Colus hirudinosus

Appearance

Fruit bodies begin their development in the form of an egg like structure. Measuring about 1 cm in diameter, the roughly spherical egg is white or mottled with brown on the upper part. Attached underneath are one or more thin white rhizomorphs. After emerging from the egg, the fruit body consists of a short, thick stalk from which between four and six vertical, arching columns arise. These columns, colored pink below and gradually deepening in color to red near the top, have a corrugated surface texture. The columns often fork near the top into additional branches that support a lattice-like, or "clathrate" dome. The meshes of the fertile net are roughly polyhedral and there is an abrupt transition from columns to lattice. The olive-green gleba is held on the bottom of and in between the meshes of the clathrate dome, and the inner side of the upper arms. It has a fetid odor, similar to feces, which attracts flies that visit the mushroom, consume the gleba, and deposit the spores elsewhere to germinate. Spores produced by "C. hirudinosus" are rod-shaped, hyaline, and measure 3.5–6.5 by 1–1.75 µm. Structurally, the spongy columns comprise a double layer of tubes, a large inner one and two or three outer ones. The remnants of the egg tissue enclose the base of the structure as a volva.

Naming

"Colus pusillus", known from Australia, is quite similar in appearance to "Colus hirudinosus", and it has not been definitively established whether there is one variable species or several species with minor morphological differences.

"Clathrus ruber" is another stinkhorn featuring a clathrate structure, but unlike "Colus hirudinosus", "C. ruber" has larger lattice mesh holes, and the lattice extends all the way to the base of the fruiting structure.

Distribution

"Colus hirudinosus" is believed to be saprobic, meaning that it obtains nutrients by decomposing dead or decaying organic matter. Fruit bodies grow in manured soil, in sand, but frequently also under "Cistus" shrubs, which has led some to suggest the fungus may also act as a facultative endophyte. The species is most widespread in Europe, particularly Mediterranean countries, but also as far north as Switzerland. In Africa, it has been reported from Algeria and Nigeria, while it has also been found in Asia and Australia. In the Caribbean, it is known only from Jamaica.