2009年 第47卷 第1期:81~84
ON TATALSMINTHUS (DIPODIDAE, RODENTIA)
摘要：Tatalsminthus was established by Daxner-H？ck(2001) based on the specimens collected from Early Oligocene Hsanda Gol Formation of Valley of Lakes in Mongolia. Having compared the specimens of Tatalsminthus with those of the other dipodid genera in Asia (Prisminthus, Banyuesminthus, Allosminthus, Heosminthus, Sinosminthus, Shamosminthus, Parasminthus, Heterosminthus and Litodonomys), the author found that Tatalsminthus was generically different from the 7 genera (Prisminthus, Heosminthus, Sinosminthus, Shamosminthus, Parasminthus, Heterosminthus and Litodonomys) in tooth features indeed, as mentioned by Daxner-H？ck, however, not so clearly from Allosminthus as Daxner-H？ck thought. Daxner-H？ck (2001:361) stated:“It(=Tatalsminthus) differs in the protoloph II(M1) and metalophid I(m2)from Allosminthus.” In her description both the protoloph II of M1 and metalophid I of m2 of Tatalsminthus are complete. Wang pointed out as early as in 1985 (pp.356, 359) that the metalophid I of m2 of Allosminthus varied from absent to complete. While synonymizing Banyuesminthus with Allosminthus, Wang(2008:22) indicated further that the protoloph II of M1 in Allosminthus also varied from absent to complete. This blurs the distinction between Allosminthus and Tatalsminthus.Tatalsminthus thus to be considered as a junior synonym of Allosminthus.
Nevertheless, Daxner-H？ck’s A.khandae should be a valid species of Allosminthus, since it differs from all the other four known species of Allosminthus in some features. It differs from A.ernos, A.majusculus, A.diconjugatus, A.uniconjugatus in lacking metalophid II on m2-3; from A.ernos, A.diconjugatus, A.uniconjugatus in having more developed mesoloph, often joining with postero-external crest of paracone on M1-2; from A.ernos and A.uniconjugatus in having complete protoloph II on M1; from A.ernos in having mesostyle on M1-2 and metaloph joining with hypocone on M1; from A.majusculus, A.diconjugatus and A.uniconjugatus in being smaller in size; from A.diconjugatus and A.uniconjugatus in having complete metalophid I on m2-3. Now, Allosminthus is composed of 5 species.
Among the distinguished features of A.khandae from other four species, excepting for the smaller size and no metalophid II on m2, most of features are advanced ones. It seems that A.khandae may represent an advanced species in Allosminthus.