Hi Ilian,
As far as I know nobody has studied the D.caspius on Corfu in great depth, as it is rare on the island. There are no clear differences except darkened eyes, and cross bars along the body. But please believe me when I tell you, the snake I photographed was a juvenile D.caspius! Oddly enough, not even around Parga and the adjacent mainland are the caspius like those on Corfu, I do not believe there are any real biological differences to define it as a separate subspecies but evolution of the bar patterning is a little unusual.
I have seen a few adult D.caspius that have been photographed on Corfu, and my Italian friend who used to live there caught many D.caspius over the years and he told me they all had the bar markings and the black eyes..
Matt 

Allow me to demostrate further with some photos, one from herpetofauna.at, and another I found on the net, the same as the dead animal I found:

I did not scale count the dead caspius, but I can easily recognise the visual differences between caspius and gemonensis without scale counts.

Matt 

Hi Matt,

That's very interesting!What do you think is the reason for that colour evolution? As far as I know the landscape on Corfu isn't much different from the one on the mainland,so it probbably has nothing to do with habitat? Or maybe I'm wrong? 

Hi Ilian,
It really is strange, I have been to Corfu many times and only found the one dead animal, I know some people who have found the occasional specimen, usually dead on road. Eduardo Razzetti sent me a presentation of his trip to Corfu and he and his colleagues caught an adult caspius identical to the one I have just shown. But otherwise it is very poorly documented on the island. Corfu and Paxos are very different to other parts of Greece, being extremely green and lush, not like the mainland area closeby.
The evolution of the stripes may have something to do with H.gemonensis also being on the island, as on no other Greek island do the two occur together. But in all honesty I really do not know.
My friend Antonio who lived in central Corfu, caught many in his years living there, I remember he said to me when he first encountered an adult caspius he thought it was a different species..
I visited Kefalonia for many years and found several D.caspius without the stripes, but no gemonensis at all, and I believe the old record of balkan whip snake on that island was a mistake. Corfu and Kefalonia are the only islands in the Ionian with caspius, but whereas Kefalonia has typical caspius, Corfu specimens are very different.
Matt 

Hi Matt,

Sometimes it can be exciting when you don't know something!:)).At least it is for me! Corfu is a very interesting place indeed and I've been fascinated by it since I was a kid reading Gerald Durrell's books!:)Unfortunately, I haven't got the chance to visit it,yet! What you're saying makes sence! If there are just two islands with caspius and the diffrent ones are found on the island where it meets H.gemonensis,probbably the last has something to do with that! The two species are really close relatives.. Could they've been interbreeding? 

That's an interesting option.

Also very nice drawing ! 

I do not think it is linked to interbreeding, the caspius are generally the same as elsewhere, dimensions, habits etc. Someone sent me a photo of a roadkilled snake they saw on Corfu, it was a caspius of around 1.6m so it still reaches the same large size as elsewhere.
But I do think the evolution of the patterning may be linked to H.gemonensis being the more dominant of the two on the island, but I'm not quite sure why...But it is strange that animals from around Parga on the mainland do not look like this. I can understand the populations of Kefalonia being normal as it is alot further south, but the strange thing about that island is that it is a Peloponnese island, and caspius is absent from the Peloponese. And so it goes on..
Matt 

Daniel,
Thanks for the comment on my drawing! I have others too, if you wish to see them!

Matt,
You say H.gemonensis is the dominant of the two! In what aspect it is dominant... because it is more munerous or something else? I'm thinking if the caspius evolved colours trying to mimic the gemonensis (like N.maura mimics vipers),but I don't see a reason for that since both species are, let's say kind of equal as strenght,size,both non-vemomous,etc. ? 

I guess that if you only take into account the head scales, it is quite difficult to make a sound judgement. See examples as links, below.
Don't you think that D caspius have most of the time what I would call "shady body scales", whereas H gemonensis do not?
One day, I would really love to meet one of these beautiful snakes from Corfu. It looks like they do not get rid of the juvenile barred pattern...

regards
Johann
Typical D Caspius (quite close from your drawing btw)
http://picasaweb.google.com/Johann.Mols/TripToGreeceMay2009#5349134197467500754
Typical H gemonensis
http://picasaweb.google.com/Johann.Mols/TripToGreeceMay2009#5349128575521008178
or
http://picasaweb.google.com/Johann.Mols/GreeceSeptemberOctober2008#5259351933376650370

Atypical juvenile H gemonensis
http://picasaweb.google.com/Johann.Mols/GreeceSeptemberOctober2008#5259351028588595554

 

Hi Johann,

I can't exactly understand what you mean by "shady body scales" !?

Your photos are amazing!Congratulations!:)

Best regards
Ilian 

I don't know whether I quite follow Matt's reasoning on caspius looking more like gemonensis in area(s) of co-occurrence. There's a contrasting ecological principle, called 'character displacement', if I remember well, which is quite the opposite: related species looking most different from one another in areas of overlap. Examples: green and natterjack toad (with e.g. many viridis-like specimens in southern Spain) and smooth newt vs. palmate (with vulgaris looking like helveticus in areas without helveticus). On the other hand, there's of course mimicry, which I would guess to be perhaps a cause of Natrix natrix astreptophora looking somewhat like Malpolon?

Furthermore, in areas of co-occurrence, you'd expect caspius to outcompete the smaller gemonensis, no?k

Don't know what might explain the Corfu enigma; nice looking snakes, in any case ;-). 

I never thought of Natrix natrix astreptophora and Malpolon monspessulanus like that, but it's very possible. 

To be honest Jeroen, I am simply guessing, there is probably no reason whatsoever why the caspius on Corfu look the way they do. Ilian, on the island gemonensis is common, and therefore the dominating whipsnake along with Platyceps najadum. Having seen around 25-30 gemonensis vs 1 dead caspius that gives you abit of an idea. I am surprised that the first observations of caspius on Corfu did not mention more about these differences, then again its first documentation was in German so maybe there was some information that I could not understand.
Matt 

Maybe your dead specimen was just a fluke looking different from the normal form? 

No Dan, all of the Dolichophis caspius that have been found on Corfu look the same. As far as I know nobody has found a typical adult like from its range elsewhere in Greece. 

For me, this Colubrid is a Dolichophis caspius for shure.
By the way:
The Link in your report Corfu 2006 to Corfu 2007 should be changed:
From ......../Field/Corfu2 to ...../Field/corfu2.php
The given link is not working in this way!!

My observations are, juvenile D. caspius have a wide variability in color and pattern.
This individual I have photographed on the island Ada (Montenegro)
photo(http://vipersgarden.at/bdm/2007/Images/doli_juv_ada.jpg)

And look at this one! Most are sure, this is a baby H. gemonensis
http://vipersgarden.at/4images/details.php?image_id=109&mode=search

http://vipersgarden.at/4images/details.php?image_id=108&mode=search

Mario 

To Ilias,

Thanks!
For the shady body scales, I meant that when encoutering an adut or a subadult (not for juvenile, though), body scales look like being highlighted on the periphery. I am not sure it is a criteria that could be used to identify the snake for sure but at least it appeared quite reliable to me.
When checking that characteristic on Matt's pics, these D Caspius just appear normal (beside te fact that they kept the barred pattern found typically with juvenile specimens).
Johann
PS note to all: Is anyone aware of cross-breeding between D Caspius and H gemonensis? 

Is there also any difference in scalation between H. gemonensis and D. caspius other than the number of ventral scales? As far as I can tell the two have identical head scalation and number of dorsal scales.
Would like to know how to differenciate sheddings of these two species apart because sometimes the skin is the only thing you have.