Phragmidium tuberculatum

A rust fungus (Pucciniales) infecting living leaves of Rosa sp.; this study corresponds interchangeably to two collections: one on Rosa canina and another on Rosa rubiginosa.

Aecia forming globose, reddish-orange structures producing aeciospores in chains from basal cells; aeciospores subglobose to ellipsoidal, slightly angular by mutual pressure, 20 to 31 µm long and 14 to 24 µm wide, hyaline-walled, ornamented with fine verrucae, and filled with abundant yellowish lipid droplets that confer their vivid colour.

Teliospores cylindrical with rounded ends, 70 to 90 µm long, 25 to 38 µm wide, brown, with 3 to 5 thick transverse septa, with a wall 5 to 7 µm thick, a long hyaline pedicel 80 to 120 µm long, and a conical hyaline apical papilla up to 20 µm long.

Herbarium material available: JTP2501/25.