SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE 191 Rediscovery of the Dice Snake N. tessellata inhabiting Croatian Adriatic Natrix tessellata (lAuRENTi , 1768), islands (cf. TóTH et al. 2006; SCHWEigER 2008, 2012; J Elić & l ElO 2011). For exam - from the island of krk, Croatia ple, for the island of krk there is only one voucher, a photograph of N. tessellata taken in spite of its natural occurrence and on April 10, 1985, by the herpetologist Mi - locally common presence in Croatia, the chael FRANZEN (cf. SCHWEigER 2008, 2012). Dice Snake Natrix tessellata (lAuRENTi , The latter author suggested that this speci - 1768), is rare or completely absent from men might be a successor from snakes intro - along most of its Adriatic coast ( JElić & duced by a reptilian dealer, who used to lElO 2011). Crucial factors for the snake’s release his surplus of unsold north Balkan presence in the region were thought to be reptiles on krk island every fall until the the availability of freshwater and concurrent early 1970s. However, regardless of the re - fish prey, which are particularly abundant cent intensive search by many field herpeto - more inland in the Dinarid karsts (e.g., logists including the authors of this paper, Plitvica lakes, Zrmanja river, krka river, no additional specimen of N. tessellata Baćina lakes, vrana lake near Zadar). could be found, and thus, this species was Thus, because of the scarcity of freshwater no longer considered part of the natural her - systems, previous published occurrences of petofauna on krk island. Dice Snakes on several Croatian islands or Figure 1 shows the positions of all pub - other areas along the Adriatic coast were lished record localities of N. tessellata on disputed ( JElić & l ElO 2011). Such litera - krk island. These include four sites: Suho ture records for N. tessellata refer to the Ričina, a watercourse near Baška (Fig. 2B; islands of Cres, krk and Prvić ( BRuNO 1980; BRuNO 1980, 1988; SOCHuREk 1985), the SOCHuREk 1985; F RANZEN 1987; M RŠić et Ponikve Dam (Fig. 2C; BRuNO 1980, 1988; al. 1989; SCHiMMENTi & F ABRiS 2000). Mis - SCHiMMENTi & F ABRiS 2000), the Jezero Dam identification and intentional introduction (Fig. 2D; BRuNO 1980) and a small marsh were further confusing the autochthony of near Miholjice south from Njivice in the Fig. 1: Outline map of the island of krk with all reported locations of findings of Natrix tessellata (lAuRENTi , 1768). Points A-E relate to the habitat pictures in Fig. 2. 192 SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE northern part of the island (Fig. 2E; FRANZEN nearest mainland (Crikvenica), but the 1987). However, the lack of vouchers, such island’s shortest distance to the mainland is as live or preserved specimens or photo - only 0.5 km at its northern tip. The speci - graphs to verify species identities for three men showed a conspicuous pale dorsal of those localities generated uncertainty ground coloration with dark spots (comp. about the accuracy of such information. e.g., JElić & l ElO 2011). More precise data SCHiMMENTi & F ABRiS (2000) alleged - about morphometrics and pholidosis was ly observed the mating behavior of N. tes - not recorded. After photographic documen - sellata on June 7, 1995, at the Ponikve Dam. tation, the specimen was released back to its They report simultaneous and frequent mat - locality. A subsequent survey of the stream ings of the grass Snake Natrix natrix area more than one year later on May 22-24 (l iNNAEuS , 1758), at the same site. The and June 4, 2013, yielded no additional Dice Snake observation might represent a specimens. Syntopic species of amphibians confusion with the helvetica morph of the and reptiles at the locality were: Pelophylax grass Snake, which superficially resembles ridibundus (P AllAS , 1771) , tadpoles of Bufo N. tessellata in its color pattern of gray dor - bufo (l iNNAEuS , 1758) , Podarcis siculus sum with black ish spots. However, the (RAFiNESquE -S CHMAlTZ , 1810) and Hier - authors were affiliated with institutes (uni - ophis gemonensis (lAuRENTi , 1768) . The versity and public aquarium) that deal with stream was well populated by Mullets most poikilothermic animals including reptiles probably Mugil cf. cephalus . The new and originated from a region (genova, italy) record of N. tessellata on krk confirms pre - that is home to both above and one more vious reports, thereby increaseing the num - species of the genus Natrix , rendering these ber of snake species of the local herpetofau - observers credible (also confirmed by v. na to a total of 11 (cf. SCHWEigER 2004, FABRiS , pers. comm.). BRuNO ’s (1980) and 2012 ). SOCHuREk ’s (1985) reports of N. tessellata interpretation of an isolated find of a gain credibility, as both authors are well single specimen is difficult and