Von Arx’s (1982) removal of Phycomyces Kunze and Spinellus Tiegh. from the Mucoraceae Dumort. to a separate family, Phycomycetaceae von Arx, is supported here. Although the sporangiophore and sporangia of Phycomyces are Mucor-like, characteristics of the sexual structures found in this genus suggest that it is not closely related to the Mucoraceae (Benjamin and Hesseltine, 1957) even as the latter family was broadly defined by previous authors (Hesseltine, 1955; Zycha et al., 1969; Hesseltine and Ellis, 1973; Benjamin, 1979; von Arx, 1981). Morphology of the zygospores of Phycomyces is illustrated by O’Donnell et al. (1976, 1978) and Cerdá-Olmedo and Lipson (1987).
Spinellus also was included in Phycomycetaceae by von Arx (1982). Mirza et al. (1979) treated Spinellus in the Dicranophoraceae Mirza. Spinellus is similar morphologically to Phycomyces because it produces a large columellate sporangium and a simple sporangiophore but the zygospores are formed on opposed suspensors (Zycha et al., 1969).
Phycomyces species are saprophytes that can be isolated from a variety of organic substances including dung, soil, and plant debris (Benjamin and Hesseltine, 1957). Spinellus is found in nature only as a facultative parasite of Agaricus L., Inobybe (Fr.) Fr., Mycena (Pers.) Roussel and other members of the Agaricales Underw. (Zycha et al., 1969).
Phycomyces is a mesophile that grows well at 25 C although zygospores may be produced optimally below 20 C (Benjamin and Hesseltine, 1959). Spinellus is a psychrophile that does not grow well above 22 C (Leadbeater and Richardson, 1963). Zygospores of Spinellus were produced in culture according to Leadbeater and Richardson (1963).
A data set consisting of six taxa from the Mortierellales Cav. Sm. and 75 spp. containing at least one species all of the genera in culture of the Mucorales Fr. (tef-1a, 18S rDNA, 28S rDNA, morphology) of O’Donnell et al. (2001) showed that the Phycomyces — Spinellus clade had 100% bootstrap support (BP). Voigt and Olsson (2008) analyzed a data set (act, tef-1a, 18S rRNA, 28S rRNA) containing selected species of 50 genera of the Mucorales resulted 100% BP (both neighbor-joining and strict consensus analysis) for the Phycomycetaceae. The latter clade also was observed by Voigt et al. (2009) based on an analysis of a data set (act, ß-tubulin, tef-1a, 18S rRNA, 28S rRNA) containing 27 genera of the Mucorales. The bigeneric Phycomycetaceae is recognized here based on both morphology and phylogenetic analysis (Voigt et al., 2009), and also is recognized by Cannon and Kirk (2007) and Kirk et al. (2008).
There currently is no known economic use for species of Spinellus. Phycomyces, especially P. blakesleeanus, biology has been extensively studied (Cerdá-Olmeido and Lipson (1987). The production of ß-carotene and other compounds has been studied in P. blakesleeanus using single and mated cultures, and the genes necessary have been elucided (Kuzina and Cerdá-Olmeido, 2006, 2007; Almeida and Cerdá-Olmeido, 2008). Sex genes have been studied in P. blakesleeanus (Dyer, 2008; Idnurm et al., 2008).
Phycomycetaceae v. Arx, 1983 (Sydowia 35: 22).
Substrate mycelium branched, yellowish; sometimes with trophocyst-like cells, aerial hyphae smooth or covered with spines. Sporophores unbranched, erect, phototrophic, arising directly from the substrate hyphae, bluish, greenish, or blackish, with a metallic luster or light brown to brown, constricted below the sporangium or apophysate. Sporangium large, more or less globose, usually containing a great number of spores. Sporangiospores globose, ovoid, to ellipsoid or broadly fusiform. Suspensors initially apposed, separating as the zygospore enlarges and becoming tongs-like, ornamented with stiff, irregularly dichotomously branched appendages, or suspensors opposed, more or less equal, nonappendaged. Zygospore globose, nearly smooth to slightly roughened or wall striate.
Type genus: Phycomyces
Key to the Genera of Phycomycetaceae
A. Sporangiophores with a greenish, metallic sheen; growth of asexual reporductive structures occurs at 25 C, sexual reporduction occurs optimally at 15 C; in nature found in organic substrates, especially dung — Phycomyces
AA, Sporangiophores dark but lacking a greenish, metallic sheen; growth only occursa below 20 C; in nature found only growing on members of the Agaricales, especially Mycena — Spinellus
Synopsis of Genera
PHYCOMYCES Kunze: Fr., 1821 [Syst. Mycol. 3: 308; nomen conserv., Art. 13.1(d) of the ICBN (McNeill et al., 2006; see Korf, 1982, 1983)]; 3 spp. (Benjamin and Hesseltine, 1959 — illus. and KEY TO SPP.); Bergman et al., 1969 — illus.; O’Donnell et al., 1976 — illus., 1978 — illus.; Mikawa, 1979 — illus.).
= Phycomyces Kunze, 1823 (In Kunze and Schmidt, Mykol. Hefte 2: 113).
SPINELLUS van Tieghem, 1875 (Ann. Sci. Nat., Bot., Sér. VI, 1:66); 3 to 7 spp.; 5 spp. in Index Fungorum (van Tieghem, 1875 — illus.; Vuillemin, 1904 — illus., 1905; Indoh, 1961—illus.; Ellis and Hesseltine, 1962; Watson, 1964 — illus., 1965; Zycha et al., 1969 — illus. and KEY TO SPP.; Hanlin, 1973 — key to spp.; Strid, 1974 — illus.; O’Donnell, 1979 — illus.; Overton, 1997 — illus.) [transferred to Dicranophoraceae by Mirza et al, 1979, and Phycomycetaceae by von Arx, 1982 and Voigt et al., 2009].
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Updated Jun 06, 2010