| Gallotia galloti gomerae BISCHOFF, 1985 Gallotia simonyi gomerana HUTTERER, 1985 Gallotia simonyi bravoana HUTTERER, 1985 Gallotia gomerana HUTTERER, 1985 |
| Taxonomie und Nomenklatur der Gomera-Rieseneidechse sind nach wie vor in Diskussion. HUTTERER beschrieb 1985 zwei unterschiedliche Taxa der Gattung Gallotia nach subfossilem Material: G. goliath bravoana und G. simonyi gomerana. Bald nachdem 1999 rezente Vertreter einer großen Eidechsenform entdeckt worden sind, begann die bis heute anhaltende Diskussion, welcher der beiden verfügbaren Namen nun anzuwenden sei. Bereits 1998 war BISCHOFF davon ausgegangen, dass die beiden fossilen Taxa identisch wären und zu G. simonyi zu stellen wären. Er synonymisierte sie unter dem Namen G. simonyi bravoana. Andere Autoren kamen aber anhand morphologischer Vergleiche zu dem Schluss, dass es subrezent drei in ihrer Größe stark unterschiedliche Gallotia-Arten (G. caesaris, G. simonyi und G. goliath) auf La Gomera gegeben haben müsste und dass die rezente große Art wohl identisch sei mit G. simonyi gomerana. Allerdings vertraten NOGALES et al. (2001) die Auffassung, dass diese Form wegen Unterschieden in der äußeren Morphologie (Pholidose und Färbung) als von G. simonyi distinkte Art, G. gomerana, zu betrachten sei. Schließlich fanden sich G. goliath bravoana zuordenbare mumifizierte Gewebereste, die sich als genetisch identisch mit der rezenten Form erwiesen, es also auch in Vergangenheit nur zwei Arten auf der Insel gegeben hat (MATEO et al. 2011). Genetische Untersuchungen (siehe COX et al., 2010) zeigten, dass die Unterschiede zu G. simonyi in der selben Größenordnung liegen wie zwischen solchen Formen der Kanareneidechsen, die als Unterarten gelten (G. caesaris / gomerae und G. galloti / eisentrauti / palmae) und sogar deutlich kleiner sind als zwischen G. a. atlantica und G. a. mahoratae, was ihre Wertung als eigenständige Art gründlich in Frage stellt!
WERNER MAYER, 2015 |
Hutterer, R. (1985) - Neue Funde von Rieseneidechsen (Lacertidae) auf der Insel Gomera. - Bonner zoologische Beiträge, Bonn, 36 (3/4): 365-394.   × To date little is known about Gigant lizards from Gomera. Old reports that had partly been incorrectly by subsequent authors, have been studies and are critically discussed here. – The author collected new fossil material on Gomera since 1981. He discovered several sites of presumably Pleistocene age one about 500 years old prehispanic site. Comparative material was collected on Hierro and Tenerife and was also available from various collections. – The lizard genus Gallotia is reviewed with regard to osteological characters useful for the identification of species. Six species, galloti, atlantica, simonyi, stehlini, goliath and maxima are treated. – The fossil remains of lizards from Gomera are described. They represent three species assigned to Gallotia goliath (Mertens, 1942; type locality Puerto de la Cruz, Tenerife), Gallotia simonyi (Steindachner, 1889; type locality Zalmor Rock, Hierro) and Gallotia galloti (Oudart, 1839; type locality Güimar, Tenerife). However, they differ from the known forms in size or characters. Therefore two new subspecies are described from Gomera: Gallotia goliath bravoana subsp. n. and Gallotia simonyi gomerana subsp. n. – The new materal proves sympatry and contemporaneous existence of three Gallotia species on Gomera during the Pleistocene. G. simonyi was also found in a prehispanic site documenting its existence 500 years ago. This record supports the statement by v. Fritsch (1870), who reported sight records of large lizards, possible G. simonyi, in the 19th century, also on Gomera. It is therefore possible that the large G. simonyi, too, has survived and may be still alive somewhere on Gomera today. Nogales, M. & Rando, J.C. & Valido, A. & Martin, A. (2001) - Discovery of a living giant lizard, genus Gallotia (Reptilia:Lacertidae), from La Gomera, Canary Islands. - Herpetologica, 57: 169-179.  × We describe the external morphology of a new giant lizard found alive on La Gomera Island (Canarian Archipelago), which had been previously described from subfossil bones. Adult size (SVL 135-190 mm) is comparable with the two largest living species (G. simonyi and G. stehlini) of the genus. It differs from the other species of Gallotia in the low number of temporal scales (21-27), presence of one elongate interprefrontal scale (linearly depressed in center) that is very infrequent in most of its congeners (small when it is present), having two distinctive lateral lines of small blue spots, and in having a blackish-brown dorsum and ventral parts ivory white. According to subfossil data, based on tooth morphology and body size, this lizard seems to correspond to the putatively extinct subspecies (G. simonyi gomerana). This taxon is sufficiently distinct to be treated as a full species, G. gomerana. Molecular data analysis from mtDNA sequences (cytochrome b and 12S rRNA) indicate that G. gomerana is closely related to G. simonyi and G. intermedia. After prospecting 70 localities in La Gomera, we only found a very small and threatened population of this species in Valle Gran Rey, in the western part of the island and living in an area of less than 1 ha. A small population size (only six individuals are known) and a large number of feral cats in their habitat makes this lizard the most endangered vertebrate of the Canaries and Europe and one of the most threatened in all the world. The species is suspected to be on the brink of extinction, so conservation measures are urgently needed, including a captive breeding plan at Valle Gran Rey, close to the natural habitat. Cox, S.C. & Carranza, S. & Brown, R.P. (2010) - Divergence times and colonization of the Canary Islands by Gallotia lizards. - Molecular Phylogenetics and Evolution, 56 (2): 747-757. × The Canary Islands have become a model region for evolutionary studies. We obtained 1.8 Kbp of mtDNA sequence from all known island forms of the endemic lizard genus Gallotia and from its sister taxon Psammodromus in order to reanalyze phylogenetic relationships within the archipelago, estimate lineage divergence times, and reconstruct the colonization history of this group. Well-supported phylogenies were obtained using maximum parsimony and Bayesian inference. Previous studies have been unable to establish the branching pattern at the base of the tree. We found evidence that G. stehlini (Gran Canaria) originated from the most basal Gallotia node and G. atlantica from the subsequent node. Divergence times were estimated under a global clock using Bayesian Markov Chain Monte Carlo methods implemented by three different programs: BEAST, MCMCTREE, MULTIDIVTIME. Node constraints were derived from subaerial island appearance data and were incorporated into the analyses as soft or hard maximal bounds. Posterior node ages differed slightly between programs, possibly due to different priors on divergence times. The most eastern Canary Islands first emerged just over 20 mya and their colonization appears to have taken place relatively quickly, around 17–20 mya. The subsequent node is consistent with cladogenesis due to colonization of Gran Canaria from the eastern islands about 11–13 mya. The western islands appear to have been colonized by a dispersal event from Lanzarote/Fuerteventura in the east to either La Gomera or one of the ancient edifices that subsequently formed Tenerife in the west, about 9–10 mya. Within the western islands, the most recent node that is ancestral to both the G. intermedia/G. gomerana/G. simonyi and the G. galloti/G. caesaris clades is dated at about 5–6 mya. Subsequent dispersal events between ancient Tenerife islands and La Gomera are dated at around 3 mya in both clades, although the direction of dispersal cannot be determined. Finally, we show that G. galloti is likely to have colonized La Palma more than 0.5 Ma after emergence of the island 1.77 mya, while G. caesaris from the same clade may have colonized El Hierro very soon after it emerged 1.12 mya. There are tentative indications that the large-bodied endangered G. simonyi colonized El Hierro around the same time or even later than the smaller-bodied G. caesaris. This study demonstrates the effectiveness of Bayesian dating of a phylogeny in helping reconstruct the historical pattern of dispersal across an oceanic archipelago. Mateo, J.A. & Crochet, P.-A. & Afonso, O.M. (2011) - The species diversity of the genus Gallotia (Sauria: Lacertidae) during the Holocene on La Gomera (Canary Islands) and the Latin names of Gomeran giant lizards. - Zootaxa, 2755: 66-68.
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