Claviceps inconspicua Langdon

Description

Sclerotia formed in the fertile florets of spikelets, replacing the ovaries and always shorter than the enclosing spikelet elements, subcylindrical-fusoid, 1.2-5 mm long, brown-almost black.

Conidia of two types

  • macroconidia formed on narrow, flask-shaped terminal conidiogenous cells on the sphacelium and later immersed in honeydew, oblong, with sides straight to slightly curved, rounded ends and occasionally slightly tapering and truncated at one end, 13-17 µm x 6-8 µm, hyaline, aseptate.
  • secondary conidia developed singly at the tips of sterigmata from germinated macroconidia above the honeydew surface, obovoid occasionally with concave sides, sometimes pyriform, 14-18 µm x 7-8 µm, hyaline, aseptate.

Ascostromata 1-several on each sclerotium, each consisting of a globose capitulum, 0.3-0.6 mm in diameter, black, prominently papillate, loose short hyphae on the surface, with a ring of short white hyphae at the base, borne by a slender stipe, 1.5-9 mm long, purple.

Perithecia immersed in capitulum, subglobose, 155-180 x 105-125 µm.

Asci cylindrical, 140-175 x 4 µm.

Ascospores hyaline, filiform.

Hosts
   
Host family: Poaceae
   
Host species: Hyparrhenia filipendula

Distribution

QLD

Comments

Langdon (1950) distinguished inconspicua from other Claviceps species on the bases of its persistent tuft of hyphae at the base of the capitulum, black capitula, and its long, broad macroconidia. He noted the similarity of aspects of the morphology of C. inconspicua with those of C. annulata and C. pusilla, suggesting that the first two species could be Australian variants of Claviceps pusilla. Langdon believed that both C. inconspicua and its host were indigenous to Australia.

Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8103.
Scale bar = 1 cm.
Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8103.
Scale bar = 500 µm.
Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8103.
Scale bar = 500 µm.
Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8103. Scale bar = 250 µm.
Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8103.
Scale bar = 500 µm.
Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8109.
Scale bar = 20 µm.
Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8109.
Scale bar = 20 µm.
Highslide JS
Claviceps inconspicua on Hyparrhenia filipendula - BRIP 8109.
Scale bar = 20 µm.