Peridyromys darocensis Daams, 1999

Crespo, Vicente Daniel, Ríos, María, Marquina-Blasco, Rafael & Montoya, Plini, 2023, They are all over the place! The exceptional high biodiversity of dormice in the Early Miocene of the Ribesalbes-Alcora Basin (Spain), Geodiversitas 45 (20), pp. 589-641 : 603-605

Peridyromys darocensis Daams, 1999

( Fig. 6 AA-AF)

LOCALITIES. — MAB5, MAB6, MAB11, and CBR0C.

MATERIAL. — MAB5 : 1 m1, 1 m2, 1 M1/M2 ; MAB6 : 1 m1 ; MAB11 : 1 p4, 1 m1, 3 m2, 1 m3, 1 M3; CBR 0C: 1 m2 .

MEASUREMENTS. — Appendix 9

DESCRIPTION

p4 (MAB11)

The tooth is subtriangular in shape. The anterolophid is long and forms a circumference with the metalophid. There is a short centrolophid. The mesolophid and the posterolophid are short and lingually connected.

m1 ( MAB 11)

The tooth is of sub-rectangular outline, with fine crestids and broad valleys. The anterolophid is short. There is a low anterotropid. The metaconid is connected to the anteroconid. The metalophid is curved, irregular and with a low connection to the endolophid. The centrolophid is irregular, longer than half of the width of the tooth, divided in two and with a median connection to the metalophid. The mesolophid is irregular and not connected to the posterolophid. There is a low posterotropid. The labial cuspids are more developed than the lingual cuspids. The posterior valley is wide. The specimen found in MAB 6 is similar to the one described here.

m2 ( MAB 11)

The tooth is sub-rectangular in shape with fine irregular crestids and wide valleys. The anterolophid is long. A low anterotropid may be connected with the metalophid (1 out of 3), barely visible (1 out of 3) or not present (1 out of 3). The metaconid is connected to the anteroconid. The metalophid is curved, irregular and it may show a low connection to the endolophid (1 out of 3) or not (2 out of 3). The centrolophid is irregular, longer than half of the width of the tooth and it may end with a further connection to the metalophid (1 out of 3) or not (2 out of 3). There may be a centrotrophid (2 out of 3) or not (1 out of 3). The mesolophid is irregular and connects to the posterolophid. There is a low posterotropid. The labial cuspids are more developed than the lingual cuspids. The posterior valley is wide. The crestids are irregular. The specimens found in CBR 0C fit in this description.

m3 ( MAB 11)

The tooth is D-shaped, without a reduced posterior part. The anterolophid is short and independent. The metalophid is curved and isolated. The anteroconid and the metaconid show a low connection. The centrolophid is long and exceeds half of the tooth width, with two constrictions. The mesolophid and the posterolophid are long and isolated. A small posterotrophid is present.

M1/M2 ( MAB 5)

The tooth shows a subquadrangular outline, with broad crests and relatively wide valleys. The anteroloph is intermediate in size and isolated. The protoloph and the metaloph form the typical V shape, joining at the lingual side. The anterior precentroloph is longer than the posterior one and they do not connect. The prototrope and the metatrope are present. The postcentroloph is of medium size. The posteroloph is long, but shorter than the anteroloph, and both are well connected on both sides.

M3 ( MAB 11)

The outline is sub-rectangular. The anteroloph is long and forms a closed ellipse with the protoloph. The endoloph is almost complete, except for the posteroloph. The precentroloph is short and the postcentroloph is long, and both are isolated. The metatrope is isolated and divided in two, the labial part is connected to the postcentroloph. The metaloph and the posteroloph are not interconnected. The posteroloph is short.

REMARKS

This species is part of the lineage formed by P. darocensis and Peridyromys sondaari Daams, 1999 , described by Daams (1999b) and Dalmasso et al. (2022). While P. darocensis has only been found in the late Ramblian (MN3, local area A) of the Calatayud-Montalbán Basin, P. sondaari is known from the middle Aragonian (MN5, local area D). According to Daams (1999b), the populations belonging to the local zone C of the MN4, would represent a transition between the two species, none of which have been found in the local biozone B. These species are clearly differentiated from P. murinus by their more chaotic pattern and higher number of extra crests in lower and upper molars, P. darocensis being simpler and less chaotic than P. sondaari ( Daams 1999b) .

The material of P. darocensis from the Ribesalbes-Alcora Basin is very scarce; it only appears in the second local area and is more abundant in MAB 11. Biometrically, our material is similar to both P. sondaari and P. darocensis but it shows the same morphological pattern as the latter one, which is simpler than in P. sondaari . We can therefore reject the possibility that our material belongs to the transitional population occurring in the MN4 of the Calatayud-Montalbán Basin. This would then be the first record of this lineage outside the Calatayud-Montalbán Basin and in the MN4.

Figures

FIG. 6. — Gliridae from the Ribesalbes-Alcora Basin. Peridyromys murinus (continued): A, left D4 (MTR2-108); B, right D4 (MTR2-107); C, right D4 (MTR2-105); D, right D4 (MAB5-553);E, right D4 (BC1-14); F, left P4 (MTR2-103); G, left P4 (MTR2-99); H, right P4 (MTR2-10); I, right P4 (MAB5-811); J, right P4 (MAB3-252); K, right P4 (BC1-83); L, right maxilla M1+M2 (MCX3-100); M, right M1/M2 (MTR2-123); N, left M1/M2 (MTR2-121); O, left M1/M2 (MTR2-114); P, right M1/M2 (MTR2-113); Q, right M1/M2 (MTR2-110);R, left M1/M2 (MTR2-13);S, left M1/M2 (MTR2-12); T, left M1/M2 (MCX7-5); U, left M1/M2 (MAB5-558); V, right M1/M2 (MAB5-254);W, right M1/M2 (MAB3-326);X, right M3 (MAB3-356);Y, right M3 (MAB3-358); Z, left M3 (MAB11-70). Peridyromys darocensis: AA, left p4 (MAB11- 73); AB, right m1 (MAB11-76); AC, right m2 (MAB11-77); AD, right m3 (MAB11-82); AE, left M1/M2 (MAB5-270); AF, right M3 (MAB11-68). Scale bar: 1 mm.