Stelis ?vulcanica? - surprise flowering

Usually I notice when plants throw out a spike - I tend to watch them like a hawk for any signs of interesting growth. Well, actually, I doubt hawks look at their orchid collections much, so I watch them like any (obsessive?) orchid-grower watches their plants... Somehow, I missed this one that sprung up in between several leaves that had grown on top of each other; I was having a look at the plant and noticing several other promising-looking growths on the leaves, and then this spike peeped out at me, in full bloom!

Stelis nanegalensis

Stelis nanegalensis

For those of you who just like the pretty pictures, stop reading now. Beyond this point Taxonomy Alert!

I obtained this plant, labelled Stelis vulcanica, last year; it appears not to be a valid name (RHS says it should be Stelis nanegalensis), but this name still seems to be commonly used. It's also possible that this is mis-identified. We first saw a "Stelis vulcanica" at an EPOS meeting last year (the first one Senior Management and I attended together, I think); someone noted (when the plant table was being discussed) that vulcanica wasn't valid and suggested it was perhaps argentata, but it seems they probably actually meant nanegalensis! In any case, Senior Management expressed the opinion that such a plant should be encouraged to appear at OOAB, so this was duly accomplished.

Anyone have a handy (up-to-date) monograph on Stelis, preferably with keys?

http://speciesidentificationtaskforce.blogspot.com/2010/07/additional-information-stelis.html has some scans of various books that are somewhat helpful; one of the references notes that argentata has a small hook on the lip of the flower, which this flower has (zoom in on the full size versions, or see crop below); at the same time, there is a nice botanical illustration of nanegalensis which clearly also shows such a "tooth". It's possible one of the authors got this wrong (such a thing is not unheard of). At the same time, I'm an absolute neophyte at plant taxonomy, so I could be totally mistaken. To me, this looks most like Luer's illustration of nanegalensis, so I suspect that is what this is

Stelis, detail of lip (crop)

Illustration of Stelis nanegalensis
from Luer in Icones Pleurothallidinarum
Note lip detail.

The initial Species Identification Task Force (SITF) blog post on Stelis nanegalensis shows the detail of the lip structure well in one of the close-up photos.

Luer's monograph contains some other little gems: interestingly, it seems that Nanegal is the town where this species was originally collected from and described (by Lindley in 1858 - the suffix -ensis in a latin name can be thought of as "comes from"); Schlechter later described (what is ultimately the same species) as vulcanica in 1915; the rules of taxonomy dictate the earliest validly published name takes priority, so hello, nanegalensis! "vulcanica" apparently stems from it having been collected in or around the Pulalagua Volcano. Apparently, one can distinguish the apparently rather similar Stelis superbiens from nanegalensis on the basis of the teeth on the lips - which suggests at least some orchids identified as superbiens are not - see for example this which clearly has 3 teeth on its lip! Sadly, I don't have access to the Icones Pleurothallidinarum, so I can't leaf through the Stelis section for general inspiration, nor see what they have to say about argentata.

S. argentata is also noted to have a (single) tooth in the center of the lip - an email from Luer suggests that argentata is very variable, and may occasionally have extra teeth (argh!); ultimately though he seems to decide that the plant the SITF is looking at is nanegalensis.

These plants seem to be quite variable in both colouration and the amount of "hairyness" on the flowers; this may be simply variability, or it may just be an unrecognised species complex ; given the diversity, range and potential habitat isolation of Andean pleurothallids, that does not seem beyond the bounds of reason.  Luer's email linked to earlier suggests it's simple variability; I'm not sure if he's a "lumper" or a "splitter". "Lumpers" are taxonomists who are conservative in assigning things species rank; "splitters" tend to like to recognise diversity as valid species.

Until otherwise noted, this does indeed seem to be "vulcanica", only the valid name for this species is Stelis nanegalensis. Time for a label update!