Just like the Scarlet/Ruby Elfcups (Sarcoscypha) pair, the Green Elfcup has also two species, but in this case they share the common name. The two species involved are Chlorociboria aeruginascens and C. aeruginosa, so which one have I been finding in the Llwydcoed woods?
There is only one way to find out, which is to measure the spores, so I went and collected a cup, packing it carefully to take home. While I was out, I also visited a site, along the tramroad, near Gamlyn and found some cups of Scarlet/Ruby Elfcup, so I collected one of those too.
At home, in order to obtain spores for examination, the each cup was placed mouth down on a microscope slide. The slides with their cups were then individually wrapped in kitchen foil, taking care not to crush the cups in the process. The foil keeps the cup in place on the slide and prevents the cup from drying out before it has shed its spores. The Sarcoscypha was nice and fleshy, but the Chlorociboria was so thin and insubstantial that I felt it needed something to help it stay moist, so I tore off a small piece of kitchen towel, about the size of my thumb nail: just large enough to cover the cup and moistened it, squeezing out the excess moisture before placing in over the cup and then wrapping the whole thing with the foil.
I left both cups overnight and by the following day when I unwrapped them, I found a nice white spore print on the slide, beneath both cups.
|The cup in place on the microscope slide, after unwrapping the protecting foil.|
|The white spore print. The slide is the standard 26mm wide.|
Taking the Chlorociboria first, I gathered the spores together on the slide with a razor blade, mixed them with a drop of water and with a cover slip placed over them, examined them under the microscope. The spores were very small and even at x400, looked tiny. However, there were just large enough to be able to measure without resorting to the fuss and palaver of using the x100 (gives a magnification of x1000) oil emersion objective.
|The tiny spores of C. aeruginascens x400 (each division equals 2.5 microns)|
Compare with the photo of the Sarcoscypha spores at the same magnification
C. aeruginascens has smaller spores than C. aeruginosa, and after measuring several spores, they all fitted comfortably within the size range expected for C. aeruginascens, so that was a result.
Turning to the Sarcoscypha cup, one of the distinguishing features is the thick hairy whitish coating (tomentum) on the outside of the cup, which in Scarlet Elfcup (S. austriaca) is curly and in Ruby Elfcup (S. coccinea) is straight or wavy.
I scraped off a tiny bit of the tomentum and placed it on a slide with Gentian Violet stain and bunged it under the microscope. Even at x40, the tomentum was obviously curly and at higher powers, the curliness is unmistakable.
|The curled Tomentum, at x200|
To be absolutely sure, the spores have to be examined, so I scraped them together, with water and a cover slip and under the microscope. The spores were nice and large, making examination easy. Immediately apparent was the shape of the ends of the spores, many of which were squared off (in a rounded sort of way), while most were rounded. According to the literature, only S. austriaca has the square ended spores, so it was almost certainly that species.
|Sarcoscypha austriaca spores (x400) showing round ended and square ended spores|
However, searching through the thousands of spores on the slide, I came across a small number of spores, from the ends of which new spores were budding. This clinched the identification, because only Scarlet Elfcup (S. austriaca) has those budding spores.
|A crop showing one of the budding spores|
|Crop, showing another budding spore.|
The problem with all this is that I have now confirmed that the Elfcups I found at that site were Scarlet, but that doesn't mean that all the Elfcups around here are. S. coccinea could also be present and the only way to be sure is to collect a cup and at the very least, examine the tomentum. That said, if you have a microscope, the spores are easy to obtain from the cup and being fairly large, are just as easy to examine for the presence of the square ended spores, so taking cups for identification isn't really an onerous task.