This is a distinctive saprobic agaric which would not readily be overlooked and yet is known to exist from a relatively small number or records since its first description in 1983. The existing records suggest a significantly fragmented yet sparse population that is widely distributed in natural old growth broadleaf temperate forest (New Zealand and Queensland) and Eucalyptus forest (Western Australia). Whether the widely separated sub-populations in New Zealand, Eastern Australia and South Western Australia represent a single taxon has yet to be confirmed. Both the macro characters and host preferences suggest strongly that there may be more than one taxon here.
The substantial loss of old growth forests in Australia has greatly reduced the habitat for this group of saprobic fungi. Changing climatic conditions with lengthening drought periods and rising temperatures may put stresses on these fungi which inhabit damp logs. There is also an increased risk of fire with extended droughts. These conditions leave this species at significant risk from stochastic events.
We estimate that the generation length for Pluteus might be of the order of 30 years and that all 43 records of this species made should be taken in to consideration in calculating a population. We think that it would be reasonable to estimate that there are 5 mature individuals for each functional individual. There are currently between 8 and 10 distinct localities for this species. Given its apparent broad spectrum of habitats it might be expected that there would be possibly 3-5 times more sites yet to be discovered. The population of mature individuals probably exceed 250 but is less than 1000. The area of occupancy may exceed 500 kms ² but wilikely to be less than 1000 km². On this basis we propose Pluteus pauperculus should be classified as “vulnerable” under B2b and D1.
The original description by E. Horak (1983) is from specimens from New Zealand, New South Wales and Western Australia (holotype specimen). Later collections from Queensland taxonomically matched the original description but appear more robust in character.
Horak (1983) originally described specimens from New Zealand and Western Australia as Pluteus flammipes var depauperata. He suggests that typical specimens of P flammipes are recognised by a brilliant orange to red-orange colour at the base of the stipe and at the margin of the lamellae.
Microscopically, the species is distinguished by slender fusoid cheilocystidia and pleurocystidia filled with yellow (KOH) plasmatic pigment.
P. flammipes is confined to southern South America where it occurs on rotten wood and debris of Nothofagus (N dombeyi) and also, rarely on Austrocedrus. The Australiasian variety is restricted to Australia and New Zealand. The host plant of the New Zealand and New South Wales material is Nothofagus(N. mooreii, N. menziesii and N. solandri). However the specimens reported from Western Australia were growing on Eucalyptus (E. calophylla,E. diversicolor).
Guard and Leonard ( 2015) description of Queensland specimens:
Cap: parabolic to convex; 12– 45 (80) mm diameter; matt, finely granulose at apex and upper portion, smooth below, venose, that is the granules form vein like patterns; yellow to golden yellow overlain with hazel brown granules that are darker on apex.
Stipe: cylindrical to flattened and twisted in some fruit bodies, +/- sub bulbous at base; 25 – 50 × 4 – 8 mm; glabrous to minutely fibrillose; very pale lemon to golden yellow.
Gills: free; crowded, broad; yellow becoming golden yellow then pinkish; lamellulae 4-5 tiers present.
Flesh: pale yellow to slightly brownish in older specimens, very thin.
Spore print: dark pink.
Spores: ellipsoid; 5.3 – 6.4 × 4.4 – 5.9 µm, average 5.9 ± 0.35 × 5 ± 0.35 µm, Q = 1.03 – 1.38, average Q = 1.19 ±0.12; inamyloid; somewhat thick walled.
Basidia: narrowly clavate to fusiod; 25 – 30 × 5 – 8 µm; four spored.
Pleurocystidia: clavate to langeniform; 50 – 95 × 12.5 – 24 µm, hyaline and thin walled. Cheilocystidia similar.
Pileipellis: a trichoderm made up of clavate, pale brown cells overlaying a subpellis of repent hyphae on the upper half of the cap, the clavate cells appear to be absent in the lower 1/3rd of the cap.
Substrate: on base of a large old well rotted log of Ligustrum lucidum. (Broad leafed privet).
