Geastrum Earth-Stars in New Zealand

The genus Geastrum is easy to recognise, but like many fungal groups it is not so easy to identify species within the genus. The late Ross Beever was interested in puffballs and their allies, and this current work builds on the collections and observations made by Ross. I wanted to get this preliminary key ‘out there’ so it can be used, hopefully to recognise interesting collections for further work. Like many of my keys it was written for my own benefit, at least in this first instance. I do not know Geastrum very well (which is probably apparent) and the process of developing a key clarifies the concepts needed to separate species in my own mind. I will change this entry as more information becomes available, and I learn more. Like most genera you can only reliably identify species using a combination of macro and microscopic characters.

Good collections of Geastrum are needed for correct identification. By that I mean examples of the fruitbody from bulb stage to fully expanded, making a note of the colour of fresh material (any pinkish/red colouration of the flesh may fade). A fruitbody still attached to a piece of substrate is useful for characterising rhizomorphs. If material in the field looks old and knocked about then don’t bother attempting to identify it. A number of the key features are ephemeral and difficult to observe in weather-worn specimens. Read the terms in the short glossary to work out which features are key.

Geastrum was last revised in New Zealand by Cunningham in 1944 (Gasteromycetes of Australia and New Zealand). He recognised the following 7 species: G. pectinatum, G.plicatum, G. minus, G. limbatum, G. velutinum, G. triplex & G. floriforme. Like many authors he adopted names from the Northern Hemisphere. Although our species look similar to northern hemisphere species, and in many cases are closely related, the current sequence data suggest they are mostly localised in their distribution and probably indigenous. They are found in both natural and modified habitats, but there are some exceptions. G. floriforme might be introduced and is identical to the northern hemisphere species. In NZ this species favours dunes and alpine areas but isn't common in macrocarpa plantations, unlike many UK records where it is found under macrocarpa. On the other hand G. coronatum aff. and G. tenuipes, both like macrocarpa plantations, and G. velutinum aff. likes pine plantations. All of these species are not exclusively limited to these habitats and other Geastrum species occur in the same habitats. 

Because our species are near, but not the same as northern hemisphere species the names are followed by ‘aff.’ meaning ‘having and affinity with’ (phylogenetically and morphologically). Most are probably undescribed species. In some cases the sequence data indicate the names cover multiple species within a complex (G. velutinum aff. & G. saccatum aff.). The separate phylogenetic species within these complexes usually have no differentiating morphological characters (that I can find at the moment).

With reference to Cunningham's names his G. pectinatum/plicatum are treated here under the name G. tenuipes. It is possible that collections with a stalk, sulcate peristome and non-ridged apophysis may turn out to be different to collections posessing a ridged apophysis and a new name will be required for that species. Likewise G. minus is generally treated as a synonym of G. quadrifidum and here would key out under G. coronatum aff. It is likely that smaller versions of G. minus auct. NZ (of which there are a few collections) represent a good species which is likely to be G. austrominimum. More collections are needed to genetically characterise G. minus in NZ (in section quadrifida). There have been no confirmed collections since 1926. G. limbatum is now generally treated as a synonym of G. coronatum. A number of collections have been historically identified as G. triplex but on closer examination they represent G. lageniforme, G. australe or G. minutisporum aff. as well as G. triplex aff. The latter species is distinctly larger than any of the others. The presence of a residual collar of pseudoparenchymatous material around the endoperidium has been shown not to be a unique and reliable feature of G. triplex (the so-called collared Geastrum), and I haven't used it as a character.

A number of names were added subsequent to Cunningham's 1944 treatment. A collection of G. drummondii was incorrectly identified. G. morganii was represented by a single collection which was used in an exhibit and not returned to PDD (duh!) but another collection related to G. morganii has been identified. G. fimbriatum has been recorded quite often but it is possible all these records refer to one of the species in our G. saccatum complex. G. fenestratum is generally regarded as a synonym of G. fornicatum and in New Zealand probably refers to G. setiferum aff.

Modern phylogenetic treatments by Zamora and colleagues (e.g. Zamora et al., 2015. Integrative taxonomy reveals an unexpected diversity in Geastrum section Geastrum (Geastrales, Basidiomycota); Persoonia, 34: 130-165) have opened up the black-box of Geastrum. They provided a phylogenetic framework to place species, and some new characters assist in identifying them. In some cases reliable identification of NZ species, even to the broad ‘species complexes’ treated here, is not easy. In particular the G. saccatum/G. lageniforme groups are difficult to separate without observation of the form of crystals attached to the rhizomorphs attached to the fruitbodies, which are often not collected. 

As mentioned above, a preliminary phylogenetic analysis of a number of NZ collections show they are closely related to some recently named southern hemisphere relatives and I have adopted those names, with the ‘aff.’ because they aren’t the same (to re-iterate what aff. means). Thus G. setiferum was named in 2002 from South America and G. minutisporum also from South America in 2016 and in both cases our species are phylogenetically close and do have different characters. They need new names. The numbers in brackets after a species name in the key refer to the Zamora classification (in the following table)and the position of representative sequences of NZ material in that classification.

