Glirudinus modestus (Dehm, 1950)

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 : 618-620

Glirudinus modestus (Dehm, 1950)

( Fig. 11 A-Z)

LOCALITIES. — MAB3, MAB5, MAB11, MAB11B, CBR0B and CBR0E.

MATERIAL. — MAB3 : 1 d4, 1 p4, 3 m1, 4 m2, 4 m3, 1 P4, 5 M1, 3 M2, 3 M3; MAB5 : 4 p4, 8 m1, 7 m2, 3 m3, 4 P4, 8 M1, 4 M2, 4 M3; MAB11 : 2 m2, 1 m3, 1 M2; MAB11 B: 1 p4, 1 m1, CBR 0B: 1 M2; CBR 0E: 1 M1.

MEASUREMENTS. — Appendix 16

DESCRIPTION

d4 (MAB3)

The tooth is subtriangular in occlusal view. The anterolophid is short. The endolophid is divided in two parts connected by a low connection. There is an anterotropid. The metalophid is connected to the endolophid and the anterolophid. The centrolophid is short, low and isolated. The mesolophid and the posterolophid are long and connected. The posterotropid is well developed and isolated. The labial cuspids are more developed than the lingual ones. The tooth has two extra crestids, making a total of seven.

p4 ( MAB 5)

The tooth is of subrectangular shape in occlusal view. The anterolophid is short. The endolophid may be divided in two (2 out of 3) or four (1 out of 4) parts. There may be one (3 out of 4) or two (1 out of 4) anterotropids, one of which is connected to the anterolophid in both sides. The metalophid may be connected to the endolophid (3 out of 4) or in both sides (1 out of 4). The centrolophid may be long and it is connected to the endolophid (2 out of 4) or short and isolated (2 out of 4). The mesolophid and the posterolophid may be long and connected (3 out of 4), or isolated (1 out of 4). The posterotropid is well developed and it may be connected to the hypoconid (1 out of 4), or isolated (3 out of 4). The labial cuspids are more developed than the lingual ones. The tooth may have three extra crestids, totaling eight (1 out of 4), or two extra crestids, with a total of seven (3 out of 4). In the material from MAB 3 and MAB 11B the centroloph is long and isolated; in the material from MAB 11B the endolophid is complete.

m1 ( MAB 5)

The tooth has a subrectangular outline, with narrow crestids and valleys. The anterolophid is short and straight. The endolophid may be complete (3 out of 6) or divided in two (3 out of 6). There may be two (1 out of 6), three (4 out of 6) or four (1 out of 6) anterotropids, and the central one may be connected either to the endolophid (5 out of 6) or to the posterior one (1 out of 6). The metalophid is complete and it may be either disconnected (2 out of 7) or connected to the anterolophid in the labial side (5 out of 7). The centrolophid is long, isolated, and almost completely developed until the labial side. Two small centrotropids may be present (2 out of 6), but they may also be absent (4 out of 6). The mesolophid and the posterolophid are long and connected. There may be one (3 out of 8), two (4 out of 8), or three (1 out of 8) posterotropids, in which case the middle one is more developed. The labial cuspids are more developed than the lingual ones. The tooth may show three extra crestids, with eight in total (1 out of 6), four extra crestids, with nine in total (1 out of 6), five extra crestids, with a total of ten (1 out of 6) or up to seven extra crestids, thus making a total of twelve (3 out of 6). In the material from MAB 3 the centrolophid is not isolated, in one specimen there is a spur behind the posterolophid, and in another specimen there are six extra crestids, with eleven in total. In the material from MAB 11B the centrolophid is connected to the mesolophid.

m2 ( MAB 5)

The tooth shows a subrectangular outline and narrow crestids and valleys. The anterolophid is long and straight. The endolophid is divided in two parts. There may be three (5 out of 6) or four (1 out of 6) anterotropids, and the central one may be connected to the endolophid (4 out of 6) or to the two posterior anterotropids (2 out of 6). The metalophid is complete and isolated from the anterolophid in the labial side. The centrolophid is long and almost reaches the labial side; it may be isolated (2 out of 5) or perpendicularly connected to the endolophid (3 out of 5). The centrotropid is absent (4 out of 5) or, if present, it is small (1 out 5). The mesolophid and the posterolophid are long and connected. There may be three posterotropids, with the central one more developed (2 out of 5), or two of them connected with the posterolophid and forming an ellipse (3 out of 5), although in one specimen the ellipse is not fully closed. The labial cuspids are more developed than the lingual ones. The tooth may show five (3 out of 5) or seven (2 out of 5) extra crestids thus making ten or twelve in total. In the material from MAB 3, in one specimen the anterotropid is connected with the anterolophid, the metalophid may be connected in both sides; in another specimen there are two centrotropids, and in other two individuals there are eight extra crestids, thus making thirteen in total. In one specimen from MAB 11 the three anterotropids are connected with the endolophid and only one posterotropid is developed.

