Holmiella junipericola, from Pem et al. (2018).

Belongs within: Pleosporomycetidae.

Wood freckles
Published 22 August 2023

Among the myriad little-known fungi inhabiting the world are members of the family Patellariaceae. These are saprobes or weak parasites, typically found growing on dead wood or bark. Among the reasons for their obscurity is their size: Patellariaceae are minute, their fruiting bodies largely looking like a dusting of black spots across their substrate. Nevertheless, Patellariaceae are distinctive enough that the family was first recognised as far back as 1838 (Yacharoen et al. 2015).

Patellaria atrata on wood, copyright Gerhard Koller.

Like other members of the diverse fungal class Dothideomycetes, Patellariaceae have bitunicate (that is, double-walled) asci from which spores are released when the inflexible outer wall is split open by the swelling of the inner wall. More specific to Patellariaceae is the production of apothecia, fruiting bodies forming a more or less flat disc against the substrate. The ascospores arise from an underlying layer called the hypothecium, and are protected from the elements by an overlying epithecium. In a small number of genera, the fruiting body forms a hysterothecium, with the sides folded up to form a structure resembling a pair of lips or a boat. In the majority of species, the fruiting bodies are superficial, lying on the surface of the substrate, but they are more rarely immersed or erumpent. The combination of bitunicate asci and apothecia is found in few taxa outside the Patellariaceae (one notable exception being the genus Rhytidhysteron, long included among the Patellariaceae but recently transferred to the distantly related Hysteriaceae on the basis of molecular data).

Cross-section of an apothecium, from Yacharoen et al. (2015).

Asexual morphs are little known, remaining unidentified for most species. Pem et al. (2018) did find molecular evidence to associate the asexual taxon Yuccamyces with Patellariaceae (the name of this genus refers not to being found growing on yuccas, but to the conidiomata in culture resembling yucca bushes).

Most studies of Patellariaceae to date have remained at the taxonomic level. Many species seem particular about their substrates. For instance, species of Holmiella are found on the bark of junipers, with particular fungi associated with particular juniper species. Hysteropatella prostii is found on the bark of apples and pears, more rarely on that of Prunus species. A few species have been found growing on lichens or other fungi. If most Patellariaceae are restricted to wood coming from a limited range of trees, and relatively few but disparate trees have been recorded as hosts to Patellariaceae, it is possible that many species of this family remain to be discovered. It just requires someone to go out and look for them.

Systematics of Patellariaceae
Patellariaceae [Lecanidiaceae, Lecanidiales, Patellariales]
|--+--Cryomyces Selbmann, de Hoog et al. 2005PG18, SH05
| | |--*C. antarcticus Selbmann, de Hoog et al. 2005SH05
| | `--C. minteri Selbmann, de Hoog et al. 2005SH05
| `--Holmiella Petrini, Samuels & Müll. 1979PG18, KC01 [=Caldesia Rehm 1889 nec Parl. 1860 nec Trevis. 1869KC01]
| | i. s.: H. macrosporaPG18
| |--H. juniperi-semiglobosae Pem, Gafforov et al. 2018PG18
| `--+--*H. sabina (De Not.) Petrini, Samuels & Müll 1979 [=Triblidium sabinum De Not. 1867]PG18
| `--H. junipericola Pem, Gafforov et al. 2018PG18
`--+--Glyphium Nitschke ex Lehm. 1886PG18, KC01 [incl. Peyronelia Cif. & Gonz. Frag. 1927KC01]
| |--G. elatumSH05
| `--G. grisonensePG18
`--+--Patellaria Fr. 1822PG18, KC01 (see below for synonymy)
| `--P. atrataPG18
`--+--Yuccamyces Gour, Dyko & Sutton 1979PG18, KC01
| |--*Y. purpureus Gour, Dyko & Sutton in Dyko & Sutton 1979DS79
| `--Y. citriPG18
`--Hysteropatella Rehm 1890PG18, KC01
|--H. clavisporaSS09
|--H. ellipticaSS09
`--H. prostiiPG18

Patellariaceae incertae sedis:
Baggea Auersw. 1866KC01
Banhegyia Zeller & Tóth 1960KC01
Endotryblidium Petr. 1959KC01
Lecanidiella Sherwood 1986KC01
Lirellodisca Aptroot 1998KC01
Murangium Seaver 1951KC01
Poetschia Körb. 1861KC01
Rhizodiscina Hafellner 1979KC01
Schrakia Hafellner 1979KC01
Stratisporella Hafellner 1979KC01
Tryblidaria (Sacc.) Rehm 1904KC01
Rhytidhysteron Speg. 1881 (see below for synonymy)KC01
`--R. rufulumPA-W02
Pseudoparodia Theiss. & Syd. 1917PG18, KC01

Patellaria Fr. 1822 nec Hoffm. 1789 nec Gmelin 1793 (ICZN) nec Pers. 1794PG18, KC01 [incl. Lecanidion Endl. 1830KC01]

Rhytidhysteron Speg. 1881 [=Rhytidhysterium Sacc. 1883; incl. Brunaudia (Sacc.) Kuntze 1898, Eutryblidiella (Rehm) Höhn. 1959, Rhytidopeziza Speg. 1885, Tryblidiella Sacc. 1883]KC01

*Type species of generic name indicated


[DS79] Dyko, B. J., & B. C. Sutton. 1979. Two new and unusual deuteromycetes. Trans. Br. Mycol. Soc. 72 (3): 411–417.

[KC01] Kirk, P. M., P. F. Cannon, J. C. David & J. A. Stalpers. 2001. Ainsworth & Bisby’s Dictionary of the Fungi 9th ed. CAB International: Wallingford (UK).

[PA-W02] Pang, K.-L., M. A. Abdel-Wahab, S. Sivichai, H. M. El-Sharouney & E. B. G. Jones. 2002. Jahnulales (Dothideomycetes, Ascomycota): A new order of lignicolous freshwater ascomycetes. Mycological Research 106 (9): 1031–1042.

[PG18] Pem, D., Y. Gafforov, R. Jeewon, S. Hongsanan, I. Promputtha, M. Doilom & K. D. Hyde. 2018. Multigene phylogeny coupled with morphological characterization reveal two new species of Holmiella and taxonomic insights within Patellariaceae. Cryptogamie Mycologie 39 (2): 193–209.

[SH05] Selbmann, L., G. S. de Hoog, A. Mazzaglia, E. I. Friedman & S. Onofri. 2005. Fungi at the edge of life: cryptoendolithic black fungi from Antarctic desert. Studies in Mycology 51: 1–32.

Yacharoen, S., Q. Tian, P. Chomnunti, S. Boonmee, E. Chukeatirote, J. D. Bhat & K. D. Hyde. 2015. Patellariaceae revisited. Mycosphere 6 (3): 290–326.

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