Threatened and Uncommon Fungi of New Zealand
Peter Buchanan, Peter Johnston, Shaun Pennycook, Eric McKenzie, and Ross Beever, New Zealand Fungal Herbarium (PDD), Landcare Research, Auckland
These pages present the document submitted in May 2002 to the Biodiversity Recovery Unit, Department of Conservation on rare fungi, by the members of the Expert Panel on Fungi, towards the preparation of the New Zealand Threat Classification Systems Lists.
Fungi - a special case
For New Zealand, as elsewhere, fungi are a special case when it comes to determining rarity and threatened status. The 'fungi' are a mega-diverse group spanning three kingdoms. Most belong in Kingdom Fungi, and others are classified in Kingdoms Protozoa and Chromista.
Fungi have, until now, been largely neglected from conservation considerations in New Zealand. Yet they are the second most biodiverse group of New Zealand organisms, behind the arthropods. New Zealand contains an estimated 20,000 species, of which only about 30% (6,500 spp.) have been recorded to date. In addition, fungi have a high ecological importance, controlling many of the most basic ecosystem processes, such as nutrient recycling. In several countries (e.g., in Europe), red data lists include hundreds of fungal names, mainly threatened macro-fungi.
For fungi, what is an individual?
Rarity is measured, in part, by the number of known individuals. Unlike plants and animals, the vegetative structure of most fungi is invisible to the naked eye because its elements are individually microscopic and occupy the substrate (plant, animal, or mineral) from which they derive nutrients. Presence of a fungus is most often assessed by visual observation of the reproductive structure only - this is particularly obvious for mushrooms and other macro-fungi, but also applies to the aggregated microscopic reproductive structures of most mould fungi. According to the definition of 'Mature individuals' in the Appendix of 'Classifying species according to threat of extinction' (Molloy et al. 2001), a reproducing unit (e.g., a fungal fruiting body) will be classed as an individual within a clone. However, that fruiting body is unlikely to survive independently of its associated mycelium. In reality, a single individual fungus may occupy less than 1 mm3 or as much as the soil volume below several hundred hectares of forest. The latter reflects the largest organism recorded globally, a North American species of mushroom in the genus Armillaria; documentation of the dimension of this individual required molecular analyses.
For the same reasons that a fungal individual is difficult to define, so too are fungal populations. Such assessment will often require molecular analysis.
Numbers of collections and assessment of rarity
Many records of fungi are supported by few collections. There are over 2,500 fungal species recorded in New Zealand that are known from fewer than four collections in the New Zealand Fungal Herbarium (Herb. PDD, Landcare Research, Auckland); of these, over 1,500 are known from a single collection.
Those species considered to be 'Nationally Critical' (50 species) are listed. Links from the 'Nationally Critical' page provide background information on six of these species. Note that the category of 'Nationally Critical' has been reserved mainly for fungi with large, easily collected, and distinctive fruiting bodies, hence excluding most micro-fungi. This bias reflects the limitations of current knowledge of micro-fungi.
A majority of the 'little-known' fungal taxa (over 1,200 species) are currently considered to be 'Data deficient' (Appendix 2). We have not allocated any other intermediate threat categories for fungi. Distribution is often inadequately known. As a crude measure of known distribution, we include include annotations for most species of their occurrence in either one or more-than-one regional districts (districts follow Crosby et al. 1998: Area codes for recording specimen localities in the New Zealand subregion. New Zealand Journal of Zoology 25: 175-183).
In addition, for over 200 species that have been described from New Zealand type specimens, there are no specimens in Herb. PDD. Most of these are listed separately (Appendix 3) and can be considered as 'data deficient', although a minority are known to be rare and have been included in Appendix 2. No attempt has been made to list the approximately 1500 species reported from New Zealand in the literature, but described intially from other countries, and not represented in Herb. PDD.
The extreme diversity of fungi make them a difficult group to handle in terms of understanding rarity. The attached lists have been derived primarily from the New Zealand Fungal Herbarium collection database. How reliable is this data? Appendix 4 contains a case study based on the family Rhytismataceae, one of the most intensively studied groups of fungi for New Zealand.
Lichenised fungi have not been included in our assessments.
Fungi restricted to rare plants
From the 396 plant species on the rare plant list received from DoC (supplied by Rod Hitchmough, 13 May 2002), Herb. PDD has 163 associated fungal collections, representing 64 species of fungi. Most of these fungi are found also on a range of other hosts, often as pathogens. Several of the fungi in this list are undescribed species, a group not considered in the other 'rare fungi' lists compiled from herbarium data and the literature. We list the potentially rare species of fungi on rare plants.
The most striking observation from collating the fungal species associated with rare plants was the lack of data. Most plants on the DoC list had no fungi reported from them. This represents a serious lack of understanding of New Zealand's rare plants, in terms of both the host-specialised fungal species likely to be associated with many of them, and the potential threats to these plants through attack by pathogens.
Globally Critical Species and Habitats
New Zealand is considered to be a centre of diversity of global significance for certain genera and ecological groups of fungi. For example, the ectomycorrhizal truffleoid genus Thaxterogaster is especially diverse in this country. Sooty mould fungi are also particularly diverse and conspicuous in New Zealand. Although they are not included in the attached lists because there is as yet no sensible way to assess their rarity on a local scale, conservation of these fungi within New Zealand is of global significance.
Habitat preservation is a key to fungal conservation. While all indigenous forest types are vital for biodiversity of indigenous fungi, additional habitats of critical importance to fungi include wetlands (e.g., for smut fungi on grasses and sedges), sand dunes (e.g., for sand-inhabiting discomycetes and agarics), and thermal regions (e.g., for specialised mycorrhizal fungi on thermal-tolerant plants).
Appendix 1. Six Examples of Rare Fungi, all considered to be nationally critical
This appendix contains illustrations and background data about six nationally critical fungal species or groups of fungi: Claustula fischeri, Russula spp., undescribed genus of Trichocomaceae, Ganoderma sp., Polyporus septosporus, and Puccinia embergieriae.
Appendix 2. Census of Rare or Little Known Species of Fungi in New Zealand (For species considered to be 'Nationally Critical' see Table 1)
This appendix has been compiled from the New Zealand Fungal Herbarium (Herb. PDD) collection database. It includes all putatively indigenous species of fungi known from less than 4 collections. Only those collections identified to species level have been included. Several groups of micro-fungi have been excluded, such as the oomycetes, trichomycetes, and yeasts. All species listed in the appendix have been classified as Data Deficient.
Appendix 3. Species described from type specimens collected from New Zealand, but with no specimens held in the New Zealand Fungal Herbarium (Herb. PDD).
Native species described from New Zealand type material, but with no specimens held in Herb. PDD; those species considered likely to be rare have been included in the 'Rare or Little Known Fungi of NZ' table (Appendix 2). Note that species described from New Zealand from exotic host substrates have been excluded.
Appendix 4. What do the numbers mean?
A case study based on the well-studied ascomycete family Rhytismataceae.