Sporangium spherical to elongate, 30-56 x 100-112 µm, nonpapillate, with or without elongate subsporangial swelling; rhizoids extensively branched, extending up to 600 µm long. Zoospores spherical to ovoid, 5.5-12.0 µm, usually uniflagellate, rarely biflagellate. The organelles show strongly polarized distribution in the zoospores, with tubular hydrogenosomes and nucleus in the posterior region, and ribosomal aggregates in the anterior region. Megahydrogenosomes absent from zoospores. Nuclear envelope is decorated with flat ribosomal aggregates. Circumflagellar rings show little tilt and have a C-shaped elongation. Ribosomal aggregates are either free in cytoplasm or are embeded in a homogeneous substratum in a group.

Piromyces communi (Gold) aemulans, differt zoosporis fasces ribosomaitum et annulum circum flagellarem amplificatam et hydrogenosomaita tubularia continentibus. Intestinus elephantis habitat.

ETYMOLOGY: dumbonica named after the most famous cartoon version of the host ("Dumbo") from which isolated but does not necessarily imply fungus is exclusive to that host.

TYPE: Figs. 2, 4, 9, 12, 13, 19, 23, 24, 31.