The edge of Europe – from a biological perspective, the Greek islands of Kastellorizo and Nisyros are part of Asia Minor: Located only a few kilometers south of the Lycian Coast, Kastellorizo is populated by numerous species of the Herpetofauna from Southern Turkey. In contrast to this, Nisyros is a – in geological dimensions – young volcano island close to the Mid Aegean Trench. Two highly interesting travel destinations!

The journey via Rhodes

Kastellorizo and Nisyros are two rather remote islands – visiting both within one week is somehow logistically challenging. To get there, we chose Rhodes as a starting point. From here, you can take the aircraft (or a ferry) to Kastellorizo. Furthermore, there is also a ferry connecting Rhodes with Nisyros. The downside of this travel schedule: three overnight stays on Rhodes – one in the beginning, one during our journey from Kastellorizo to Nisyros and one in the end of the trip. Compared to the calm and laid-back atmosphere on the small islands, Rhodes was somehow uninspiring: mass tourism, habitat destruction, hustle and bustle… As we also had visited Rhodes before, we weren’t too motivated in herping. Consequently, Stellagama stellio (Starred Agama) and Anatololacerta pelasgiana (Pelasgian Rock Lizard) were the only species seen.

Part 1: Kastellorizo

In former years we had visited Kastellorizo in early spring. Now, in mid-May, there were already some tourists on the island. However, there are hardly any cars on this calm island of only 9 square kilometers and the atmosphere was still laid-back. With its Venetian houses surrounding the harbor, with wooded hills behind and steep limestone rocks, this island is a Mediterranean pearl. Furthermore, the water temperature was already agreeable for swimming: perfect conditions for our stay!

Compared to our previous visits, the island was dry and hot and we also found other herp species than in early spring: We only found very few specimens of Ablepharus anatolicus (Snake-eyed Skink) and Ophiomorus kardesi (Limbless Skink) this time. However, Heremites auratus (Levant skink) was very abundant this time and we also came across some Platyceps najadum (Dahl’s Whip Snake) – two species we didn’t encounter at all in early spring. This demonstrates that herpetological observations strongly depend on the season.

A short remark on Mediodactylus danilewskii: This former subspecies of Mediodactylus kotschyi (Kotschy’s Gecko) has recently been put into species rank by KOTSAKIOZI et al. (2018). Regarding external characteristics both species look very similar. However, there seem to be significant differences: In areas like the Cyclades or Peloponnese, Mediodactylus kotschyi is often highly abundant and can frequently be seen basking together with Lacertids on rocks or dry stone walls. In contrast to this, southeastern Aegean Mediodactylus seems to be much rarer and competitively weak. Moreover, we never found these geckoes on Kastellorizo in full sun. The specimen on the picture was photographed in-situ and it consequently avoided sun and rested in the shade of a wall. (This resembles to the situation on Rhodes: There, Mediodactylus only occurs on satellite islets – like Prasonisi – but lacks on the main island. We also found these geckoes only under stones there, but not active by day in full sun).

We had received a hint from Philippos Katsiyiannis to also have a look at the sea as there would be Chelonia mydas (Green Sea Turtle). Actually, there were Sea Turtles in the harbour but first we only saw some Caretta caretta (Loggerhead Turtles). Taking a closer look, we found that there was also Chelonia mydas among them. It was great to watch these turtles in the shallow water! Actually, there are not many places in the Mediterranean there this species can be observed so easily.

Lacertids of the Kastellorizo Archipelago

During our first visit in 2011, we encountered Anatololacerta sp. on Kastellorizo, not knowing which species it referred to and whether there was a stable population on the island. In 2017, we found those lizards again and in 2018, genetic analysis revealed that they are some introduced Anatololacerta pelasgiana from Rhodos. However, Greek scientist discovered another population of lizards on the nearby islet of Psomi, about 500 meters off the Kastellorizo coast. These lizards turned out to be Anatololacerta finikensis: A widespread species on the adjoining Turkish mainland but the first and so far only record of this species in Greece. Due to its small habitat on Psomi, this species could actually be regarded as Europe's rarest Lacertid. (We will not discuss here whether the Kastellorizo Archipelago belongs to Europe - Just ask any local Greek, if you want to know...)

