Pliospalax, Kormos, 1932

Skandalos, Panagiotis, W., Lars & Ostende, Hoek, 2023, Wear-dependent molar morphology in hypsodont rodents: The case of the spalacine Pliospalax, Palaeontologia Electronica (a 47) 26 (3), pp. 1-20 : 3-4

Genus PLIOSPALAX Kormos, 1932

Type Species. Pliospalax macoveii (Simionescu, 1930)

Sarıca and Şen (2003) were the last to revise the Spalacinae . According to them, the mediumsized genus Pliospalax is characterized by four reentrant folds; two in the labial and two in the lingual side of the m1. In addition, the molar has a rounded anterior part and a weak mesolophid. The protosinusids of the m1 and m2 are shallow and form enamel islands, even in younger specimens. The m2 mesolophid is weak or absent. The protocone of the M1 is entirely incorporated into the anteroloph and a weak mesoloph may be present. The M2 anterocone is also fused with the anteroloph and the mesoloph is completely fused with the paracone, surrounding the mesosinus as an enamel island. The species included in Pliospalax are P. macoveii (Simionescu, 1930) ; P. compositodontus Topachevski, 1969 ; P. sotirisi (De Bruijn et al., 1970) , P. tourkobounensis De Bruijn and Van der Meulen, 1975 , and Pliospalax complicatus Şen and Sarıca, 2011 .

Pliospalax macoveii (Simionescu, 1930)

This species was described from the Romanian Pliocene locality of Mălușteni. Originally assigned to Prospalax by Simionescu (1930), it was selected as type species of Pliospalax by Kormos (1932). Topachevski (1969), in his research on the fauna from the USSR, considered Pliospalax synonymous to Microspalax , thus listing the species as M. macoveii . According to Topachevski (1969), the species lacks the mesoloph on the M1 and M2. The m1 of younger specimens have a free mesolophid that fuses with the metaconid in a later wear stage. In addition, the entoconid fuses with the posteroloph.

Pliospalax compositodontus (Topachevski, 1969)

The species was first described from the type locality of Andreevka (MN 13), in Ukraine (Topachevski, 1969). The Ukrainian spalacine was originally assigned to the genus Microspalax . Şen (1977) assigned the species to Pliospalax . However, later examination by the same author determined that some molars from Çalta had been mistakenly determined as P. compositodontus and they were in fact unworn m2 of P. macoveii . Finally, De Bruijn (1984), Sarıca and Şen (2003) and Şen and Sarıca (2011), assigned the species to Pliospalax .

Examining the occlusal surface of the molars, Topachevski (1969) distinguishes the species based on the well-developed mesoloph of the M1 which does not disappear throughout the different stages of wear. The mesolophid of the m1 is well developed, separated from the metaconid. The entoconid is not incorporated into the posterolophid (Topachevski, 1969).

Pliospalax sotirisi (De Bruijn et al., 1970)

The species was first described from the Greek locality of Maritsa (MN 14), on Rhodes island. De Bruijn et al. (1970) originally assigned the species to Spalax . However, five years after the first publication of the species, De Bruijn and Van der Meulen (1975) assigned the species to Pliospalax . The species is also known from the Greek locality of Samos (Vasileiadou and Sylvestrou, 2009). However, the latter assemblage is poor, comprising only three upper molars. In addition, Black et al. (1980) referred to P. cf. sotirisi an m2 and an m3 from the island of Samos. The mesosinusid of the m2 reaches the anterior border of the molar, and the anterosinus and the mesosinus of the M1 become enamel islands in a similar wear stage (De Bruijn et al., 1970).

Pliospalax tourkobouniensis De Bruijn and Van der Meulen, 1975

De Bruijn and Van der Meulen (1975) described Pliospalax tourkobouniensis from the Greek locality of Tourkobounia-1 (MN 16). The youngest of the Pliospalax species is characterized by the presence of a mesoloph on the M1 molar and traces of the posteroloph. In addition, in advanced wear stages of the m1, the protosinusid disappears and the mesosinusid becomes shallow. The sinusid does not reach the crown basis.

Pliospalax complicatus Şen and Sarıca, 2011

The latest described Pliospalax species, P. complicatus , comes from Amasya (MN 13), in Turkey (Şen and Sarıca, 2011). It is characterized by the fusion of the m1 anteroconid into the anterolophid. The metaconid is not part of the anterolophid and it connects with the anteroconid. The anterosinusid is present, the metalophulid is double and the protoconid does not have a posterior arm. The m1 has a well-developed mesolophid and M1 lacks the mesoloph. P. complicatus differs from all the species of Pliospalax by the presence of an anterosinusid on the m1 (Şen and Sarıca, 2011).