geographically widely separate, due to a combination of oceanic dispersal, sea-level change, volcanism and glaciation. Based on anatomical and genetic data, the Tasmanian mudfish is sister to the New Zealand mudfishes. The divergence is too recent for this wide distribution to result from the separation of New Zealand and Australia 83 million years ago. The Tasmanian mudfish is amphidromous, spending its first 2–3 months at sea, and it is likely that this was the means of dispersal to New Zealand. All five of the New Zealand mudfishes have lost this migratory life cycle. Of the New Zealand species, the Canterbury and Chatham mudfishes are the least departed from the ancestral form, retaining small pelvic fins and a more Galaxias-like shape. The Chatham Islands emerged from the sea recently, possibly 2–3 million years ago, so the ancestors of the Chatham mudfish must have retained the amphidromous life cycle until after dispersal to these islands. The Tasmanian mudfish is found in Tasmania and in southern Victoria, on either side of the Bass Strait, and New Zealand's brown mudfish is found on either side of Cook Strait. Both species likely extended their range during the Pleistocene, when the sea levels were low and there were land connections between the respective islands, and were subsequently separated when sea levels rose again. There is a large gap in the brown mudfish distribution in the lower North Island. This is possibly due to the effects of volcanism causing local extinction, and the species was unable to recolonise affected catchments as it has lost the highly mobile amphidromous life cycle. The absence of brown mudfish (or other Neochanna species) from the southern half of the west coast of the South Island is likely due to glaciation in the late Pleistocene, although there has been some range expansion into the glacier-affected areas. The black and Northland mudfishes are the only species with a near-overlapping distribution. The black mudfish is found broadly throughout the northern North Island, surrounding the much smaller distribution of the Northland mudfish, which is only found on the Kerikeri volcanic plateau. It is suggested that the common ancestor of both species was found throughout the northern North Island, but it was divided into two populations by high sea levels during the Pliocene. These two populations then separated into the Northland mudfish in the north, and the black mudfish in the south. After sea levels fell