Desmana sp.

Rzebik-Kowalska, Barbara & Rekovets, Leonid I., 2016, New data on Eulipotyphla (Insectivora, Mammalia) from the Late Miocene to the Middle Pleistocene of Ukraine, Palaeontologia Electronica 12 (1), pp. 1-31 : 8-12

Desmana sp.

Figures 4.1-4.7 , 5.1-5.6 , 6.1

Material. Verkhnya Krynitsa 1 (early MN 16), the left?I2 and a fragment of the right mandible damaged in its anterior and lower side (without process) with damaged p4. MNI = 1. Catalogue number 29/1/4. Popovo 2 (late MN 16), left C, left P2, left P4, right M1, left?i3, left?p2, two left m3 (one damaged). MNI = 2. Catalogue number 29/II/ 4. Popovo 1 ( MN 16/ MN 17), left M1, fragment of right mandible with m1 – m3, left m1. MNI = 1. Catalogue number 29/I/4.

Description. According to Rümke (1985, p. 44) in the genus Desmana “it is difficult, often even impossible, to distinguish the I2 from the I3.” The tooth from Verkhnya Krynitsa 1 is most likely the I2 ( Figure 4.1-2 ). The cross-section of its crown is elliptical, the buccal side is convex and the lingual side is flat. The cusp is situated more or less in the middle of the crown. Two medial crests start from its tip: the posterior crest (the posterocrista) is longer and sharper. The buccal side is surrounded by a wide and flat cingulum. The root of the tooth is straight and heavy. The C ( Figure 4.3-4 ) is also elliptical with one high cusp situated more or less in the center of the crown. The anterocrista is slightly shorter and steeper than the posterocrista which is also longer. The buccal side of the crown is slightly convex, the lingual side almost flat. The wide and flat cingulum is visible on its lingual side. Small cingular bulges are present on the anterior and posterior sides of the tooth. There are two rather heavy and divergent roots. The P2 ( Figure 4.5 ) is fixed in a small part of the jaw. It is relatively large and its crown is sturdy. It is wider posteriorly than anteriorly. The crests running from the tip of the cusp are not very sharp. The buccal side of the crown is convex, the antero-lingual rather flat and postero-lingual concave. The anterior and posterior ends of the crown are rounded. A wide and protruding cingulum runs around the crown except for the short buccal part between the roots. The tooth has two heavy, divergent roots. The P4 ( Figure 4.6 ) has a sub-triangular outline. The antero-buccal and antero-lingual sides are convex, the postero-buccal and postero-lingual parts are concave. The paracone anterocrista is obtuse, the parastyle is not large. The posterocrista bends slightly to the buccal side and forms a small cusp, namely the metacone. The protocone is well individualized and separated from the paracone by a valley: small and shallow in the anterior and large and deep in the posterior part of the tooth. The hypocone is a clear cusp situated posteriorly to the protocone. The wide and protruding cingulum surrounds the tooth except for the protocone. The postero-lingual cingulum bears a small cuspule, the hypocone. The tooth has three roots. The M1 ( Figure 4.7 ) has a deeply divided mesostyle, well individualized parastyle separated from the paracone by a valley and connected to the protoconule by a short crest. The accessory cusp is situated between the protocone and metaconule (?hypocone). The tooth has part of the anterior (between the paracone and protoconule), antero-labial and posterior cingula. The postero-labial cingulum is damaged. The root part of the tooth is damaged and only a trace of one root is present.

The crown of?i3 ( Figure 5.1-2 ) is low and strongly asymmetrical. Its buccal side is narrow and almost flat, the lingual one is wide and concave. Only the tip of the cusp is inflated. The antero and posterocristids are blunt. The anterior, lingual and posterior cingulids are present. The tooth has one root. The?p2 ( Figure 5.3-4 ) is damaged on its tip of the cusp as well as in the postero-lingual side which was rather concave. It has an elliptical cross-section. It is rather stout with its buccal side convex and its antero-lingual side flat. Its only cusp is situated in the middle of the crown, and its anterior crest is moderately sharp. The tooth is pointed towards the anterior and rounded in the posterior sides. The cingulid is well developed, more protruding in the anterior than in the postero-buccal side. There are two rather heavy roots. The small p3 is completely damaged. It has one root. The p4 is a heavy compact tooth. Its postero-lingual side is damaged. The damaged talonid was rather narrow, open on its buccal side. The buccal side of the tooth is strongly convex, the lingual side less convex. As the posterocristid is also damaged, the presence of a metaconid cannot be confirmed. The tooth has anterior, lingual and posterior (partially damaged) protruding cingulids (the buccal one is damaged). It has two heavy rounded roots. The lower molars m1–m3 ( Figure 6.1 ) are typical for desmans. They are heavy and have sturdy obtuse cusps. Their oblique cristids are long and end near the tip of the metaconid. Their cingulids are wide. In the m1 ( Figure 5.5 ) and m2 they are present on anterior, buccal and posterior sides. On the m3 ( Figure 5.6 ) the cingulid occurs on the anterior and buccal sides reaching the protoconid/hypoconid valley. In the m2 and m3, the anterior cingulids widens in the antero-lingual corner and forms a kind of parastylid. The entostylid is present in the m1 and m2. The teeth have two heavy roots.

