Octopus stinkhorn

Clathrus archeri, commonly known as octopus stinkhorn or devil's fingers, is a species of fungus in the family Phallaceae. First described by Miles Joseph Berkeley in 1859 from specimens collected in Tasmania, its current binomial name, Clathrus archeri, was established in 1980.

The fruiting bodies undergo two stages: they first resemble white eggs from which four to eight arms later emerge, reaching up to 10 cm (4 in) in length. The arms are pinkish-red in colour and covered in a gelatinous, dark-olive mass of spores called gleba. In maturity, the fruiting bodies smell like rotten meat, attracting flies and other insects that feed on the gleba and spread the spores. Clathrus archeri is edible, but accounts of its taste vary.

Although the native range of C. archeri is disputed, it is found in Africa, Australia, and New Zealand, and has since spread to Europe, North America, and South America, potentially qualifying it as an invasive species. C. archeri occurs on a variety of soil types, but prefers acidic and humid soils, and commonly fruits on mulch and forest litter.

Taxonomy

Clathrus archeri was first described in 1859 by Miles Joseph Berkeley from specimens collected in Tasmania. It received its current binomial name, Clathrus archeri, in 1980. The species has 12 recognised synonyms. A 2006 molecular analysis of about 40 Phallales species found that C. archeri belongs to a clade containing Aseroe rubra, Clathrus ruber, Laternea triscapa, and Clathrus chrysomycelinus. New Zealand mycologist Jerry Cooper noted in 2020 that "the phylogenetic data do not support the inclusion of this species [Clathrus archeri] in the genus Clathrus", instead recommending the name Anthurus archeri.

Etymology

The genus name Clathrus is derived from Ancient Greek κλειθρον, meaning 'lattice'. The specific epithet, archeri, is named in honour of the Australian architect William Archer. The species is commonly known as the 'devil's fingers' or 'octopus stinkhorn'. Other sources also refer to the fungus as the 'devil's mushroom', 'cuttlefish stinkhorn', 'stinkopus' or 'squidward mushroom'.

Description

Clathrus archeri grows in two distinct stages, first an egg stage followed by the fungal arms emerging. In the first stage, it forms a white, spherical, ovoid, or egg-shaped structure, usually 3–4 cm (1.2–1.6 in) tall, with thread-like mycelium at the base. Next, between four and eight pinkish-red arms emerge from the egg. Each arm can grow up to 10 cm (4 in) in length, and their upper surfaces are coated in dark greenish-brown, spore-bearing gleba that becomes black when dry. Fruiting bodies have a lifespan of a day or two. The spores are elliptical, smooth, and 3.5–6 × 1.5–2 μm in size. Sisson (2023) notes the peak season of the fungus in New Zealand is from October to June.

Clathrus archeri is sometimes confused with the species Aseroe rubra. It differs from A. rubra in its larger size and the presence of gleba along the arms; in A. rubra, the gleba is confined to the central area. C. archeri also generally has thick, unfused arms, although the tips are sometimes fused before maturity.

In laboratory settings, C. archeri was found to grow best at 26 °C (79 °F) on a compost agar medium with a pH of 6.0. Under these conditions, the thallus grew at a radial rate of up to 2.9 mm (0.11 in) per day over a period of four weeks. C. archeri produces white mycelium which eventually turns pink. The surface of the hyphae secretes calcium oxalate crystals, which are hypothesised to create a protective hydrophobic layer around the hyphae.

Edibility

Some authors regard C. archeri as inedible, but others consider the fungus edible and have experimented with eating the fungus in its young stage. American mycologist David Arora recounts that the young eggs, which are contained in a gelatinous layer of spore mucilage, left an aftertaste for hours. Arora says the flavour "wasn't bad" and describes the texture as "slippery". Another source from 2001 says that the fungus is edible in its young stage but that the smell and taste are unpleasant.

Distribution and habitat

Distribution

The native distribution range of Clathrus archeri is disputed. Johnson & Jürgens (2010) list Africa and Australasia as the species' native range, while Pietras et al. (2021) and consider the species native only to Australia and New Zealand. New Zealand mycologist Jerry Cooper claims that the species was introduced to New Zealand from Australia and that it was considered uncommon in both countries in the 1930s. Cooper also writes that "it is quite possible that neither Australia or New Zealand represent the indigenous range of this species".

The species has been present in Europe since the early 20th century, after first being discovered in 1914 in Britain and France. The fungus was presumably introduced to Europe from Australian wool imports or in supplies for World War I. It initially spread from France to Belgium, and later to Austria, Germany, Switzerland, and Italy; more recently, C. archeri has been recorded in Bosnia and Herzegovina, Czechia, Croatia, Poland, Slovenia, Romania, and Ukraine. The fungus has also been recorded in South America and Madagascar. In regions outside its native range, C. archeri is considered potentially invasive as defined by the International Union for Conservation of Nature, but its impacts on native ecosystems are unknown.

Habitat

As a saprotroph, C. archeri decays dead organic material. C. archeri occurs on a variety of soil types and commonly fruits on mulch and forest litter, but does not grow in calcareous soils. In Australia and New Zealand, the fungus has been observed fruiting on woody debris from Eucalyptus and Nothofagus trees. C. archeri appears to have a preference toward acidic and humid soils. C. archeri is commonly found in urban areas, such as gardens and parks, where it may have spread via transported wood chips and mulch.

Ecology

The fruiting bodies of C. archeri use flies and other insects to disperse their spores. These insects are attracted to the putrid smell of the fungus, described as "rotten meat" by Piętka, Byk & Byk (2021) and other authors, and consume the spore-bearing gleba on the arms. The spores later germinate after being excreted by the insects. Johnson & Jürgens (2010) reported insects from three families as visitors to C. archeri: Calliphoridae, Muscidae, and Sarcophagidae. The strategy of attracting flies by mimicking the smell of carrion is referred to as sapromyiophily and is shared by other members of the family Phallaceae. Multiple lineages of flowering plants have independently evolved the same strategy to attract pollinators, an example of convergent evolution across taxonomic kingdoms.

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External links

• Media related to Clathrus archeri at Wikimedia Commons
• Clathrus archeri discussed on RNZ Critter of the Week, 17 March 2023