A new longjaw galaxias species (Teleostei: Galaxiidae) from the Kauru River, North Otago, New Zealand

Abstract

A population of “longjaw galaxias”, long known to be present in the Kauru River, a small tributary of the Kakanui River in North Otago, is shown to be a distinct species using both morphological and molecular characters. It is described here as Galaxias cobitinis n. sp., which has: origin of anal fin anterior to that of dorsal fin, only 15 principal caudal fin rays, only 5 pelvic fin rays, and only 51–53 vertebrae. In these and other morphological characters it differs from G. prognathus Stokell. One specimen from the Hakataramea River, lower Waitaki River system appears to also be G. cobitinis. Molecular evidence suggests long isolation from the Kauru River of “true” longjaw galaxias G. prognathus and from rivers draining the high Southern Alps (type locality: Wilberforce River, tributary of the Rakaia River), perhaps dating back as long as 11–4 million years ago (late Miocene‐early Pliocene). This prolonged isolation contrasts with hypothesised more recent isolation of populations of the Galaxias vulgaris species group in the Kakanui River from other populations of that species group. Thus, sympatric species of Galaxias have contrasting biogeographic histories in the Kakanui River.

Keywords:

• Galaxiidae
• Galaxias cobitinis
• new species
• Kauru River
• longjaw galaxias