Pleurotus in New Zealand

There are relatively few species of Pleurotus in New Zealand, although the genus is superficially similar to Hohenbuehelia, Scytinotis, Crepidotus and Conchomyces. The genus Pleurotus was last revised in New Zealand by Segedin (1995, Australian Systematic Botany, v8, pp453-482). However I believe there are a number of issues with that revision that undermine the reliability.

P. purpureo-olivaceous has a dark brown polished caps, a rubbery texture and pale greyish gills. It can be mistaken for Hohenbuehelia species in the petalodes group and so the gills should always be checked, for the absence of the large metuloid cystidia characteristic of Hohenbuehelia (with a hand-lens and preferably microscope). Some darker forms of P. australis can look similar but are not rubbery and the gills are not grey. Phylogenetically P. purpureo-olivaceous is distinct from all other species of Pleurotus (unsurprisingly). The remaining NZ species are rather similar, with cap colours variable from cream to brown (but not dark brown and polished), and a stipe varying from absent to lateral and fruitbodies occurring singly to clustered on wood. They can only reliably be distinguished by micro-characters.

P. djamor is the name given globally to a cluster of phylogenetically related but distinct entities. Some of the cultivated shop versions in this group are yellow, pink or creamy/white. The complex is represented in New Zealand by P. parsonsiae (described by Greta Steveson in 1964), and that name should be used in preference to P. djamor. P. parsonsiae has caps that are brownish. Current sequence data demonstrate the NZ taxon is distinct and identical to some collections from Kenya, whilst the Cook Islands have their own species in the  P. djamor complex Members of the complex always have some skeletal hyphae in the stipe and are consequently rather tough an chewy. By skeletal hyphae I mean hyphae with refractive thickened walls (and with or without clamps). Sometimes the term dimitic is used but perhaps not appropriately. Segedin in her 1995 re-description of P. parsonsiae may not have examined the correct specimen because she did not note the presence of skeletal hyphae. My examination of the type held at Kew clearly demonstrates their presence As a consequence of not observing these hyphae in P. parsonsiae the name P. opuntiae (which also has skeletal hyphae) was applied by Segedin 1995 to the same taxon.  True P. opuntiae  is not present in New Zealand. 

A recent paper (Zervakis et al, 2019, Fungal Biology v123, pp188-199) discusses the P. djamor complex and includes New Zealand taxa. They are  in error regarding their comments on P. parsonisae. The type collection was not studied by the authors and so they accepted erroneous subsequent re-descriptions by Segedin et al 1995 and came to incorrect conclusions about the use of the name P. parsonsiae in New Zealand.

Sequences of verified collections of P. australis from New Zealand are phylogenetically intermixed with collections from Australia and represent the same species in both countries. The cap can become quite dark brown and shiny but the fruitbody is not rubbery and gills not greyish like P. purpureoolivaceous. Some species of Pleurotus produce 'coremia' - a black slimy exudate on the growing caps which consists of asexual spores (conidia). This asexual stage has been referred to the genus Antromycopsis. Pleurotus australis is one of these species and is therefore placed in the subgenus Coremiapleurotus along with P. cystidiatus and P. fuscosquamulosus. In Segedin's 1995 paper the species is assigned to subgenus Pleurotus without coremia and that is clearly incorrect. In addition she places Pleurotus purpureo-olivaceus in subgenus Coremiapleurotus. On phylogenetic grounds that seems doubtful and I have not observed coremia in that species. In my opinion some collections of P. australis and P. purpureo-olivaceous were confused by Segedin, but unfortunately a number of collections mentioned in the paper seem to have been misplaced and cannot be re-examined. It is possible that Stevenson's type collection of P. purpureo-olivaceus is in fact the same as P. australis, which would make the name a later synonym of P. australis, and a new name would be needed for our large purplish species on beech. Of the potentially available names P. rattenburyi is almost certainly a synonym of P. australis and not P. purpureo-olivaceus. To resolve this confusion the type collections of all the relevant species housed at Kew require re-examination (i.e. P. purpureo-olivaceous, P. rattenburyi and P. crawfordiae).

It should be noted that P. parsonsiae, P. australis and P. pulmonarius are all confirmed as occurring on Cabbage Tree (as well as other trees).

P. pulmonarius is yet another species complex with our version clustered with material from Asia. P. pulmonarius forms a distinct clade with P. ostreatus & P. eryngii.

P. velatus was described from New Zealand by Segedin et al as a species possessing a veil. However re-examination of the type indicates no visible veilar remnants (but there are some fragments of a spider's web). The cap is sparsely velutinate in younger frbs but not as a consequence of veilar remnants. The type is the only collection and more collections showing the purported characters are required to validate its recognition. It may just represent a form of P. pulmonarius or P. parsonsiae.Such variants are known elsewhere.

The true Oyster MushroomP. ostreatus is not present in natural environments in New Zealand. Until recently P. ostreatus was listed as an Unwanted Organism by the Ministry for Primary Industries because there were no verified records of its occurrence prior to the 'New Organisms' HSNO act of 1996. That status has recently changed because a voucher collection from a supermarket in 1995 was found to represent P. ostreatus (in a broad sense). The species was then de-listed as a 'new organism' and can now be imported and grown. However, it is worth noting that most cultivated strains labelled P. ostreatus are not the same as the designated epitype from Germany, so, strictly speaking, the cultivated version is not true P. ostreatus.

 

1

Frb rubbery in texture. Cap dark brown to purplish brown, polished. Gills pale grey. Spores < 9 um long.

P. purpureoolivaceous

1’

Frb not rubbery in texture. Cap usually paler. Gills cream to yellow. Spores > 9um long.

2

2

Skeletal hyphae absent in all tissue Cap grey to brown (sometimes dark). Spores 11 x 4, Q=2.8 (often longer)

P. australis

2’

Cap paler – cream to tan/fawn. Spores 10um or smaller, Q < 2.7

3

3

Cap grey to tan/fawn. Multiple caps usually fused at the base. Always some skeletal hyphae in the stipe. Spores 10 x 4um, Q=2.5

P. parsonsiae (P. djamor NZ)

3’

Cap cream to tan/fawn. Caps not fused at the base. Skeletal hyphae absent or restricted to lamellae trama. Spores 10 x 4um, Q=2.5

P. pulmonarius

References:

Segedin, B.P.; Buchanan, P.K.; Wilkie, J.P. 1995: Studies in the Agaricales of New Zealand: new species, new records and renamed species of Pleurotus (Pleurotaceae). Australian Systematic Botany 8: 453-482

Zervakis G.I., Venturella G., Fryssouli V., Inglese P., Polemis E., Gargano M.L., 2019. Pleurotus opuntiae revisited – An insight to the phylogeny of dimitic Pleurotus species with emphasis on the P. djamor complex. Fungal Biology, 123(3): 188-199

Posted on August 3, 2016 11:24 PM by cooperj cooperj

Comments

Really! From all those names in NZFungi there are only four species. Also interesting that Greta Stevenson's Pleurotus parsonsiae is a version of Pleurotus djamor. All of a sudden the genus Pleurotus just got easy. Thanks for these posts which really help to clarify what is here in our forests.

Posted by codfish over 7 years ago

We do have and undescribed Sarcomyxa in NZ.
There are sequences, but unfortunately no photos or descriptions to go with them.
Were the spores amyloid?

Posted by cooperj over 5 years ago

Add a Comment

Sign In or Sign Up to add comments