It isn’t easy to incorporate photographs into this journal entry so those will have to wait.

NZ Trial Key to Geastrum

1

Endoperidial body with a stalk (sometimes quite short).

2

1’

Endoperidial body sessile. 

4

2

Persistome sulcate or radially ridged fibrillose, clearly delineated. Stalk with apophysis. Base of endoperidium usually ridged (apophysis), sometimes with a torn collar.

 G  tenuipes (7d)

2’

Persistome fibrillose but without ridges, not delineated. Mycelial layer encrusting debris (hypogeous). Stalk without apophysis.

3

3

Endoperidium surface silky, usually pale steel grey, sometimes with white flecks of crystals. Stoma edge fibrillose. Without apophysis.  Endoperdium to 2cm diam.  Without long endoperidial setae.

Within Cunningham’s NZ collections there are records of G minus, with an endoperdium < 7 mm diam. which are not G coronatum and not G quadrifidum and probably represent G austrominumum.

G coronatum aff. (7b)

3’

Endoperidium surface minutely furfuraceous, without flecks of white crystal, pale tan. Stoma edge torn. Often with apophysis. Endoperdium with thick-walled setae > 70um. Stalk often short but present.

G setiferum aff. (6)

4

Flesh becoming pink. Endoperidium tomentose 

5

4’

Flesh not becoming pink. Endoperidium smooth or tomentose/pruinose

8

5

Peristome not delineated (concolorous). Rhizomorph crystals in rosettes. Endoperidium minutely tomentose. Stoma edge torn.

6

5’

Persistome delineated. Spores < 6um. Rhizomorph crystals prism shaped. Stoma edge fibrillose.

7

6

Spores > 8um diam., setae short. Not encrusting litter. Peristome concolorous but raised/sunk.

G australe (4)

6’

Spores < 7um. Peristome not differentiated at all.

G rufescens aff.  (4)

7

Mycelial layer finely tomentose and encrusting debris towards perimeter. On soil, not wood. Spores 2-3um. Bulb morphology unknown. Endoperidium minutely furfuraceous. Emergent setae short, < 50um. See also PDD100967 under G. velutinum.

G minutisporum aff. (10a)

7’

Not encrusting debris. Mycelial layer coarsely felty. Spores 3.5-4.5 um. Bulb without beak. Endoperidium smooth. Emergent setae absent. The NZ G. velutinum complex consist of at least 4 species for which no separating characters have been found, except  PDD100967 with very small spores, 2.4um on average.

G velutinum s.l. 4 spp. (10b)

8

Rays hygroscopic (the thin white petal-like rays totally enclose the dried frb). Hypogeous frb. Mycelial layer not encrusting soil (peels off rapidly). Peristome not delineated. Coastal and dry areas. Spores 5.5-7um

G floriforme (11)

8’

Not hygroscopic. Peristome delineated or not.

9

9

Endoperidium >= 20mm diam. Peristome ±delineated. Stoma with silvery/greyish fibres. Endoperidium flecked minutely white with crystals (characters of PDD95584). Spores > 4um. I’m not convinced the ‘collar’ character you will see mentioned elsewhere is good for diagnosis. If spores > 8um then see G. australe

G triplex aff. (14)

9’

Endoperidium < 20mm diam.  Spores < 4 um on average

10

10

Peristome sulcate and conical. Endoperidium slightly pruinose. Mycelial layer encrusting debris.

G. morganii aff. (2c)

10’

Peristome fimbriate/fibrillose

11

11

Peristome not delineated. Mycelial layer encrusting debris. Presence requires confirmation by sequencing. Some sequenced material named G fimbriatum is actually G saccatum s.l.

G fimbriatum? (5)

11’

Peristome delineated. Mycelial layer absent or present (and then not encrusting debris)

12

12

Rays not sharply acute and drying hook-like. Rhizomorph crystals acicular. Mycelial layer a persistent weak pale brown mycelium towards perimeter (unlike G. saccatum ss)  but hardly encrusting debris. Basidia bladder-like (not seen in NZ material). Surface of bulb +- felty. Endoperidium minutely furfuraceous, with short, inflated setae [but surface smooth setae absent and smaller spores in PDD97802 sp.3 ]. Sp.1 and sp2. Are morphologically identical.  See also G fimbriatum auct NZ

G saccatum aff. 3 spp. (2b)

12'

Rays acute and drying like sharp hooks. Rhizomorph crystals horn-like (thin, cylindrical, ridged/irregular surface). Mycelial layer totally absent and under surface white/smooth (unlike G. lageniforme ss). Basidia lageniform ('Florence flask' - Google it) (not seen in NZ material). Surface of bulb smooth. Peristome delineated. Endoperidium smooth, no bladder-like setae.

G lageniforme aff. (2a)

The Zamora et al classification of Geastrum, and NZ representatives

#

Section

Subsection

Colls

1

Campestria

 

 

2a

Corollina

Lageniformia

G lageniforme aff.

