Changement taxonomique de Cordylus Cataphractus ...

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Cordylus Cataphractus > Ouroborus cataphractus (2011)

A recent revision of the genus by Ed Stanley et al in Molecular Phylogenetics and Evolution 58 (2011) 53 - 70. Between a rock and a hard polytomy: Rapid radiation in the rupicolous girdled lizards


Extrait de cet article:

Ouroborus gen. nov.

Type species (monotypic): Cordylus cataphractus Boie 1828, here designated.

Content: O. cataphractus (Boie 1828).

Etymology: The ouroborus is the symbol of a dragon biting or swallowing its own tail to form a circle, and refers to the characteristic defensive behavior of the type species, in which the tail is grasped in the mouth and the plated dorsum and spiny tail presented to attackers (hence the common name armadillo lizard). Latinized version of the Greek Image , oura – tail and boros – devouring. The word is masculine.

Definition: Body flattened to subcylindrical in cross-section, medium to large-bodied (maximum SVL 105 mm), robust. Limbs of moderate length, digits unreduced. Dorsal and scales greatly enlarged (in 15–17 transverse rows) and spinose, caudal scales forming large spines; six large keeled occipitals. Tongue darkly pigmented. Viviparous, giving birth to 1–2 young.

Distribution: Semi-arid regions of the western portions of the Western and Northern Cape provinces of South Africa.

The unusual defensive and social behavior displayed by these animals makes them highly distinctive members of the Cordylidae, leading Broadley (2006) to predict that Cordylus cataphractus would be placed in a monotypic genus. Analysis of the three nuclear genes recovers O. cataphractus near the base of the Cordylinae, along with the similarly robust, spinose genus Smaug. The association of spinose forms is further supported by the presence of tongue pigmentation in both genera (Lang, 1991) and a large diploid chromosome number that is shared by S. giganteus and O. cataphractus ([Olmo and Odierna, 1980] and [Odierna et al., 2002]). However, analysis of both the mitochondrial genes and the fully concatenated dataset returns Ouroborus as closely related to Karusasaurus, a relationship that has been recovered by previous studies (Frost et al., 2001; Melville et al., unpublished data). The conflicting positions of Ouroborus and Karusasaurus from the nuclear and mitochondrial DNA are consistent with an ancient hybridization event with subsequent mitochondrial introgression.



Sources :
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