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Scleroderma in NZ

Scleroderma is ectomycorrhizal and the species appear to be rather host specific in New Zealand according to current sequence data. The host specificity makes their identification a little easier. In addition to the species treated in the key, a Scleroderma has been reported in New Zealand with conifers, but I have not examined collections and no molecular work has been done. It is likely to be an additional introduced species.

Beware of using the name S. citrinum which is a yellow species with broad-leaved trees in Europe and the Eastern USA. The name is commonly misapplied around the rest of the world.

The species with tea-tree and Eucalyptus pose a problem for naming. Cunningham did the previous work on NZ species (1920-1940's) and he adopted overseas names and didn't place any importance on the associated ectomycorrhizal host species. Consequently his treatment is confused.

First the Eucalyptus associated species - S. radicans was named in Australia (presumably with a mrytaceous/Eucalyptus host) by C.G. Lloyd in 1906, but Guzman, in his 1970 global monograph, considered it to be a synonym of S. albidum, a species named from a garden in North Africa in 1899 and the host tree not mentioned. The name S. albidum has now become generally accepted for common Eucalypt associated Scleroderma species around the world wherever the tree is planted. However, current phylogenetic data indicate there are several Eucalypt associated species to which the name S. albidum has been applied. It seems possible S. radicans provides the correct name for at least one of these species. I will use the name S. radicans for the Eucalypt associated species in NZ until proven incorrect. The NZ material is different to other currently sequenced material of Eucalypt-associated species.

Now the NZ tea-tree associated species - Most NZ collections with tea-tree got lumped under the name S. flavidum by Cunnningham. That was originally described from the USA, and is now considered to be a synonym of S. cepa. Neither species is present in NZ, synonyms or not. Records of S. cepa in New Zealand are always ageing specimens of one of the other species listed here.

We have a coarse scaly species associated with tea-tree in geothermal areas, and it was known by Cunningham, but does not have an existing name. Here I am calling it Scleroderma sp. 'geothermal' and it needs more collections and characterisation.

We have just one other species associated with tea-tree but there are three potential names to consider. Cunningham named S. flavidum forma macrospora for some material with tea-tree. The spores are actually quite variable in size so the name is misleading. I am using this as a stop-gap name for the tea-tree associated species in New Zealand. It is distinctive microscopically because the large spines are broad-based and confluent, giving a spiny/reticulate appearance to the spores, which is quite different to other NZ Scleroderma, including S. albidum/radicans with Eucalyptus. I will use this name for the NZ tea-tree associated species for the moment, but it is unsatisfactory and a new name is needed. Cunningham did not typify the name (being just a forma) and he introduced it for both Australian and New Zealand collections, presumably with a variety of hosts tree species, which he did not note. Sequences of NZ material indicate an NZ-only clade for this species, but with one sample from China. The clade is closely related to a group of species labelled S. albidum from Brazil associated with Eucalytpus (but is not the same as all Brazilian collections of S. albidum !) and also S. aurantium from Pakistan, also associated with Eucalyptus. S. aurantium is a name of uncertain application. It has been misapplied in Europe for S. citrinum and elsewhere for S. cepa. The original use is possibly the same as S. verrucosum. S. aurantium has been used in NZ for the Scleroderma associated with P. radiata but the use of that name is so confused it is best buried and the real identity of the yellow pine associate requires clarification.

There is one more name to consider for the NZ tea-trea species. C.G. Lloyd, working in the 1920's, was sent a Scleroderma by Helen Dalyrimple from Dunedin and Lloyd named it S. caespitosum. Cunningham was always rather frustrated and dismissive of Lloyd's contributions and considered it to be yet another synonym of his adopted US name S. flavidum. It is possible this provides an earlier name for our tea-tree species, but the original description, and the epithet suggests this is a synonym of the introduced S. bovista. The original material (in formalin) requires re-examination (and I have now tracked it down in the Lloyd herbarium at Beltsville).

So, to conclude, it would seem the myrtaceous associated Scleroderma species globally need some work. They can't all be S. albidum, and certainly older names, like S. radicans, need serious re-evaluation. In addition the NZ tea-tree associated species are not the same as Australian Eucalyptus associated species.

Finally, Scleroderma is a a popular species for inclusion in mycorrhizal additives to enhance tree growth in nurseries and plantations. Whilst that is marginally acceptable for exotic plantation trees, it is not acceptable in native tree nurseries. It is critically important to get the right fungal species for the particular native tree, otherwise we are deliberately introducing and spreading potentially invasive species. These fungi are much more host-specific than previously assumed (at least in this part of the world). Fungi need to be eco-sourced, just like native plants they grow with.

1 With Kunzea/Leptospermum 2
1' With introduced trees (Eucalyptus, Quercus, Salix, Populus) 3
2 Geothermal areas. Without a pseudostipe. Peridium bright yellow/orange, with coarse scales.  Spores <= 11um, spines not pronounced. S. sp. 'geothermal'
2' With pseudostipe. Peridium yellow, furfuraceous but not scaly. When old splitting radially and opening up like S. cepa. Spores 10-16(19) um. Spines with broad bases and confluent. S. flavidum f. macrospora auct NZ
3 Spores reticulate. Peridium relatively smooth. With northern hemisphere broadleaf trees. S. bovista
3' Spores spiny. Peridium scaly or smooth 4
4 With Eucalyptus. Peridium relatively smooth. With pseudostipe. Spines to 1 um. S. radicans auct.
4' With other broadleaf trees. Peridium scaly 5
5 Spores 8-13um (incl. spines), spines to 1.5 um. Pseudostipe well developed S. verrucosum
5' Spores 12-18um (incl. spines), spines 1.4 to 2.5um. Pseudostipe short S. areolatum

 

Posted by cooperj cooperj, September 23, 2016 03:42

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