Leptoscaptor robustior, Ziegler, 2003

Ziegler, Reinhard, 2003, Moles (Talpidae) from the late Middle Miocene of South Germany, Acta Palaeontologica Polonica 48 (4), pp. 617-648 : 625-626

Leptoscaptor robustior gen. et sp. nov.

Fig. 3 .

Etymology: From Latin robustior ,more robust. The humerus is more robust than in the type species L. bavaricum .

Holotype: Right humerus, NHMA P35−58 /6, fig. 3A.

Measurementsoftheholotype: GL (10.5), Bp (6.35), BpwT (5.70); SD (2.56), BdwE (5.14), Bp*100/GL (60.5).

Type locality: Petersbuch 35 (details see p. 618).

Age : Uppermost part of the Middle Miocene (MN 8 according to Rummel 2000, means MN 7+8.)

Paratypes (measurements see Tables 1, 2).—Petersbuch 35: NHMA P35−57A1 , right dentary fragment with teeth; CRW P35−57+ 58, 4 dentary fragments with teeth, left maxilla fragment with p4, 7 isolated teeth, 11 humerus fragments, right ulna fragments .

Referred material (measurements see Tables 1, 2).—Petersbuch 48: CRW P48−93–94, left dentary fragment with p3–p4, right maxilla fragment with M2, 3 isolated teeth, 3 humerus fragments.

Diagnosis.—Medium−sized species of Leptoscaptor with postcranial elements more robust than in the type species and with two mental foramina on the dentary.

Description of the holotype

Pectoral crest, deltoid process and the epicondylar spines are broken. The long axis of the elliptical head is directed parallel to the shaft. The marked scalopine ridged separates two areas in different planes. The brachialis fossa is moderately deep. The anterior aspect shows the pectoral process in midshaft position and a concave area delimited by pectoral crest, pectoral ridge, and greater tubercle. Above the distal epiphysis there is a wide olecranon fossa and a small supratrochlear fossa. The broad trochlea only leaves a narrow notch, separating trochlea and the fossa for the m. flexor digitorum profundus ligament.

Description of paratypes and referred material

Dentary.—There are five fragments of the horizontal ramus from Petersbuch 35, and one from Petersbuch 48. The consistent presence of two mental foramina is characteristic: below the anterior roots of p3 and p4 (once), beneath the posterior root of p2 and between the roots of p4 (twice), below the anterior root of p3 and under the posterior root of p4 (once) in the Petersbuch 35 sample. In the Petersbuch 48 specimen one mental foramen is situated beneath the anterior root of p3, another below the anterior root of p4. In two specimens the alveoles of the double−rooted p2–p3 and the single−rooted canine are preserved. The Petersbuch 48 dentary also preserves the canine alveolus and the two incisor alveoli, indicating that i2 was larger than i1.

Teeth.—In the morphology of the preserved teeth there is no difference to those of L. bavaricum .

Postcranialbones.—Aside from the type specimen there are 11 additional humerus fragments from Petersbuch 35 and three from Petersbuch 48, which correspond in robustness. The ulna fragment from Petersbuch 35 was referred because of matching size. It has a deep abductor fossa.

Comparisons

L.robustior is quite similar to the type species of the genus L. bavaricum . Only this species can be confused and needs to be differentiated. L. robustior differs in:

– the consistent presence of two mental foramina, which are situated slightly more posterior,

– a distinctly more robust humerus.

Discussion

In the small talpid sample from Petersbuch 35 there are only two species: Proscapanus sansaniensis and Leptoscaptor robustior . As both species differ markedly in size and robustness of the humerus they are easily distinguishable. Assuming that there are not two different species, one being represented by teeth only and the other exclusively by postcranial elements, the association of postcranial elements and dental remains in Leptoscaptor robustior is without alternative. In the Petersbuch 48 talpid fauna there are only three species, which also can be readily distinguished: P. sansaniensis , Talpa minuta and L. robustior . The difference in robustness of the nearly complete humeri from Petersbuch 35 and 48 lies well within the range of a population. The more robust humerus of L. robustior indicates a better fossorial adaptation than in L. bavaricum . Without humeri the Leptoscaptor species are hardly distinguishable. Nevertheless, I am convinced that they represent different biological adaptations (see also chapter discussion of L. bavaricus ).

Figures

Fig. 3. Leptoscaptorrobustior gen. et sp. nov., Petersbuch 35. A. Right dentary with p4–m1, NHMA P35−57A1, buccal view; ca. × 10. B. Holotype, right humerus, NHMA P35−58/6, in anterior (B1) and posterior (B2) views; ca. × 7.5.