Prejeto / Received: 11.10.2011 Sprejeto / Accepted: 15.6.2012
Morphological evidence for the presence of the Danube Crested Newt, Triturus dobrogicus (Kiritzescu, 1903), in Slovenia
David STANKOVIČ1 & Teo DELIČ2
1	Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Groblje 3, SI-1230 Domžale, Slovenia; E-mail: david.stankovic@bf.uni-lj.si
2	Cesta 27. aprila 31, SI-1000 Ljubljana, Slovenia; E-mail: tejc86@gmail.com
Abstract. We offer preliminary reports on the presence of the Danube Crested Newt, Triturus dobrogicus, in Slovenia. This species reaches its western border of distribution in Hungary, Austria and Croatia, but untill recently it was not known from Slovenia. Here we report on the first record of this species in Slovenia, found in Dolinsko polje of the Prekmurje region during the herpetological surveys carried out in the spring of 2009 and 2010. The species identity was determined by coloration, body shape and the Wolterstorf Index values. Only with additional genetic analysis could we answer if this is a pure population or whether hybridisation with T. carnifex is present.
Key words: Triturus dobrogicus, Dolinsko polje, Slovenia, Wolterstorff Index
Izvleček. PRVA NAJDBA PANONSKEGA PUPKA, TRITURUS DOBROGICUS (KIRITZESCU, 1903), V SLOVENIJI - V bližini Slovenije je panonski pupek poznan iz Avstrije, Hrvaške in Madžarske. Spomladi 2009 in 2010 smo na Dolinskem polju v Prekmurju na podlagi vzorca obarvanja, oblike telesa in Wolterstorffovega indeksa prvič določili in zabeležili to vrsto v Sloveniji. V prispevku so predstavljeni preliminarni rezultati, medtem ko bodo za ugotovitev, ali je populacija iz Dolinskega polja čista ali pa se križa z velikim pupkom, potrebne nadaljnje genetske analize.
Ključne besede: Triturus dobrogicus, Dolinsko polje, Slovenija, Wolterstorfov indeks
The Crested Newt (Triturus cristatus) superspecies consists of closely related parapatric taxa, which are characterized by narrow hybrid zones and share a complex evolutionary history (Arntzen et al. 2007, Espregueira Themudo et al. 2009). The large-bodied Crested Newts differ both in genetic and morphological features (Wallis & Arntzen 1989). The most reliable features for morphological distinction of the taxa are the number of rib bearing vertebrae (RBV) and the Wolterstorff index (WI): length of forelimb x 100 / inter-limb length (Arntzen & Wallis 1999). Ivanovic et al. (2007) showed that the size and the shape of the head are not reliable characters for this group, especially as the skull of T. dobrogicus undergoes significant post-metamorphic changes.
NATURA SLOVENIAE 14(1): 23-29
Biotehniška fakulteta v Ljubljani in Nacionalni inštitut za biologijo, Ljubljana, 2012
In Slovenia, the only Crested Newt species recorded so far is T. carnifex (Poboljšaj 2003, Veenvliet & Kus Veenvliet 2008). T. dobrogicus is spread throughout the Pannonian Basin and, after a gap in the Iron Gates area, along the Danube floodplain and its tributaries, where it is found in oxbows, along river margins and other permanent water bodies, and can coexist with fish. It was recorded in close vicinity of the Slovenian border, both on the Austrian and Hungarian sides (Mayer 2001, Puky et al. 2005); in Croatia, the nearest records were made near the confluence of the Mura and Drava Rivers and south-east of Zagreb (Kalezic et al. 1990, Tvrtkovic 2006). However, there are examples in the literature where the presence of T. dobrogicus x T. carnffex hybrids has either been speculated or it could be concluded so from the data. First, »The IUCN Red List of Threatened Species« (Artzen et al. 2008) states that individual hybrids of T carnffex x T. dobrogicus occur in north-eastern Slovenia (Mura River). Secondly, Kalezic et al. (1990), Crnobrnja-Isailovic et al. (1997) and Kalezic et al. (1997) found a Crested Newt population in vicinity of Radenci (Turjanci) in north-eastern Slovenia that showed both RBV number (Crnobrnja-Isailovic et al. 1997) and WI values (Kalezic et al. 1990) that could be characteristic of either T. dobrogicus x T. carnffex hybrids or T. cristatus (Arntzen & Wallis 1999). However, it seems most improbable that the latter species would have been encountered in this area (Espregueira Themudo et al. 2009). Specifically for this population, the WI values for females span from just above the diagnostic threshold for T. dobrogicus, across the range characteristic for T. cristatus and into the lower half of the variation for T. carnifex, while WI values for males were well above the diagnostic threshold for T. dobrogicus and mostly in the range characteristic of T. cristatus and T. carnffex (the WI range for T. dobrogicus is < 54.0 for males and < 46.2 for females and for T. carnffex 63.7 -67.09 for males and 53.9 - 59.19 for females - Arntzen & Wallis, 1999). Also, Kalezic et al. (1997) studied both qualitative traits and morphometric characteristics of Crested Newts in the western Balkans and identified Radenci (Turjanci) populations as T. carnffex, they did not find significant differences in regard to other studied T. carnifex populations. Although morphological characters, especially when backcrosses are involved, are not necessarily intermediate in Triturus hybrids (Kalezic et al. 1997, Arntzen & Wallis 1999), this appears to be the case at least with the RBV count in T. carnffex x T. dobrogicus hybrid populations in the adjacent areas (Vedropolje, Croatia and Donja Čadjavici, Bosna and Herzegovina; Arntzen & Wallis 1999). Furthermore, there are known hybrid and pure T. dobrogicus populations in Austria near to Radenci (Mayer 2001). Therefore, the deviation of RBV count and the WI in Radenci population is either a result of hybridisation or can be attributed to intraspecific biological variation. Similar conclusions can be made for Žumberak and Slavonski Brod populations from Croatia (Kalezic et al. 1990, Crnobrnja-Isailovic et al. 1997, Kalezic et al. 1997).
During the herpetology surveys of the Prekmurje region, Slovenia, in the spring of 2009 and 2010, T. dobrogicus-ike specimens (Fig. 1) were recorded for the first time. The research area was limited to the eastern part of the Dolinsko polje, consisting of a floodplain forest, Murska Šuma, and adjacent swampy meadows. In this area, there are a few large and a number of smaller and shallower oxbows (Fig. 2). The area is typical sparsely inhabited Pannonian lowland. Newts were captured with dip nets and floating water traps and with torches at night. All specimens were released to the original sites of capture after measurements were taken. Material was identified based on chromatic and morphological characters indicated, mainly upon WI; inter-limb distance was measured excluding the extremities as recommended by Arntzen & Wallis (1994). The newts were anesthetized with MS 222 diluted to 0.3 % (Sigma-Aldrich, Vienna), photographed and measured on the site with 0.1 mm precision vernier calliper.
Figure 1. Male (left) and female (right) specimens of the Danube Crested Newt, T dobrogicus, from a small oxbow east
of the Muriša oxbow (Photo: Teo Delic). Slika 1. Samec (levo) in samica (desno) panonskega pupka, T dobrogicus, iz manjše mrtvice vzhodno od Muriše (Foto: Teo Delic).
Figure 2. A typical habitat of the Danube Crested Newt, T dobrogicus (Photo: David Stankovic). Slika 2. Habitat, značilen za panonskega pupka T dobrogicus (Foto: David Stankovic).
