Pseudobellatona relicta Topachevsky, Nesin & Topachevsky, 1993

Čermák, Stanislav & Rekovets, Leonid I., 2010, Early Pliocene ochotonids (Mammalia, Lagomorpha) from Southern Ukraine, Geodiversitas 32 (1), pp. 107-120 : 116-117

Pseudobellatona relicta Topachevsky, Nesin & Topachevsky, 1993 ( Fig. 2S )

MATERIAL EXAMINED. — One isolated left p3 (No. 37-2542) of brownish colour (the holotype and only known specimen).

LOCALITY. — Krasnopol (Odessa province, Ukraine); Early Pliocene (Ruscinian, MN 14) ( Fig. 1).

EMENDED MEASUREMENTS. — L × W of p3 is 1.56 × 1.69 (measurements of the specimen taken by the authors) compared with 1.65 × 1.90 after Topachevsky et al. (1993).

REDESCRIPTION

The only available hypselodont p3, without traits of conical structure, belongs to a medium-large sized ochotonid. The occlusal surface is wider than long, it is cut by proto- and hypoflexids; the paraflexid is absent – only a slight depression is visible on its anterolingual enamel wall. The top of the anteroconid is sharp and buccally moved. The protoflexid is long, narrow, and curved posteriorly; it reaches the longitudinal axis of the tooth. The hypoflexid is also narrow; it penetrates lingually half of the posteroconid width; in its distal part it is bent anteriorly.

COMPARISON AND REMARKS

In its general occlusal pattern, the tooth is somewhat similar to some advanced(non rooted) representatives of Sinolagomyinae , particularly to the Early-Middle Miocene species of the genus Bellatona Dawson, 1961 known from Central and Eastern Asia ( Dawson 1961; Erbajeva 1988; Zhou 1988; Qiu 1996). Nevertheless, the studied p3 sharply differs from them in its much longer and cemented protoflexid. The other p3 features (i.e. long and narrow hypoflexid, anteroconid with concave enamel walls and sharp tops) are much more developed and indicate a more advanced degree of evolution typical rather for the Pliocene species of Ochotoninae than for the Miocene clades of Sinolagomyinae .

In its buccaly situated anteroconid and little developed paraflexid, the specimen from Krasnopol also resembles Bellatonoides eroli Sen, 2003 known from the Early Vallesian (MN 9) localities 8A and 120 of the Sinap Tepe area ( Turkey) and B. kalfense known from the Vallesian (MN 9 or 10) locality Kalfa (see above for details). The former species of Bellatonoides differs from the specimen under study in its more developed paraflexid (in two specimens filled with cement, N = 6, loc. 8A of the Sinap Tepe) and in its rounded anteroconid (in two specimens its outline is rather triangular, N = 9, loc. 8A and 120 of the Sinap Tepe). The latter species, B. kalfense , differs from the Krasnopol ochotonid (in addition to above mentioned characters for Bellatonoides from Turkey) in its notably larger size (L of p3 is 1.65-2.15 sensu Lungu 1981).

Among the relevant Ochotona species, the studied specimen is the most similar to O. antiqua ; particularly in its size and anterior morphology of anteroconid. Nevertheless, it distinctively differs from this species in lacking the paraflexid of p3.

Most of the above discussed characteristics fit with those of the ochotonids, although based on the available material, the evaluation of their actual meaning is very difficult. In our opinion, this specimen cannot be attributed to Hypolagus (compare with Averianov 1998) because of its much smaller size, its much longer and narrower protoflexid (some extreme p3 morphotypes of Hypolagus from the Biharian of the Czech Republic possess similarly developed protoflexid; Čermák unpublished data), and its different morphology of the buccal part of hypoconid (compare with Dawson 1958; Averianov 1996; Fladerer & Reiner 1996; Fladerer & Fiore 2003). It is probable that this only available p3 from Krasnopol belongs to an aberrant individual of O. antiqua . In any case, its more precise taxonomic determination is still impossible.

In conclusion, based on the available combination of the all above discussed characters in the only available (type) specimen, it is not possible to unequivocally discriminate it from all other ochotonid genera/species and to attribute it to any taxonomic level lower than Ochotonidae clade sensu Sen (2003). Thus, we assign herein taxon Pseudobellatona relicta as incertae sedis within Ochotonidae clade sensu Sen (2003).

Figures

FIG. 2. — Morphology of p3 in studied ochotonids from the Early Pliocene (Early Ruscinian, MN 14) of southern Ukraine (Odesskaya Province):A-L, Ochotona antiqua Argyropulo & Pidoplichko,1939 from Novopetrovka (I, lectotype);M-Q, O. antiqua from Frunzovka-1; R, Ochotona sp. 1 from Frunzovka-1; S, Pseudobellatona relicta Topachevsky,Nesin & Topachevsky,1993 from Krasnopol (holotype). All teeth are figured as left specimens (A, C, K-M and P are reversed). Scale bar: 1 mm.