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Miyagia pseudosphaeria (Mont.) Jørst.

Description
Uredinia on leaves or stems, amphigenous, mostly abaxial, scattered or aggregated into groups sometimes concentrically on leaf spots about 1 mm diam. that are purplish with a diffuse chlorotic margin on the adaxial surface but without pigmentaion on the abaxial leaf surface, subepidermal, round, up to 250 µm diam., yellow to yellowish brown; paraphyses marginal, cylindrical or clavate, yellowish brown to reddish brown, 25‒90 × 5‒15 µm; wall 1.0‒2.5 µm thick, sides walls gradually becoming thicker towards apex.

Urediniospores ellipsoidal, obovoid or irregularly polyangular, often with a flattened base up to 6 µm wide, pale yellow, 21‒39 × 15‒20 µm; wall 2‒4 µm thick, echinulate.

Hosts
Host family: Asteraceae
Host species: Sonchus oleraceus

Distribution
ACT, NSW, QLD, TAS, VIC, WA

Comments
Miyagia pseudosphaeria is widespread across southern and northern Australia on Sonchus oleraceus (common sowthistle), which is an important introduced European weed. The rust first appeared in Australia in 1953 and virulent strains may have potential for the biological control of its host (McCarren and Scott, 2008).

Highslide JS
Miyagia pseudosphaeria on Sonchus oleraceus - BRIP 53660.
Highslide JS
Uredinia of Miyagia pseudosphaeria on Sonchus oleraceus - BRIP 52196.
Scale bar = 1 cm.
Highslide JS
Urediniospores and paraphyses of Miyagia pseudosphaeria on Sonchus oleraceus - BRIP 52196.
Scale bar = 100 µm.
Highslide JS
Urediniospores and paraphyses of Miyagia pseudosphaeria on Sonchus oleraceus - BRIP 52236.
Scale bar = 10 µm.
Highslide JS
Urediniospores of Miyagia pseudosphaeria on Sonchus oleraceus - BRIP 53638.
Scale bar = 10 µm.