Description
Description after Bor et al. 2012 [17759]:
Picking of the Miste shell grit yielded some large dasyatid teeth of female morphotype which during our current studies on batoids inhabiting the Early and Middle Miocene North Sea Basin (Reinecke et al., 2011) [13836] were recognized as a new species (Pl. 42; Pl. 43, Figs 1-2). In large samples of isolated dasyatid teeth, as the one from the Miste Bed, it is often difficult to combine male and female teeth into different individual species. After having identified male teeth of Taeniurops cavernosus, Dasyatis probsti and D. rugosa (see illustrations and discussion in respective chapters) and separated from the overall Miste sample, a small number of male teeth remained which showed unique, consistent morphological characteristics (Pl. 43, Figs 3-6). These are very similar in some characteristics to the female teeth, which are identified as a new species of the genus Plesiobatis Nishida, 1990 [1803]. An antero-lateral female tooth is chosen as holotype. Another four female and three male teeth are defined as paratypes.
The holotype (Pl. 42, Fig. 1a-e) has a stout, massive crown and a low root. In profile view (Pl. 42, Fig. 1d), the crown has the outline of a right-angled triangle, in which the traces of the orthogonal labial and lingual crown faces have similar lengths and the basal crown margin forms the long edge. In occlusal view (Pl. 42, Fig. 1a), the shape of the crown is that of a distorted rhombus with two shorter (the labial and lingual visors) and four longer edges (the labio- and linguo-lateral crown margins). The labial visor is angular with the labio-lateral crown margins (Pl. 42, Fig. 1c). The laterally projecting corners of the labio-lateral crown margins join the linguo-lateral crown margins at right angles. The transverse crest has a rounded profile (Pl. 42, Fig. 1d) and is only slightly arched in lingual direction (Pl. 42, Fig. 1a). The labial face is rather flat in the apical region, lacking a labial depression, but transversally and apico-basally convex in the basal region (Pl. 42, Fig. 1d). It is completely covered by an dense web of very small, circular to elongate pits separated by sharp ridges (Pl. 42, Fig. 1b). The ornamentation closely approximates the labial visor and labio-lateral crown edge (Pl. 42, Fig. 1b) and covers the transverse crest and apical region of the lingual crown faces (Pl. 42, Figs 1a, d, e). The latter are smooth, slightly convex in the basal part and axially join each other at the prominent lingual ridge. The basal labial crown edge is smooth, very broad and flat to weakly convex. It abruptly narrows in direction of the lingual visor (Pl. 42, Fig. 1c). The trace of the root-crown junction is marked by a narrow depression (Pl. 42, Fig. 1c). The short lobes of the holaulacorhize root are laterally only slightly diverging at the basis and in lingual direction do not extend much beyond the lingual visor. The lobes are separated by a broad, deep groove into which opens a large foramen. Few, very small foramina are scattered on the faces of the root lobes.
A partially corroded female tooth (Pl. 42, Fig. 6) with hexagonal outline of the crown (in occlusal and basal view), a high transverse crest and narrower crown width than the holotype is probably from an anterior file. Female teeth from more lateral files than the holotype (paratypes 1, 2; Pl. 42, Figs 2, 3) show wider crowns, a rounded labial crown margin and a wider lingual visor which has a straight or slightly concave margin (Pl. 42, Fig. 2a). In all these specimens the ornamentation of the labial face and the width of the basal labial crown edge is very similar. Female teeth from very lateral to commissural files (paratypes 3 and 4; Pl. 42, Figs 4, 5) have laterally extended crowns with a large and flat labial face and a low transverse crest, that is strongly arched lingually.
Male teeth (Pl. 43, Figs 3-6) tend to have higher and less wide crowns than female teeth. Teeth in anterior files (paratype 5; Pl. 43, Fig. 3) have a narrow crown basis and a short, triangular, lingually bent cusp with straight lateral cutting edges (in labial view). In occlusal or basal view, the diameters of the crown basis are isometric. The labial visor is strongly convex (Pl. 43, Fig. 3b, d), not angular, and the crown apex commonly truncated by wear (Pl. 43, Fig. 3a, c). A labial depression is not observed. The labial face is ornamented with a fine pattern of deep, rounded pits, comparable to that of the female specimens. This ornamentation completely covers the labial face and extends close to the labial visor. Wrinkles and pits are present also in the apical region of the lingual face near the cutting edges. The basal labial crown edge is smooth, broad and convex in profile (Pl. 43, Fig. 3d). The subvertical lingual crown face is laterally flat, but more convex near the basis, The lingual visor shows a pair of smooth, lateral bulges (situated just above the lingual extensions of the root lobes) with an axial depression in between (Pl. 43, Fig. 3c). The root is much lower than the crown (Pl. 43, Fig. 3c, e) and shows a single, large foramen in the middle of the groove.
Male teeth from more lateral files have lower crowns with erect or weakly inclined cusps (paratypes 6-7; Pl. 43, Figs 4-5). The lateral cutting edges are concave towards the crown apex and the pits of the ornamentation are flatter than in anterior teeth.
The Miste Bed has also produced some teeth, much smaller than 2 mm in width, which resemble the larger female teeth of Plesiobatis vandenboschi in crown proportions and details of ornamentation (Pl. 43, Figs 1, 2). These are considered to be teeth of juvenile/subadult females and/or males.

Remarks
shark-references Species-ID=13431;
valid after Bor et al. (2012) p. 71 [17759];

References