Prodistylomys wangae Bi & Meng & Wu & Ye & Ni 2009, n. sp.
Creators: name: Bi, Shundong
name: Meng, Jin
name: Wu, Wenyu
name: Ye, Jie
name: Ni, Xijun
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Ctenodactylidae
Prodistylomys
Prodistylomys wangae

description: Prodistylomys wangae, n. sp.
Figure 8, table 1
HOLOTYPE: IVPP V16016.1, right fragmentary mandible with broken incisor and complete p4–m2.
REFERRED MATERIAL: IVPP V 16016.2, right M3; V 16016.3, left fragmentary mandible with broken i2–p4, and m1–m2; V 16016.4, right fragmentary mandible with broken i2 and p4–m2; V 16016.5, left m1.
LOCALITY AND AGE: Locality XJ200601 (47 ° 23.198 9 N, 86 ° 47.981 9 E) in Burqin County of Xinjiang, Suosuoquan Formation, early Miocene.
ETYMOLOGY: The species name, wangae, is in honor of our colleague, Wang Banyue, for her contribution to the study of distylomyids.
REPOSITORY: The specimens are stored in the collections of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing.
DIAGNOSIS: Slightly larger than P. lii and P. xinjiangensis. Differs from P. lii in having weak roots, thicker cement, rounded lingual apex of m1 trigonid, shorter talonid on m2. Differs from P. xinjiangensis in having thicker cement, rounded lingual apex of m1 trigonid, and the absence of the metaflexid on lower molars.
DESCRIPTION: The M3 trigon is semicircular in outline, with a straight posterior margin (fig. 8A). The enamel is very thick, becoming thinner on the posterior margin. The hypoflexus extends to the base of the crown and becomes shallower while approaching the base. The mesoflexus extends L of the height of the crown and is fused toward the base, suggesting a rudimentary root. On the contrary, in P. lii, both flexi are fused, showing a well-developed root. The talon is circular shaped, much narrower than the trigon.
The state of the masseteric crest is typical for the genus; the ventral crest is strong and extends under p4 and the dorsal crest is absent. The lower incisor extends posteriorly to underneath m3. The lower incisor is similar in its general morphology and microstructure to that of Distylomys burqinensis except that the pulp cavity is significantly smaller (fig. 5A, D).
The p4 is shorter than m1 (fig. 8C). The trigonid is much narrower than the talonid compared with that in P. lii and P. xinjiangensis and has a stout anterolophid. The anterolophid is blunt and lies well toward the labial side of the tooth rather than in the center. Only thin cement is present in the flexids. The talonid has a vestigial posterolophid.
Only m1 and m2 are preserved (fig. 8C; table 1). The lower molars are bilophodont, and hypsodont. The crown expands toward the base. The trigonid is subelliptical with a rounded anterior wall and a long axis oriented slightly anterolabial-posterolingually. The flexids are Ushaped with thin cement; the mesoflexid shallows but extends all the way to the base, and the hypoflexid extends down 2/3 of the height of the crown where it closes, indicating a rudimentary root (fig. 8B). The talonid is narrower than the trigonid, and is compressed with acute labial and lingual angles. The m1 and m2 are identical in crown morphology, but m2 is shorter than m1, and the lingual apex of its trigonid is more acute.
COMMENT: Although the Xinjiang specimens are very similar to Distylomys in crown morphology, the rudimentary roots of the cheek teeth, shorter trigonid and narrower talonid on lower molars, and thinner cement suggest that it is better to assign the specimens to the genus Prodistylomys rather than to Distylomys. P. wangae differs substantially from P. lii in showing a tendency to the loss of roots and subelliptical trigonid. It differs from P. xinjiangensis in the absence of the posterolophid (or metaflexid) and subelliptical trigonid.
description: Published as part of Bi, Shundong, Meng, Jin, Wu, Wenyu, Ye, Jie & Ni, Xijun, 2009, New Distylomyid Rodents (Mammalia: Rodentia) from the Early Miocene Suosuoquan Formation of Northern Xinjiang, China, pp. 1-20 in American Museum Novitates 3663 on page 13, DOI: 10.1206/665.1, http://zenodo.org/record/4735501