Systematic revision and redefinition of the genus <i>Scirrotherium</i> Edmund & Theodor, 1997 (Cingulata, Pampatheriidae): Implications for the origin of pampatheriids and the evolution of the South American lineage including <i>Holmesina</i>

Abstract

The intrageneric relationships of the pampatheriid genus Scirrotherium and its affinities with supposedly related genera, i.e. Kraglievichia and Holmesina, are revised through parsimony phylogenetic analyses and new comparative morphological descriptions. For this work was analyzed unpublished material of pampatheriids (numerous osteoderms, one partial skull and a few postcranial bones) from Neogene formations of Colombia. The results show that Scirrotherium is paraphyletic if we include all its referred species, i.e. Scirrotherium hondaensis, S. carinatum and S. antelucanus. The species S. carinatum is closer to Kraglievichia paranensis than to S. hondaensis or S. antelucanus, then it is proposed the new name K. carinatum comb. nov. The relationships between S. hondaensis and S. antelucanus could not be resolved, so these species should be designated in aphyly. In spite of failing to recover S. hondaensis and S. antelucanus as one single clade, here is preferred to maintain the generic name Scirrotherium in both species from diagnostic evidence. New emended diagnoses for Scirrotherium, S. hondaensis and Kraglievichia are provided. The genus Holmesina was found monophyletic and located as the sister clade of Scirrotherium + Kraglievichia. The evolutionary and biogeographical implications of the new phylogeny and taxonomical re-arrangements are discussed. It is claimed a possible geographical origin of the family Pampatheriidae and Scirrotherium in low latitudes of South America as early as Early Miocene (Burdigalian) times. The South American ancestor or sister taxon of Holmesina is predicted as morphologically more similar to Scirrotherium than to Kraglievichia.