Galaxias tabidus 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 : 330-331

Galaxias tabidus Schwarzhans sp. nov.

Fig. 6H–I.

Etymology: From Latin tabidus , melting, diminishing, referring to the anterior and posterior indentations of the ventral rim.

Type material: Holotype: NMNZ S.52723 ( Fig. 6H) . Paratypes: 2 specimens NMNZ S.52724 ( Fig. 6I) .

Type locality: West of Lauder , Otago .

Type horizon: Lauder shell bed, early Miocene.

Diagnosis.—Thin otoliths with moderately compressed outline with short rostrum. Ventral rim with angular indentations anteriorly below rostrum and posteriorly below posterior tip. Inner face almost flat. No excisura; instead angular indentation of anterior rim above ostium. Ostium narrow, short; cauda longer than ostium, terminating close to posterior rim of otolith. Ventral field on inner face wide, with indistinct ventral furrow far from ventral rim of otolith.

Description.—Moderately compressed thin otoliths. Size up to 2.5 mm. Rostrum short, pointed; no excisura, small; instead about 100 ° angular indentation of anterior rim above ostium. Dorsal rim high, rounded, anteriorly pronounced, posteriorly regularly inclining. Posterior tip median, above tip of cauda. Ventral rim shallow, with two 90–100 ° indentations, one anteriorly below rostrum, the other below posterior tip. Rims slightly undulating. OL:OH = 1.3; OH:OT about 3.5.

Inner face nearly flat, only slightly curved at the rostrum, smooth, with long, narrow, moderately deepened, nearly median sulcus. Ostium very narrow, anteriorly open; cauda similarly narrow, straight, reaching close to posterior rim of otolith below its posterior tip. OL:SuL = 1.1–1.15; CaL:OsL about 2.5. Dorsal field wide, with small, shallow depression. Ventral field wide, with indistinct ventral furrow far from ventral rim of otolith.

Outer face flat, smooth.

Remarks.— Galaxias tabidus is restricted in distribution to the Lauder shell bed, which is probably stratigraphically younger than the other Bannockburn locations sampled and represents a different facies, many kilometres from the deltaic environment of the sites near St Bathans. Its otoliths are easily recognized by the very distinctive shape of the ventral rim, which resembles otoliths of the Recent New Zealand species G. fasciatus Gray, 1842 (see Fig. 4C), the “pseudo”−excisura above the ostium and the thin, fragile appearance with an almost flat inner face and a long sulcus.

Stratigraphic and geographic range.—Bannockburn Formation, Lauder.

H. NMNZ S.52728, inner face. I–O. Prototroctes vertex Schwarzhans sp. nov. from early Miocene, Bannockburn Formation, Manuherikia River, HH 1a. I. Holotype, NMNZ S.52729, outer face (I 1), inner face (I 2), posterior (I 3), anterior (I 4), dorsal (I 5), and ventral (I 6) views. J–N. Paratypes NMNZ S.52731a–e, inner face. O. Deformed specimen NMNZ S.52732a, inner face (O 1), posterior view (O 2), ventral view (O 3).

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