True’s beaked whale (Mesoplodon mirus) in Macaronesia

The True s beaked whale (Mesoplodon mirus, True 1913) is a poorly studied member of the speciose Ziphiidae family. Its distribution in the North Hemisphere is thought to be restricted to the temperate or warm temperate waters of the North Atlantic, while a small number of stranding records from the Southern Hemisphere suggest a wider distribution, extending from the Atlantic coast of Brazil to South Africa, Australia and the Tasman Sea coast of New Zealand. Here we i) report the first molecular confirmation of the occurrence of True s beaked whales around the Azores and Canary Islands (Macaronesian ecoregion), the species’ southern limit in the northeast Atlantic; ii) describe a new colouration for this species; and iii) contribute to the sparse worldwide database of live sightings, including the first underwater video, of this species. In November 2012, a 390 cm male True’s beaked whale stranded in El Hierro, Canary Islands. In July 2004, a subadult male True’s beaked whale was found floating dead near Faial, Azores. Species identification was confirmed in both cases using mitochondrial DNA control region and cytochrome b gene markers. The whale that stranded in the Canary Islands had a clearly delimited white area on its head, extending posteriorly from the tip of the beak to cover the blowhole dorsally and the gular grooves ventrally. This colouration contrasts with previous descriptions for the species and it may be rare, but it demonstrates that True s beaked whales show variable colourations in the North Atlantic. This is confirmed by sightings data. Given the presence of this species around the Azores and the Canary Islands, it would be expected that True s beaked whales also occur in the area between these archipelagos, including the islands of Madeira.