Abstract
The Longman’s beaked whale (Indopacetus pacificus) is one of the rarest cetaceans worldwide. Since it was first described as its own species in 1926, they have been observed alive at sea on several occasions, and less than 20 strandings have been reported worldwide to date. Thus, basic information regarding this species, such as the maximum size of adult individuals or body length at birth, remains unknown. In this study, the external appearance and DNA analysis of a female Longman’s beaked whale stranded on Miyako Island, Okinawa, Japan, are reported. The external appearance of the specimen matched the features of the Longman’s beaked whale presented in previous studies. The mitochondrial DNA control-region sequences obtained from the specimen also matched the reference sequences of the species deposited in GenBank. Based on these features, the specimen was confirmed as a Longman’s beaked whale. The specimen was estimated to be neonate because of its body length (235 cm) and the clear several fetal folds observed on its body surface. To the best of our knowledge, this is the first report of a confirmed new born neonate of Longman’s beaked whale in the world.
Highlights
The Longman’s beaked whale (Indopacetus pacificus), known as the Indo-Pacific beaked whale or tropical bottlenose whale, is considered one of the rarest cetacean species worldwide
These measurements were compared to the values for 11 specimens of Longman’s beaked whale found in South Africa, Maldives, Taiwan, Hawaii, New Caledonia, and Okinawa in Japan to compare the external appearance of the Miyako specimen with the characteristic features of the Longman’s beaked whale reported in previous studies (Dalebout et al 2003; Yao et al 2012; West et al 2013; Garrigue et al 2016; Kobayashi et al 2020)
External appearance External figures The cetacean stranded on a beach on Miyako Island, Okinawa, Japan was a female specimen with a body length of 235 cm
Summary
The Longman’s beaked whale (Indopacetus pacificus), known as the Indo-Pacific beaked whale or tropical bottlenose whale, is considered one of the rarest cetacean species worldwide. Longman (1926) described it as a member of the genus Mesoplodon based on the skull characters of the specimen. Moore (Moore 1968; Moore 1972) elevated it as its own genus Indopacetus in later years, based on the discovery of the second skull in Somalia (Azzaroli 1968). In the western North Pacific, few sighting records for this species exist in Japanese waters (Ministry of Agriculture, Forestry and Fisheries: https://www.jfa.maff.go.jp/j/ sigen/20170321redlist.html), though detailed information is not known. Even though the sighting information is increasing in recent years, the total number of strandings reported for this species is less than 20 cases worldwide. The basic information for this species, such as Kobayashi et al Marine Biodiversity Records (2021) 14:4 the maximum, minimum, and average body lengths, are still not certain
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