Assessment Notes

Justification

Although it is only known from a few specimens, this species is expected to have a population size exceeding 1000 mature individuals, with no significant decline. It is therefore assessed as Least Concern.

---

Taxonomic notes

This is a New Zealand endemic, described in 1924 based on a specimen from 1921, and not collected again on mainland New Zealand. It has been recorded on Stewart Island and subantarctic Auckland Island 2000-2006.

---

Geographic range

This is a New Zealand endemic species which has been recorded from alpine southern South Island (although not since its original collection in 1921), Stewart Island, and the subantarctic Auckland Islands.

---

Population and Trends

Although it is only known from few collections, its host populations appear not to be limiting as both recorded Veronica species are widespread in southern New Zealand including the subantarctic islands. Its population size is likely to exceed 1000 mature individuals, and no significant decline is likely.

Population Trend: Unknown

---

Habitat and Ecology

This species is a pathogen of Veronica species (native shrubs) - it has been recorded on V. subalpina (1921 type collection only, on mainland NZ) and on V. elliptica (remaining five collections, one on Stewart Island and four on Auckland Island - the latter sub-Antarctic). V. subalpina is broadly distributed, occurring in the mountains of Westland and Canterbury, South Island and extending further south into Fiordland. V. elliptica is reported to have a wide distribution on mainland New Zealand - as a coastal shrub from mid-North Island west coast southwards and on the South Island west coast, and on the southern-most east coast of the South Island, as well as occurring on the subantarctic Auckland Island. While both recorded hosts are widespread, the fungus is so far only known from five collections, one on the mainland and five on Auckland Island. 

Leaf symptoms caused by the fungus are dramatic and diagnostic, as described from the 1924 German protologue (Google translation): “The fruiting bodies are formed under the cuticle, which is torn into shreds, often visible for a longer time on the surface of the fruiting bodies, and is probably held in place by the mucus developed by the fungus. The hyaline hypothecium is extremely small-celled plektenchymatisch and rests on a flat base of the epidermis. The spores are surrounded by a hyaline strongly swelling mucus envelope.”

---

Threats

While very rare (one record) on the mainland, the fungus may be quite common on the subantarctic Auckland Is. The main threat therefore may be climate disruption.

---

Conservation Actions

There are no current conservation actions, although removal of introduced mammals from Auckland Is. is probably securing the host Veronica.

Research is needed to check the identity of hosts and to establish whether the specimen on V. subalpina (1921 and only mainland specimen of O. callistea - from Lake Harris, Otago Lakes, South Is.) is the same fungal species as those specimens on V. elliptica from Auckland Islands and Stewart Island. Modern specimens of O. callistea from V. subalpina would assist further knowledge of this species. With such conspicuous disease symptoms and a relatively common plant host, the lack of fungal specimens since 1921 is unexpected.

---

Use and Trade

The species is not utilized.

---

Source and Citation

Buchanan, P. 2019. Orbiliopsis callistea. The IUCN Red List of Threatened Species 2019: e.T154816078A154817244. Accessed on 21 November 2025.

---

• Country occurrence