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Hypocreopsis amplectens T.W. May & P.R. Johnst.

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Scientific name
Hypocreopsis amplectens
Author
T.W. May & P.R. Johnst.
Common names
Tea-tree Fingers
IUCN Specialist Group
Cup-fungi, Truffles and Allies
Kingdom
Fungi
Phylum
Ascomycota
Class
Sordariomycetes
Order
Hypocreales
Family
Hypocreaceae
Assessment status
Published
Assessment date
2019-07-26
IUCN Red List Category
CR
IUCN Red List Criteria
C2a(i)
Assessors
Buchanan, P. & May, T.
Reviewers
Dahlberg, A. & Minter, D.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/80188449/185681031

Justification

Hypocreopsis amplectens is an extremely rare endemic fungus in southeastern Australia and the south Island of New Zealand. It is probably a myco-parasite on fruit-bodies of Hymenochaete, growing on dead fine wood mainly of Myrtaceae in forests with an understorey of myrtaceous shrubs. Despite intense survey effort for this readily recognisable and persistent fungus for more than 30 years, it has only ever been seen at seven sites, at some of which it no longer can be found. It is currently estimated to be present at no more than 10 sites with no more than maximum 42 mycelial individuals at each site. The population size is estimated to range between 50-400 mature individuals with the most likely number 200. The sites are highly fragmented as they are located 10-100 km from each other in highly cleared landscapes. Therefore, sites are here considered as equal to sub-populations.

There is continuing significant disturbance and/or land clearing that is expected to impact on population numbers. Nyora in Victoria is a good example as there is motor bike riding and horse riding that is widening trails adjacent to the known site, and sand mining around all boundaries of the reserve that is totally removing native vegetation and potentially affecting the water table. Overall we consider an ongoing habitat decline in area and quality with a possible extinction at some previously recorded sites. 

With a small population size, low numbers of individuals in each subpopulation, and ongoing habitat decline resulting in a continuing decline in population size, this fungus is assessed as Critically Endangered C2a(i).



Taxonomic notes

Hypocreopsis amplectens is a distinctive macro-fungus, discovered in the 1990s and formally described in 2007 on the basis of material from Australia and New Zealand. Collections from the two countries are identical morphologically. ITS sequences of the one New Zealand collection and a collection from Australia are identical. First observed in Australia in 1993, at Nyora, and informally known as Hypocreopsis sp. “Nyora” until its formal description.

Geographic range

Hypocreopsis amplectens is endemic to Australia (Victoria and northeast New South Wales) and New Zealand (South Island).

In Victoria, Hypocreopsis amplectens has been observed at four known sites in close proximity to the east and south-east of Melbourne. The specific sites are Wanderslore (Yarra Valley), Greens Bush (Mornington Peninsula) and two sites in West Gippsland: Adams Creek Nature Conservation Reserve (near Nyora) and Grantville. It has been a target species of the Fungimap fungi mapping scheme since 1999. In that time, only 13 records have been submitted to Fungimap, making it one of the least recorded of the 100 target species (frequently recorded species have more than 1,000 records). In total, including other data such as herbarium specimens, there are 17 separate records of Hypocreopsis amplectens from Victoria from the four sites, over the period 1992 to 2018. At Green Bush several surveys in recent years have failed to locate fruit-bodies.

In New South Wales, there is a single Fungimap record that is an observation from the New England area in northern New South Wales, accompanied by a photograph. From the photograph, this is certainly a member of the genus Hypocreopsis, and quite similar in appearance to Hypocreopsis amplectens, but there is no voucher collection. On balance, given that the species does occur also in New Zealand, this occurrence is accepted. Three years after the original record the observer re-visited the site and could not locate the species.

In New Zealand it is known from only two sites 100 km apart. (1) Klondyke Corner, Arthur's Pass, Canterbury, where known from only one specimen collected there in 1983. The Reserve is readily accessible from the highway and is a well-known site to visit for mycologists. This and similar forests in New Zealand have been intensively sampled for many years for Hypocreales, without locating further material. (2) Waterfall Track, Hanmer Springs (verified photo by Mike Pilkington). This site is frequented by mycologists and has specifically been re-visited by mycologists searching for this species several times in recent years and not re-found.

Population and Trends

Overall this is an extremely rare fungus with a highly fragmented distribution across the known range.

The species has in total been recorded from seven sites (see Geographic Range). Taking into account the distinctive and long-lasting fruitbodies and high survey effort and that it has not been re-found at three sites in recent one to several decades, we take a precautionary approach and estimate that the total number of sites is unlikely to exceed ten. Known occurrences are often rather specific microhabitats characterized by upright or partially fallen, dead branches of myrtaceous plants along with swamps and streams nearby. This particular habitat specificity may account for its rarity.

Each substrate unit (i.e. piece of wood) is considered to support a single mature individual, even when there is more than one fruit-body present. Recording so far has not counted substrate units, only fruit-bodies. However, many of the fruit-bodies are single, and so counts of fruit-bodies more or less match counts of individuals.

Some 44 mature individuals have been recorded ranging from 1 to 21 per site, with 41 mature individuals recorded from Victoria. In that state, intensive surveys at Wanderslore have located 21 fruit-bodies. At Nyora, at any one time, there have only been in the order of 10 fruit-bodies. At Grantville, at any one time there have only been in the order of 5 fruit-bodies. At Green's Bush, there have been no more than 5 fruit-bodies. At the site in New South Wales one functional individual has been recorded and at the two sites in New Zealand two functional individuals have been recorded. It is noted that not all fruit-bodies are necessarily mature, as some may be immature (not showing ostioles) or overmature (decayed and no longer releasing spores), and therefore the counts of mature individuals inferred from fruit-bodies provide a maximum estimate.  