2b

Corollina

Marginata  

G saccatum aff. 3 spp.

2c

Plicostomata

 

 G. morganii aff.

3

Elegantia

 

 

4

Exareolata

 

G rufescens aff.  , G australe

5

Fimbriata

 

G fimbriatum?

6

Fornicata

 

G setiferum aff.

7a

Geastrum

Arenaria

 

7b

Geastrum

Geastrum

G coronatum aff.

7c

Geastrum

Quadrifida

 G austrominimum?

7d

Geastrum

Sulcostomata

G tenuipes

8

Hariotia

 

 

9

Hieronymia

 

 

10a

Myceliostroma

Epigaea

G minutisporum aff.

10b

Myceliostroma

Velutina

G velutinum s.l. 4 spp.

11

Papillata

 

G floriforme

12

Pseudolimbata

 

 

13

Schmidelia

 

 

14

Trichaster

 

G triplex aff.

Glossary

Apophysis – collar/ring like swelling on stalk or junction of endoperidium and stalk.

Binding litter - The outer mycelial layer can bind litter or not, and this is a key feature. This doesn’t mean lumps of substrate that can be trapped by rays bent backwards. It means fine material firmly embedded within and stuck to the mycelial layer on underside of the rays. It is an indication the closed fruitbody was hypogeous (buried), and not sitting on the surface before it opened. However, soil encrusted layer may flake off, as a whole or in bits, and so I find this a difficult character to be absolutely certain about. The point of attachment of the fruitbody is often smooth, so don’t be fooled by that.

Endoperdium – the globe-like structure in the centre of the earth-star, specifically the skin of that structure. The texture of the surface is a useful feature. In some species it is obviously smooth/polished, but in most species it is superficially matt and under a lens either looks smooth or minutely hairy (tomentose), sometimes with aggregations of white crystals.

Exoperidium – The outer skin of the fruitbody can form three major layers. The outer mycelial layer (which can be simple or double), a middle fibrous later, and an inner pseudoparenchymatous (fleshy) layer. Outer and inner layers are evanescent, flaking off, sometimes lost entirely. Any pinkish colour to the fleshy layer is an important feature. The exoperidium splits into petal-like rays, which fold back.

Fornicate – rays arched downward and tips attached to remains of a separated exoperidial layer forming a basin in the soil. In some species the rays arch downward but without a separated cup layer.

Hygroscopic – You need to wet dried material to see the rays open out and then close up again as it dries. However, dried fruitbodies of hygroscopic species will be closed with the rays entirely covering the endoperidium so it isn’t visible. In non-hygroscopic fruitbodies the closed rays won’t cover over the endoperidium.

Mesoperidum – sometimes seen as a transient layer on surface of fleshy layer and surface of endoperidium, but usually dispersing rapidly.

Peristome – the circular zone around mouth, often different to rest of endoperidium (delineated) in either colour, texture, or raised/sunken. The area can be radially fibrillose, sulcate (ridged/pleated/folded) or smooth. Sometimes the term seems to have been used to refer just to the edge of the stoma rather than the circular zone surrounding the mouth.

Rhizomorphs - the rope-like hyphae connecting the fruitbody to the mycelium in the soil. They often have small (microscopic) crystals stuck to them, and the shape/form of these crystals is very useful fo separating groups. 

Saccate – an endoperidium sitting inside exoperidium at maturity, i.e. the globe is sitting in a bowl, not pushed up and exposed. Conversely the endoperidium looking like it is sitting on an upturned bowl (and then often with a stalk).

Stalk – between the endoperidium and exoperidium. Present or absent, and with or without an apophysis. Sometimes difficult to see without a vertical section.

Stoma – mouth where spores emerge. Edge of the stoma may be regular, fibrillose or ragged.

Posted by cooperj cooperj, October 06, 2016 02:06

Comments

Thumb

Great stuff Jerry - especially handy to have the glossary.

Posted by dougalt over 2 years ago (Flag)
Thumb

Ran the four Geastrums collected with Carol Hobart in native lowland mixed forest (i.e. Nothofagus and Podocarps) through your key and Cunningham. Two general points:
1. Couplet 4 needs to clarify whether the pink reaction is on the flesh of the endoperidium and is the colour then held or does it fade as in Scleorderma areolatum.
2. Couplet 9 ' states: 'Peristome delineated' but does not specify what by. Some earthstars have a pale zone around the peristome, others have a groove, I guess you are including both. The couplet then leads to 10 and the first part of that couplet says: 'Peristome not dilineated'. Something has gone wrong here.
Notes on the outcomes on the collections accompany the specimens that will be on there way to you shortly.
Pat Leonard

Posted by pat-leonard about 2 years ago (Flag)
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The intro states the reddening is ephemeral.
Delineation means visibly different, regardless of what makes it look different.
Fixed couplet 10.

Posted by cooperj about 1 year ago (Flag)

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