Howbeit: We wanted to see these lizards. Finding a boat to get there wasn’t easy: As Psomi islet is located very close to the Turkish border, most skippers were worried to get in trouble with the Turkish authorities. But finally, we managed to find a brave guy to bring us there. However, reaching Psomi, he got increasingly nervous. After only about 10 minutes of taking pictures he anxiously called us to come back: έλα! έλα! At least, there were some shots on the camera chip, already – mission accomplished…

Part 2: Nisyros

Nisyros, together with Santorini, Milos and Methana is part of the south Aegean volcanic arc, a chain of active volcanos in the southern Aegean. On Nisyros, volcanic activity is striking: The center of the island consists of a caldera with an impressive crater landscape inside. The volcano still dominates life on the island – once a day, things are getting busy: A ferry brings visitors from Kos to Nisyros; they are carried to the crater with busses; the crowd gets out of the busses to admire the volcano. Most of them do not get beyond the take away at the entrance of the visitors center. After one hour they disappear and the island becomes a silent place, again. Apart from this, it seems that this island has been overlooked by mass tourism. Outside of the main village Mandraki, which is focused on the mentioned day trippers, there is very few touristic infrastructure on this lonely island.

We travelled to Nisyros by ferry from Rhodes, with stop-overs on Chalki and Tilos, two dry and karstified limestone islands. In contrast to these, Nisyros looks quite different: When approaching the island by boat it appears rather green. Actually, it has rich vegetation with fern, oak trees and olive groves. The volcano soil seems to be a better water storage than limestone.

A volcano island with rich vegetation – sounds like perfect conditions for a second “Galapagos“ where endemic species can develop, similar to the situation on e.g. Milos. However, Nisyros is just too young: If geologists are right, the whole island emerged less than 150 k years ago – a rather short period for the development of new species. Therefore, the interesting question on Nisyros is which species managed to populate the island since its genesis. Immigration is possible from other Aegean Islands as well as from the Turkish mainland.

There seems to exist very few herpetological literature about the island. However, the publication of CATTANEO (2006) turned out rather informative. He found nine reptile species on the island: Hemidactylus turcicus, Stellagama stellio, Blanus strauchi, Anatololacerta pelasgiana, Ophisops elegans (Snake-eyed Lizard), Ablepharus kitaibelii, Chalcides ocellatus (Ocellated Skink), Dolichophis caspius (Caspian Whip Snake) and Platyceps najadum – We encountered most of the mentioned species, but we didn’t find Chalcides ocellatus and Platyceps najadum. Hence, the island shows a typical Asia Minor species range. Actually, it is located east of the Mid Aegean Trench and therefore belongs to Asia (from a biological perspective).

Anatololacerta pelasgiana on Nisyros

On Rhodes, Anatololacerta pelasgiana is a common species which occupies a wide range of habitats: rocks, dry stone walls as well as gardens. As Nisyros has a lot of suitable habitats, we expected this species to be quite abundant here.

However, searching for this species turned out quite tricky: EISELT & SCHMIDTLER (1986) give a rather vague location (“in the volcano crater”) for this species. CATTANEO (2006) mentions the village Emporio. There, we searched twice but didn’t find any Anatololacerta. A travel blog finally provided the decisive hint: It showed a picture of Anatololacerta pelasgiana with the reference “Parletia” – We found out that “Parletia” is a rock formation in the southeastern part of the caldera. Exactly there, we finally came across these lizards. Remarkably, they only were encountered on big rock formations but they seem to avoid the omnipresent dry stone walls. Compared to Rhodes, this species seems to have quite narrow habitat preferences on Nisyros.

The population size on Nisyros can hardly be estimated. Although it seems to be rather rare in the areas we visited, additional populations could presumably occur in the rocky peak areas of the Profitis Ilias Mountain which we didn’t visit during our stay. Overall, our observations are just some “snapshots”; maybe this species is more abundant during early spring.

Towards the Mid Aegean Trench

The uninhabited volcano islands of Pergousa and Pachia are located about 5 km west of Nisyros, just at the Mid Aegean Trench – or more precisely: slightly east of it. Both islands have populations of Podarcis erhardii (Aegean Wall Lizard) which are quite remarkable:

1. It is the only case of a reptile species reported so far which has crossed the Mid Aegean Trench from west to east – usually, the MAT acts as a natural barrier which separates the European from the Asia Minor herpetofauna (LYMBERAKIS, 2010).

