Octopus stinkhorn

Clathrus archeri, commonly known as octopus stinkhorn or devil's fingers, is a species of fungus in the family Phallaceae. This species was first described in 1859 in a collection from Tasmania. The species received its current binomial name, Clathrus archeri, in 1980. The fruiting bodies undergo two stages; first it resembles a white egg, and it later hatches into four to six arms, which can reach 10 cm (4 in) in length. The arms are pinkish-red in colour and are covered with a dark-olive spore-bearing gleba. In maturity, the fruiting bodies smell like rotten meat, which attracts flies and other insects to the gleba on the arms to then spread the spores.

Clathrus archeri is edible, but the reception of the taste has been varied. C. archeri's native distribution range is disputed. It is known to be found in Africa, Australia, and New Zealand. The fungus has since been spreading to other continents, such as Europe, North America, and South America. It can potentially be considered an invasive species. C. archeri occurs on a variety of soil types and commonly fruits on mulch and forest litter. It seems to prefer acidic and humid soils.

Taxonomy

Clathrus archeri was first described from a collection from Tasmania in 1859 by Miles Joseph Berkeley. It received its current binomial name, Clathrus archeri, in 1980. The species has 12 recognised synonyms. According to a molecular analysis published in 2006, out of about 40 Phallales species used in the study, C. archeri is most closely related to Aseroe rubra, Clathrus ruber, Laternea triscapa, and Clathrus chrysomycelinus. New Zealand mycologist Jerry Cooper similarly noted in his 2020 notes of the Phallales in New Zealand that "the phylogenetic data do not support the inclusion of this species [Clathrus archeri] in the genus Clathrus". Cooper recommended the use of 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 the '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 to ovoid egg shape, usually 3–4 cm (1.2–1.6 in) tall, with thread-like mycelium at the base. Next, between 4 and 8 pinkish-red arms emerge from the egg. Each arm can grow up to 10 cm (4 in) in length and is coated in spore-bearing gleba on the upper surface which is dark greenish-brown in colour (becoming 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. Like other members of the family Phallaceae, the strong putrid smell of the gleba shows convergent evolution with some angiosperm flowers called sapromyophilous flowers. Sisson (2023) notes the peak season of the fungus in New Zealand is from October to June.

The species, Aseroe rubra, is sometimes confused with C. archeri. It differs from Aseroe rubra in its larger size and the presence of gleba along the arms; in Aseroe rubra, the gleba is confined to the central area. Clathrus 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 in 26 °C (79 °F) on a compost agar medium with a pH of 6.0. Under these conditions, the thallus grew up to 2.9 mm (1⁄8 in) a day over four weeks and in a radial shape. C. archeri produces white mycelium and eventually turns a pink colour. On the surface of the hyphae, calcium oxalate crystals are secreted. It is hypothesised that this outer layer of crystals creates a protective hydrophobic layer around the hyphae.

Edibility

The fungus is edible and nonpoisonous. American mycologist David Arora recounts trying to eat the young eggs, which are contained in a gelatinous layer of spore mucilage that left an aftertaste for hours. Arora says the flavour "wasn't bad" and described the texture as "slippery". Another source from 2001 says that the fungus is edible in its young stage, but the smell and taste is unpleasant.

Distribution and habitat

Distribution

Clathrus archeri's native distribution range is disputed. Pietras et al. (2021) and Johnson & Jürgens (2010) list that Africa, Australia, and New Zealand are the native distribution areas. New Zealand mycologist Jerry Cooper said that the species was introduced to New Zealand from Australia, and the species in both countries the species was considered uncommon in the 1930s. Cooper also said that "it is quite possible that neither Australia nor New Zealand represent the indigenous range of this species". The fungus has been spreading to other continents, such as Europe and North America, and is potentially considered an invasive species in accordance with the International Union for Conservation of Nature's definition of an invasive species.

The species has been present in Europe since the early 20th century, with the first discovery of the fungus being 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. 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.

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 avoids calcareous soils. In Australia and New Zealand, the fungus has been observed fruiting on woody debris from Eucalyptus and Nothofagus trees. It is also commonly found in urban areas, such as gardens and parks, where it may have spread via transported wood chips and mulch. C. archeri appears to have a preference toward acidic and humid soils.

Ecology

The fruiting bodies of C. archeri use flies and other insects to disperse their spores. They are attracted to the putrid smell of the fungus, described as "rotten meat", and consume the spore-bearing gleba on the arms, which the spores will 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.

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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