Macalpinomyces Langdon & Full.

Type

Macalpinomyces eriachnes (Thüm.) Langdon & Full. on Eriachne sp.

Synonyms

Endosporisorium Vánky

Description

Sori in species of Poaceae, in different organs (ovaries, culms) producing hypertrophy or less often not, covered by a peridium of host tissue permeated by hyphae. True columella lacking.

Spores pigmented, tightly packed, usually polyangular, filling the sori.

Sterile cells of variable size and wall thickness, solitary or grouped, hyaline or pale, embedded and scattered in the spore mass. At maturity, spore mass disintegrating into irregular groups of variable size or into single spores.

Spore germination of Ustilago-type.

Host-parasite interaction by intracellular hyphae coated by an electron-opaque matrix.

Septa poreless at maturity.

Comments

Until 1995, Macalpinomyces was regarded as being monotypic, and was characterised by giant, thick-walled, pale sterile cells and pigmented spore masses that at maturity break into ‘pseudo spore balls’ or into single spores. Vánky (1996, 1997) twice emended the generic description of Macalpinomyces to accommodate ten apparently closely related smuts, preferring to establish a well-delimited genus rather than creating numerous, small, often monotypic, closely related genera. However, recent DNA sequence studies have indicated that Macalpinomyces is most probably monotypic with other species referable to either Sporisorium or Ustilago (Stoll et al., 2005). Furthermore, DNA sequence analysis indicates that M. eriachnes may comprise two distinct species (Stoll et al., 2005). More work is required to resolve the classification of grass-infecting smut fungi that have been placed in Macalpinomyces, Sporisorium and Ustilago.

Macalpinomyces sensu Vánky (1996, 1997) contains c. 40 species of which 12 are represented in Australia, including seven endemic taxa.

Species in Australia
 
Macalpinomyces arundinellae-setosae
Macalpinomyces brachiariae
Macalpinomyces digitariae
Macalpinomyces eriachnes
Macalpinomyces mackinlayi
Macalpinomyces neglectus
Macalpinomyces ordensis
Macalpinomyces sharmae
Macalpinomyces spermophorus
Macalpinomyces tubiformis
Macalpinomyces viridans

Key based on host taxonomy
 
On ArundinellaMacalpinomyces arundinellae-setosae
On Brachiaria1
1.  Sori c. 1 mm long. Sterile cells 13-22 µm longMacalpinomyces brachiariae
Sori 2-5 mm long. Sterile cells 5-12(-14) µm longMacalpinomyces ordensis
On ChrysopogonMacalpinomyces tubiformis
On DigitariaMacalpinomyces digitariae
On EriachneMacalpinomyces eriachnes
On EulaliaMacalpinomyces mackinlayi
On Setaria1
1.  Spores 9-13(-14) µm long, echinulateMacalpinomyces neglectus
Spores 7-10.5(-11) µm long, punctate-verruculoseMacalpinomyces sharmae
On Sporobolus1
1.  Spores moderately densely verrucose-echinulateMacalpinomyces spermophorus
Spores sparsely, coarsely echinulateMacalpinomyces viridans