often specu - known experts of reptiles. However, BRuNO lative. As for the lack of information on a (1980) once uttered to intentionally publish reproductive population (and not just a wrong localities to promote others to search handful historical records of Dice Snakes), harder in those areas (cf. SCHWEigER 2012). N. tessellata may not belong to the perma - But in this case, we have no indication that nent fauna of krk. From an eco-biogeo - he has done so with his Dice Snake obser - graphical point of view, it may be interest - vation from krk island, and hence, include ing, that similar to N. tessellata , the Eastern his records on the plausible grounds that (i) Montpellier Snake Malpolon insignitus suitable habitat is available on the island (g EOFFROy DE ST-H ilAiRE , 1809), occurs on (pers. obs.), (ii) a few different records from the mainland and on the neighboring island krk island made by other authors corrobo - of Cres ( BRuNO 1980; T óTH et al. 2006), rate his finding, and (iii) there are records of whereas a viable population on krk was Dice Snakes from other, nearby islands (see never reliably confirmed. Single specimens below). observed on that island were classified On September 28, 2011, at 15:45 h, an introduced ( SOCHuREk 1985; S CHWEigER adult specimen of N. tessellata (Tl approx. 2012). Surprisingly, a recent field expedi - 60 cm, Fig. 3) was found by one of the tion rediscovered three Dice Snakes on the authors (Mk) in the channelized stream veli inland freshwater lake vrana on Cres Potok (Fig. 2A) in the north-eastern part of island ( BuRić & B AŠkiERA in press), indi - this island. Air temperature was 20 °C. The cating the presence of a natural population stream flows into the gulf of Soline in an there. area known as Meline, situated between the The origin of the individual reported villages of Čižići and Soline (45.14906 N, here from krk remains unclear and the 14.59949 E; 0-1 m a. s. l.). The stream bed question about any permanent, reproductive consists largely of stones, but bank and bed population unanswered. The bright col - become more muddy upstream of the estu - oration of the new specimen is typical to ary. The locality is approx. 7 km from the Dice Snakes from along the northern Dal - SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE 193 Fig. 2: Habitats of Natrix tessellata (lAuRENTi , 1768) at current and historical finding locations on the island of krk. A - Part of the veli potok stream, where the new record of N. tessellata comes from (photographed on May 24, 2012; photo: M. kuDlÁČEk ); B - Suho Ričina (photographed on June 3, 2013); C - Ponikve Dam (photographed on May 25, 2012); D - Jezero Dam (photographed on June 6, 2013); E - Marsh near Miholjice (photographed on May 18, 2007). Photos B−E: P. vlČEk . matian coast (e.g., JElić & l ElO 2011), and i.e., directly introduced or a successor of thus hints at a regional origin. The newly specimens introduced in the past, or (ii) found specimen is either (i) allochthonous, autochthonous, i.e., a natural immigrant or 194 SHORT NOTE HERPETOZOA 27 (3/4) Wien, 30. Jänner 2015 SHORT NOTE Fig. 3: The specimen of Natrix tessellata (lAuRENTi , 1768) from the veli Potok watercourse on the island of krk, found on September 28, 2011. Photo: M. kuDlÁČEk . member of a local indigenous population. malnutrition or lack of proper hibernation Although deliberate release even of allo - sites. This could explain their apparent rari - chthonous reptiles on krk that may include ty on the island. Furthermore, frequent trans - Dice Snakes, cannot be doubted ( SCHWEi- marine dispersal would require a healthy gER 2012), no visibly sustainable population source population on the nearby mainland. of N. tessellata appears to have developed Such are not known, and the coastal stretch since, although successful introductions are on the mainland next to krk island provides known from elsewhere in Europe (e.g., little quality habitat for N. tessellata with no MEBERT 2011 b; O BST & S TRASSER 2011; records to date ( JElić & l ElO 2011). TROBiSCH & gläSSER -T ROBiSCH 2011). However, with a closer look at the vis- The potential for autochthony of N. à-vis coast using satellite and Panoramio tessellata on krk island is likely to exist, as images (googleEarth), the authors perceived this species exhibits remarkable migratory a few small mainland water courses, where abilities, resulting in a dynamic and fast col - still undetected N. tessellata may exist in onization of suitable habitats and subse - low numbers. For example, the town quent rapid population growth (e.g., BENDEl Crikvenica provides potential habitats at the 1997; B AHA El DiN 2011; M EBERT 2011b, stream Dubračina and its upstream widen - 2011c; STRugARiu et al. 2011; vElENSký et ing, lake Tribaljsko. The mouth of the river al.