The body shape and the chromatic features taken into account were more characteristic of T. dobrogicus than T. carnffex. All specimens were lean built with short legs and had white-stippled sides, black to dark brown gular coloration with angular white spots and deep orange ventral surface with many small to medium sized sharply delineated black roundish black spots, which showed a tendency to unite longitudinally. By way of comparison, T. carnffex is a larger medium built newt with large legs and usually has yellow ventral colouration with few large roundish blurred and ill-defined blotches and spots (Arntzen & Wallis, 1999, Jehle et al. 2011). Measurements of WI and localities are presented in Tab. 1. In total, fifteen adult newt specimens from five sampling localities were collected. For thirteen specimens, the WI is within the known range of variation for T. dobrogicus, while two specimens had WI values just above and were identified as possible T. carnffex x T. dobrogicus hybrids; none of the individuals was classified as T. carnifex. All newts were either captured in floodplain woodland or oxbows, were they coexist with fish. T. carnffex populations in Slovenia rarely coexist with fish and are therefore almost never found in oxbows. T. carnffex populations from other parts of Prekmurje and the rest of Slovenia were studied quite intensely in the recent years in accordance with Natura 2000 implementation, and there are no reports on populations that were morphologically as distinct as this population from Dolinsko polje (Poboljšaj & Lešnik 2003, Cipot & Lešnik 2007, Lešnik & Cipot 2007).
Table 1. List of known localities inhabited by the Danube Crested Newt, Triturus dobrogicus(Tdob), and hybrids, Triturus dobrogicus x Triturus carnifex (Tdob x Tcor) from NE Slovenia with geographic coordinates, applied survey method and biometric data. WI diagnostic range for T. dobrogicus was taken from Arntzen & Wallis (1999).
Tabela 1. Seznam najdišč panonskega pupka, Triturus dobrogicus (Tdob), in križancev panonskega in velikega pupka, Triturus dobrogicus x Triturus carnifex (Tdob x Tcar) iz SV Slovenije z geografskimi koordinatami, metodo lova in biometričnimi podatki. Značilen razpon WI za T. dobrogicus je povzet po Arntzen & Wallis (1999).
Habitat type	Lat	Lon	Survey method	Sex	Length of forelimb [mm]	Inter-limb length [mm]	Wolter -storff index [%]	Determination based on WI
oxbow	46°28'56''	16°32'27	water trap	juvenile	11	24	45,83	Tdob
oxbow	46°29'14''	16°32'6''	water trap	male	16,5	31,9	51,72	Tdob
oxbow	46°29'14''	16°32'6''	water trap	male	14,9	28,5	50,17	Tdob
oxbow	46°29'40''	16°32'6''	water trap	female	15,4	38,5	40	Tdob
forest	46°30'1''	16°30'49''	torching	male	16,1	32,4	49,69	Tdob
forest	46°30'0''	16°30'41''	torching	male	15,3	29,7	51,52	Tdob
forest	46°30'0''	16°30'41''	torching	female	19,3	45,1	42,8	Tdob
oxbow	46°28'37''	16°34'23''	water trap	male	17,3	32	54,06	Tdob x Tcar
oxbow	46°28'37''	16°34'23''	water trap	male	17,3	35,1	49	Tdob
oxbow	46°28'37''	16°34'23''	water trap	male	23,1	45,4	50,88	Tdob
oxbow	46°28'39	16°34'52''	water trap	female	18,8	44,7	42,06	Tdob
oxbow	46°28'39	16°34'52''	water trap	female	20	49,1	40,73	Tdob
oxbow	46°28'39	16°34'52''	water trap	female	19,3	41,6	46,39	Tdob x Tcar
oxbow	46°28'39	16°34'52''	water trap	female	15,5	40,4	38,37	Tdob
oxbow	46°28'39	16°34'52''	water trap	female	20	48,5	41,24	Tdob
Based on chromatic and morphological characters, geographical characteristics and habitat type, we can conclude that the range of T. dobrogicus also extends into Slovenia, at least into Dolinsko polje. Further morphological (RBV) and genetic analyses on mitochondrial and independent nuclear loci are required to undisputedly determine if this population is a pure T. dobrogicus population or whether hybridisation with T. carnifex is present.
The Danube Crested Newt is a strictly protected species under the Bern Convention and furthermore listed as globally Near Threatened by the IUCN (2008) with an additional comment of being close to qualifying for Vulnerable. In Slovenia, T. dobrogicus is protected by the Decree on Protected Wild Animal Species Annex II Chapter B. This chapter lists animals that are not considered to be indigenous to Slovenia and their habitats are protected by law only, if they appear or expand to Slovenia without human interference. This is clearly the case with T. dobrogicus. The absence of records for T. dobrogicus in Slovenia does not indicate recent colonization or introduction by humans, but is more likely to be a consequence of a high degree of similarity with T. carnffex and inappropriate survey methods for this species (dip nets). T. dobrogicus is also protected by the EU Habitats Directive, where it is listed on Annex II and therefore requires designation of Special Areas of Conservation. This means that it is protected by the Directive only in designated Nature 2000 areas, while T. carnffex is also protected by Annex IV, which additionally provides protection outside those areas. Protection of their hybrids presents an interesting question and cannot be addressed similarly to the protection of Bombina bombina x B. variegata hybrids, where both parent species are listed only on Annex IV.
