Lestodon armatus Gervais, 1855

Lestodon armatus Gervais, 1855

Referred material: Cranium: PIMUZ A/ V 491 ( Fig. 10 View Fig ); right mandible bearing four teeth, upper left jaw bearing four teeth, one tibia fragment, one phalanx, one rib: PIMUZ A/ V 492; two ribs and one mandible: PIMUZ A/ V 493 ( Fig. 11 View Fig ); one caniniform: PIMUZ A/ V 494.

Comment: Te genus Lestodon was exclusively diagnosed on the basis of cranial and dental characters with a U- or V-shaped nasal-frontal suture, a prezygomatic constriction, a snout roof consisting only of the nasal compared to other ground sloths (Bargo et al., 2006a), and a strong diastema separating the large triangular caniniform from the molariforms (Esteban, 1996; Pascual et al., 1966). Long considered highly diverse, Lestodon is now recognized as monospecific by containing the single species Lestodon armatus (Czerwonogora & Fariña, 2013) . PIMUZ A/V 491 corresponds to an almost complete cranium possessing all the diagnostic characteristics of the genus. Te strongly pronounced diastema is also found between the cf1 and the mf 1 in the mandibles of PIMUZ A/V 492 and PIMUZ A/V 493. Although the hemimandible of PIMUZ A/V 492 belongs to a particularly young specimen, a lateral widening at the front of the caniniform forms a large shelf clearly visible in the adult specimen PIMUZ A/V 493. Te latter has only triangular caniniforms while the three molariform ones are absent. Te alveolar cavity of mf3 is bilobate with an anterior lobe larger than the posterior; this dental shape is present in the last molariform in Lestodon (e.g., Varela et al., 2022). PIMUZ A/V 494 exhibits only the tip of a triangular caniniform that appears triangular in cross-section. Although the tooth is not complete, its size suggests it belonged to a small specimen highlighting the presence of a second juvenile of L. armatus in the Roth collection at PIMUZ. For each of the mentioned specimens, a reassignment to the genus Lestodon seems to correspond, even for the most fragmentary remains. I therefore propose a reassignment of these specimens to L. armatus . For this species, the major scientific interest lies in the completeness of the skull PIMUZ A/V 491 allowing analyses of the cranial shape but also to explore the endocranial structures, which are still unknown. Te presence of several well-preserved vertebrae also offers the possibility to functional studies on the axial skeleton of ground sloths. However, the most relevant specimens are the two juveniles in the Roth collection at PIMUZ because the morphological variation resulting from ontogeny is still poorly known for Lestodon .