The Orbiliaceae are a
family of
saprobicsac fungi. It is the only family in the
monotypic class Orbiliomycetes and the monotypic
orderOrbiliales. The family was first described by
John Axel Nannfeldt in 1932 and now contains 288
species in 12
genera.[1] Members of this family have a widespread distribution, but are more prevalent in
temperate regions.[2] Some species in the Orbiliaceae are
carnivorous fungi, and have evolved a number of specialized mechanisms to trap
nematodes.
Description
Orbiliaceae do not have stromata, dense structural tissue that produces
fruit bodies. They have small disc-shaped
apothecia, that are typically convex, brightly colored or
translucent.[2] Their
ascospores are small (typically less than 10 x 1
μm),
hyaline, and have an oval or ellipsoidal shape.[3]
Species are usually found in wood on both wet and dry habitats.[2]Anamorph species are
hyphomycetous.[4]
Nematophagy
This family is well known for its many
nematophagous species.[5] Shortly after coming into contact with its prey, fungal
mycelia penetrate the nematode and spontaneously differentiate into functional structures, known as traps, which will ultimately digest the nematode's internal contents.[6] There are 5 types of trap mechanisms recognized in this family:[6][7][8][9]
Adhesive network: the most common trap, formed by
hyphal outgrowths that recurve into themselves to form nematode-trapping loops.
Adhesive knob: a roughly spherical cell, attached to the hyphae either directly or on an erect stalk. Adhesive knobs are typically closely spaced along a section of hyphae.
Nonconstricting rings: always found with the adhesive network traps, and formed from thickening hyphae that curve and fuse to the supporting stalk.
Adhesive column: a layer of cells on a hyphae with an adhesive surface.
Constricting rings: these are rings of hyphae that swell rapidly inwards upon contact with the nematode, quickly (in 1–2 seconds) "
lassoing" the victim.
Genera
According to the most recent classification of Ascomycota,[10] the Orbiliaceae contain only two (
teleomorph) genera, the Hyalorbilia and the Orbilia. Hyalorbilia is distinguished from Orbilia by having
asci without a stalk that arise from
croziers, a hemispherical to broadly conical, thin-walled apex, asci and
paraphyses in a gelatinous matrix, and an ectal excipulum (the outer surface of a cup-like apothecium) of horizontal textura prismatica.[11][12]
In 2007, a new species was described from southwestern China with morphological features intermediate between Orbilia and Hyalorbilia. This species, named Pseudorbilia bipolaris Y. Zhang, Z.F. Yu, H.O. Baral & K.Q. Zhang, was placed into its own genus in the Orbiliaceae to accommodate its distinctive features.[20]
References
^Kirk, Paul M.; Cannon, Paul F.; Minter, David W.; Stalpers, Joost A., eds. (2008).
"Orbiliaceae". Ainsworth & Bisby's Dictionary of the Fungi. CABI. p. 485.
ISBN978-0-85199-826-8.
^
abcCannon, P. F.; Kirk, P. M., eds. (2007). "Orbiliaceae". Fungal Families of the World. CABI. pp. 251–252.
ISBN978-0-85199-827-5.
^Blackwell M, Alexopoulos CJ, Mims CW (1996). Introductory Mycology. New York: Wiley.
ISBN0-471-52229-5.[page needed]
^Bisby GR, Ainsworth GC, Kirk PM, Aptroot A (2001). Ainsworth & Bisby's Dictionary of the Fungi. Oxon: CAB International. p. 369.
ISBN0-85199-377-X.
^Drechsler, Charles (1 July 1937). "Some Hyphomycetes that Prey on Free-Living Terricolous Nematodes". Mycologia. 29 (4): 447–552.
doi:
10.1080/00275514.1937.12017222.
^Stirling GR (1991). Biological control of plant parasitic nematodes. Wallingford, UK: C.A.B. International.
ISBN0-85198-703-6.[page needed]
^Webster, J; Descals, E. (1979). "The teleomorphs of water-borne Hyphomycetes from fresh water". In Kendrick, Bryce (ed.). The Whole Fungus: The Sexual-asexual Synthesis. National Museum of Natural Sciences. pp. 419–451.
ISBN978-0-660-00146-3.
^Pfister, Donald H. (1 May 1994). "Orbilia fimicola, a nematophagous discomycete and its Arthrobotrys anamorph". Mycologia. 86 (3): 451–453.
doi:
10.1080/00275514.1994.12026433.
^Pfister, DH (1995). "Helicoon sessile, the anamorph of Orbilia luteorubella". Inoculum. 46.
Mycological Society of America: 34.
^Webster, John (June 2011). "Convergent evolution and the functional significance of spore shape in aquatic and semi-aquatic fungi". In Rayner, A. D. M.; Brasier, C. M.; Moore, David (eds.). Evolutionary Biology of the Fungi: Symposium of The British Mycological Society Held at the University of Bristol April 1986. Cambridge University Press. pp. 191–201.
ISBN978-0-521-27925-3.
NAID10019290922.
^Li Y, Hyde KD, Jeewon R, Cai L, Vijaykrishna D, Zhang K (2005). "Phylogenetics and evolution of nematode-trapping fungi (Orbiliales) estimated from nuclear and protein coding genes". Mycologia. 97 (5): 1034–46.
doi:
10.3852/mycologia.97.5.1034.
hdl:10722/53351.
PMID16596955.