m3 ( MAB 3)

The tooth is elongated and D-shaped in occlusal view. The anterolophid is long and straight. The endolophid may be divided in two (1 out of 2) or be undivided (1 out of 2). There are three anterotropids; either the central one is the most developed and connected to the endolophid (2 out of 4), or the two posterior ones are connected to the endolophid (1 out of 4), or the posterior one is the most developed, but the central one is connected to the endolophid (1 out of 4). The metalophid is long and it may be connected labially and isolated lingually (2 out of 4), connected to the endolophid and isolated from the anterolophid (1 out of 4), or connected in both sides (1 out of 4). The centrolophid is long and narrow. The mesolophid and the posterolophid are long and lingually connected. There may be two posterotropids, with the anterior one connected to the endolophid (1 out of 4), or three of them, with the middle one connected to the hypoconid (3 out of 4). The labial cuspids are better developed than the lingual ones. The tooth may show five (1 out of 4) or six extra crestids (3 out of 4), thus totaling ten or eleven crestids. The material from MAB 11 follows this description. In the material from MAB 5, some specimens have two posterotropids.

P4 ( MAB 5)

The outline of the tooth is subelliptical. The anterolophid is long and it is connected to the protoloph in the labial side, and in the lingual side it may show a low connection (2 out of 3) or be isolated and connected to the protoloph in the middle of the tooth (1 out of 3). The protoloph is long and connected to the endoloph. There may be a low prototrope, posteriorly a long isolated centroloph, and another low centroloph (2 out of 3), or there may be only a centroloph (1 out of 3). The metaloph is long and connected in both sides to a long posteroloph. The tooth may have one (1 out of 3) or two (2 out of 3) extra crests, thus totaling six or seven in total. The material from MAB 3 fits in this description.

M1 ( MAB 5)

Tooth subrectangular in outline. The anteroloph is short and connected to the protoloph in the labial side. In one specimen the anteroloph is divided and it is connected to the protoloph in the middle of the tooth. An anterotrope may be present (4 out of 8) or not (4 out of 8). The protoloph is long and developed until the posterior side of the molar. There may be one long prototrope (5 out of 8) or two of them (3 out of 8). The precentroloph is long and connected to the endoloph.One (6 out of 8) or two (2 out of 8) centrotropes may be present. The postcentroloph is long, but shorter than the precentoloph, in one specimen it is isolated. The metatrope may be unique and small (7 out of 8), or double (1 out of 8). The metaloph is long and connected labially to the postcentroloph and the protoloph, while lingually the metaloph is connected only to the protoloph. A posterotrope may be present (2 out of 8) or not (6 out of 8). The posteroloph is long and connected in both sides to the anterior crests. The lingual ornamentation is poorly developed. The tooth may show three (4 out of 8), five (2 out of 8), or seven (2 out of 8) extra crests, making in total nine, eleven or thirteen crests. The material from MAB 3 may show one, two or three prototropes; in one specimen the precentroloph is connected to the posterior one and to the metaloph; in another specimen there are three centrotropes; all of the specimens have six extra crests, with twelve in total. In the material from CBR 0E, there are two centrotropes, which first start from the ectoloph as a single one that later becomes split in two.

M2 ( MAB 5)

The tooth is subcuadrangular in outline. The anteroloph is short, and it is connected to the endoloph and the ectoloph. The ectoloph is divided in two and the endoloph is complete. There is an anterotrope. The protoloph is long. There may be two prototropes, in which case the posterior one is longer (2 out of 3), or three of them (1 out of 3). The precentroloph is long and it is connected to both the ectoloph and the endoloph. The postcentroloph may be long, similar to the precentroloph (1 out of 3), or shorter (2 out of 3). The centrotrope is well developed and connected to the ectoloph. The metaloph is long and it is connected in both sides. The posteroloph is short and connected in both sides with the anterior crests. The lingual ornamentation is developed. The tooth has five extra crests thus making a total of eleven crests. The material from CBR 0B is similar to the one described here. In MAB 3, the anterotrope may be divided; in one specimen the prototrope is connected to the precentroloph; in another one the centrope is isolated, and there may be six extra crests, with twelve in total. In MAB 11, the anteroloph is not connected to the endoloph, which is divided in two, the postcentroloph is shorter and there may be six extra crests making a total of twelve.