The importance of the first record of T. dobrogicus in Slovenia is even greater as this species inhabits habitats that are different from those of T. carnffex, which leads to different requirements for its successful conservation, protection and management. Apart from genetic analysis, we have to proceed with further investigation of the distribution of this amphibian and also re-evaluation of previous studies to determine whether its presence has been overlooked elsewhere in the Slovenian lowlands. If genetic analysis reveals that Dolinsko polje population is a hybrid population, it should still be protected by more strict measures of conservation and considered as Annex II species.
Povzetek
Spomladi leta 2009 in 2010 smo v Sloveniji prvič potrdili pojavljanje panonskega pupka (Triturus doborogicus). Panonski pupek je razširjen po Panonski nižini in poplavnem pasu Donave od Djerdjapa dolvodno, kjer naseljuje mrtvice, rečne rokave, struge počasi tekočih voda ter druga večja in trajnejša vodna telesa. V vodi se zadržuje dlje kot veliki pupek (Triturus carnifeX) in pogosteje sobiva z ribami. Od velikega pupka, ki je v Sloveniji sicer splošno razširjen, ga ločimo po relativno krajši dolžini nog, vitkejšemu telesu, manjši velikosti, večjem številu reber in vzorcu obarvanosti. Prve osebke te dvoživke smo našli v Murski Šumi in njeni bližini. Določili smo jih po vzorcu obarvanosti in obliki telesa - predvsem na podlagi Wolterstorffovega indeksa, to je razmerja med dolžino nog in dolžino trupa. Ker se veliki in donavski pupek lahko križata, zgolj na podlagi morfoloških podatkov ne moremo z gotovostjo trditi, da gre za populacijo čistih donavskih pupkov in da ne prihaja vsaj do občasnega križanja. Panonski pupek je zaščiten po Bernski konvenciji, na rdečem seznamu IUCN pa je označen kot potencialno ogrožena vrsta. V EU je zaščiten s Habitatno direktivo, kjer je uvrščen v Prilogo II, in nacionalno z Uredbo o zavarovanih prostoživečih vrstah. V tej Uredbi je uvrščen v Prilogo 2 Poglavja B, to je seznam v Sloveniji alohtonih vrst, katerih habitati pa postanejo zaščiteni, če se ta vrsta k nam razširi brez človeške pomoči. Če se izkaže, da v populaciji prihaja do križanja z velikim pupkom, jo vendarle velja zaščiti v skladu s Prilogo II Habitatne direktive.
Acknowledgements
The authors would like to express their thanks to David O'Brien from the Scottish Natural Heritage for kindly checking the English language.
References
Arntzen J.W., Bugter R.J.F., Cogälniceanu D., Wallis G.P. (1997): The distribution and conservation status of the Danube crested newt, Triturus dobrogicus. Amphibia-Reptilia 18: 133-142.
Arntzen J.W., Espregueira Themudo G., Wielstra B. (2007): The phylogeny of crested newts (Triturus cristatus superspecies): nuclear and mitochondrial genetic characters suggest a hard polytomy, in line with the paleogeography of the centre of origin. Contrib. Zool. 76(4): 261-278.
Arntzen J.W., Kuzmin S., Jehle R., Denoel M., Anthony B., Miaud C., Babik W., Vogrin M., Tarkhnishvili D., Ishchenko V., Ananjeva N., Orlov N., Tuniyev B., Cogälniceanu D., Kovacs T., Kiss I. (2008): Trtturus dobrogicus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.1. <www.iucnredlist.org>.
