Claviceps glabra Langdon

Description

Sclerotia formed in the fertile florets of spikelets and replacing the ovaries, subglobose, tip conical and flattened on the sides, 1-3 mm x 1 mm, black, and almost the same length as the lemma.

Conidia of one type

  • macroconidia formed on narrow, flask-shaped terminal conidiogenous cells on the sphacelium and later immersed in honeydew, shape variable, (i) elliptical or curved 13-21 x 4-7 µm, (ii) reniform, oblong (straight-slightly curved and some with one end slightly tapering), or broadly lunate with rounded ends, 10-15 x 3-5 µm, hyaline, aseptate.

Ascostromata mostly one per sclerotium, each consisting of a globose capitulum 0.5-0.6 mm in diameter, chestnut-coloured, papillate, glabrous, borne by a thin, cylindrical stipe 3-6 mm long x 0.25-0.3 mm in diameter, straw-cream.

Perithecia immersed in capitulum, oval, 165-180 x 155-130 µm.

Asci cylindrical, 70-110 x 3 µm, base slightly attenuated, with a hemispherical cap.

Ascospores filiform, equal to the ascus in length, hyaline.

Hosts
   
Host family: Poaceae
   
Host species: Digitaria longiflora
Digitaria orbata

Distribution

QLD

Comments

C. glabra is a rare, indigenous species found only on Digitaria spp. in Queensland. Langdon (1942) considered that the lack of development of loose hyphae during the early stages of differentiation of the ascostroma into the stipe and capitulum distinguished it from all other known Claviceps species.

Highslide JS
Claviceps glabra on Digitaria longiflora - BRIP 8100.
Scale bar = 500 µm.
Highslide JS
Claviceps glabra on Digitaria longiflora - BRIP 8100.
Scale bar = 500 µm.
Highslide JS
Claviceps glabra on Digitaria longiflora - BRIP 8100.
Scale bar = 250 µm.