogram](/source/Cladogram) of the source depict *Carassea* as [sister](/source/Sister_group) to *Pycnothelia* and close to *Metus*.[3]

The authors considered four options: sinking *Pycnothelia* and *Metus* into *Cladonia*, transferring *connexa* into *Pycnothelia*, doing nothing pending more data, or erecting a new genus. They rejected the first two because it would create [ad hoc](/source/Ad_hoc) name changes without complete [taxon](/source/Taxon) sampling and because *Pycnothelia* is a small, [morphologically](/source/Morphology_(biology)) uniform, temperate genus unlike the tall, densely branched, tropical *connexa*. They chose to recognise a new genus, *Carassea*, with the type and only species *Carassea connexa* ([basionym](/source/Basionym) *Cladonia connexa*, described by Vainio in 1887). The family Cladoniaceae was expressly recircumscribed to include *Carassea* along with *[Cladia](/source/Cladia)*, *[Cladonia](/source/Cladonia)*, *[Heterodea](/source/Heterodea)*, *Metus*, *[Pilophorus](/source/Pilophorus_(fungus))*, *[Pycnothelia](/source/Pycnothelia)*, *[Ramalea](/source/Ramalea)*, and *[Thysanothecium](/source/Thysanothecium)*.[3]

## Description

The (the basal crust or squamules present in many *Cladonia* relatives) is unknown for *Carassea*. The standing part of the lichen (the [podetia](/source/Podetia)—upright, stem-like branches) reach about 3–5 cm (1.2–2.0 in), occasionally to 15 cm (6 in). They are whitish to pale brown-grey and become strongly browned towards the tips. Branching is very regular and (each branch forks into two equal parts), and the numerous branchlets frequently fuse together (), producing rounded heads and eventually large, continuous, net-like cushions. The podetia lack the cup-shaped tips () seen in many *Cladonia*, and they also lack [soredia](/source/Soredia) and the small leaf-like scales (podetial ) that some relatives show. The outer surface may be smooth and glossy near the tips; a true is absent, though there is a thin corticoid layer.[3]

Asexual [conidiomata](/source/Conidiomata) occur at the tips of the finest branchlets; these are flask-like and black, with narrow, curved, colorless [conidia](/source/Conidia) about 12–15 × 0.5 μm. Sexual structures ([apothecia](/source/Apothecia)) arise characteristically on the sides of the upper branchlets rather than at their ends: small knob-like form just below the tips and develop into short-stalked, red-brown ; mature [ascospores](/source/Ascospore) were not seen in the available material. [Thin-layer chromatography](/source/Thin-layer_chromatography) shows a consistent chemical pattern of the [secondary metabolite](/source/Secondary_metabolite) compounds [atranorin](/source/Atranorin), [lichesterinic acid](/source/Lichesterinic_acid), and [protolichesterinic acid](/source/Protolichesterinic_acid); medullary beta-orcinol [depsides](/source/Depside)/[depsidones](/source/Depsidone) are lacking in *Carassea*, as in its close relatives *Pycnothelia* and *Metus*. These structural and chemical traits, together with the distinctive branching and lateral apothecia, separate *Carassea* from look-alike members of *Cladonia*.[3]

## Habitat and distribution

*Carassea* is a [tropical](/source/Tropical) lineage with a very restricted range in south-eastern Brazil. The type and other confirmed collections are from the [Serra do Caraça](/source/Serra_do_Cara%C3%A7a) area in [Minas Gerais](/source/Minas_Gerais), including the [type locality](/source/Type_locality_(biology)) at about 1,500 m elevation (municipality of [Catas Altas](/source/Catas_Altas)). Fieldwork in the 1990s confirmed that the species still occurs in the region, where its densely anastomosing branches form conspicuous cushions. No occurrences outside Brazil were reported in that work.[3]

## References

1. Hyde, K.D.; Noorabadi, M.T.; Thiyagaraja, V.; He, M.Q.; Johnston, P.R.; Wijesinghe, S.N. et al. (2024). ["The 2024 Outline of Fungi and fungus-like taxa"](https://www.researchgate.net/publication/385939154). *Mycosphere*. **15** (1): 5146–6239 [5250]. [doi:10.5943/mycosphere/15/1/25](https://doi.org/10.5943/mycosphere/15/1/25). [hdl:11577/3540520](https://hdl.handle.net/11577/3540520)

1. Stenroos, Soili; Myllys, Leena; Thell, Arne; Hyvönen, Jaakko (2002). "Phylogenetic hypotheses: Cladoniaceae, Stereocaulaceae, Baeomycetaceae, and Icmadophilaceae revisited". *Mycological Progress*. **1** (3): 267–282. [doi:10.1007/s11557-006-0024-9](https://doi.org/10.1007/s11557-006-0024-9)

1. Vainio, Edvard August (1887). [*Monographia Cladoniarum universalis: I.*](https://www.biodiversitylibrary.org/page/5587907) (in Latin). Vol. 4. Acta Societatis pro Fauna et Flora Fennica. p. 288.

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