Myxodus sackdillingensis, Striczky & Pazonyi, 2014

Striczky, L. & Pazonyi, P., 2014, Taxonomic study of the dormice (Gliridae, Mammalia) fauna from the late Early Pleistocene Somssich Hill 2 locality (Villány Hills, South Hungary) and its palaeoecological implications, Fragmenta Palaeontologica Hungarica 31, pp. 51-81 : 58-61

Glis sackdillingensis ( Heller, 1930)

1930 Myxodus sackdillingensis n. sp. – HELLER, p. 281–282, pl. XVI. figs 5a-b, 6.

1962 Glis sackdillingensis ( Heller, 1930) – DEHM, p. 46–47.

1963 Glis sackdillingensis ( Heller, 1930) – KOWALSKI, p. 553–558, fig. 12.

1986 Glis sackdillingensis ( Heller, 1930) – AGUILAR et al., p. 141, fig. 3a-c.

Description – P 4: Rounded tooth, with five ridges. The first ridge (anteroloph) is isolated, slightly arched anteriorly. The second ridge (protoloph) is long, and joined with the third one (anterior extra ridge) on the central part of the tooth. The fourth and the fifth ridges (metaloph and posteroloph) are isolated.

M 1: The tooth has rounded square shape and seven ridges. The first and third main ridges (anteroloph and protoloph) are isolated; there is a small, isolated ridge (anterior extra ridge) between the latter two. The fourth ridge is isolated (anterior centraloph), whereas the fifth and seventh ridges (metaloph and posteroloph) are joined on the palatinal side. Between the latter two ridges, there is a small, isolated ridge (posterior extra ridge).

M 2: Labiopalatinally elongated tooth, with seven ridges. The first ridge (anteroloph) is joins with a small ridge (anterior extra ridge) on the central part of tooth. The third and fourth ridges (protoloph and anterior centraloph) are isolated. The fifth and seventh ridges (metaloph and posteroloph) are joined on the palatinal side. The sixth small ridge (posterior extra ridge) is joined with the seventh ridge on the labial side.

M 3: Triangular tooth, with eight ridges. The first and third ridges (anteroloph and protoloph) are joined on the palatinal side. The anterior extra ridge (second ridge) is longer than the anterior centraloph (fourth ridge). These former ridges are joined on the palatinal side. The fifth ridge (posterior centraloph) is isolated. The extra ridges (second and sixth ridges) are joined on the labial side. The seventh ridge (metaloph) is small and isolated. The eighth ridge (posteroloph) is also joined the two extra ridges on the labial side.

P 4: Triangular tooth, with five ridges. The first and the second ridges (anterolophid and metalophid) are joined on both sides. The third ridge (mesolophid) is isolated, whereas the fourth and fifth ridges (posterior extra ridge and posterolophid) are joined on the labial side.

M 1: Anteriorly elongated, narrowed tooth, with seven ridges. The first, second and third ridges (anterolophid, anterior extra ridge and metalophid) are joined on the labial side. The fourth ridge (centralophid) is short and isolated.

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The fifth, sixth and seventh ridges (mesolophid, posterior extra ridge and posterolophid) are joined on the labial side.

M 2: Squared tooth, with seven ridges. The first and second ridges (anterolophid and anterior extra ridge) are joined on the labial side. All other ridges are isolated.

M 3: Shield shaped tooth, which is rounded on the posterior side, with seven ridges. The first, second, third and fourth ridges (anterolophid, anterior extra ridge, metalophid and centralophid) are joined on the labial side. The fifth ridge (mesolophid) is isolated, whereas the sixth and seventh ridges (posterior extra ridge and posterolophid) are joined on the labial side.

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Remarks – Two species of the genus Glis have been described from the Pliocene: G.minor Kowalski, 1956 and G.sackdillingensis ( Heller, 1930) ( KOWALSKI 1956; AGUILAR et al. 1986), whereas several species of the genus have been observed in the Pleistocene: G. sackdillingensis , G. mihevci Aguilar et Michaux, 2011 , G. perkoi Aguilar et Michaux, 2011 and the extant G. glis (Linnaeus, 1766) ( KOWALSKI 1963; AGUILAR & MICHAUX 2011). A gradual size increase of the molars is observed in Glis from the Pliocene until recently. Morphology has evolved in this time span from primitive forms with transversal crests, synclines open on the lingual side in the upper molars and labial side in lower ones and accessory ridges reduced in P 4 and M 3 ( KOWALSKI 1956; JÁNOSSY 1966; AGUILAR & MICHAUX 2011; MANSINO et al. 2013). According to a recently accepted view, the edible dormouse ( G. glis ) is descendant of G. sackdillingensis .

Altogether, 4 P 4, 28 M 1 (9 G. sackdillingensis ; 19 G. minor ), 13 M 2, 6 M 3, 2 P 4, 16 M 1 (8 G. sackdillingensis ; 8 G. minor ), 12 M 2 and 10 M 3 teeth of Glis were found in the Somssich Hill 2 samples. In case of G. sackdillingensis M 1, the lengths of teeth vary between 1.7 and 1.95 mm, whereas the lengths of M 1 are 1.68–1.91 mm ( Fig. 5 ). Within the sequence of locality, G. sackdillingensis was found with G. minor in most cases (layers 5, 13, 24, 28, 30–31, 40 and 45). The number of specimens of the latter taxon is usually lower than in the case of G. minor , but in cases of layers 4, 29–31, 36, and 40 G. sackdillingensis is the dominant dormouse in the fauna ( Fig. 6 ; see also Fig. 12 ).

Figures

Fig. 5. Biplot of the length and width measurements made on Glis teeth from the Somssich Hill 2 locality. a = lower M; b = upper M1

Fig. 6. Glis sackdillingensis teeth from the Somssich Hill 2 locality

Fig. 12. Number of specimens of the two Glis species (G. sackdillingensis and G. minor), Muscardinus avellanarius and Dryomimus eliomyoides within the sequence of Somssich Hill 2 locality