Claviceps annulata Langdon

Description

Sclerotia formed in the fertile florets of spikelets and replacing the ovaries, cylindrical, 7-8 x 1 mm, chestnut-coloured or brown, covered in fine papilla for the whole length.

Conidia of two types

  • microconidia formed on narrow, flask-shaped terminal conidiogenous cells on the sphacelium and later immersed in honeydew, subglobose-globose, 3-4 µm in diameter, aseptate, hyaline.
  • macroconidia formed on narrow, flask-shaped terminal conidiogenous cells on the sphacelium and later immersed in honeydew, oblong, straight or slightly curved, sides parallel, rounded ends, 7-13 x 3-6 µm, hyaline, aseptate.

Ascostromata 1 or 2 per sclerotium, each consisting of a globose capitulum 0.4-0.9mm in diameter, chestnut-coloured, papillate with perithecial beaks separated, with a ring of loose hyphae at the base, borne by a cylindrical stipe 4-10 mm long x 0.3-0.5 mm in diameter, umber sometimes iron chestnut, twisted in the upper portions and with longitudinal grooves,
fine, sparse hairs covering the surface.

Perithecia immersed in the capitulum, subglobose, 150-165 x 130-150 µm.

Asci cylindrical, attenuated towards base, 70-125 x 4 µm, with a hemispherical apical cap.

Ascospores filiform, slightly shorter than the ascus, hyaline.

Hosts
   
Host family: Poaceae
   
Host species: Eulalia aurea

Distribution

NSW, QLD

Comments

This rare, indigenous fungus has been collected only on Eulalia aurea at three sites in Queensland and New South Wales. Langdon (1942) noted that although C. annulata closely resembled C. pusilla during the early stages of sclerotium germination it differed from that latter species by the colour of the stroma and the size and shape of the perithecia. He also considered that the colour of the sclerotia, the size and shape of the conidia, and the ring of hyphae around the base of the capitulum were distinct amongst Claviceps species.

Highslide JS
Claviceps annulata on Eulalia aurea - BRIP 8102.
Highslide JS
Claviceps annulata on Eulalia aurea - BRIP 8102.
Scale bar = 1 mm.
Highslide JS
Claviceps annulata on Eulalia aurea - BRIP 8102.
Scale bar = 1 mm.
Highslide JS
Claviceps annulata on Eulalia aurea - BRIP 8102.
Scale bar = 500 µm.
Highslide JS
Claviceps annulata on Eulalia aurea - BRIP 8102.
Scale bar = 10 µm.
Highslide JS
Claviceps annulata on Eulalia aurea - BRIP 8102.
Scale bar = 10 µm.