2. It is somehow strange that Podarcis erhardii managed to populate the small islets of Pergousa and Pachia but not the bigger nearby island of Nisyros.

3. Furthermore, it is surprising that the Pachia lizards seem to be closely related to the ones on Levitha Island, 70 km from Pachia (LYMBERAKIS, 2008). Apparently, the colonization started from there – and not from the much closer islands of Syrna or Astypalea.

The populations on Pachia and Pergousa haven’t been referred to any subspecies so far. But they probably belong to the group of the eastern Aegean deep water islands (like e.g. Astypalea). No pictures of these lizards have been publicly available before – a job for us! After a while we found a skipper who was willing to bring us to the islands. First, we visited Pergousa, a flat and easy accessible island, afterwards we went to Pachia, a steep island with rocky cliffs.

On Pergousa, Podarcis erhardii was abundant but extremely shy. Even in the early morning the fleeing distance was very high. The lizards were hectically running in between the thorny bushes – they seem to be rather ground-dwelling. Taking pictures of these critters was quite challenging.

Pachia has the easternmost known population of Podarcis erhardii. Also here, this species seems to be ground-dwelling. However, we were running out of time and our skipper became inpatient (and also the local colony of seagulls wasn’t very happy about our presence). Hence, our visit on this island was very short.

The lizards on these islands are an impressive example for the success story of Podarcis erhardii which seems to be able to populate even the most remote islet in the Aegean.

Conclusion

Within one week, we had visited some fantastic islands: Kastellorizo with its high biodiversity is always worth a visit. The little known island of Nisyros turned out to be a jewel of the Eastern Aegean, which still has a lot to discover – definitely a place we would like to come back!

Literature:

CATTANEO, A. (2006) - A contribution to the knowledge of the herpetofauna of the Aegean island of Nisyros (Dodecanese) - Il Naturalista Siciliano, Ser. IV, 30 (3-4): 485-494.

EISELT, J. & SCHMIDTLER, J.F. (1986) - Der Lacerta danfordi-Komplex (Reptilia: Lacertidae). - Spixiana, München, 9 (3): 289-328.

KALAENTZIS, K. & STRACHINIS, I. & KATSIYIANNIS, P. & OEFINGER, P. & KAZILAS, C. (2018) - New records and an updated list of the herpetofauna of Kastellorizo and the adjacent islet Psomi (Dodecanese, SE Greece). - Herpetology Notes, 11: 1009-1019

KARAKASI, D. & ILGAZ, C & KUMLUTA, Y. & CANDAN, K. & GÜCLÜ, Ö. & KANKILIC, T. & BESER, N. & SINDACO, R. & LYMBERAKIS, P. & POULAKAKIS, N. (2021) - More evidence of cryptic diversity in Anatololacerta species complex Arnold, Arribas and Carranza, 2007 (Squamata: Lacertidae) and re-evaluation of its current taxonomy - Amphibia-Reptilia (2021) DOI:10.1163/15685381-bja10045

KOTSAKIOZI, P.; JABLONSKI, D.; ILGAZ, Ç.; KUMLUTAS, Y.; AVCI, A.; MEIRI, S.; ITESCU, Y.; KUKUSHIN, O.; GVOZDIK, V.; SCILLITANI, G.; ROUSSOS, S.; JANDZIK, D.; KASAPIDIS, P.; LYMBERAKIS, P.; POULAKAKIS, N. (2018) - Multilocus phylogeny and coalescent species delimitation in Kotschy's gecko, Mediodactylus kotschyi - Molecular Phylogenetics and Evolution 125: 177-187

LYMBERAKIS, P.; POULAKAKIS, N.; KALIONTZOPOULOU, A.; VALAKOS, E.; MYLONAS, M. (2008) - Two new species of Podarcis (Squamata; Lacertidae) from Greece. - Systematics and Biodiversity, 6 (3): 307–318.

LYMBERAKIS, P. & POULAKAKIS, N. (2010) - Three Continents Claiming an Archipelago: The Evolution of Aegean’s Herpetofaunal Diversity - Diversity 2010, 2: 233-255.

PAYSANT, F. (2005) - Herpetological notes on the Island of Kastellorizo (South-east Aegean, Greece) - Herpetozoa 18 (1/2) Wien: 80-83