Leeches are tricky, they certainly dont look the same, where did you collect them? have you tried comparing them morphologically (mouth parts and suckers, etc.)? Best way would to do molecular work on them.

Thank you Edward. Leeches are really tricky. I'm going to compare morphology and I'll try to do molecular analysis. I have a doubt about the little red forms because I don't know if they could be juveniles.

Hi there! There is a manuscript of mine providing some molecular data on Placobdella costata which has just been accepted for publication in JZSER. I'll keep you informed about its status and forward you a copy of it to you as soon as possible, in case you are interested. All the best!

Federico

Thanks a lot, Federico. I'm waiting the copy of your paper. I'm very interested in Placobdella costata as parasite of Mauremys leprosa, so your information is very useful for me. All the best. Best regards.

Alfonso 

To date, we collected it on Emys orbicularis galloitalica (southern Italy) and Emys trinacris (Sicily) only :-)

Regarding your third picture, the dorsal coloration pattern is a typical one for P. costata

before conducting a molecular study, a dissection of salivary gland and their parallel position compared to proboscis could help you. their juveniles and adults have similar pattern. your first picture is dubious and it is probably another species. check the book by Nesemann and Neubert, 1999 on leeches.

I agree with Kaveh, the third photo is a typical P.costata. The first and second photo are impossible to identify (for me), but they don't look like them and possible concern another species. Even in juveniles of P. costata there is a color pattern.

in Menorca (Balearic islands) some leeches Placobdella costata parasitized Emys orbicularis most commonly in summer.

Oh! I forgot to update the publication status of my works dealing with Placobdella. Here they are:

http://folia.paru.cas.cz/pdfs/fol/2016/01/29.pdf

and

http://onlinelibrary.wiley.com/doi/10.1111/jzs.12117/abstract

And both of them are available on my ResearchGate profile.

I'm keeping on studying Placobdella costata. I am currently investigating the P. costata molecular diversity in Sicily vs. Peninsular Italy.

These are leeches parasiting Emys orbicularis in Menorca.

Dear Jonathan, that's interesting! At least the specimens first two pictures do not seem to look like P. costatal!

Thanks for your valuable comments. The second photo seems an image of Helobdella. But we couldn't identifie the species.