Abstract: Abundant fossil material of the genus Pliopentlagus from three localities representing the late Late Miocene through Late Pliocene in Auhui Province, China, are studied in morphological and statistical detail. Three species are recognized: Pl. huainanensis, Pl. dajushanensis sp. nov., and Pl. anhuiensis sp. nov., in decreasing age. Although a number of characters overlap among those species, if the specimens from each locality are treated statistically as populations, three species can be distinguished. Further, when they are arranged by their geologic age, they clearly show that average size increases, the ratio of EL in p3 decreases, the ratio of AER in p4–m2 decreases, the ratio of thin enamel band on the lingual face of the talonid in p4–m2 decreases, and the relative length of the palatal bridge decreases. Thus, these three species can be interpreted to represent a gradually evolving sympatric lineage, from the late Late Miocene through Late Pliocene. These three species of Pliopentalagus seem to have gradually evolved toward Pentalagus, but at least one character contradicts this idea, and the phylogenetic relationship between Pliopentalagus and Pentalagus may not be so simple.

摘要： 近年,作者在安徽淮南大居山陆续发现了数量很多的上新五褶兔化石,其中包括保存较完整的数十个头骨及上百个下颌骨,均产自新洞、无名洞及铁四局洞穴、裂隙堆积,分别记述为大居山上新五褶兔Pliopentalagus dajushanensis sp. nov.和安徽上新五褶兔Pl.anhuiensis sp. nov. 两新种。 淮南地区的晚新生代洞穴和裂隙堆积十分发育,其中常含有丰富的脊椎动物化石,而且在时、空分布上有一定的规律。区内洞穴和裂隙堆积垂直分布至少有6 个水平层,最高的第6层海拔高度为160 m(如大居山老洞),第5 层(如大居山新洞、无名洞)及第4 层(如大居山铁四局洞穴)的海拔高度分别为130 m 和90 m,属于新近纪,常含有丰富的上新五褶兔化石;第3 层为第四纪早期(如大居山西裂隙),未见上新五褶兔,代之出现丝绸兔(Sericolagus sp.),第2 层为中更新世(如大顶山西裂隙),出现野兔(Lepus sp.)。 迄今为止,安徽淮南地区共发现了3 种上新五褶兔化石,即淮南上新五褶兔Pl.huainanensis (金昌柱,2004)、大居山上新五褶兔Pl.dajushanensis sp. nov. 及安徽上新五褶兔Pl.anhuiensis sp. nov. ,至少涉及了3 个不同地质时期的动物群:一为Pl.huainanensis, Kowalskia neimengensis, Adcrocuta eximia 等代表的老洞晚中新世动物群,二为Pl.dajushanensis sp. nov.和Promimomys asiaticus 等代表的新洞早上新世动物群,三为Pl.anhuiensis sp. nov. 和Kowalskia yinanensis 所代表的晚上新世动物群。淮南地区发现的3 种上新五褶兔地史分布较连续,演化特征明显,它们构成上新五褶兔连续的进化系列。从晚中新世至晚上新世,淮南大居山上新五褶兔体型从小变大;p3 较原始的釉岛状后内褶沟逐渐向舌侧开放(晚中新世种Pl.huainanensis 的后内褶沟均为釉岛状,早上新世种Pl.dajushanensis 为83.9%,晚上新世种Pl.anhuiensis 为33.3%);p4- m2 的前外褶沟逐渐退化,其下跟座舌侧的釉质层越来越变细。 依性状分析,安徽发现的3 种上新五褶兔化石与日本琉球奄美黑兔(Pentalagus furnessi)具有密切的亲缘关系,但从日本奄美黑兔的p4- m2 完全缺失前外褶沟、颊齿褶沟釉质层的褶曲异常复杂等衍生性状看,上新五褶兔和奄美黑兔的系统演化关系较为复杂,尚有待发现更多早更新世的材料进一步探讨。