Hoplocercus Fitzinger 1843

Hoplocercus Fitzinger 1843

Proposed standard English name: weapontails

Proposed standard Spanish name: lagartijas de cola armorizada

Hoplocercus Fitzinger (1843:78). Type species (by monotypy): Hoplocercus spinosus Fitzinger; Boulenger (1885:199); Peters & Donoso-Barros (1970:148).

Pachycercus Dugès and Braconnier in Duméril (1854:558). Type species (by monotypy): Pachycercus aculeatus Dugès and Braconnier.

Definition. The most inclusive crown clade exhibiting a depressed, short tail (tail length <snout-vent length), with enlarged spiny scales dorsally and laterally, synapomorphic with that of Hoplocercus spinosus Fitzinger 1843.

Diagnosis. A depressed, short tail (tail length <snout-vent length), with enlarged spiny scales dorsally and laterally is unique to Hoplocercus among hoplocercines. Moreover, Hoplocercus differs from Enyalioides and Morunasaurus (character states in parentheses) in having the anterior opening of the Vidian canal on the ventral surface of the parabasisphenoid (anterior surface of the parabasisphenoid [dorsum sella] lateral to the sella turcica; Wiens & Etheridge 2003); a non-autotomic tail (autotomic; Etheridge 1967); slender and rounded sacral diapophyses (robust and flattened; Wiens & Etheridge 2003); and transverse processes of caudal vertebrae increasing in length from first to fourth caudal vertebra (decreasing in length throughout column; Wiens & Etheridge 2003). Hoplocercus can be further distinguished from Morunasaurus by having a parietal eye.

Composition. One currently recognized, extant species: Hoplocercus spinosus (Fitzinger 1843).

Remarks. Hoplocercus is the sister taxon of all other hoplocercines (i.e., Enyalioides and Morunasaurus), from which it is estimated to have diverged roughly 35 million years ago (Mean = 34.64; HPD = 28.04–41.67; Torres-Carvajal & de Queiroz 2009).