Pseudocolus fusiformis

What You Should Know

Pseudocolus fusiformis is an inedible stinkhorn mushroom in the Phallaceae, a family well known for a remarkable range of fruit body types. It is the most widely distributed member of the genus Pseudocolus and has been found in the United States, Australia, Japan, Java, and the Philippines.

The malodorous smell comes from the dark greenish slimy gleba covering the inside faces of the arms and attracts insects that help to disperse the spores.

This little stinkhorn features three or four tapered, orange arms that arise from a shared stem structure, separate gracefully, and then rejoin at their tips. In most specimens, the overall shape is reminiscent of an elongated teardrop, like the specimens in the photos to the right, but occasionally Pseudocolus fusiformis is wider toward the top, or even arched at the apex.

When the outer wall (peridium) of the egg splits open, three to five slender, tapering, pink to orange arching arms rise from a common stalk. The arms are whitish at their bases and the tips are often united. The greenish, slimy, fetid spore mass covers the inner surfaces of the arms.

Some related species such as Mutinus caninus are considered to be edible (or even delicacies) in the immature egg stage; however, the foul smell of stinkhorns at maturity would likely deter most individuals from eating them.

Other names: Stinky Squid.

Pseudocolus fusiformis Mushroom Identification

1. Ecology

   Saprobic; growing alone or gregariously; often found in urban settings but sometimes appearing in woods as well; year-round, depending on climate; Australasia, Japan, Africa, South America, and, in North America, from Maine through Mexico to Central America.

2. Immature Fruiting Body

   Initially a whitish "egg," partially submerged in the substrate, from which the stinkhorn emerges with development.

3. Mature Fruiting Body

   3–6 cm high, consisting of a short stem dividing into 3–4 vertical arms that are joined at their tips. Stem about 1–1.5 cm long and 1 cm thick; whitish to pale orange; hollow; surface spongy and finely pocketed; encased in a white, sack-like volva; attached to numerous white rhizomorphs. Arms with flattened or concave outer sides and convex inner sides; 0.5–1 cm thick; tapering to apex; spongy and pocketed; hollow; orange to reddish-orange; inner, convex surfaces covered with dark brown spore slime when fresh.

4. Odor

   Strong and unpleasant.

5. Microscopic Features

   Spores 3–4 x 1–1.5 µm; cylindric; smooth; hyaline to ochraceous in KOH. Sphaerocysts of the arms 12–28 µm across; subglobose to irregular; smooth; hyaline in KOH; walls about 1 µm thick. Hyphae of the volva 2–10 µm wide; smooth; hyaline in KOH; thin-walled; occasionally branching. Clamp connections not found.

Pseudocolus fusiformis Look-Alikes

1. Clathrus archeri

   4–8 red arms that usually separate at the top and fold backward.

2. Clathrus columnatus

   Can look very similar but features a consistently arched apex and arms that arise individually out of the basal volva, rather than from a stem structure.

Pseudocolus fusiformis Taxonomy

The first appearance of this species in the literature was in 1890, under the name Colus fusiformis, when Eduard Fischer wrote a description based on a painting he found in the Paris Museum of Natural History. In his 1944 monograph on the Gasteromycetes of Australia and New Zealand, Gordon Herriot Cunningham considered this naming to be a nomen nudum—not published with an adequate description.

However, it was valid under the rules of the International Code of Botanical Nomenclature. In 1899 Penzig described the species Colus javanicus based on a single specimen found on Java, and a year later Fischer amended the name of his original Colus fusiformis to Colus javanicus, as he was not satisfied with the quality of his original description. Despite his doubts on the validity of his description, his original naming is both legitimate and has priority over C. javanicus.

In 1907, Curtis Gates Lloyd described the new genus Pseudocolus, and reduced several species to synonyms of Pseudocolus fusiformis.

The first North American description of this species (as Colus schellenbergiae) was in 1916 by David Ross Sumstine; Johnson later (1929) transferred this to Pseudocollus schellenbergiae. Although Cunningham (1931) revised the genus Anthurus to include members of Pseudocolus, Dring in 1973 considered the genera to be distinct. Up until the appearance of an extensive study published in 1980, 13 different binomials had been used in the literature to name the species.

Sources:

Photo 1 - Author: Katja Schulz from Washington, D. C., USA (Creative Commons Attribution 2.0 Generic)

Photo 2 - Author: Jon (watchcat) (Creative Commons Attribution-Share Alike 3.0 Unported)

Photo 3 - Author: Whitney Curran (FungiWACii) (Creative Commons Attribution-Share Alike 3.0 Unported)