Systematics and Biodiversity 1 (3): 339–439 Issued 16 February 2004 DOI: 10.1017/S147720000300121X Printed in the United Kingdom C The Natural History Museum Fur seals and sea lions (Otariidae): identification of species and taxonomic review Sylvia Brunner Australian Marine Mammal Research Centre, University of Sydney, NSW 2006, Australia CSIRO Sustainable Ecosystems, GPO Box 284, Canberra City, ACT 2601, Australia ∗ University of Alaska Museum, 907 Yukon Drive, Fairbanks AK 99775, United States submitted December 2002 accepted May 2003 Contents Abstract 340 Introduction 340 Materials and methods 343 Results 344 Description of species: sea lions Steller sea lion – Eumetopias jubatus 345 Southern sea lion – Otaria byronia 352 Australian sea lion – Neophoca cinerea 354 Hooker’s sea lion – Phocarctos hookeri 354 California sea lion – Zalophus californianus californianus 357 Galapagos sea lion – Zalophus californianus wollebaeki 357 Japanese sea lion – Zalophus californianus japonicus 360 Description of species: fur seals Northern fur seal – Callorhinus ursinus 360 Antarctic fur seal – Arctocephalus gazella 363 Subantarctic fur seal – Arctocephalus tropicalis 363 New Zealand fur seal – Arctocephalus forsteri 366 South African fur seal – Arctocephalus pusillus pusillus 366 Australian fur seal – Arctocephalus pusillus doriferus 368 Guadalupe fur seal – Arctocephalus townsendi 370 Galapagos fur seal – Arctocephalus galapagoensis 370 South American fur seal – Arctocephalus australis 371 Juan Fernandez fur seal – Arctocephalus philippii 374 A comparison of subspecies Arctocephalus pusillus 374 Zalophus californianus 374 Arctocephalus australis 375 The Otariidae 377 Discussion 378 References 384 Appendices I Summary details of specimens 386 II Univariate statistics for male and female otariids 405 ∗Correspondence address 339 340 Sylvia Brunner Abstract The standard anatomical descriptions given to identify species of the family Otariidae (fur seals and sea lions), particularly those for the genus Arctocephalus, have been largely inconclusive. Specimens of some species conformed more to the description of others, overlapping in many identifying characteristics. Recent re-examination of the genetic basis of taxonomic diversity within otariids required matching by comprehensive new studies of skull morphometry based on large sample sizes, to provide a sound basis for re-appraisal of species limits in the family. The typical skull morphology of otariids fall into two general characteristics: a short, mesocephalic skull observed primarily in the fur seals and a more dolichocephalic skull common in most sea lions. Subfamily separation of otariid seals was not supported. Instead, a separation of genus, species and subspecies was proposed, with re-arrangement of taxonomy at the levels of genus, species and subspecies. Arctocephalus australis, A. forsteri and A. galapagoensis appeared congeneric, with only subspecific differences in morphology. Arctocephalus townsendi and A. philippii appeared congeneric, yet were morphologically divergent from the remaining Arctocephalus. Skulls of Zalophus californianus japonicus were significantly different from those of Z. c. californianus and Z. c. wollebaeki, and were considered a separate species of Zalophus. ...in no family of mammals, probably, have more diversities of opinion been expressed by zoologists, both with respect to the number of species in the family and their arrangement in genera and subfamilies, than in the Otariidae. (Turner, 1888) Key words otariid, fur seal, sea lion, taxonomy, description, morphometrics, skull, species, subspecies Introduction ‘Otariinae’ Otaria ´ In many treatments, the Pinnipedia are a suborder of Carnivora Peron, 1816 byronia and divided into three families: Odobenidae or walruses, the (de Blainville, 1820) Eumetopias Phocidae or true seals and the Otariidae or eared seals (Rand, Gill, 1866 jubatus 1956; King, 1983). The family Otariidae are commonly sep- (Schreber, 1776) Neophoca arated into the subfamilies Otariinae, the sea lions and Arcto- Gray, 1866 cinerea ´ cephalinae, the fur seals, based on the presence (in fur seals) (Peron, 1816) Phocarctos or absence (in sea lions) of abundant underfur. This distinc- Gray, 1844 hookeri tion is dubious, as abundant secondary hairs may have evolved (Gray, 1844) Zalophus twice in the history of the Otariidae or may have been retained Gill, 1866 californianus randomly as a primitive feature of marine mammals and are (Lesson, 1828) californianus indicative of a shallow-water adaptation to conserve body heat (Lesson, 1828) wollebaeki in an aquatic environment (Repenning et al., 1971). (Sivertsen, 1953) japonicus Although most researchers today recognize there is little (Peters, 1866) ‘Arctocephalinae’ substance for a