Monday, February 8, 2016

[PaleoMammalogy • 2016] Lutraeximia umbra • A New Otter from the Early Pleistocene of Pantalla (Italy), with remarks on the Evolutionary History of Mediterranean Quaternary Lutrinae (Carnivora, Mustelidae)

Lutraeximia umbra
Cherin, Iurino, Willemsen & Carnevale, 2016

Artwork by D.A. Iurino. 
DOI: 10.1016/j.quascirev.2016.01.008 


• We describe the cranium of a Lutrinae from central Italy (late Villafranchian).
• It is the first otter cranium in the Early Pleistocene of the Mediterranean area.
• We refer the specimen to Lutraeximia umbra, gen. et sp. nov.
• Phylogenetic analysis allows recognizing a clade of Quaternary Mediterranean otters.
• This evidences the past large diversity of Lutrinae in the Mediterranean.

Here we describe a well-preserved sub-complete lutrine cranium from the late Villafranchian (Early Pleistocene) of Pantalla (Italy) and we assign it to the new taxon Lutraeximia umbra, gen. et sp. nov. The new genus Lutraeximia is characterized by a relatively short and large cranium, with a peculiar shape of the postorbital area and a short and vertical muzzle in lateral view. We refer to the same genus the partially complete skeleton of Lutra trinacriae from the Middle-Late Pleistocene of Sicily. Lutraeximia umbra was a medium-large otter (predicted body mass larger than 13.5 kg) with a unique combination of characters in the upper dentition.

A phylogenetic analysis based on craniodental characters places Lutraeximia umbra in a monophyletic clade including the living Lutrogale perspicillata plus the extinct Lutrogale cretensis and three Pleistocene otters from Italy: Sardolutra ichnusae and the sister taxa Lutraeximia trinacriae and Lutraeximia umbra. The recognition of this clade evidences the broad diversity of peri-Mediterranean Lutrinae during the Pleistocene.

Keywords: Lutraeximia; Lutrinae; Otter; Phylogeny; Pantalla; Villafranchian

Fig. 10. Sequential reconstruction of the head of Lutraeximia umbra, gen. et sp. nov., from Pantalla (Italy).
From top to bottom: 3D retrodeformed model of the cranium SBAU 337654, reconstructed head and cranium overlapped, life appearance.
Artwork by D.A. Iurino. DOI: 10.1016/j.quascirev.2016.01.008  

Systematic paleontology
Class: Mammalia Linnaeus, 1758
Order: Carnivora Bowdich, 1821

Family: Mustelidae Fischer, 1817
Subfamily: Lutrinae Bonaparte, 1838

Lutraeximia gen. nov.
Type species: Lutraeximia umbra, sp. nov.

Etymology: From the Latin words lutra, otter and eximia, distinct, outstanding.

Included species: Lutraeximia umbra, sp. nov.; Lutraeximia trinacriae ( Burgio and Fiore, 1988) (=Nesolutra trinacriae Burgio and Fiore, 1988; Lutra trinacriae Willemsen, 1992).

Diagnosis: Lutrinae with cranium relatively short and large; postorbital constriction slightly shorter than its wider section and with a small narrowing in the caudal end; muzzle short and with a nearly vertical rostral margin in lateral view; M1 relatively smaller than P4.

Lutraeximia umbra sp. nov.

Holotype: SBAU 337654, a sub-complete dorsoventrally compressed cranium missing the mastoid and jugular processes, both P3, left P1 and left I3. The rostral part of the frontals and nasals are ventrally crushed, with the latter collapsing into the nasal cavities. The cranium pertains to an adult individual.

Etymology: Umbria is the region of central Italy where the type specimen was found.

Type locality, horizon and age: The holotype is from the locality of Pantalla, about 30 km S to Perugia (Italy; 42°52′46.79″N, 12°24′23.26″E; Fig. 2). The mammal assemblage of this locality was recovered from a 15 m-thick stratigraphic succession referred to the Early Pleistocene Santa Maria di Ciciliano Unit (Gentili et al., 1997). Fossils were found in two different levels in the middle-upper portion of the succession: fluvial silty sands below, interpreted as crevasse-splay deposits; silty clays above, interpreted as a drained paleosol (Gentili et al., 1997). SBAU 337654 comes from the former level. Besides the Lutrinae described here, the mammal assemblage includes Apodemus cf. A. dominans, Canis etruscus, Vulpes sp., Lynx issiodorensis valdarnensis, Acinonyx pardinensis, Sus strozzii, Pseudodama nestii, Leptobos aff. L. furtivus, Equus sp., and Mammuthus cf. M. meridionalis ( Gentili et al., 1997 and Cherin et al., 2014). From a biochronological point of view, the assemblage can be referred to the Olivola/Tasso Faunal Units (Gentili et al., 1997), in a time interval ranging approximately between 1.9 and 1.7 Ma (Rook and Martínez-Navarro, 2010).

Marco Cherin, Dawid Adam Iurino, Gerard Willemsen and Giorgio Carnevale. 2016.  A New Otter from the Early Pleistocene of Pantalla (Italy), with remarks on the Evolutionary History of Mediterranean Quaternary Lutrinae (Carnivora, Mustelidae). Quaternary Science Reviews. 135; 92–102.  DOI: 10.1016/j.quascirev.2016.01.008

Todi, trovato cranio completo di lontra preistorica: «Nuova specie tutta umbra»