The Entomophthorales (Schröter, 1893b; Underwood, 1899), or the fungi now treated in the order, have usually been maintained separately from the Mucorales. These fungi have often been included in a single family: Entomophthoraceae (Schroeter, 1889; Underwood, 1899; Fitzpatrick, 1930; Waterhouse, 1973), two families: Basidiobolaceae and Entomophthoraceae (Kreisel, 1969—Pilobolaceae placed there also), Benjamin, 1979), three families: Ancylistaceae, Basidiobolaceae, and Entomophthoraceae (Batko, 1974; Humber, 1981a; Tucker, 1981; Ben-Ze’ev and Kenneth, 1982), or six families: Ancylistaceae, Basidiobolaceae, Completoriaceae, Entomophthoraceae, Meristacraceae, and Neozygitaceae (Humber, 1989), or with five familes when Basidiobolaceae is included in an order of its own. At present the five family system appears to be the most natural, with the following characteristics being of some use in familial delimitation: (1) mode of sporangiolar delimitation [discussed in some detail by Benjamin (1979)], (2) method of gametangial conjugation and morphology of mature resting spores, (3) karyology, response of nuclei to staining with bismark brown and aceto-orcein, and presence or absence of a central nucleolus in the primary sporangiolum, (4) morphology of conidiophores and rhizoids, and (5) pathobiology (Humber, 1981a, 1989; Tucker, 1981; Ben-Ze’ev and Kenneth, 1982). Karyology is the character of choice in determining family affinities since there are three types produced: 1) nuclei relatively small, with little heterochromatin, a prominant nucleolus, and difficult to observe (Ancylistaceae, Meristacraceae, Neozygitaceae; Entomophthorales), 2) nuclei relatively large, with little heterochromatin, a prominant nucleolus, and indistinct during mitosis (Basidiobolaceae, Basidiobolales), and 3) nuclei relatively large, with much heterochromatin, no nucleolus, and visible throughout mitosis (Entomophthoraceae and possibly Completoriaceae; Entomophthorales).
Recent molecular studies (see under Basidiobolaceae) have indicated that the Basidiobolaceae should elevated to ordinal status. Its final disposition will depend on additional molecular studies but Basidiobolus will remain in the Basidiobolales until a decision has been regarding its true affinities.
ENTOMOPHTHORALES Schröter, 1893 [In Engler and Prantl, Die natürl. Pflanzenfam. 1(1): 134].
= Ancylistales Fitzpatrick, 1930 (The lower fungi. Phycomycetes, p. 117).
Saprobes, or obligate parasites of plants or animals. Somatic state consisting of a well-defined mycelium, which may fragment and form hyphal bodies, or naked protoplasts. Sporophores branched or unbranched. Spores uni-, pleuri-, or multinucleate, forcibly discharged or passively released. Resting spores usually zygospores. Nuclei of three types, each type typical of at least one of the five recognized families.
Type family: Entomophthoraceae Warming.
KEY TO THE FAMILIES OF ENTOMOPHTHORALES
A. Sporophores with a vesicle subtending the spore; gametangia, if present, with small, beaklike accessory cells;contents of secondary spores and somatic hyphae in some species may divide and produce small protoplasts (appearing multispored); all cells uninucleate; nuclei large, all over 10 µm in length, with a prominent central nucleolus, not staining in aceto-orcein —— Basidiobolaceae (Basidiobolales)
AA. Sporophores without a subsporal vesicle; gametangia, if present, without accessory cells; spores and mycelium not producing internal protoplast-like structures; cells not all uninucleate; nuclei small, most less than 10 µm in length —— B
B. Nuclei variable, 2-15 µm in length during interphase, with much heterochromatin (staining readily with aceto-orcein and Bismark Brown; nucleolus not prominant; nucleu
s remaining visible during mitosis —— Entomophthoraceae (Entomophthorales)
BB. Not as above —— C
C. Nuclei relatively large, nucleoplasm appears granular (chromatin condensed at interphase); conidiophores short and unbranched, arising from vegetative cells, conidiogenous cells produced; conidia unitunicate, hyaline, forcibly discharged by papillar eversion; obligate intracellular parasites of fern gametophytes —— Completoriaceae
CC. Nuclei 2-5 µm in length, with little heterochromatin (not staining in aceto-orcein or Bismark Brown); nucleolus prominant; nucleus usually inconspicuous during mitosis; outer spore layer spore when mounted in liquid; Saprobes or parasites of insects, fresh water algae, soil invertebrates —— D
D. Conidiophores upright, each bearing several conidia; parasitic on soil invertebrates (nematodes and tardigrades —— Meristacraceae
DD. Conidiophores usually unbranched, conidia borne terminally; saprobes or pathogens of insects, soil invertebrates, fresh water algae, or cause mycotic infections —— E
E. Spores (conidia, zygospores) tend to be melanized (pale gray to black in color); zygospores bud from the conjugation point of two hyphal bodies; obligate parasites of mites and insects (esp. Homoptera —— Neozygitaceae
EE. All spores hyaline; zygospores formed as a result of conjugation between adjacent hyphal cells or scalariform conjugations between two hyphae; saprobes or obligate parasites of desmid algae, soil invertebrates, or faculative mycotic disease agent of animals —— Ancylistaceae
Updated Jan 31, 2009