Given the previously stated estimate of ten sites in total (i.e. three undiscovered sites) but also taking into account that the species may be extinct at some sites, we infer a minimum of 50 mature individuals globally. Overall, the number of mature individuals is estimated to be in the range from 50 to 400 with the most likely estimate around 200. 

The number of individuals in the largest subpopulation (Wanderslore) is estimated as 21-42.

There are three areas each separated by more than 800 km; New Zealand, Victoria and New South Wales in Australia. The known sites in Victoria are highly fragmented with each site being a small reserve in a matrix of largely cleared vegetation separated by up to (10-)20-50 km. In New Zealand, the area between the two known sites (> 100 km) is almost entirely cleared of native vegetation. We suspect the undetected sites to occur somewhat randomly within the overall range. Overall, we can consider sites largely as equivalent to sub-populations in the sense of IUCN.

Habitat in some known sites is well conserved (such as at New England), but at others there is continuing significant disturbance and or land clearing that could reasonably be expected to impact on population numbers. For example, at Nyora, there is motor bike riding and horse riding that is widening trails adjacent to the known site, and sand mining around all boundaries of the reserve that is totally removing native vegetation and potentially affecting the water table. At Hanmer Springs, there is invasion of native vegetation by pine trees. Therefore, we consider an ongoing habitat decline in area and quality. In addition we note that it is possible that the fungus is extinct at some sites previously recorded.

Population Trend: decreasing


Habitat and Ecology

Hypocreopsis amplectens forms fruit-bodies on wood but is most likely to be a myco-parasite rather than a saprobe. Fruit-bodies are often overlying or near fruit-bodies of Hymenochaete, which is a resupinate fungus, and it is assumed at present that Hymenochaete is the host. The identity of the Hymenochaete is not known, and nor is it known if there is one or more species of Hymenochaete associated with Hypocreopsis amplectens. Reproduction is by spores. There are no known resting stages (such as sclerotia) and therefore establishment of new individuals is presumably from spores. Spores are not thick-walled or darkly pigmented, and so are assumed not to survive fire.

Generation length is inferred as around seven years as follows: For wood-decay fungi, Dahlberg and Mueller (2011) suggest a 20-50 year span for 3 generations. The span is based on the time taken for the substrate to decay. Given that Hypocreopsis amplectens occurs only on small diameter of wood, we take the lower value.

In Australia, this species occurs in heathy woodlands or forests on dead wood that is mostly standing or partially fallen (rather than lying close to the ground), in relatively long unburnt sites, not burnt for 30 years or more. Host plants include Leptospermum myrsinoides, L. continentale, Melaleuca squarrosa, Banksia marginata and Kunzea leptospermoides - with the Hypocreopsis frequently associated with a species of the fungus Hymenochaete, which is assumed to be the host of the Hypocreopsis. Several observations note that fruit-bodies are in ‘sheltered’ or ‘shady’ areas, but it is also recorded from more open areas.

In New Zealand, the single specimen collected (in 1983) was from a forest reserve on bark of native silver beech (Fuscospora cliffortioides). Kunzea is present in the site. Beech forests are widespread in upland areas of New Zealand. A fungal host was not observed in the New Zealand specimen.

Threats

For the Australian populations, fire is a significant threat, especially repeated fires at short intervals. Due to the occurrence on standing, dead wood of relatively small diameter (about 5-10 cm), the entire substrate could be consumed by fire. It is not known how Hypocreopsis amplectens re-colonizes after fire, but it is assumed to be from unburnt populations as spores are not expected to survive fire. Because it is a myco-parasite, re-establishment after fire also requires re-establishment of the presumed host (Hymenochaete sp.). There has been a recent (February 2019) wildfire at Grantville, that did not burn the area where Hypocreopsis occurs, but indicates the real threat of wildfires.

Land clearing is a significant threat. Immediately adjacent to the type locality in the Adams Creek Nature Conservation Reserve, sand mining, which completely removes the native vegetation, is being actively carried out. Since the discovery of the species in the 1990s a new sand mine, occupying an area of about 50 hectares has been established.

Climate change is a potential threat, through increasing the intensity and frequency of fires, and also increased temperatures. Because Hypocreopsis ameplectens forms fruit-bodies on aerial substrates, of relatively low diameter, it is particularly exposed to higher temperatures.

For the New Zealand occurrence in North Canterbury, the forest reserve where the single known New Zealand specimen was collected is a secure alpine habitat, next to highway access, but unlikely to be affected by fire (relatively high rainfall) or land subsidence. However, the area is under significant threat from invasive pines.

Conservation Actions

The known sites are all in areas managed for nature conservation. The Adams Creek Nature Conservation Reserve was preserved in the first place partially on the basis of the occurrence of Hypocreopsis amplectens. There is a very active survey programme for the species being carried out by Fungimap, including visiting known and potential sites, and photo-monitoring of known individuals.

However, there is no active management of Hypocreopsis amplectens in the reserves where it occurs, apart from avoiding controlled fire at the Adams Creek site.
It would be beneficial for the long term survival of this species if an ex-situ population could be established.

Further research needed, includes carrying out targeted surveys in suitable habitat. The existing populations need monitoring, especially response to fire. Identification of the host fungus is also required. For the New Zealand specimen, that is without obvious presence of a fungal host, DNA sequences from surrounding tissue may give an indication of host species. Identification of the host could potentially then be used to search for additional records of H. amplectans associated with specimens of the possible host.

Use and Trade

The species is not utilized.

Source and Citation

Buchanan, P. & May, T. 2019. Hypocreopsis amplectens. The IUCN Red List of Threatened Species 2019: e.T80188449A185681031. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T80188449A185681031.en .Downloaded on 30 January 2021

Country occurrence