Pristiophorus striatus, Underwood & Schlögl, 2013

Underwood, Charlie J. & Schlögl, Jan, 2013, Deep-water chondrichthyans from the Early Miocene of the Vienna Basin (Central Paratethys, Slovakia), Acta Palaeontologica Polonica 58 (3), pp. 487-509 : 490-492

Pristiophorus striatus sp. nov.

Fig. 4H–K.

Holotype: SNM Z 27441 , anterior oral tooth.

Etymology: From the striated ornament on the oral teeth.

Type locality: Cerová−Lieskové, Vienna Basin, Slovakia.

Type horizon: Lakšárska Nová Ves Formation, late Karpatian (equivalent to latest Burdigalian), Miocene.

Material.—Two additional oral teeth and an incomplete rostral tooth; SNM Z 27439, SNM Z 27440, SNM Z 27442.

Diagnosis (based on oral teeth).—Teeth considerably wider than high. Cusp well developed relative to other members of the genus but forms less than half of height of crown and less than quarter of width of crown. Bases of cusp form sharp angle with linguo−occlusal edge of crown. Labial crown face with widely spaced and irregular vertical folds, some reaching close to base of cusp or linguo−occlusal edge, others very short and limited to labial crown edge.

UNDERWOOD AND SCHLÖGL—MIOCENE DEEP−WATER SHARKS FROM SLOVAKIA 491

0.5 mm (G)

Folds do not bifurcate and all reach crown labial edge. Labial edge of crown slightly crenulated with no differentiated labial protuberance.

Description.—The oral teeth of this species are small, being up to 1.3 mm wide. In all cases the tooth was far wider than high, being more than twice as wide as high when viewed labi−

http://dx.doi.org/10.4202/app.2011.0101

ally. The labial face of the crown is weakly rhombic, being widest in the centre and tapering towards the lateral extremities which are somewhat rounded. A short but sharp and very clearly demarcated cusp is present at the centre of the occlusal crown edge. The cusp is about as high as wide and is less than half the height of the crown. The crown labial face is flat to very weakly convex, with the labial face of the cusp being weakly convex. The labial face of the crown is ornamented by weak but sharp edged folds. These folds originate from the basal edge of the crown and extend vertically across the crown to various degrees, with some folds reaching the base of the cusp or close to the occlusal edge, but others being limited to the immediate vicinity of the basal edge. The folds are irregularly spaced and do not appear to form any systematic pattern, and do not bifurcate. There are weak crenulations where the folds meet the basal face of the crown. The labial and lingual crown faces are separated by a well developed cutting edge, and form an angle of less than 90°. The lingual crown face is flat, but is expanded below the cusp to form a well developed but narrow uvula. Short, weak and irregular folds are seen on the lingual crown face and weak crenulations are present at its base. The crown overhangs the root on all sides, with the labial and lingual faces of the root being low and concave. The root is hemiaulacorhize and typically weakly “V” shaped when viewed basally. The basal face of the root is flat, and flared laterally, with the root being slightly wider than the crown. Several large foramina are present near the centre of the lingual face of the root, and a single large foramen is present to one side of the uvula on the labial root face.

The rostral tooth is very small and incomplete. The blade is oval in cross section and has a weak cutting edge on one side but is otherwise smooth. The root is not preserved. This is probably a secondary rostral tooth or one of the reduced teeth from the ventral surface of the rostrum.

Remarks.— Pristiophorus has been recorded from a number of Cenozoic chondrichthyan assemblages, including from the Miocene of Europe. However, these records are based predominantly on rostral teeth (e.g., Barthelt et al. 1991, and referrences therein; Vialle et al. 2011). Many of these fossil rostral teeth of Pristiophorus are not distinguishable from those of extant species and for that reason we suggest that Pristiophorus species based on rostral teeth should be considered as nomina dubia unless they can be shown to have autapomorphic characters. As a result, although it is possible that the species present here is conspecific with the type material of Pristiophorus suevicus Jaekel, 1890 , this cannot be demonstrated, as the holotype of P. suevicus cannot be regarded as diagnostic.

Pristiophorus striatus sp. nov. differs from most other species of Pristiophorus in possessing wide and low teeth with a well defined cusp and a labial ornament. The ornamented labial face is shared with Pristiophorus lacipidinensis Adnet, 2006 from the Eocene of France, but this species differs in having fewer folds that frequently do not reach the basal edge of the crown, as well as a larger and less clearly differentiated crown. Pristiophorus rupeliensis Steurbaut and Herman, 1978 from the Oligocene of Belgium (as figured in Hovestadt and Hovestadt−Euler 1995) has incipient ornamentation along the labial basal crown face but this never forms elongate folds; in addition the teeth are high and typically possess a well developed labial protuberance.