Eucyon debonisi, Montoya & Morales & Abella, 2009

Montoya, Plinio, Morales, Jorge & Abella, Juan, 2009, n. sp., a new Canidae (Mammalia, Carnivora) from the latest Miocene of Venta del Moro (Valencia, Spain), Geodiversitas 31 (4), pp. 709-722 : 710-717

Eucyon debonisi n. sp.

Nyctereutes cf. donnezani – Morales & Aguirre 1976: 34, pl. 1, figs 1-5.

Canis sp. – Morales & Aguirre 1976: 38, pl. 1, figs 6-8.

Nyctereutes aff. donnezani – Morales 1984: 30, fig. 10, pl. 2, fig. 3.

Vulpes sp. – Morales 1984: 33, fig. 11, pl. 2, fig. 2.

“ Canis ” cf. monticinensis – Rook 1992: 153.

Eucyon cf. monticinensis – Spassov & Rook 2006: 130.

HOLOTYPE. — MGUV 14780 ( VV-1549 ), fragment of right maxilla with P2, P4-M2; MGUV 14781 ( VV-1624 ), fragment of left maxilla with I3-M2; MGUV 14779 ( VV- 1522 ), right mandible with p2-p3. Associated elements, very probably belonging to the same individual. Stored in the Museu de Geologia de la Universitat de València.

ETYMOLOGY. — In honour to Prof. Louis de Bonis, in recognition of his important contribution to the knowledge of the fossil carnivores.

LOCALITY AND AGE. — Venta del Moro, province of Valencia, Spain. Late Miocene, late Turolian (MN13).

DIAGNOSIS. — Eucyon of small size, with slender mandible and dentition; M1 with generally strong parastyle; strong lingual cingulum that closes completely the valley present in the talon.Mono-cuspidated inferior premolars,except p4 that possesses distal cusps; m2 with a wide trigonid, without paraconid, narrow talonid with a very weak entoconid.

DIFFERENTIAL DIAGNOSIS. — Eucyon debonisi n. sp. is smaller than all the other Eucyon species excepting E. intrepidus Morales, Pickford & Soria, 2005 (= E. minimus Haile-Selassie & Howell, 2009 ). The differences with E. davisi ( Merriam, 1911) are, the greater size of the M 2 in relation with the M1, the more developed cingulum and the presence of a valley in the talon of the M1. When compared with E. monticinensis ( Rook, 1992) this new species has a stronger parastyle but a less developed lingual cingulum and a more closed valley in the talon of the M1. Besides, it has a more slender dentition and mandible than E. monticinensis and possesses a diastema between p1 and p2 and between p2 and p3. It differs from E. marinae Spassov & Rook, 2006 in the absence of a distal cuspid in the p3. The m1 of E. debonisi n. sp. differs from those of E. intrepidus and E. wokari García, 2008 in the more simple morphology of the talonid, that remains undivided.

MATERIAL EXAMINED. — All the studied specimens are stored in the two following Spanish institutions: Museu de Geologia de la Universitat de València (Burjassot)- Venta del Moro ( MGUV-VV) and Museo Nacional de Ciencias Naturales ( CSIC, Madrid)-Venta del Moro ( MNCN-VM).

MGUV 14779 , 14780 , 14781 ( VV-1522-1549 - 1624 ) (holotype), fragment of right mandible with p2-p3, fragment of right maxilla with P2, P4-M2, fragment of left maxilla with I3-M2 ; MNCN VM-1 , fragment of maxilla with incomplete P2 and P3 ( Morales & Aguirre 1976: pl.1, fig. 2) ; MNCN VM-2 , right P4 ( Morales & Aguirre 1976: pl.1, fig. 3) ; MNCN VM-3 , fragment of right maxilla with M1-M2 ( Morales & Aguirre 1976: pl. 1, fig. 1) ; MNCN VM-4 , fragment of mandible with p3 and incomplete

m1 ( Morales & Aguirre 1976: pl. 1, figs 4, 5); MNCN VM- 5, right P4 ( Morales & Aguirre 1976: pl. 1, fig. 8); MNCN VM- 15, right p3; MNCN VM- 50, rigth m1 ( Morales 1984: pl. 2, fig. 2); MNCN VM- 51, left m1 ( Morales 1984: pl. 2, fig. 3); MGUV 14752 ( VV- 9248), maxilla with both dental series; MGUV 14753 ( VV- 9325), fragment of left mandible with p2-m1; MGUV 14777 ( VV- 75), left M2; MGUV 14778 ( VV- 793), right upper canine; MGUV 14782 ( VV- 2148), right m1; MGV 14784 ( VV- 4187), left M1; MGUV 14785 ( VV- 4312), left M2; MGUV 14786 ( VV- 4352), right P4; MGUV 14787 ( VV- 4515), left mandible with p1-p2 and m2; MGUV 14788 ( VV- 5315), fragment of right mandible with p4-m2; MGUV 14791 ( VV- 7100), left m1; MGUV 14793 ( VV- 8150), incomplete left m1; MGUV 18471 ( VV- 12464), left lower canine; MGUV 18472 ( VV- 12493), left P4; MGUV 18473 ( VV- 13282), right m1; MGUV 18474 ( VV- 13284), right m1; MGUV 19179 ( VV- 14346), right M1; MGUV 19180 ( VV- 14368), left M1; MGUV 19181 ( VV- 14309), right M1; MGUV 19623 ( VV- 12736), right m2; MGUV VV- 14601, left m1; MGUV VV- 14713, right p3; MGUV VV- 14788, p4; MGUV VV- 14793, right m1; MGUV VV- 14889, left M1; MGUV VV- 14906, right m2; MGUV VV- 14988, left M2; MGUV VV- 15125, right m1; MGUV 15753 ( VV- 9568), left astragalus; MGUV 19183 ( VV- 13763), left calcaneus; MGUV 19184 ( VV- 14181), right calcaneus; MGUV VV- 14624, right navicular.

