Calvatia boninensis

A large puffball from the Bonin Islands

Calvatia boninensis is a puffball, a fungus whose spores develop inside a closed fruit body instead of on gills under an open cap. The original 1939 description by S. Ito and S. Imai gives a large, ovoid to head-shaped fruit body up to about 14 cm across, with a broad sterile base shaped like an inverted cone, a very thin outer skin that is nearly smooth and wrinkles at the base, and brown tones. Inside, a spongy sterile layer called the subgleba can be separated from the darker spore-bearing gleba. The spores are ellipsoid to oblong and finely roughened.

A later Chiba taxonomic account gives a wider size range, 50 to 160 mm high and 30 to 170 mm broad. It describes a thin papery outer layer that darkens and sloughs away, a shiny inner layer that breaks into fragments, a gleba that is white when young and becomes ochre with age, and a well-developed spongy base. The same account separates the species from the similar Calvatia craniiformis by spore shape: ellipsoid to cylindrical spores here, globose to subglobose in that species. Field identification is difficult for that reason, because the two can look alike before the spores are examined.

A name with a disputed edge

Calvatia boninensis S. Ito & S. Imai is an accepted name in the Species Fungorum and GBIF backbone records. Global databases place the genus in the Lycoperdaceae, while the 2026 Chinese edible-fungi catalogue uses the Agaricaceae for the family section that contains the entry. The original paper records that an earlier Japanese collection had been treated as Calvatia craniiformis var. gardneri. Current nomenclature routes that variety to C. gardneri, not to C. boninensis, so the names should not be merged.

The Japanese, Chinese and Thai names do not settle the identity. The Thai popular page that carries a local name gives spore characters that conflict with the primary taxonomic description, so its identification cannot be taken as proof for the Ogasawara taxon.

Where it grows, and where the records disagree

The species is terrestrial and grows in woodland on rich soil or humus. Its genus is saprotrophic, feeding on dead organic matter, and no particular host tree is documented for it. The Kyoto Prefecture Red Data Book describes growth on leaf litter and humus at several central and western Japanese sites.

The strongest verified records come from the Ogasawara Islands. A 2018 National Museum of Nature and Science survey reports 64 voucher specimens from Chichi-jima, Haha-jima and Ani-jima, with collection sites and dates. Its authors treat the species as a candidate Ogasawara endemic. Earlier Japanese literature reported it from Honshu, but those authors noted differences in mainland specimens and did not accept those records as conspecific. The 2006 Chiba paper, by contrast, cites reports across tropical, subtropical and warm-temperate eastern Asia. These accounts disagree, and the reported range should not be presented as settled.

Chinese observations filed under the name on iNaturalist are community identifications, some marked research grade on a single identification. They are leads for the range question, not confirmed records.

Season

The original type was collected on 5 November 1936. The 2018 Ogasawara survey lists fruiting bodies collected from May through November, including June and July collections on Chichi-jima and Ani-jima and November collections on Chichi-jima and Haha-jima. These are collection dates from a voucher list, not a controlled study of fruiting. The Kyoto Red Data Book gives July to October for its mainland records, whose identity the 2018 authors dispute. The sources support a range from spring to late autumn in the Ogasawara specimens and do not establish a narrower or universal season.

Food use: listed as edible, not tested

The 2026 Chinese catalogue lists the species as edible, and a 2019 review of edible and medicinal mushrooms in China marks it edible on the strength of older Chinese and Japanese references. Those are classifications in food catalogues. Neither records a preparation, a cooking method or a tested safety result for this species.

Thai local accounts under the name เห็ดตาปู้ describe eating the young mushroom, sometimes in a curry. A 2023 field survey at Ubon Ratchathani University says that a Thai handbook lists young specimens as edible, but the people it interviewed locally did not eat it. The accounts are anecdotal, and no species-specific toxicology or clinical assessment was found in the sources consulted. No medicinal use is established for this species.

Safety and look-alikes

Nothing on this page is an instruction to collect, identify or eat this fungus. The sources give no species-specific safety verdict. A food listing or a local account does not establish that a wild specimen is safe, and a white interior, cooking or a picture does not prove identity or safety.

Puffball-like fruit bodies can be confused with the young button stage of Amanita species,. The Michigan State University Extension warning and the U.S. Food and Drug Administration's Bad Bug Book both note this risk for the wider group. Those are general warnings and do not describe this species. Calvatia boninensis is separated from C. craniiformis by its spores, which requires microscopic examination.