M3 ( MAB 5)

The tooth is subtrapezoidal in outline. The endoloph is complete and the lingual ornamentation is well developed. The anteroloph is long and connected to a long protoloph. A prototrope may be present (2 out of 3) or not (1 out of 3). The precentroloph is long and connected to the labial side, and it almost reaches the lingual side. There may be a centrotrope (2 out of 3) or not (1 out of 3). The postcentroloph may be long and connected in both sides (2 out of 3) or of medium size (1 out of 3). There are three metatropes, connected to the labial side (1 out of 3), or only two (2 out of 3), in which case the middle one is the longest. The metaloph and the posteroloph are short and they are connected forming an ellipse. The tooth has four extra crests, which makes ten crests in total. In the material from MAB 3 the anterotrope and the prototrope may be divided, the precentroloph is connected to the endoloph and to the ectoloph, afterwards there are six crests that gradually fuse together towards the lingual side and become a single crest, the postcentroloph, in one specimen there are eight extra crests, thus totaling fourteen, in another only two extra crests are present, making a total of eight.

REMARKS

Glirudinus modestus has a long stratigraphic range that extends from the lower Ramblian (MN2) until the middle Aragonian (MN5) ( Daams 1999a). This taxon clearly differs from G. undosus in its smaller size and the higher complexity of their crests pattern. Daams (1985) classified the molars of this species according to their complexity. The lower molars described here could be included in the most complex morphotype (the third one), like the specimens from the site of Buñol. On the other hand, due to their more complex ectoloph, the upper molars in our material do not fit in any previously described category. However, these categories were erected with few specimens. Although, according to Daams (1985), the endoloph is complete in the oldest sites (Ramblar 1 and 7, Bañon 5), as it is the case in our material, the site of Bouzigues, with more abundant specimens, includes all the morphotypes present in the Calatayud-Montalbán Basin. This species is present in the Vallès-Penedès Basin ( Jovells-Vaqué et al. 2018; Casanovas-Vilar et al. 2022).

The systematics of the small-sized Glirudinus is still to be resolved, since two species have been described ( Glirudinus gracilis Dehm, 1950 and G. modestus ) in the site of Wintershof West, and a third one in Petersbuch 2 ( G. minutus ), which overlap in size and morphology ( Mayr 1979; Wu 1993; De Bruijn 1998). De Bruijn (1998) categorized this genus in two groups: a first one, with a simple dental patttern, which comprises those species from Greece, Turkey and other European sites ( Glirudinus engesseri Ünay, 1994 , Glirudinus eggingensis Werner, 1994 , Glirudinus euryodon , Glirudinus glirulus Dehm, 1935 , Glirudinus haramiensis Ünay, 1994 and G. modestus ), and a second one that includes the species from Central and Soutwestern Europe, which have in common a more complex dental pattern, and only differ in their size ( G. gracilis , Glirudinus minutus Wu, 1993 and G. undosus ). We have ascribed our material to the species G. modestus , the smallest species present in the Ribesalbes-Alcora Basin, due to its complex dental pattern, which is similar to the one described byDaams (1985) for G. modestus in the Calatayud-Montalbán Basin. We therefore consider the classification of De Bruijn (1998) as inadequate, since this author groups G. modestus with the species characterized by a simple dental pattern, whereas its morphology clearly belongs to the group with a more complex pattern. In addition, the remains from Ribesalbes-Alcora are, in general, smaller than those from Blanquatère 1, ascribed to Glirudinus intermedius Aguilar & Lazzari, 2006 ( Aguilar & Lazzari 2006).

Figures

FIG. 11. — Gliridae from the Ribesalbes-Alcora Basin. Glirudinus modestus: A, left d4 (MAB3-385); B, left p4 (MAB5-625); C, left p4 (MAB5-842); D, left p4 (MA- B11B-3); E, right m1 (MAB5-850); F, left m1 (MAB5-260); G, left m1 (MAB3-443); H, right m2 (MAB5-845); I, right m2 (MAB5-851); J, left m2 (MAB3-409); K, left m2 (MAB11-84); L, right m3 (MAB3-475); M, left m3 (MAB3-476); N, right m3 (MAB5-852); O, right P4 (MAB5-587); P, left P4 (MAB5-815); Q, right M1 (MAB5- 821); R, right M1 (MAB5-820); S, right M1 (MAB5-562); T, left M1 (MAB3-280); U, right M2 (MAB3-278); V, left M2 (MAB5-112); W, right M2 (MAB11-64); X, right M3 (MAB5-589); Y, left M3 (MAB5-588); Z, left M3 (MAB3-365). Myoglis cf. antecedens: AA, right P4 (MAB3-474); AB, right M3 (MAB3-367). Scale bar: 1 mm.