MEASUREMENTS

See Tables 1 and 2.

DESCRIPTION

MGUV 14779, 14780, 14781 (VV-1522-1549- 1624), holotype ( Fig. 1 )

Slender P4, with a well-individualized protocone. Continuous and strong lingual cingulum. Very smooth labial cingulum. It has a quite marked mesial crista in the paracone with a thick base but not so prominent as a real parastyle. Strong mesial cingulum, wide in its labial edge. Sharp paracone. The M1 has a smooth medial inflexion in the buccal wall, a well-marked inflexion in the distal wall and a convex mesial wall. The paracone has a pyramidal shape, and a weak lingual crista. Dune-shaped protocone, fused to the paraconule and metaconule, thus closing completely the central valley. The lingual cingulum is quite developed, displaced towards the distal part and fused to the base of the metaconule and the paraconule closing a deep valley between them. The molar is surrounded by a moderate cingulum in which a strong parastyle stands out. In occlusal view, the M2 shows a similar shape to that of M1, with a strong stylar platform. The cingulum has a moderate size, even in lingual view, where a shallow and plain valley is present. The P3 has an elongated crown, narrow, and with only one cusp. The mesial crista is displaced towards the lingual part. The distal crista ends in a tiny basal cusp. It has very smooth cingula. The P2 is similar in shape to the P3. The P1 has just one root, with a strong internal cingulum and a small distal cusp. The mesial crista is also located in the lingual border.

The mandible has rodent tooth marks and lacks all the teeth excepting the p2 and the p3. The p2 is separated by a diastema from the p3and from the canine. Both premolars are similar in shape, but the p2 is smaller and more vertical than the p3. It possesses a quite vertical mesial cristid, wide in its base, while the distal cristid is more enlarged. The p3 lacks a distal accessory cuspid, but has a small cuspid at the base of the distal cristid. The cingula are very smooth.

MGUV 14752 (VV-9248), maxilla with both dental series ( Fig. 2 A-C)

The infraorbital foramen is located at the level of P3. The canine has a moderate size and a sharp distal edge. The molars are larger and quite more worn than those of the holotype. When compared with the holotype, the P4 has a strong cingulum, with a wider mesial corner. The M1 has a very strong parastyle and the M2 possesses a higher labial cingulum.

MGUV 14753 (VV-9325), left hemimandible with p2-m1 ( Fig. 3 G-I)

The p2 has only one cuspid with a quite vertical mesial cristid that turns to be slightly wider towards its base. It has a large distal cristid that, instead of a distal cuspid, has a slight incision marking a change (from more to less steep) in the slope. The p3 is broken, but a small cuspid in the distal part of the talonid can still be observed. The p4 is narrow, with a high principal cuspid and a vertical mesial cristid in which the basal end has turned slightly wider. The distal cuspid is high and strong, and has a well-developed talonid that has a low central cuspid. The m1 has a high protoconid, which possesses a small disto-buccal cristid. The paraconid has a vertical mesial cristid, and although the metaconid is broken, its large size can be deduced. The talonid is well developed and the hypoconid, which has a pyramidal shape, runs in a parallel way to the mesio-distal molar axis. The distal cristid of the hypoconid ends in a small hypoconulid. The entoconid is quite small and is well separated from the hypoconid. Its mesial cristid is elongated and possesses an individualized cuspid.

MGUV 14787 (VV-4515), very well-preserved left hemimandible with p1, p2 and m2 ( Fig. 3 A-C) The mandibular body is very slender and shows a broken angular process. Its shape differs only slightly from the European fox ( Vulpes vulpes Linnaeus, 1758 ). The p1 is quite reduced and isolated by diastemas. The p2 is poorly preserved and is also separated from the p3 by another diastema. The m2 has a wide trigonid, mesio-buccally expanded; the cingulum is only present at the base of the protoconid. This molar lacks the paraconid, and only a small lump is present instead. The metaconid is as high as the protoconid but the latter is wider. The talonid is a simple and narrow cuspid, with a moderate hypoconid and a very small entoconid.

