Pennatomys, Turvey & Weksler & Morris & Nokkert, 2010

Turvey, Samuel T., Weksler, Marcelo, Morris, Elaine L. & Nokkert, Mark, 2010, Taxonomy, phylogeny, and diversity of the extinct Lesser Antillean rice rats (Sigmodontinae: Oryzomyini), with description of a new genus and species, Zoological Journal of the Linnean Society 160 (4), pp. 748-772 : 758-759

GENUS PENNATOMYS GEN. NOV.

Type species: Pennatomys nivalis gen. et sp. nov. Etymology: From the Latin ‘ pennatus ’, winged or feathered, combined with ‘ mys ’, the standard suffix for mouse. In honour of Elizabeth S. Wing, to commemorate her extensive contributions to Caribbean zooarchaeology.

Diagnosis: Oryzomyine rodents with short and blunt nasals; dual articulation of lacrimal with maxillary and frontal; slightly convergent anterior interorbital region; subtle supraorbital crests; posterior margin of incisive foramen terminating immediately posterior to anterior margin of alveolus of M1; long bony palate (mesopterygoid fossa does not extend anteriorly between maxillary bones); well-developed capsular process in mandibular ramus; and single anterior masseteric crest. M1 with undivided anterocone and well-developed mesoloph, with anterior protocone– paracone crista; M2 without protoflexus, and mesoflexus with single internal fossette; M3 with developed mesoloph, but posteroloph absent or vestigial, and hypoflexus narrow and disappearing with moderate wear. m1 with enclosed anteromedian fossettids, but without anteromedian flexid; with small ectolophid and ectostylid. Mesolophid and mesostylid present, connected to entoconid by lingual cingulum. All lower molars with anterolabial cingula. M1–M3 with three alveolar roots, m1 with four roots (including accessory), m2 with three roots, and m3 with two roots. Additional morphological information is provided under the species description below.

Differences from other genera: From the available material, Pennatomys does not seem to possess any remarkable anatomical feature that is not also shared with other oryzomyines. The combination of several traits, however, differentiates this taxon from all other oryzomyines. Pennatomys displays three synapomorphies for a ‘ Nectomys ’ subclade within clade D of the Oryzomyini (see Weksler, 2006): absence of protoflexus and presence of single mesofossette on M2 ( Fig 10A, B ), and single anterior masseteric crest ( Fig. 10J ). Pennatomys can be differentiated from all other members of the Nectomys subclade, including Megalomys , by a combination of the following characters: dual articulation of the lacrimal with the maxillary and frontal (other taxa have major articulation with the maxillary), absence of accessory root on M1 (labial accessory root present in other taxa), and absence of posteroloph (posteroloph present in other taxa). Additional character differentiation among the three described oryzomyine taxa from the Lesser Antilles ( Pennatomys , Megalomys , and O. victus ) is shown in Table 2.

Figures

Figure 10. Maxillary and mandibular tooth rows and cranial elements of Pennatomys nivalis gen. et sp. nov. A–C, maxillary tooth rows. A, FLMNH-EAP 05270001 (St. Eustatius). B, NHM M 82456 (Nevis) (reversed for comparison). C, FLMNH-EAP 05270002 (St. Eustatius). D–G, mandibular tooth rows. D, NHM M 82452 (holotype: Nevis). E, NHM M 82460 (Nevis). F, FLMNH-EAP 05270003 (St. Eustatius) (reversed for comparison). G, FLMNH-EAP 05270004 (St. Eustatius) (reversed for comparison). H–I, maxilla, FLMNH-EAP 05270002 (St. Eustatius). J, mandible, labial view, FLMNH-EAP 05270003 (St. Eustatius). K, paired frontals, FLMNH-EAP 05270005 (St. Eustatius). Scale bars: 1 mm.