Galaxias papilionis 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 : 328-330

Galaxias papilionis Schwarzhans sp. nov.

Fig. 6A–D.

Etymology: From Latin papilio, butterfly, referring to the shape of the dorsal and ventral fields resembling the wings of a butterfly.

Type material: Holotype: NMNZ S.52717 ( Fig. 6A) . Paratypes: 11 specimens (8 specimens NMNZ S.52718, HH1d bed; 3 specimens NMNZ S 52719 , HH1 a bed), ( Fig. 6B–D) .

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

Type horizon: HH1d bed, Bannockburn Formation, early Miocene.

Diagnosis.—High−bodied outline with expanded dorsal and ventral rims. Inner face almost flat. Rostrum short and thin. Excisura broad; posterior rim with deep and wide excisura−like incision joining up with the caudal tip. Ostium narrow, short; cauda longer than ostium, opening towards posterior rim of otolith. Ventral field on inner face wide, without distinct ventral furrow.

Description.—Compressed thin otoliths with high−bodied outline. Size up to 3 mm. Rostrum short, thin, pointed, with ventral concavity or indentation; excisura wide; antirostrum indistinct. Posterior tip inferior, broadly rounded, with deep, broad incision joining to tip of cauda. Dorsal rim high, rounded, postdorsally expanded. Ventral rim moderately deep, posteriorly expanded. All rims smooth. OL:OH = 1.05–1.25; OH:OT = 3.2–3.5.

Inner face almost flat, smooth, with long, narrow, deepened, nearly median sulcus. Ostium very narrow, anteriorly open; cauda similarly narrow, straight, its posterior tip reaching posterior rim of otolith and joined to postdorsal incision, resulting in a posterior “excisura” and a posterior sulcus opening. OL:SuL = 1.1–1.2; CaL:OsL = 1.7–2.3. Dorsal field wide, with broad, shallow depression. Ventral field wide, with no distinct ventral furrow.

Outer face flat, rather smooth.

Variability and ontogeny.—The expression of the short ros−

SCHWARZHANS ET AL.—MIOCENE FISH FAUNA FROM NEW ZEALAND 329

B 3 1 mm

trum is variable to some extant as well as the excisura of the posterior rim. The latter is less well developed in small specimens.

Remarks.— Galaxias papilionis looks like G. bobmcdowalli taken to an extreme. It differs in the flat inner face, the very short, fragile, pointed rostrum and the deep posterior

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

“excisura” with both dorsal and ventral rims expanding over it. Interestingly, G. papilionis represents the earliest Galaxias species occurring in the Bannockburn Formation near its base in the HH1d bed. It is rather rare in the next sampled bed up−section, the HH1a bed, but it is uncertain whether this represents a stratigraphic event or an ecological one.

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