Arntzen J.W, Wallis G.P. (1999): Geographic variation and taxonomy of crested newts (Triturus cristatussuperspecies): Morphological and mitochondrial DNA data. Contributions to Zoology 68: 181-203.
Cipot M., Lešnik A. (2007): Dvoživke Krajinskega parka Goričko: razširjenost, ekologija, varstvo (Življenje okoli nas). Center za kartografijo favne in flore, Miklavž na Dravskem polju, pp. 16-17.
Crnobrnja-Isailovic J., Dzukic G., Krstic N., Kalezic M.L. (1997): Evolutionary and paleogeographical effects on the distribution of the Triturus cristatus superspecies in the central Balkans. Amphibia-Reptilia 18: 321-332.
Espregueira Themudo G., Wielstra B., Arntzen J.W. (2009): Multiple nuclear and mitochondrial genes resolve the branching order of a rapid radiation of crested newts (Triturus, Salamandridae). MPE 52: 321-328.
Ivanovic A., Vukov T.D., Džukic G., Tomaševic N., Kalezic M.L. (2007): Ontogeny of skull size and shape changes within a framework of biphasic lifestyle: A case study in six Triturus species (Amphibia, Salamandridae). Zoomorphology 126(3): 173-183.
Jehle R., Thiesmeier B., Foster J. (2011): The Crested Newt: A dwindling pond dweller. Laurenti-Verlag, Bielefeld, Germany, pp. 9-15.
Kalezic M.L., Džukic G., Mesaroš G., Crnobrnja-Isailovic J. (1997): The crested newt (Triturus cristatus superspecies) in ex-Yugoslavia: Morphological structuring and distribution patterns. Univ. Thought, Nat. Sci. 4: 39-46.
Kalezic M.L., Džukic G., Stamenkovic S., Crnobrnja J. (1990): Morphometries of the crested newt (Triturus cristatus complex) from Yugoslavia: Relevance for taxonomy. Arh. biol. nauka 42(1-2): 17-37.
Lešnik A., Cipot M (2007): Dvoživke Triglavskega narodnega parka: razširjenost, ekologija, varstvo (Življenje okoli nas). Center za kartografijo favne in flore, Miklavž na Dravskem polju, pp. 18-19.
Mayer W. (2001): Unterarten und Geschwisterarten. In: Cabela A., Grillitsch H., Tiedemann F. (Eds.), Atlas zur Verbreitung und Ökologie der Amphibien und Reptilien in Österreich: Auswertung der herpetofaunistischen Datenbank der herpetologischen Sammlung des naturhistorischen Museums in Wien. Umweltbundesamt, Wien, 880 pp.
Puky M., Schad P., Szövenyi G.M. (2005): Magyarorszag herpetologiai atlasza / Herpetological Atlas of Hungary. Varangy Akciocsoport Egyesület, Budapest, pp. 35-38.
Poboljšaj K. (2003): Dvoživke - Amphibia. In: Sket B., Gogala M., Kuštor V. (Eds.), Živalstvo Slovenije. Tehniška založba Slovenije, Ljubljana, 664 pp.
Poboljšaj K., Lešnik A. (2003): Strokovna izhodišča za vzpostavljanje omrežja Natura 2000: Dvoživke (Amphibia). Center za kartografijo favne in flore, Miklavž na Dravskem polju, pp. 41-48.
Tvrtkovic N. (2006): Veliki panonski vodenjak. Danube crested newt. / Triturus dobrogicus (Kiritzesku, 1903). In: Tvrtkovic (Ed.), Crvena knjiga vodozemaca i gmazova Hrvatske (Red Book of Amphibians and Reptiles of Croatia). Ministarstvo kulture, Državni zavod za zaštitu prirode, Zagreb, 94 pp.
Veenvliet P. & Kus Veenvliet J. (2008): Dvoživke Slovenije: priročnik za določanje. Zavod Symbiosis, Grahovo, pp. 44-45.
Wallis G. P., Arntzen J. W. (1989): Mitochondrial-DNA Variation in the Crested Newt Superspecies: Limited Cytoplasmic Gene flow Among Species. Evolution 43(1): 88-104.