Phragmidium bulbosum

This study corresponds to the telial stage of the species (the phase preceding basidium formation), causing reddish-brown necrotic spots on the upper leaf surface.

A parasitic rust fungus attacking living leaves of Rubus sp. (brambles), with telia occurring on the lower leaf surface in dense tufts/fascicles, rounded to irregular in outline, 0.2 to 0.5 mm across, forming aggregates up to 1 mm, black and carbonaceous due to the accumulation of mature teliospores.

Teliospores cylindrical, dark brown, with 3 to 6 transverse septa (predominantly 4 to 5 septa), 55 to 90 µm long (excluding the papilla), 28 to 35 µm wide, with a cell wall 3.5 to 4.5 µm thick, bearing an apical hyaline papilla 5 to 15 µm long (5 to 7 µm wide at its base), and a long, persistent hyaline pedicel 75 to 150 µm long, swollen at the base to 10 to 15 µm wide.

Herbarium material available: JTP2608/25.