Pamphilus rhoumensis is another interesting case (see viewtopic.php?f=14&t=5623) where the initial description of an alleged subspecies was based upon somewhat scant evidence, if there actually ever was any evidence of a subspecies at all.Gibster wrote:Gibster wrote:rhoumensis in Surrey!!!! (Or as I dubbed it in 2010's failed effort to clear up on the UK subspecies -my rhounemesis)Sorry mate, I was saying that tongue-in-cheek. Obviously it is not of the endemic Hebridean race!!!millerd wrote:Is that what it looks like? I knew it was a bit different. What are the characteristics it is displaying that make it resemble a far distant subspecies?
Dave
rhoumensis is (by all accounts) a very hairy, glaucous beast with a distinctly ghostly appearance in flight. Your individual is pretty silvery, but is several hundreds of miles south of where it should be (ie Rhum!)
I caught the ferry to Rhum last year in an attempt to connect with the endemic race, but rather carelessly got carried away chatting and neglected to notice that we'd berthed until the ferry began backing out of the harbour!!! DOH! The only other stop was at neighbouring Canna, so we tried there instead...just in case. Then the rain came in and all we managed were a handful of Meadow Brown splendida (cool name, they live up to it too!), Fox Moth larvae and a rain-lashed mystery Crambid. Rhum, just a few miles over the sea, somehow remained bathed in sunlight grrrrrrrrrrr.
Cheers,
Gibster.
J.W. Heslop-Harrison (again) described the race in 1948, originally claiming that the 'subspecies' was unique to Rum (=Rhum). Subsequently H-H extended the distribution to include Raasay, Uist, Eriskay and the Barra isles despite having visited Uist in the early '40's and not noting anything peculiar about the small heath population while there. The differences between rhoumensis and the nominate are subtle (Gibster - your description above (glaucous...with a distinctly ghostly appearance in flight) would seem to refer more to the extreme tullia scotica from the very far north of Scotland
).Pamphilus rhoumensis
-Slightly duller upperside ground colour
-Grey uniformity of the hindwing underside
-Narrower, paler 'halo' surrounding the eye-spot on the forewing underside
This description was based upon a small number of specimens, and little work has been carried out since in attempting to determine whether this form deserves subspecific status, or indeed the range and distribution of the morph. The status of the subspecies has been contested on more than one occasion (albeit with little more evidence than that for the existence of a subspecies). Very few specimens exist from Rum and there has been precious little research into the small heath populations in Scotland and the Scottish Islands even to this day.
The problem with basing such assumptions upon a small series of ancient specimens collected by one or two individual scientists is the potential for the series to have been selectively collected, or for a particular characteristic to have been present in just one season.
An example of this could be the silver spotted skipper: A few years ago I noted a considerable number of very dark specimens on one particular down. They were very dark indeed, with little of the usual fulvous colouration. Were I a 19th century collector I could easily have collected a short series of particularly dark specimens and presented them as an isolated subspecies. Indeed, there are instances where this has actually happened, such as in the case of adonis blues from the Ventnor downs which were presented as a separate subspecies (ssp. vestae) on the basis of one series of small, silvery males with dark undersides that were collected from the downs in the 1930's. Regarding the silver spotted skippers, it is now known that particularly dark forms will be produced in exceptionally hot summers.
It is to be expected that populations of the small heath from different individual islands will vary, each having adapted to the local selection pressures and from microgeographical and microclimatic influences, however the status of a distinct subspecies of the small heath on Rum has yet to be determined.
Piers.
Thanks for the detailed analysis Piers