New Zealand endemic, described in 1924 based on a specimen from 1921, and not collected again on mainland New Zealand. Recorded on Stewart Is. and subantarctic Auckland Is. 2000-2006.
6 New Zealand collections, only one (the 1921 type from Lake Harris, Otago) from mainland NZ. Otherwise known only from Stewart Island and the Subantarctic Islands. Spectacular disease symptoms on leaves. Perhaps quite common in subantarctic Auckland Is.? Climate change a threat?
Subantarctic Auckland Is., Stewart Is., and alpine southern South Island.
Only known from 1 collection on mainland New Zealand, and 5 collections on the subantarctic Auckland Is. Host populations appear not to be limiting as both recorded Veronica species are widespread.
Pathogen of Veronica species (native shrubs). - recorded on V. subalpina (1921 type collection only, on mainland NZ) and on V. elliptica (remaining 5 collections, one on Stewart Is. and 4 on Auckland Is. - 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 Is. While both recorded hosts are widespread, the fungus is only known from 5 collections, 1 on the mainland and 5 on Auckland Is.
[The host V. elliptica was (famously) reported on Disappointment Island, to the west of the remote Auckland Is., as the only source of firewood and wood to construct a boat for 16 survivors from the 1907 wreck of the Dundonald, and for “wooden spoons, wooden hooks, and oars of the crooked veronica elliptica”. On Auckland Is. (1975), it was reported to be “common on the coast. The most salt-tolerant shrub, often found in very exposed coastal sites”]
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.”
While very rare (1 record) on the mainland, the fungus may be quite common on the subantarctic Auckland Is. The main threat therefore is probably climate disruption.
None current, although removal of introduced mammals from Auckland Is. is likely securing the host Veronica.
Check identity of hosts. Is the specimen on V. subalpina (1921 and only mainland specimen of O. callistea - from Lake Harris, Otago Lakes, South 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.
Sydow, H. 1924: Beiträge zur Kenntnis der Pilzflora Neu-Seelands - I. Annales Mycologici 22(3-6): 293-317