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Uredo zehneriae Thüm

Description
Uredinia on lower leaf surface, subepidermal, erumpent, round, less than 1000 μm, yellowish brown, peridium present.

Urediniospores globose, subglobose or obovoid, apex obtuse, yellowish brown, 19.5‒25 × 16‒22 μm; wall 1‒2.5 μm thick, sometimes thickened at the base, smooth to very finely echinulate, with 2‒3 equatorial germ pores.

Hosts
Host family: Cucurbitaceae
Host species: Melothria cunninghamii

Distribution
NSW, QLD

Comments
Uredo zehneriae was first described on Zehneria scabra from South Africa by Thümen (1877). Berndt (2007) suggested U. zehneriae was the uredinial stage of Puccinia rhytidioderma, which he described from Zehneria scabra in Uganda. Simmonds (1966) first reported U. zehneriae from Queensland on Melothria cunninghamii. Teliospores have not been seen in the Australian specimens. Uredo zehneriae is the only rust known on Cucurbitaceae in Australia.

Highslide JS
Uredo zehneriae on Melothria cunninghamii - BRIP 56948.
Scale bar = 1 cm.
Highslide JS
Urediniospores of Uredo zehneriae on Melothria cunninghamii - BRIP 56948.
Scale bar = 10 µm.