Measurements. See Tables 3 and 4.

Systematic Position and Distribution. The identification of Desmana species is difficult because some of their diagnoses are based on the morphology of p4 (absent in the described material with the exception of one damaged specimen from Verkhnya Krynitsa 1) and on the mutual size of antemolars in upper and lower jaws (mostly isolated teeth occur in the Ukrainian material) and the number of antemolar roots. Molars, comparatively frequent in fossil material, are in all forms of Desmaninae very uniform and useless in specific identification. For this reason only some speculation based on the overall size of all teeth present in the collection and their geological age could be helpful. However, the size of specimens is not always reported. The monograph of Rümke (1985) does not provide incisor dimensions and in Ukrainian papers ( Pashkov and Topachevsky, 1990; Topachevsky and Pashkov, 1990) there are no measurements of molars.

So far four species of the genus Desmana were described from Ukraine. These include D. jalpugensis Pashkov and Topachevsky, 1990 and D. kujalnikensis Pashkov and Topachevsky, 1990 found in Late Pliocene (MN16) localities and D. nogaica Topachevsky and Pashkov, 1990 and D. gureevi Topachevsky and Pashkov, 1990 known from the Early Pleistocene (former late Late Pliocene, MN17). Rzebik-Kowalska and Nesin (2010) cited D. cf. nehringi Kormos, 1913 from a locality dated to the Late Miocene (MN13) and Rekovets and Pashkov (2009) mentioned D. moldavica Pashkov and Topachevsky, 1990 (the Early/Late Pliocene boundary, MN15/MN16), Galemys cf. kormosi (beginning of the Late Pliocene, early of MN16) and D. cf. jalpugensis (middle of MN16).

Several species of Desmana were also described from neighboring countries: D. verestchagini Topachevsky, 1961 from Russia (MN14), D. moldavica (MN16) and D. meridionalis Topachevsky and Pashkov, 1990 (Early Pleistocene, former MN17) from the Republic of Moldova, D. thermalis Kormos, 1930 (Pleistocene, Early Biharian) from Hungary as well as D. amutriensis Rădulescu, Samson and Ştiucă, 1989 (Early Pliocene, MN14, MN15) and D. radulescui Ştiucă, Petculescu and Arghir, 2003 (Late Pliocene, MN16) from Romania. However, for reasons mentioned above, many Ukrainian remains (mostly isolated teeth) of this genus were described as Desmana sp. or Desmaninae gen. et sp. indet.

The majority of remains from Verkhnya Krynitsa 1 and Popovo 2 and 1 also represent isolated and damaged teeth and their inclusion into any species is unfeasible.

The remains described above could either belong to different species or to one species, especially since their size is more or less uniform and they were all collected in localities of similar age (between the Early/Late Pliocene boundary and the early Late Pliocene [MN15/MN16, middle of MN16]). Their detailed size and morphological comparison with all known forms of European Desmana indicates that they are smaller or have different proportions than those of D. jalpugensis , D. kujalnikensis , D. nogaica , D. gureevi , D. moldavica , D. meridionalis and D. radulescui . On the other hand, they are larger than remains of D. verestchagini , D. nehringi , D. inflata Rümke, 1985 and D. amutriensis .

As seen in Table 3 and Table 4 their size is close to the size of Desmana thermalis and D. kujalnikensis . However in morphology there are some differences between them (e.g., P4 from Popovo 2 has a well-developed hypocone, which is not very distinct in the P4 of D. thermalis and D. kujalnikensis ). Concerning the age, Desmana from Popovo 2 (late MN16) is closer to D. kujalnikensis which is also from MN16, whereas D. thermalis is younger, its older specimens come from localities dated to MN17.