MGUV 15753 (VV-9568), left astragalus

( Fig. 4 E-H)

Measurements: proximo-distal length = 20 mm, latero-medial length = 12.3 mm, dorso-plantar length = 10.3 mm.

The trochlea bears two high lips separated by a deep valley that runs from the proximo-plantar edge to the disto-dorsal neck. The neck is quite elongated towards the medio-distal part and ends in the facet for the navicular. This facet is smooth, convex, and oval-shaped, with its major axis running from the latero-dorsal vertex to the medio-plantar one. The facet for the calcaneus has two different surfaces, the larger one being located just on the opposite part of the trochlea for the tibia, whereas the smaller one is placed on the lateral tip of the distal end of the facet for the navicular. The latter is a small facet, which hardens the articulation between the astragalus and the calcaneus, thus avoiding lateral movements between them.

This astragalus has been compared with those from E. davisi ( Harrison 1983) and E. monticinensis ( Rook et al. 1991) . They seem to be quite similar in shape but both species are clearly larger than E. debonisi n. sp.

MGUV 19183 (VV-13763) left calcaneus and MGUV 19184 (VV-14181), right calcaneus ( Fig. 4 A-D)

Measurements:left calcaneus, proximo-distal length = 31.3 mm, latero-medial length = 11.3 mm, dorsoplantar length = 11.9 mm; right calcaneus, proximodistal length = 32.1 mm, latero-medial length = 12 mm, dorso-plantar length = 12.4 mm.

The calcaneus is quite elongated, especially the distal third of the bone, between the posterior articular surface for the astragalus and the distal end (facet for the cuboid). Both the lateral and medial faces are quite smooth and straight, with a very small lateral development of the trochlear process and reduced sustentaculum tali when compared with other carnivores. The articular surfaces for the astragalus are very similar to those of Canis aureus Linnaeus, 1758 . However, the distal part of the posterior articulation surface is much more concave and the anterior articulation surface is larger than in this species.The calcaneal tuberosity is quite robust, and has a shallower groove for the large terminal tendons of the muscles soleus and gastrocnemius, when compared with the studied canids.

The calcaneus of E. debonisi n. sp. has been compared with that of E. davisi ( Harrison 1983) , and apart from being smaller, it shows some differences. The trochlear process and the groove in the calcaneal tuberosity are more developed in E. davisi , whereas the articulation surfaces for the astragalus are quite more elongated in E. debonisi n. sp.

MGUV VV-14624, right navicular ( Fig. 4I , J) Measurements: proximo-distal length = 7.4 mm, latero-medial length = 10.6 mm, dorso-plantar length = 9.6 mm.

This is a quite cubic bone, with a concave proximal surface and a straight distal one. The facet for the astragalus is somehow more circular than that of the studied extant canids. This is a consequence of the weaker development of the latero-plantar notch. It has smooth medial and dorsal surfaces, while both the lateral and especially the plantar parts are much rougher. The facet for the cuboid is a small rounded smooth surface located in the lateral part of the bone that is distally projected. In the plantar facet there is a quite developed and rounded tuberosity for the attachment of the ventral calcaneus-navicular and ventral naviculo-cuneiform ligaments.

Figures

FIG. 1. — Holotype of Eucyon debonisi n. sp. from Venta del Moro (Spain): A-C, fragment of left maxilla with P2-M2 (MGUV 14781); D-F, fragment of right maxilla with P2 and P4-M2 (MGUV 14780);G-J, right mandible with p2-p3 (MGUV 14779);A, B, D, E, I, J, stereo- photographs of occlusal views; C, F, lateral views; G, buccal view; H, lingual view. Scale bar: 10 mm.

FIG. 2. — Eucyon debonisi n. sp.from Venta del Moro (Spain):A-C, maxilla with both dental series (MGUV 14752); B, C, detailed views of the left maxilla with P3-M2; D, E, right upper canine (MGUV 14778); A, ventral view; B, occlusal view; C, lateral view; D, lingual view; E, buccal view. Scale bars: 10 mm.

FIG. 3. — Eucyon debonisi n. sp. from Venta del Moro (Spain): A-C, left hemimandible with p1, p2 and m2 (MGUV 14787); D-F, fragment of right hemimandible with p4-m2 (MGUV 14788); G-I, fragment of left hemimandible with p2-m1 (MGUV 14753); J-L, left m1 (MGUV 14791); M-O, right m1 (MGUV 18474); A, D, G, L, O, lingual views; B, F, H, K, N, occlusal views; C, E, I, J, M, buccal views; Scale bars: 10 mm.

FIG. 4. — Eucyon debonisi n. sp. from Venta del Moro (Spain): A-D, left calcaneus (MGUV 19183); E-H, left astragalus (MGUV 15753); I, J, right navicular (MGUV VV-14624); A, E, dorsal views; B, H, medial views;C, G, plantar views;D, F, lateral views;I, proximal view; J, distal view. Scale bar: 10 mm.