New species of the ground sloth Parocnus from the late Pleistocene-early Holocene of Hispaniola

Juan Almonte,Robert Mcafee,Renato Rimoli,Sophia Beery,Phillip Lehman,Siobhan Cooke

doi:10.18435/vamp29369

Abstract

Parocnus dominicanus sp. nov. represents a new species of megalonychid ground sloth from theAltagracia Province of southeastern Dominican Republic. Specimens of multiple individuals, including oneassociated partial skeleton, were recovered from two separate underwater caves in the Parque Nacional delEste through collaborations with museums and cave divers between 2009–2013. Parocnus dominicanus sp.nov. is distinguished by its small size compared to that of P. serus, with percent differences in limb elementlengths ranging from 13−24%. Numerous cranial and post-cranial elements also exhibit morphological characterstates that are not attributable to size variations. The recovery of multiple individuals within each localitydemonstrates a size dimorphism, possibly sexual, which parallels patterns exhibited by P. serus. The twospecies are also geographically distinct, with no examples of co-occurrence at any localities to date. Parocnusdominicanus sp. nov. and P. serus share character states that are distinct from those of the Cuban species, P.browni, and which suggest differential usage of the forelimb. The exact age of the specimens described here isunknown, however, Parocnus has been dated to the Holocene in Haiti.http://zoobank.org/urn:lsid:zoobank.org:pub:12E495D3-E261-4522-9854-D3B4C2D5FFB8

Highlights

Parocnus (Miller 1929) is currently known from Holocene deposits from two of the Greater Antilles islands, Cuba and Hispaniola (Steadman et al 2005)
The two species appear to be geographically isolated from each other, as specimens conforming to the size and morphology of P. dominicanus have only been found from Padre Nuestro and La Jeringa, and both localities are devoid of any specimens that could be attributed to P. serus
An argument could be made that P. dominicanus is a small sexual morph of P. serus, but that seems unlikely given that the known P. dominicanus localities have multiple individuals, making it unlikely that only smallest P. serus individuals were fossilized

Summary

Introduction

Parocnus (Miller 1929) is currently known from Holocene deposits from two of the Greater Antilles islands, Cuba and Hispaniola (Steadman et al 2005). The history of this genus is complex; various elements attributed to Parocnus have previously been assigned to a number of different genera and species. Initial descriptions of some Cuban specimens used the name Mesocnus (Matthew 1931), which is mostly viewed as a junior synonym (see White and MacPhee 2001). Some Parocnus elements have been attributed to Neocnus comes (Paula Couto 1967; White and MacPhee 2001). Regardless, the presently accepted taxonomy recognizes just two species of Parocnus: P. browni (Matthew 1931) of Cuba and P. serus (Miller 1929) of Hispaniola

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Discussion

Conclusion