Arthrorhaphis Poelt & Hafellner is a genus of c. 13 closely related and rather polymorphic taxa, which is widely distributed in montane to alpine regions of the world. Free-living species mostly occur on or among decaying bryophytes and higher plants (or even decaying lichens), or on sandy soil (rarely on rocks). Parasitic or commensalistic species occur on several crustose (Baeomyces, Dibaeis), foliose (Arctoparmelia, Melanelia) or fruticose (Cladonia) lichen genera. The genus is currently placed into the Arthrorhaphidaceae within the Ostropomycetidae (see also Miadlikowska & al. 2014). The European species were monographed by Obermayer (1994), who also provided a general key; other keys were provided by Clauzade & Roux (1985) and Wirth & al. (2013). The phylogenetic analysis by Frisch & al. (2022) showed that all taxa with finally autonomous lichenised thallus are closely related. Genetically distinct clades correlated with morphology and/or geographical distribution are present both in A. alpina and A. citrinella. A. alpina var. jungens and A. vacillans were recovered as sisters within A. alpina s.lat.. A. citrinella s.lat. can be subdivided into several species. A. citrinella s.str., characterized by a thallus entirely consisting of small loose to compact aggregations of granular soredia, growing on saxicolous bryophytes, while common in Northern Europe, appears to be much rarer in the Alps than the recently-described A. vulgaris. The latter has a thallus of discrete to confluent areoles, growing on soil, terricolous bryophytes and plant remains, or parasitic on Baeomyces. In the TSB herbarium there is no sample from the Italian Alps corresponding to A. citrinella s.str., so I have provisionally attributed all of its records to A. vulgaris. A revision of Italian material is needed.
The present key includes the 5 species known from Italy (Nimis 2016) plus 3 further species which should be looked for in the Italian Alps.

References

Clauzade G., Roux C. 1985. Likenoj de Okcidenta Europo. Ilustrita determinlibro. Bull. Soc. Bot. Centre-Ouest, N. Ser., N. Spec. 7. Royan, 893 pp.
Frisch A., Ohmura J., Holien H., Bendiksby M. 2022. A phylogenetic survey of the ascomycete genus Arthrorhaphis (Arthrorhaphidaceae, Lecanoromycetes) including new species in Arthrorhaphis citrinella sensu lato. Taxon 2022, https://doi.org/10.1002/tax.12718
Hansen E.S., Obermayer W. 1999. Note on Arthrorhaphis and its lichenicolous fungi in Greenland. Bryologist, 102, 1: 104-107.
Ihlen P.G. 1998. The lichenicolous fungi on species of the genera Baeomyces, Dibaeis, und Icmadophila in Norway. Lichenologist, 30, 1: 27-57.
Kocourková J. & Boom P.P.G. van den 2005. Lichenicolous fungi from the Czech Republic II. Arthrorhaphis arctoparmeliae spec. nov. and some new records for the country. Herzogia, 18: 23-35.
Miadlikowska J., Kauff F., Högnabba F., Oliver J.C., Molnár K, Fraker E., Gaya E., Hafellner J., Hofstetter V., Gueidan C., Otálora M.A.G., Hodkinson B., Kukwa M., Lücking R., Björk C., Sipman H.J.M., Burgaz A.R., Thell A., Passo A., Myllys L., Goward T., Fern 2014. A multigene phylogenetic synthesis for the class Lecanoromycetes (Ascomycota): 1307 fungi representing 1139 infrageneric taxa, 317 genera and 66 families. Mol. Phylogenet. Evol., 79: 132-168.
Nimis P.L. 2016. The lichens of Italy. A second annotated catalogue. EUT, Trieste, 740 pp.
Obermayer W. 1994. Die Flechtengattung Arthrorhaphis (Arthrorhaphidaceae, Ascomycotina) in Europa und Grönland. Nova Hedwigia, 58: 275-333.
Santesson R., Tønsberg T. 1994. Arthrorhaphis aeruginosa and A. olivaceae, two new lichenicolous fungi. Lichenologist, 26, 3: 295-299.
Wirth V., Hauck M., Schultz M. 2013. Die Flechten Deutschlands. Stuttgart, Ulmer. 2 voll., 1244 pp.

Last modified: September, 3, 2022

Project Dryades, Department of Life Sciences, University of Trieste - CC BY-SA 4.0