Wednesday, November 15, 2017

[Herpetology • 2016] Rhynchocalamus dayanae • An Integrative Systematic Revision and Biogeography of Rhynchocalamus Snakes (Reptilia, Colubridae) with A Description of A New Species from Israel

Rhynchocalamus dayanae
Tamar​, Šmíd, Göçmen, Meiri & Carranza, 2016
Dayan’s Kukri Snake  ||  DOI: 10.7717/peerj.2769 


The colubrid snakes of the genus Rhynchocalamus are seldom studied and knowledge of their ecology and life history is scarce. Three species of Rhynchocalamus are currently recognized, R. satunini (from Turkey eastwards to Iran), R. arabicus (Yemen and Oman), and R. melanocephalus (from the Sinai Peninsula northwards to Turkey). All are slender, secretive, mainly nocturnal and rare fossorial snakes. This comprehensive study is the first to sample all known Rhynchocalamus species in order to review the intra-generic phylogenetic relationships and historical biogeography of the genus.

We revised the systematics of Rhynchocalamus using an integrative approach and evaluated its phylogeography. The phylogenetic position within the Colubridae and the phylogenetic relationships within the genus were inferred using 29 individuals belonging to the three known species, with additional sampling of two other closely-related genera, Muhtarophis and Lytorhynchus. We analysed three mitochondrial (12S, 16S, cytb) and one nuclear (c-mos) gene fragments. Phylogenetic trees were reconstructed using maximum likelihood and Bayesian inference methods; the latter method also used to provide the first time-calibrated molecular phylogeny of the genus. We generated a nuclear network and carried out a topology test and species delimitation analysis. Morphological comparisons were used to differentiate among species and to describe a new species from Israel. The studied material was comprised of 108 alcohol-preserved specimens, 15 photographs, and data from the literature for the examination of 17 mensural, 14 meristic, and two categorical characters.

The molecular results support Rhynchocalamus as monophyletic, and as having split from its sister genus Lytorhynchus during the Late Oligocene. The three recognized species of Rhynchocalamus comprise four independently evolving groups. The molecular results reveal that the genus began to diverge during the Middle Miocene. We revealed that the best-studied species, R. melanocephalus, is paraphyletic. A population, formally ascribed to this species, from the Negev Mountain area in southern Israel is phylogenetically closer to R. arabicus from Oman than to the northern populations of the species from Israel, Syria and Turkey. Herein we describe this population as a new species: Rhynchocalamus dayanae sp. nov.

We identify four species within RhynchocalamusR. satunini, R. arabicus, R. melanocephalus, and R. dayanae sp. nov., the latter, to the best of our knowledge, is endemic to southern Israel. The onset of Rhynchocalamus diversification is very old and estimated to have occurred during the Middle Miocene, possibly originating in the Levant region. Radiation probably resulted from vicariance and dispersal events caused by continuous geological instability, sea-level fluctuations and climatic changes within the Levant region.

Figure 4: Habitus comparisons of Rhynchocalamus taxa. Dorsal view.
(ARhynchocalamus dayanae sp. nov. (unvouchered specimen; Road no. 40, near Mitzpe Ramon, Negev Mountain, Israel; photo by Simon Jamison); (B) R. melanocephalus (ZMHRU2007-69; Tartus, Syria; photo by Bayram Göçmen); (C) R. satunini (ZMHRU2015/0; Artuklu, Mardin province, Turkey; photo by Bayram Göçmen); (D) R. arabicus (CN4780; Wadi Ayoun, Dhofar Governorate, Oman; photo by Gabriel Martínez). 

Etymology. The specific epithet, “dayanae,” is named in honour of Professor Tamar Dayan, director of the Steinhardt Museum of Natural History at Tel Aviv University and curator of the Terrestrial Vertebrate Collection. This naming of the new species constitutes a special recognition of Professor Dayan by two of her former students (KT and SM) to acknowledge her immense contribution to the conservation of Israeli fauna, and her efforts in establishing the National Natural History Museum at Tel Aviv University, and in promoting taxonomy, conservation and ecology studies in Israel.

Karin Tamar​, Jiří Šmíd, Bayram Göçmen, Shai Meiri and Salvador Carranza. 2016. An Integrative Systematic Revision and Biogeography of Rhynchocalamus Snakes (Reptilia, Colubridae) with A Description of A New Species from Israel. PeerJ. 4:e2769. DOI: 10.7717/peerj.2769

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