Prodistylomys mongoliensis, Oliver & Carro-Rodríguez & López-Guerrero & Daxner-Höck, 2023

Oliver, Adriana, Carro-Rodríguez, Patricia M., López-Guerrero, Paloma & Daxner-Höck, Gudrun, 2023, A new framework of the evolution of the ctenodactylids (Mammalia: Rodentia) in Asia: new species and phylogenetic status of distylomyins, Zoological Journal of the Linnean Society 199 (3), pp. 633-655 : 641-643

Prodistylomys mongoliensis sp.nov.

Figs. 6-7 , Supporting Information Model S3

Zoobank registration: urn:lsid:zoobank.org:pub:BFCC9D7E-4122-4CF0-8523-9CE6C9CC5891 .

Distylomys / Prodistylomys sp. ( Höck et al. 1999: 118).

Distylomys sp. ( Daxner-Höck and Badamgarav 2007: 16, 18).

Prodistylomys nov. spec. 1 ( Oliver et al. 2017a: 61).

Prodistylomys nov. spec. 1 ( Daxner-Höck et al. 2017: 130, tab. 1, fig. 47k)

Etymology: The species name refers to Mongolia, the country where the new species was found.

Holotype: NHMW 2012 /0051/0001, Rightm2 ( Fig.6A ; ModelS3).

Paratype: HTE-012; NHMW 2012 /0051/0002-0006 ( Fig. 6B ) .

Type locality: Hotuliin Teeg (HTE-012).

Diagnosis: Large-sized species of Prodistylomys . Lower m2 with long metaflexid and posterolophid; upper M1 and M2 with metaflexus almost connected to the ectoflexus; M3 with a fossette.

Differential diagnosis: Prodistylomys mongoliensis sp. nov. differs from P. wangae , P. lii , and P. taatsinius by its larger size, m2 with metaflexid, and an M3 with a vertical fossette. Prodistylomys mongoliensis sp. nov. differs from P. xinjiangensis by its larger size and different proportions of the trigonid/talonid ( P. mongoliensis sp. nov. longer and wider trigonid than talonid; the opposite in P. xinjiangensis ).

Prodistylomys mongoliensis sp. nov. differs from P. mengensis by its larger size and upper molars, including M3 with a vertical fossette instead of a dentine isthmus.

Other fossil layers: HTE-003; NHMW2012/0052/0001-0002 ( Fig. 7 ).

Measurements: Table 4 .

Stratigraphic range: Early Miocene, Mongolian biozone D.

Geographical range: Valley of Lakes, Mongolia.

Description of the new material flom Hotuliin Teeg (HTE-012)

m1/m2: Bilophodont and hypsodont teeth. The specimens have two roots. The shape of the trigonid is fusiform (2/3) or rhomboidal, with the metaconid and protoconid narrower than the anterolophid (1/3). Both the metaconid and the protoconid are sharp. The trigonid is larger than the talonid in one (1/3) and smaller in two (2/3). The talonid is rhomboidal to subrhomboidal. The entoconid and the hypoconid are sharp. The mesoflexid and the ectoflexid are V-shaped, open, and deep. The metaflexid is deep.

M1/M2: The teeth are hypsodont and rooted with one root. There is cement in the flexus. The trigon is kidney shaped and larger than the talon. The mesoflexus is deep, almost connected reaching the lingual border of the teeth.

M3: The only specimen is broken in the posterior border. It is hypsodont and rooted, with two roots. The flexus is filled with cement. The trigon is kidney shaped, whereas the talon is semicircular. The flexus is closed and forms a fossette.

Remarks: Prodistylomys mongoliensis sp. nov. occurs in two samples of Hotuliin Teeg (HTE-012 and HTE-003) in the region of Taatsin Gol.

Figures

Figure 6. Prodistylomys mongoliensis sp. nov. from the type locality of Hotuliin Teeg, Valley of Lakes, Mongolia:(A) holotype of Prodistylomys mongoliensis sp. nov. from Hotuliin Teeg (HTE-012), (NHMW 2012/0051/0001). Right m2; (B) HTE-012 (NHMW 2012/0051/0002) M3 left. Left-side specimens are underlined. Scale bar: 1 mm.

Figure 7. Upper and lower cheek teeth of Prodistylomys mongoliensis sp. nov. from the Valley of Lakes (Mongolia). From Hotuliin Teeg: (A) HTE-003 (NHMW 2012/0052/0002) M1/2 right; (B) HTE-003 (NHMW 2012/0052/0001) m2 left. All teeth are at the same magnification.Right-side specimens are underlined. Scale bar: 1 mm.