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KEYS TO SOME COMMON GENERA OF MOULDS

GROUP II

1. Colonies composed of hyphae, or at least with some hyphae present 2

1. Colonies lacking hyphae; short chains of "budding" cells may be produced 16









2. (1) Spores 1-celled 3


2. Spores with more than one cell 14







3. (2) Spores and hyphae colourless or brightly coloured 4


3. Spores and/or hyphae dark coloured 10







4. (3) Spores produced in chains 5


4. Spores not produced in chains 7







5. (4) Spores produced from small clusters of tapering phialides, often rather pointed at the ends

Paecilomyces

Compare with Penicillium (Group I), Talaromyces (Group IV) and Verticillium (Group II)


5. Spores produced by the simple fragmentation of hyphal segments into individual cells 6







6. (5) Colonies very slow growing (slower than 5 mm/week), often grey, often with a strong earthy odour; hyphae usually less than 1 Á in diameter

Streptomyces


6. Colonies growing faster, with a fruit-like odour or odourless, hyphae larger

Geotrichum

Compare with Geomyces (Group IV)







7. (4) Spores produced in sporangia, with sporangia often broken and represented only by simple blunt sporangiophores (no swollen columella); colonies often velvety in texture and pink to brown

Mortierella

Compare with Mucor (Group I) and Absidia (figure 2B)


7. Spores produced externally 8







8. (7) Spores produced in large numbers and completely covering the surface of large terminal cells; cells of conidiophores often flattening in alternating planes as they dry; colonies often producing black stony sclerotia

Botrytis

Compare with Chromelosporium (not treated here)


8. Spores produced at the tips of terminal cells and never covering them; cells of the conidiophore not flattening characteristically upon drying 9







9. (8) Conidia produced in small round masses at the tips of phialides; phialides in whorls, tapering gradually to a very narrow tip

Verticillium

Compare with Acremonium (Group I)


9. Conidia produced singly at the ends of short branches; or in short chains, not on phialides; spore-producing cells not in whorls

Chrysosporium

Sepedonium and Trichophyton (both Group V) and Geomyces (Group IV) are similar







10. (3) Spores produced in sporangia or in fruiting bodies 11


10. Spores produced externally 12







11. (10) Spores produced within densely hairy fruiting bodies (perithecia), very dark; asci present when young

Chaetomium


11. Spores produced in sporangia (Go back to 7)







12. (10) Conidiophores united to form large synnemata that have a sterile base and a spore-bearing upper part, often accompanied by spores of Echinobotryum (Group V)

Cephalotrichum

Compare with Trichurus and Graphium (both Group III)


12. Conidiophores never united to form such structures 13







13. (12) Spores arising in dense masses directly from swellings on the vegetative mycelium; colonies usually rather flat and moist

Aureobasidium

Compare with Exophiala (Group III)


13. Spores completely covering the terminal cells of erect conidiophores; colonies cottony and rather dry; black sclerotia often present

Botrytis







14. (2) Spores with transverse walls only, colourless; colonies white to pink; often associated with eelworms

Orbilia

Compare with Trichothecium (Group V). Species formerly referred to Arthrobotrys, Candelabrella, Dactylella, Geniculifera, and Monacrosporium also belong here.


14. Spores with transverse and vertical walls, dark brown 15







15. (14) Conidiophores more or less straight because of their elongation directly through the scar of the previous spore, bearing only one spore at a time

Stemphylium

Compare with Pithomyces (Group IV)


15. Conidiophores often with a slight zigzag appearance due to new growth from just below the tip, often bearing a spore at each bend

Ulocladium

Compare with Pithomyces (Group IV) and Curvularia (not treated here)







16. (1) Cells very small, seldom more than 1-2 Á in diameter, dividing by simple fission into two equal-sized daughter cells, sometimes containing a single internal spore

Bacteria


16, Cells usually larger than 1-2 Á in diameter, dividing by budding, with the daughter cell seen as a small "bubble" arising from the wall of the parent cell, sometimes containing one or more internal spores (ascospores)

Yeasts

Compare Aureobasidium (Group II), Candida and Exophiala (both Group III)

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