Contributions to Zoology, 68 (3) ..-.. (1999)J. W. Arntzen; Graham P. Wallis: Geographic variation and taxonomy of crested newts (Triturus cristatus superspecies): morphological and mitochondrial DNA data
Discussion

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Taxonomy and phylogeny

The depth of the differences among taxa, and the relative sharpness of the contact zones led us to follow earlier suggestions to raise the taxa to full species status (Bucci-Innocenti, Ragghianti and Mancino, 1983) as have others (Frost, 1985). The available data, unfortunately, do not support a single phylogenetic hypothesis for the four taxa comprising the T. cristatus superspecies. RBV is primitively 14 in the genus Triturus (B. Lanza et al., in prep.), rendering RBV of 13 an autapomorphic character state for T. marmoratus and RBV of 15 - 18 a synapomorphic character state series for T. carnifex - T. cristatus - T. dobrogicus. This character alone would suggest that T. karelinii represents the oldest extant crested newt lineage, followed by T. carnifex, T. cristatus and T. dobrogicus. This evolutionary classification is supported somewhat ambiguously by the phenetic analysis of protein electrophoretic data (Crnobrnja, Kalezi’c and D’zuki’c, 1989) but contradicted by another such study (Litvinchuk et al., 1994). The phylogenetic analysis of molecular data (mtDNA RFLP’s) suggests a different phylogeny. Looking at the most-parsimonious mtDNA tree (Wallis and Arntzen, 1989: Fig. 4), a tree that optimizes RBV character-state change [tree : character structure

(MAR,PYG:13)/ancestor:14/(KAR?,KAR:14(CAR?,CAR:15(CRI:16,DOB:17,18)))]

involves moving only the ‘DOB’ branch (with terminal taxon number 11). [CAR? and KAR? refer to deeply differentiated haplotype lineages within T. carnifex and T. karelinii. We now recognize the first of these as belonging to T. carnifex macedonicus (see below) while the other will be subject to taxonomic description at the subspecific level (S. Litvinchuk et al., in. prep.)]. If DOB were placed with the T. cristatus (CRI) haplotypes, increased RBV becomes a derived character interior to the tree, with the more massive built newts basal. Although this haplotype tree has 70 steps as opposed to 67 in the published maximum parsimony tree (Wallis and Arntzen, 1989: Fig. 4), there is no bootstrap support above 50% for any of the crested newt species-level structure. That is to say, the relationship DOB(KAR(CAR,CRI)) is only defined by three synapomorphies in total and the tree could more conservatively be depicted as a four-way polychotomy at this level. This incomplete resolution is appreciated by Wallis and Arntzen (1989: 99) and emphasised by further analysis (Faith and Cranston, 1991; Faith, 1992). However, strong support is obtained from the ‘CAR’ and ‘CAR?’ mtDNA haplotypes for the sister taxon status of Italian and central Balkan crested newts. These groups of populations are also united by the synapomorphic character state RBV = 15. We therefore consider the crested newts from the central Balkan to belong to T. carnifex. The range of this species is disjunct (see below). Newts from both parts of the range are phenotypically distinct: T. carnifex from the western (Italian and Slovenian) part of the range typically have few, large, ill-defined black dots on the bellies, whereas T. carnifex from the eastern part of the range (F. R. Yugoslavia and Greece) have ventral coloration patterns with many sharp-edged spots, as Freytag (1988) observed, not unlike that of T. cristatus (Plates I-II). Crested newts of the eastern group were described as Molge karelinii var. macedonica Karaman, 1922. Considering the morphological and genetic differentiation between the forms, we propose raising this taxon to the subspecies level and, supported by phylogenetic arguments, classifying it as belonging to T. carnifex (not T. karelinii as suggested by Karaman, 1922). Therewith, Triturus carnifex var. albanicus Dely, 1959 is a junior synonym of T. carnifex macedonicus (Karaman, 1922). Following our correspondence with co-author J. Crnobrnja-Isailovi’c (J. W. Arntzen, in letter, 1996) this taxonomic solution is accepted by Kalezi’c et al. (1997), although the taxon is incorrectly referred to in feminine gender.

The two more massive newt species, T. karelinii and T. carnifex, show much greater restriction site variation than the other two species (Wallis and Arntzen, 1989). They also have slightly larger mitochondrial genomes and a greater tendency for insertions in the control region (Wallis, 1987). These factors suggest that the two northern species may have been subjected to long-term small population size during glaciations (Wallis and Arntzen, 1989), and it is conceivable that the evolutionary change in vertebral count is related to this population genetic feature.