Recognition and distribution of Polysiphonia morrowii (Rhodomelaceae, Rhodophyta) in New Zealand

Polysiphonia morrowii, a species native to the North Pacific, is believed to have been introduced to Chile, Turkey, Italy and France. This species was first recorded from New Zealand in 2011, based on collections made in 2004 from two sites on South Island, but no commentary was provided in the distribution or characteristics of the material collected. In 2009, as part of a study on macroalgae associated with soft sediment habitats in New Zealand, several samples of P. morrowii were collected from Otago Harbour, a location already known to host 17 non-indigenous macroalgal species. However, this species has gone unnoticed in New Zealand. We present the current understanding of the distribution of this species in New Zealand, and the distinguishing features of the specimens collected, to assist with biosecurity and monitoring programmes. Including this report of P. morrowii, there are now seven species of Polysiphonia and Neosiphonia that are regarded as non-indigenous in New Zealand.