Hi Dave,
Good question! I can only speculate on this one, but I suspect it must over-winter as a larva. Chalkhill Blue eggs hatch early in the spring, but in order to overtake them developmentally, and appear as an adult in Late May/June, a polonus egg would have to hatch in February or March, which seems highly unlikely. £100 if you can find a wild polonus caterpillar.
BWs, Neil
Without DNA tests I think the jury is still out on this one ...
David M wrote:I know icarus is genus polyommatus but I had always thought bellargus was lysandra until I read this thread.
You'll have to blame the taxonomists on this one. It depends on which references you use and of course the date of publication of the reference. With regards to the Adonis Blue, Polyommatus (Lysandra) bellargus, the element of the name in parenthesis, Lysandra, refers to what is commonly accepted as a sub genus. The genus was originally Lysandra, or going back even further Papilio. Another example would be the Chalkhill Blue, Polyommatus (Lysandra) coridon. Jeremy Thomas and Richard Lewington in, The Butterflies of Britain and Ireland (2010), use the parenthesis form of description.
No doubt it will all change again in the future, otherwise taxonomists would be out of a job!
What I can say is it is a male Adonis Blue (Polyommatus (Lysandra) bellargus) and it is an aberration; but which one, if indeed it has a name. I can confirm that the colours in the image are true to the actual specimen; at least when viewed on my monitor. Neil has already quite rightly ruled out polonus and explained the issues regarding ultraviolet light and colour stabilisation of preserved specimens. My feeling is that the colour of the specimen is likely to be as good today as it was when it was captured in 1936. I certainly don’t claim to be anything of an expert when it comes to aberrations and have discussed this particular specimen’s ‘identity’ with a number of entomologists more qualified than I.
Ab. suffusa, Tutt (1896), was an early candidate. This is described from a male specimen as being ‘Dark leaden blue’, which this specimen certainly isn’t. It has also been suggested that it could be ab. pallida, Austin (1890), = pallida, Mosley (1896). This is the form often referred to as a hybrid between icarus and bellargus. The description reads ‘The upperside pale lavender’. It also goes on to say, ‘The underside with the usual white rings but no spots, the rings being blind’. The spots are not blind on my example, though this alone would not rule out pallida. Ab. argentea, Tutt (1909) has also been considered. It is described from a male specimen as ‘The upperside silvery-grey’, and goes on to say, ‘The underside dark grey without red marginal spots’; again, my example has the red marginal spots, though this fact alone would not rule it out. Ab. czekelii, Aigner (1905) was also considered. This is described from a male specimen as ‘The upperside bluish-grey’, which this specimen certainly is - at least to my eyes; there is no description of the underside. Having exhausted the resources easily available to me my personal view has changed on several occasions, though I currently believe it to be referable to ab. suffusa, Tutt (1896) though I’m by no means 100% sure.
Just to complicate matters further, it needs to be considered that even a named aberration can itself be subject to a range of variation (one of the factors influencing my identification as possibly ab. suffusa); therefore often making the actual ‘identification’ subjective. To be as sure of the identification as possible would involve a lot of research looking at named aberrations in museum collections - and even then the identification will end up being purely of personal opinion if there is not an 'identical' visual match. Online image databases are of course available but the quality of the pictures can often be poor, reflect colour distortions, and are consequently of limited use. Whilst undertaking this research I have looked at a number of images of the same specimen from different sources and to be fair, if it wasn't for the structural features of the specimen, it would be very easy to assume you were looking at several different examples and consequently a variety of different aberrations ...
Folkestone, as shown on the data label, was once a very rich locality for bellargus and bellargus aberrations. Historically it was a well-worked locality by early entomologists, particularly prior to the war years, as it was easily accessible from London. Environmental conditions are well known to influence the occurrence of certain aberrations - the extreme weather that often hits the county of Kent, still to this day, therefore plays an important factor in the aberrational forms that occur there.
It has also been suggested that it could be ab. pallida, Austin (1890), = pallida, Mosley (1896). This is the form often referred to as a hybrid between icarus and bellargus.
How many specimens of each of these rare aberrations (suffusa, argentea, czekelii &c.) exist? 1, 10, 100, 1000 ...? Are all recurrent forms pretty comprehensively known, or is it reasonably likely that some have escaped attention up till now, being very rare and rather short-lived? Does an aberration have to be shown to be recurrent to merit a name?
In answer to David's question, yes, chromosome analysis has proven such specimens (polonus) to be genuine hybrids.
I had reduced the options to ab. suffusa or ab. czekelii , slightly favouring the latter, but as Mark quite rightly points out, the naming of some of the trickier abs. is a dark art requiring detailed research.
Still on polonus, and on a slight tangent - the French edition of Lafranchis (the Europe guide, not the France guide) has two photos of this and there are a further 8 photos on the attached DVD. Some of them would more easily be passed off for coridon than bellargus in the field.
It's definitely worth updating the English Lafranchis to the French (which was produced afterwards), if only for the extra pictures.
padfield wrote:Does an aberration have to be shown to be recurrent to merit a name?
It seems that ab. naming is very loose.
I tend to assume most abs. are the result of genetic defects, such as a control gene failing to operate correctly, for example, turning eye-spots into stripes. Similar effects on these mechanisms can also arise from temperature changes at the chrysalis stage. I would imagine that there is an almost infinite possibility for variation, arising from such causes.
It seems odd to me to describe a hybrid as an 'ab.'
"It seems odd to me to describe a hybrid as an 'ab.'"
Correct. The following is taken from Pete's text on the species page for Adonis:
"Very rarely this species is known to hybridise with its close relative the Chalkhill Blue, resulting in specimens that bare traits from each species and a colouration that appears (in the male) to be half way between each species in their typical forms. This butterfly is traditionally known as ab. polonus, although being a hybrid it is not an aberration as such at all. Strictly speaking it should probably be known as bellargus x coridon."
padfield wrote:Still on polonus, and on a slight tangent - the French edition of Lafranchis (the Europe guide, not the France guide) has two photos of this...
You're right, Guy.
P.171: "Lysandra x polonus - probably a rare natural hybrid between lysandra bellargus and lysandra coridon with intermediate characters on both sides of wings. Known from central and southern Europe where it flies in summer. Tinge of the blue is variable".
What intrigues me here is the 'Lysandra x polonus'.
If the 'x' denotes a hybrid and 'polonus' denotes an aberration, isn't the above indicating a hybrid between a genus and an aberration?
