PIRELLA Bainier, 1882 ( Étude sur les Mucorinées, p. 83); 2 spp. (Hesseltine, 1960; Benny and Schipper, 1992—monograph).
Mucor Micheli ex L.: Fr. subgen. Pirella (Bain.) Schröt., 1893 [In Engler & Prantl, Die natürl. Pflanzenfam. 1(1):125; fide Hesseltine, 1960].
= Mucor Micheli ex L.: Fr. sect. Piromyces Naumov, 1935 [ Opredel. Mukoroykh ( Mucorales) , Ed. 2, p. 29; nomen nudum, without a Latin diagnosis, Art. 36.1 of the ICBN (Greuter et al., 2000); fide Hesseltine, 1960].

Large, deliquescent-walled sporangia are formed like those of Helicostylum and Thamnidium. Persistent-walled sporangia, often with a columella that intrudes deeply into spore layer, are produced on relatively long twisted and contorted branches. Zygospores have pigmented and ornamented zygosporangial walls and opposed, more or less equal suspensors (Benny and Schipper 1992).

Type species: P. circinans

Species of Pirella:
P. circinans Bainier, 1882 ( Étude sur les Mucorinées, p. 83).
P. naumovii (Mil’ko) Benny & Schipper, 1992 (Mycologia 84:55).

Two species, P. circinans and P. naumovii, are currently included in Pirella (Benny and Schipper, 1992). Pirella circinans was often isolated from rodent dung collected in California; P. naumovii is known only from the initial isolate (Benny and Schipper, 1992). Mil’ko (1968) transferred Pirella spp. to Circinella, whereas P. circinans was included in Absidiaceae (Mucorales) by von Arx (1982), and the Mucoraceae s.l. by Hesseltine and Ellis (1973).


Benny, G.L., and M.A.A. Schipper. 1992. Observations on Thamnidiaceae (Mucorales). IV. Pirella. Mycologia 84:52-63.

Greuter, W., J. McNeill, F.M. Barrie, H.M. Burdet, V. Demoulin, T.S. Filgueiras, D.H. Nicolson, P.C. Silva, J.E. Skog, P. Trehane, N.J. Turland, and D.H. Hawksworth (Eds.). 2000. International code of botanical nomenclature ( St. Louis code ). Reg. veget. 138:1-474.

Hesseltine, C.W. 1960. The zygosporic stage of the genus Pirella (Mucoraceae). Am. J. Bot. 47:225-230.

Hesseltine, C.W., and J.J. Ellis. 1973. Mucorales, pp. 187-217, In G. C. Ainsworth, F. K. Sparrow, and A. S. Sussman (Eds.). The Fungi. Vol. 4b. Academic Press, New York. 504 p

Mil’ko, A.A. 1968. De nomenclatura mucoralium nonnullorum clavibus diagnosticis specierum Circinellae, Thamnidii et Kickxellae adjectis. Nov. Syst. Plant. non Vascul. 1968:79-88.

von Arx, J.A. 1982 [1984]. On Mucoraceae s. str. and other families of the Mucorales. Sydowia 35:10-26.

Updated Mar 13, 2005