Myotis cf. reductus ZIEGLER 2003

Rosina, Valentina V. & Rummel, Michael, 2019, The Early Miocene Bats (Chiroptera, Mammalia) From The Karstic Sites Of Erkertshofen And Petersbuch 2 (Southern Germany), Fossil Imprint 75 (3 - 4), pp. 412-437 : 424-427

Myotis cf. reductus ZIEGLER 2003

Text-fig. 7a–e, h, i

M a t e r i a l a n d m e a s u r e m e n t s. Erkertshofen 1: SNSB-BSPG 1962 XIX 4200, left mnd without teeth: C inf. (al.) 0.65 × 0.45; p2 (al.) 0.50 × 0.40; p3 (al.) 0.35 × 0.30; Hmdm1 1.50.

Erkertshofen 2: BSP 1974 XIV 1208, right M1, 1.40 × 1.55; BSP 1974 XIV 1209, left M2, ≈1.2 × ≈1.75; BSP 1974

XIV 1202, left p4, 0.80 × 0.75; BSP 1974 XIV 1201, right C inf., 0.85 × 0.80 × 1.20; BSP 1974 XIV 1199, left C inf., 0.85 × 0.80 × 1.20.

Petersbuch 2: BSP 1976 XXII 4799, right mnd with p4–m3: p2 (al.) 0.45 × 0.45; p3 (al.) 0.45 × 0.45; p4 0.85 × 0.70; m1 1.35 × 0.78 × 0.80; m2 1.30 × 0.85 × 0.85; m3 1.28 × 0.80 × 0.45; Hmdm1 1.43; PCMRCh87, right m3, 1.20 × 0.70 × 0.65.

D e s c r i p t i o n a n d c o m p a r i s o n. The crowns of the upper molars (specimens BSP 1974 XIV 1208 and BSP 1974 XIV 1209; Text-fig. 7a, b ) show the paraconules and the distinct para- and metalophs. The postprotocrista extends to the lingual bases of the metacones and forms a small hypocone. Thus, the trigon basins of the molars are closed. All these are the typical features of Myotis . Both upper molars from Erkertshofen 2 correlate well with each other in size, implying their belonging to one taxon. They differ from the early Miocene M. cf. sanctialbani from Petersbuch 28 (MN 3, Germany; Rosina and Rummel 2012: tab. S1, supplementary data) in being smaller in size and in having a small hypocone ( Text-fig. 7a–c , Tab. 7; Rosina and Rummel 2012: 474, fig. 6). They are smaller in size than the middle Miocene M. bavaricus ZIEGLER, 2003 (MN 7/8, Petersbuch 6, 10, 18; Ziegler 2003; Tab. 7). The early Miocene M. aff. murinoides (e.g. SMNS 45742.1) from Stubersheim 3 (MN 3, Germany; Ziegler 1994: 104) and from Oberdorf 3 (MN 4, Austria; Ziegler 1998) is smaller than the fossils under study, which also show a more developed paraconule and paraloph in the upper molar crowns (compare Text-fig. 7A–C with Ziegler 1994: 107, pl. 3, figs 1–3, Ziegler 1998: 95, pl. 8, figs 11, 12). In comparison with the fossils from Erkertshofen 2, the species M. murinoides (LARTET, 1851) from Sansan (MN 6, France) is smaller in size ( Baudelot 1972: 24, tab.) and has a more developed hypocone ( Baudelot 1972: 35, fig. 14). Thus, the upper molars from Erkertshofen 2 are most similar to those of M. aff. reductus from Petersbuch 28 (MN 3; Text-fig. 7a–c ).

The edentulous mandibular fragment (specimen SNSB- BSPG 1962 XIX 4200) from Erkertshofen 1 has three alveoli of the lower incisors while the alveolus of the third incisor is the largest ( Text-fig. 7e ). The alveolus of the canine is roundish. The small premolars are single-rooted. The roundish alveoli of the small premolars are all located at the midline of the tooth-row and their form indicates that the crown of p3 was smaller than p2. The root alveoli of the p4 are about the same size that indicates an elongated crown in this tooth ( Text-fig. 7E ). All these are typical features of the genus of Myotis . The alveoli of the small premolars of another mandibular fragment (specimen BSP 1976 XXII 4799) from Petersbuch 2 are similar in size, the paralophids of the myotodontal lower molars are less curved and the talonid of m3 is less reduced. All these are features indicate its affiliation to Myotis . It differs from Submyotodon in being larger, in having larger alveoli of the i3 and p2, and also in having a more elongated crown on the p4 ( Ziegler 2003: 478, fig. 6). Both mandibular fragments from Erkertshofen 1 and Petersbuch 2 are smaller than M. bavaricus and differ from it in having smaller p2–3 (compare with the holotype of M. bavaricus p2 (al.) 0.60 × 0.65). Thus, the mentioned mandibular fragments are closest in size to M. aff. reductus from Petersbuch 28 and Petersbuch 62 (Tab. 7; Rosina and Rummel 2012).

As typical for Myotis , the crowns of the lower canines from Erkertshofen 2 (specimens BSP 1974 XIV 1201 and BSP 1974 XIV 1199) are uncompressed in anteroposterior direction. They have pronounced, but low, anterolingual cuspules of cingulid, not strongly pressed to the tooth bodies, and a flattening of the distal part of the cingulids ( Text-fig. 7d ). Morphologically they are similar to the lower canines of M. bavaricus but somewhat smaller in size (Tab. 7). For morphological and also biostratigraphic reasons, the lower canines from Erkertshofen 2 were attributed to M. aff. reductus from Petersbuch 28, which is somewhat smaller than M. bavaricus in size, but the lower canines of which are unknown.

The p4 from Erkertshofen 2 (specimen BSP 1974 XIV 1202) has an elongated crown with a well-developed cingulid ( Text-fig. 7h ) that is typical of many Myotis species. It is somewhat smaller in size than the p4 of both the M. bavaricus and M. aff. murinoides (specimen NHMW 1997z0024/0001/2; Ziegler 1998: 95, pl. 8, fig. 10) from Oberdorf 3. On the other hand, the p4 from Erkertshofen 2 is larger than M. murinoides from Sansan (Tab. 7). Morphologically it is closest to M. aff. reductus from Petersbuch 28 and Petersbuch 62, especially in the twolobed shape of the crown with pronounced anterolingual and posterolingual cuspules ( Text-fig. 7h ; Rosina and Rummel

2012: 474, fig. 6E). However, the poor preservation of the fossils, only allows tentatively proposing their taxonomic unity with M. aff. reductus .

Figures

Text-fig. 7. a–e, h, i – Myotis cf. reductus: a – BSP 1974 XIV 1209, left M2, Erkertshofen 2, occlusal view; b – BSP 1974 XIV 1208, right M1, Erkertshofen 2, occlusal view; c – left maxillary fragment with M1–2, NMA P28/0345, Petersbuch 28, ventral view; d – BSP 1974 XIV 1199, left C inf., Erkertshofen 2, lingual (c1) and occlusal (c2) views; e – SNSB-BSPG 1962 XIX 4200, left mnd without teeth; Erkertshofen 1, occlusal (e1) and lateral (e2) views; h – BSP 1974 XIV 1202, left p4, Erkertshofen 2, occlusal view; i – PCMRCh87, right m3, Petersbuch 2, occlusal view; f, g – cf. Myotis sp., right C inf., Petersbuch 2, lingual view: f – PCMRCh25, g – PCMRCh88; j – M. aff. reductus, NMA P62/0331, right dentary fragment with p4–m1, Petersbuch 62, occlusal view.