Fungalpedia – Note 3302, Pneumocystomycetes

 

Pneumocystomycetes O.E. Erikss. & Winka [as ‘Pneumocystidomycetes’], Myconet 1(1): 9 (1997).

Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.

Index Fungorum, Faceoffungi, MycoBank, GenBank.

Classification: Taphrinomycotina, Ascomycota, Dikarya, Fungi.

Non-filamentous yeast-like organisms, aggregated and parasitic cells in mammalian alveoli, thin-coated, uninucleate, divided by fission. Asci crassitunicate, tetra- or octosporum. Ascospores globose or round, 8-spored, thick-walled (Eriksson and Winka 1997; Cushion et al. 2004).

Life mode and distribution: parasitic on mammals as they aggregate in mammalian alveoli and P. carinii causes pneumonia (PCP) in immunocompromised (esp. AIDS) patients (Mills 1986; Kirk et al. 2008) and cancer patients (Sepkowitz et al. 1992; Sepkowitz 1993). 

Notes: The genus Pneumocystis P. Delanoë & Delanoë was introduced by Delanoë and Delanoë (1912). For almost eight decades, Pneumocystis was regarded as a protozoan taxon (Stringer 2002) but Edman et al. (1988) confirmed that Pneumocystis is related to Saccharomyces cerevisiae using rRNA. Later, Stringer et al. (1989) confirmed that the members of Pneumocystis are related to Candida albicans, Neurospora crassa, and Cryptococcus neoformans as well. 

Eriksson (1994) introduced the family Pneumocystaceae O.E. Erikss. and the order Pneumocystales O.E. Erikss. to accommodate Pneumocystis. Later, Eriksson and Winka (1997) introduced the class Pneumocystomycetes. 

Type genus: Pneumocystis P. Delanoë & Delanoë 1912.

Other accepted species: Species Fungorum – search Pneumocystomycetes.

 

References

Delanoë P, Delanoë M. 1912 – Sur les rapports des kystes de Carini du poumon des rats avec le Trypanosoma lewisi. CR Acad Sci (Paris) 155:658–660.

Edman JC, Kovacs JA, Masur H, Santi DV et al. 1988 – Ribosomal RNA sequence shows Pneumocystis carinii to be a member of the fungi. Nat 334:519-522.

Eriksson OE, Winka W. 1997 – Supraordinal taxa of Ascomycota. Myconet. 1:1–16.

Eriksson OE. 1994 – Pneumocystis carinii, a parasite in lungs of mammals, referred to a new family and order (Pneumocystidaceae, Pneumocystidales, Ascomycota). Syst Ascomycetum 13:165–180.

Kirk PM, Cannon PF, Minter DW, Stalpers JA et al. 2008 – Ainsworth & Bisby’s dictionary of the fungi, 10th edn. CABI, Wallingford, pp 439.

Mills J. 1986 – Pneumocystis carinii and Toxoplasma gondii infections in patients with AIDS. Rev Infect Dis 8:1001–1011.

Sepkowitz KA, Brown AE, Telzak EE, Gottlieb S et al. 1992 – Pneumocystis carinii pneumonia among patients without AIDS at a cancer hospital. Jama 267:832–837.

Sepkowitz KA. 1993 – Pneumocystis carinii pneumonia in patients without AIDS. Clin Infect Dis17(Supplement_2):416–422.

Stringer JR. 2002 – Pneumocystis. Int J Med Microbiol 292:391–404.

Stringer SL, Hudson K, Blase MA, Walzer PD et al. 1989 – Sequence from ribosomal RNA of Pneumocystis carinii compared to those of four fungi suggests an ascomycetous affinity. J Protozool 36:14S–16S.

 

Entry by

Nalin N. Wijayawardene, Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing, Yunnan 655011, P.R. China, Tropical Microbiology Research Foundation, 96/N/10, Meemanagoda Road, 10230 Pannipitiya, Sri Lanka, Department of Bioprocess Technology, Faculty of Technology, Rajarata University, Sri Lanka

 

Published online 29 September 2026

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