subfamilial split of the Otariidae, subfamilial Callorhinus recognition still appears in the literature. For instance, Rice Gray, 1859 ursinus (1998, p. 22) stated that “...studies showed that all the living (Linnaeus, 1758) Arctocephalus species [of otariids] fall into two monophyletic groups which Geoffroy Saint-Hilaire and Cuvier, 1824 australis many authors recognize as subfamilies: Arctocephalinae for (Zimmerman, 1783) australis the fur-seals, and Otariinae for the sea-lions”. The two groups (Zimmerman, 1783) gracilis of otariids are also referred to commonly as fur seals and sea (Nehring, 1887) galapagoensis lions. To address the issue of subfamilies, a morphometric Heller, 1904 gazella comparison of the two groups is made in this study. (Peters, 1875) forsteri The southern fur seals are placed in the genus Arctoceph- (Lesson, 1828) tropicalis alus that currently comprises eight extant species, whereas the (Gray, 1872) pusillus northern fur seal, Callorhinus ursinus, is classified as a separ- (Schreber, 1776) pusillus ate, monotypic genus. The sea lions comprise five monotypic (Schreber, 1776) doriferus genera. (Wood Jones, 1925) philippii The most widely accepted nomenclature for the Otariidae (Peters, 1886) townsendi is described below, and is based primarily on King (1983). (Merriam, 1897) Rice (1998) introduced some changes to the taxonomy in his systematic review of marine mammals; these are currently not The standard anatomical descriptions given to identify as widely accepted as that of King (1983), and are reviewed in species of otariids, particularly those for the genus Arcto- this study. cephalus, have been largely inconclusive. Specimens of some Identification and taxonomy of otariid seals 341 species conform more to the description of others, overlapping the number exceeded 50, most of which proved to be syn- in many identifying characteristics (King, 1983). The prob- onyms (Sivertsen, 1954). Peron´ (1816)1 first identified the lems of identification lie primarily in the original taxonomic eared seals under the genus Otaria. The eared seals were then studies that were based on small sample sizes, sex and age raised to the rank of family by Brookes (1828), under the name bias, and misidentified specimens. Allen (1880, p. 227) stated Otariadae. This classification was not generally adopted until that “...of about fifty synonyms pertaining to the Eared Seals, 1866, when it was revised by Gill (when introducing the name probably two-thirds have been based, directly or indirectly, Otariidae) and used immediately by Gray and subsequently upon differences dependent on sex and age, and the rest upon by most researchers (Allen, 1880). Gray, Turner and others the defective descriptions of these animals by travellers ...”. had previously considered the Eared Seals a subfamily of the Morphometric studies on species of Arctocephalus have Phocidae for which Gray, at different times, used the names rarely focused on more than one or two species at a time, Otariina and Arctocephalina, the latter also being adopted for making any comparative studies difficult. King (1983) stated the name of the group by Turner in 1848 (Allen, 1880). that species of Arctocephalus are so widely dispersed over the Allen (1870) divided the Otariidae into two groups, world that it has always been difficult to get reasonable num- Trichophocinae for the sea lions and Oulophocinae for the bers of specimens of each species, and to assemble enough fur seals, alluding to their pelage. Von Boetticher (1934) re- skulls in one place for comparative analyses. Repenning et al. jected Allen’s names and identified the sea lion and fur seal (1971) analysed a significant number of skulls but were able groups with the names of their included genera. He also added a to access only a small number of mixed age and sex of some third category: the ‘mitte-robben Phocarctinae’ to contain only species available at that time (e.g. A. townsendi, A. philippii, P. hookeri, presumed to possess pelage intermediate between A. gazella, Z. c. japonicus), basing their results on the fur seals and sea lions (Scheffer, 1958). these. Sivertsen (1954) had only one specimen each of Gray (1869) divided the family into five tribes, Otari- A. philippii and A. townsendi that he used to separate these from ina, Callorhinina, Arctocephalina, Zalophina and Eumetopina, the Arctocephalus as a distinct genus, Arctophoca. Repenning primarily with reference to the number of postcanines (PCs) et al. (1971) used a larger sample size (11 A. townsendi and five and the position of the posterior pair. He also separated these A. philippii) although their samples included both sexes and tribes into two ‘sections’, based on the posterior extension of contained at least five subadults and three juveniles.