Mataichthys taurinus Schwarzhans, 2012

Schwarzhans, Werner, Scofield, R. Paul, Tennyson, Alan J. D., Worthy, Jennifer P. & Worthy, Trevor H., 2012, Fish remains, mostly otoliths, from the non-marine early Miocene of Otago, New Zealand, Acta Palaeontologica Polonica 57 (2), pp. 319-350 : 344-346

Mataichthys taurinus Schwarzhans sp. nov.

Fig. 14G–L.

Etymology: From Latin taurinus , bull−like, referring to the resemblance of the dorsal rim of the otolith to the horns of a bull.

Type material: Holotype: NMNZ S.52742 ( Fig. 14G) . Paratypes: Eight specimens, NMNZ S.52743, same location as holotype ( Fig. 14H–L) .

Type locality: Home Hills, Manuherikia River near St Bathans , Otago .

Type horizon: HH1a bed, Bannockburn Formation, early Miocene.

Further material.— 128 specimens: 116 specimens, same location as holotype ; 10 specimens, same location as holotype, HH1b bed, trench excavation .

Diagnosis.—OL:OH = 1.15–1.25. Anterior−ventral and posterior−ventral projections moderately pronounced, usually almost symmetrical. Dorsal rim high, thin, dentate or with central concavity of variable depth. OL:SuL 1.7–2.4.

Description.—Robust, high−bodied otoliths up to 5.5 mm long. OH:OT = 3.2–3.6. Anterior−ventral and posterior−ventral projections mostly distinct and symmetrically developed, or posterior−ventral projection more strongly. Dorsal rim high, thin, dentate or with central concavity of variable depth, usually deep in large specimens. Anterior−dorsally pronounced expansion in the absence of a central dorsal incision. Ventral rim nearly straight, horizontal. Anterior rim blunt, slightly concave, sometimes with anterior−dorsal lobe, posterior rim blunt, with marked concavity at level of cauda. Rims irregularly undulating.

http://dx.doi.org/10.4202/app.2010.0127

Inner face nearly flat, with mostly smooth surface. Sulcus with median position, not very large, moderately deepened, typical shoe−sole shape, slightly inclined. Dorsal field high, with dorsal depression opening into incision of dorsal rim. Ventral field narrow, somewhat elevated, with distinct ventral furrow at moderate distance from ventral rim.

Outer face slightly convex with small central umbo, smooth.

Remarks.—Otoliths of M. taurinus resemble M. procerus in their compressed, high−bodied appearance, which is expressed in the low index OL:OH of less than 1.3. They differ in the thin dorsal rim with its dentations or, more commonly, central incision. Specimens 3.5 mm long and smaller tend not to have developed this dorsal incision, but are still often recognizable by their anterior−dorsal lobe. Specimens below 2.5 mm long may not always be distinguishable. Due to its dorsal incision, otoliths of M. taurinus may at times also resemble those of M. rhinoceros , particularly when eroded. The main difference is the more compressed shape (index OL:OH = 1.15–1.25 versus 1.3–1.5 in specimens longer than 3.5 mm) and the thin, narrowly incised dorsal rim (versus broad concavity and thick rim).

Stratigraphic and geographic range.—Bannockburn Formation, Manuherikia River.