Habitat: rainforest under restoration.
Notes: this collection matches Horak’s Pluteus pauperculus in almost all its characters, except that it is considerably more robust than the New Zealand and Western Australian collections on which the species is based. Note that the species was originally named P. flammipes var depauperatus.
There are several endemic Pluteus species in Australia that are found in both wet sclerophyll and humid forests. Pluteus pauperculus was formally described in 1983 and renamed in 2000. Horak suggests that it is readily recognized because of its dark yellow brown cap and slender yellowish stipe with red at the base. It was described from New Zealand and New South Wales. In the two decades that have passed since its description mycologists have recorded it from New Zealand to Western Australia. It is not however certain that this is a single uniform species. We this fungus species forward tentatively, recognizing that further taxonomic work may reveal a complex of species here.
Pluteus pauperculus has been recorded in New Zealand (North and South Island) and Australia (New South Wales, Queensland, Tasmania, Victoria and Western Australia).
Known occurrences described in Global Biodiversity Information Facility and the Atlas of Living Australia:
North Island 2 records
South Island 3 records
New South Wales 1 record
Queensland 5 records
Tasmania 4 records
Victoria 9 records
Western Australia 16 records
Pluteus pauperculus is a saprotrophic fungus that has been found on rotting wood, logs and stumps in the broadleaf temperate forests of New Zealand and Eastern Australia and in the Eucalyptus forests of Southwestern Australia.
. The original description by E. Horak (1983) describes specimens on rotten wood in NSW and New Zealand (Nothofagus moorei and N. menziesii and N. solandri) and in Western Australia on Eucalyptus (E calophylla and E diversicolor). Records describing associated wood are sparse but P. pauperculus has been described in broadleaf podocarp forest and one record notes a growth on rotting Puriri (Vitex lucent) wood.
All reported specimens are from non-developed (natural) areas.
No specific threats can be attested yet the significantly fragmented population with sparse records of specimens existing in natural (non-urbanised) areas demonstrates significant risk from stochastic events.
Known threats to the regions where P. pauperculus occurs are:
The southwest of Western Australia is a biodiversity hotspot with habitat reduction occurring historically from agricultural modification, logging and urbanization (Burbidge, 2010). Fire is an expected future threat due to the increasingly dry periods experienced in this area (Mockrin, 2019).
Fire from forestry practice and adjacent landowners is a recognised threat to fire sensitive species in Mapleton National Park and presumably to saprobic fungi that require old growth. Fortunately the region of the park where P pauperculus has been collected has reportedly remained fire free since 1923. Pest incursion from non-native plants (Lantana camara, Morning Glory (Ipomoea circa) and silver leaf desmodium (Desmodium uncinatum) can occur to a distance of 50 meters from tracks (Queensland Government, 2013).
Large areas of temperate forest are protected from logging. Climate change may increase the risk of fires.
Historically Tasmania’s forests have been extensively impacted through land clearance, logging and the effects of invasive species.
There are no conservation actions to protect Pluteus pauperculus and by legislative default all unclassified species are considered by the Queensland Government as of “Least Concern”.
There is a requirement for the conservation of habitat (including old growth substrate) from urban, commercial and agricultural incursion.
Research is required to determine the extent and population size of this species along with population trends and biotic and abiotic threats. Further exploration of the biology of this saprobic fungus including the ecological significance of its mycelial network, habitat preferences, longevity and fruiting patterns is required.
Burbidge, A., 2010. Global hotspot under stress: while the south-west corner of Western Australia is recognised as a global biodiversity hotspot, its unique ecosystems have suffered land clearing, introduced pests and weeds, a changed fire regime, loss of water and salinisation. climate change may tip the balance for some species, unless effective action is taken. - Free Online Library. Eco 153, 2.
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GeoCAT Editor- [WWW Document], 2019. URL http://geocat.kew.org/editor (accessed 5.22.19).
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Queensland Government, 2013. Mapleton National Park and Mapleton National Park (Recovery) Management Statement 2013.