Rekovets and Pashkov (2009) listed three species of desmans from localities studied in this paper. Based on one fragment of mandible with p2–p4, they mentioned Desmana moldavica from Verkhnya Krynitsa 1 (early MN16). The p4 from the D. moldavica holotype measured by Pashkov and Topachevsky (1990) is slightly larger (L= 2.60 mm, W= 1.80 mm) than the p4 from the same locality (see Table 3) and cited here as Desmana sp. The same authors mentioned Desmana cf. kormosi from Popovo 2. As they did not give any characters, dimensions or drawings of these specimens (P2, M3 and p4), a comparison with teeth described above is impossible. Besides, Rümke (1985) demonstrated that the species “ kormosi ” should be placed in the genus Galemys [ G. kormosi ( Schreuder, 1940) ], not Desmana . However, teeth from Popovo 2 described in this paper are larger than any teeth of Galemys species, and they surely belong to Desmana .

One mandible (whole? or fragmentary?, with or without teeth and processes?) from Popovo 1 was classified by Rekovets and Pashkov (2009) as Desmana cf. jalpugensis . The m1 described in the present paper may also belong to this species. However, the lack of a description, measurements or drawing in the paper of Rekovets and Pashkov (2009) also excludes a comparison.

In this situation the scanty and badly preserved material of the large Desmaninae from Verkhnya Krynitsa 1, Popovo 2 and 1 are tentatively ascribed to Desmana sp.

The large number of species described from Europe and from Ukraine and its adjacent territories (some of them on the basis of scanty material) as well as the lack of knowledge on their individual, geographic and stratigraphic variation suggest that a review of the genus Desmana is badly needed.

cf. Desmana sp.

Figure 6.2-6.3

Material. Verkhnya Krynitsa 2 ( MN 11/ MN 12), left humerus. MNI = 1. Catalogue number 29/2/5.

Description. The humerus ( Figure 6.2-3 ) is very slender. The pectoral process is long and the wedge-shaped area is not very well marked on its external side. The teres tubercle is rather long. The entepicondyle is broken. The elliptical entepicondylar foramen is large. The supratrochlear fossa is large and deep. The ectepicondyle is large. The olecranon fossa is shallow and the head is large.

Measurements. See Table 4.

Systematic Position. The humerus found in this locality belongs to the genus Desmana . Its preserved parts compared with homologues in D. moschata ( Linnaeus, 1758) are morphologically identical. On the other hand, it is larger than the humerus of Mygalinia hungarica found in the same locality as well as larger than all known humeri of Ruemkelia , Galemys and of the oldest Desmana e.g., D. verestchagini (MN14). The DW of: D. verestchagini is 2.00 mm; D. thermalis is 2.89 mm; and G. kormosi is 2.22 mm (from plate 1, figures 1- 3, p. 109, Rümke, 1985). The length of the DW from Verkhnya Krynitsa 2 equals 3.22 mm and is closer to the length of the DW of D. thermalis . However, the last form is known only from localities dated to the Early Pleistocene.

So far no species of Desmana occurs earlier than the beginning of the Ruscinian (MN14) (the genus Desmana has not been found in sediments from before MN14). Indeed, Rekovets and Pashkov (2009) listed D. cf. verestchagini in Verkhnya Krynitsa 2 and Nesin (2013) D. cf. nehringi and D. ( Archaeodesmana ) sp. in Odessa, sixteenth Station of Bolshoy Fontan and Vinogradovka 1 (MN13) but they did not give any documentary evidence. Moreover the humerus described above is too large to represent D. verestchagini and D. nehringi . If this specimen really comes from this locality (Verkhnya Krynitsa 2) (we should take into consideration that it could come from a younger layer in the same locality or from another, younger locality) it would be the oldest record of the genus Desmana and move its first appearance to the Miocene. More material is needed to clarify this problem.

Figures

FIGURE 4. Desmana sp. from Verkhnya Krynitsa 1 (1-2) and from Popovo 2 (3-7). Left?I2, 1, buccal; 2, occlusal view (c.n. 29/1/4/1). Left C: 3, buccal; 4, occlusal view (c.n. 29/II/4/1). 5, Left P2, occlusal view (c.n. 29/II/4/2). 6, Left P4, occlusal view (c.n. 29/II/4/3). 7, Right M1, occlusal view (c.n. 29/II/4/4).

FIGURE 5. Desmana sp. from Popovo 2 (1-4 and 6) and Popovo 1 (5). Left?i3: 1, buccal, 2, occlusal view (c.n. 29/II/ 4/5). Left p2: 3, buccal; 4, occlusal view (c.n. 29/II/4/6). 5, Left m1, occlusal view (c.n. 29/I/4/1). 6, Left m3, occlusal view (c.n. 29/II/4/7).

FIGURE 6. 1, Desmana sp. from Popovo 1 (1). fragment of right mandible with m1–m3 in buccal view (c.n. 29/I/4/2); (2-3) cf. Desmana sp. from Verkhnya Krynitsa 2, left humerus, 2, dorsal side, 3, ventral side (c.n. 29/2/5/1).