Mesocapromys sanfelipensis (Varona in Varona & Garrido, 1970 )

Viñola López, Lazaro W., Garrido, Orlando H. & Bermúdez, Alberto, 2018, Notes on Mesocapromys sanfelipensis (Rodentia: Capromyidae) from Cuba, Zootaxa 4410 (1), pp. 164-176 : 168-171

Mesocapromys sanfelipensis (Varona in Varona & Garrido, 1970)

San Felipe Hutia, Little Earth Hutia

Capromys sanfelipensis Varona en Varona & Garrido, 1970:3.

Capromys sanfelipensis Varona, 1974b:66 (subgen. Mesocapromys ). Mesocapromys (Paracapromys) sanfelipensis: Kratochvil et aI., 1978b:46. M [esocapromys]. sanfelipensis: Woods et al., 2001: 336 .

Mesocapromys sanfelipensis: Silva et al., 2007: 156 .

Referred material: An almost complete skull, very well preserved ( Fig. 3B and fig.4C). The specimen lacks the posterior portion of the parietal, most of the occipital, basioccipital, left temporal, and the left auditory bulla. Of the dentition, only the left fourth premolar is preserved. The specimen is currently deposited in Alberto Bermudez’s personal collection. (AB.d3000).

Locality and age: It was collected by Runel Riveron on July of 2015 in Salon del Cuervo, a cave room within Cueva del Indio, close to the town La Jaula, Municipality of San Jose de las Lajas, Mayabeque Province, western Cuba. Rojas et al. (2012) carried out an extensive paleontological study in this cave and made some interpretations about the origin and evolution of the deposit and the surrounding area, based on the taphocoenosis association and the stratigraphy of the deposit. Neotectonic and stratigraphic data, and ecological requirements of some of the species found (e.g. Cyanolimnas cerverai , † Grus cubensis , † Chelonoidis cubensis ) suggest the region was dominated by semideciduous forest and periodically inundated savannah during the Pleistocene-Holocene transition around 10 ka years ago. However, Rojas et al. (2012) did not report remains of Mesocapromys . The age proposed for the deposit was based on paleoecological association (see Rojas et al., 2007). Macroscopic and microscopic analysis of some fossils found in association to AB.d3000; shows great replacement and destruction of the original organic matrix by minerals during diagenesis, indicating it is not a good candidate for C-14 dating.

Description and comparison: The generic position of the specimen is beyond question ( Kratochvil et al., 1978; Silva et al., 2007). As mentioned by Varona in Varona & Garrido (1970), the only taxon with which M. sanfelipensis could be confused is M. auritus , but there are well-defined cranial characters that separate both taxa. The skull AB.d3000 is relatively larger than modern M. sanfelipensis and M. auritus while maintaining the same proportions observed in M. sanfelipensis with respect to the relationship between length vs. width of the premolar and length of the diastema vs. alveolar length of the molariform series. The skull is large and low in both species. The frontal is depressed in the interorbital region with the external edges curving upwards, forming well defined supraorbital crests and lacking the postorbital process. Narrow posterior npp are like modern M. sanfelipensis (in contrast to wide in M. auritus ) and lies at the same height of the nasals. The lower zygomatic root is of similar deep as in M. sanfelipensis , while shallower in M. auritus . The szr is wide as in M. sanfelipensis while almost absent or very narrow in M. auritus . The auditory bulla is relatively large, being nearly the length of the molariform series like modern M. sanfelipensis ( Varona & Garrido, 1970) . On the premolar, the hypoflexid meets the mesoflexid by preposition like in M. sanfelipensis , while the hypoflexid is separated from the mesoflexid in M. auritus ( Fig. 5 . The inferior edge of the zygomatic arch is slightly inclined interiorly, like in the San Felipe Hutia.

The morphology, size, and disposition of the basicranial foramina in M. sanfelipensis is highly variable ( Fig. 3 ) and overlies with the variation range of M. auritus (Silva et al., 2007) ; indeed, this character cannot be used to separate the two species as was assumed in the original description ( Varona & Garrido, 1970). The width of the basioccipital and the basisphenoid is also variable; in some skulls, both are wide ( Fig. 3a ) whereas in others are narrow ( Fig. 3b ). In the fossil specimen, the basisphenoid bone is narrower than the modern ones ( Fig. 4c ). The posterior edge of the palatine of AB.d3000 is nearly U-shaped and presents a middle spine, as in other recent specimens. The external edge of the palatine is also more open in modern skulls ( Fig. 4a ). The vertex of the anterior edge of the palatine is localized at the height of the limit between the 2nd and the 3rd molar, in modern specimens it can be found between the limit of the 2nd and the 3rd and the middle of the 3rd molar.

Ten of the seventeen measurements evaluated on the fossil skull are larger than on modern specimens ( Table 1). However, only 4 of them are 5% greater, the interorbital width (5.3%), the nasal width (8.9%), the premolar length (6.4%), and the alveolar length of the molariform (11.6%).

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Figures

FIGURE 3. Dorsal view of the skull of M. sanfelipensis (A) CZACC 1.198 holotype (♂), (B) AB.d3000 (fossil), and M. auritus (C) CZACC 1.189 holotype (♂).

FIGURE 4. Ventral view of the skull of Mesocapromys sanfelipensis (A) CZACC 1.198 holotype (♂), (B) CZACC 1.261 (♀), (C) AB.d3000 (fossil), and M. auritus(D) CZACC 1.189 holotype (♂). Notice in A and B the extreme variation in the size and disposition of the basicraneal foramina.

FIGURE 5. Occlusal view of the superior premolar of M. auritus (A) and M. sanfelipensis (B) Notice the gap between the hypoflexid and the mesoflexid (*)in M.auritus.