Will New Whales Be Discovered?

Compared with terrestrial predators, the ~90 species of cetaceans (WoRMS 2012) ranging from wolf-sized to the largest animals ever, are a mind-boggling array. They’re the Pleistocene megafauna that, until recently, survived mostly intact (Anderson 2001) and no place on land, even Recent sub-Saharan Africa, can really compare with our oceans. It’s shocking that on top of this vast menagerie, one author claimed as many as 15 species remain to be discovered, including exotic beasts such as an 18 meter baleen whale with two dorsal fins (Raynal 2001). In a previous article I argued that particular hypothetical species, Amphiptera pacifica, was far more likely to be an early observation of (an anomalous?) Caperea than anything new and began to wonder if the discovery of unmistakable new species is at all probable. It isn’t.

The critical flaw with Raynal (2001) is that it conflates description and discovery. As for why this is problematic, the dolphin Tursiops australis was described in 2011 but the holotype was collected in 1914 and one lectotype is from 1902 (Charlton-Robb et al. 2011). Differences between the “new” species and other Bottlenose Dolphins are very subtle, so there’s no reason to think the 1902 specimen was the first our species ever encountered. I’d wager that encounter took place closer to 40,000 years ago. There is of course no way to determine who really discovered a species, but determining the earliest scientifically-documented specimen should be more feasible.

It didn’t work out as well as I expected; for 32 of the 90 species I used, the original source did not give a date for the holotype, no holotype existed, or I failed to locate the source. This resulted in me using the same date for “discovery” as the description, an event which only actually happened  once (Lahille 1912). As I planned on finishing this article… ever, I was primarily concerned with holotypes, so there are undoubtedly many earlier specimens I overlooked. My limited data still managed to find a difference of 12.6 years between description and discovery; for the 58 species with data, this average was 19.3 years. Strikingly, the four species described in the 21st Century were on average discovered 55 years earlier, with the most recent being from 1976. Here is a decade-by-decade comparison of description and “discovery”:

It’s interesting how the “discovery” data appears to have a more normal (“bell curve”) distribution. Furthermore, the average date of discovery (1841.5) is closer to the first description (1675, 166.5 years) than the present (171.5 years). This does not bode well for new discoveries and again, I have to point out that most of my dates for “discovery” are probably far too late. For an alternate view, here is a graph of cumulative species descriptions and “discoveries”:

The last cetacean to be “discovered” was Balaenoptera omurai in 1976 and it is certainly notable they were initially considered to be small “form” of Bryde’s Whales (Sasaki et al. 2006). The first Mesoplodon perrini specimen (not a holotype) was discovered in 1975 and mistaken for M. hectori (Dalebout et al. 2002). Mesoplodon peruvianus has a holotype from 1975, but one beached specimen was photographed as early as 1955 (Reyes et al. 1991; Pitman & Lynn 2001). The porpoise Neophocaena asiaeorientalis was described in 1972 but the holotype was from 1922 (Helgen & McFadden 2001). So not only is there a sizable gap between description and discovery in these recent cases, all of the species have close relatives they either have been or could be confused for. If there are still cetaceans out there awaiting discovery, it would seem far more likely that they’re lookalikes hiding in plain sight than the fantastical species Raynal (2001) proposed.

Don’t get me wrong, I think that exciting discoveries will continue to be made about cetaceans; Orcas come in numerous distinct forms and it’s likely other dolphins have some fairly distinct inshore/offshore forms as well, plus there are still some very mysterious beaked whales roaming around.

References:

Anderson, P. (2001) Marine Mammals in the Next One Hundred Years: Twilight for a Pleistocene Megafauna? Journal of Mammalogy 82(3) 623—629 Semi-Available

Andrews, R. (1908) Description of a new species of Mesoplodon from Canterbury Province, New Zealand. Bulletin of the American Museum of Natural History 24 203—215. Available

Anderson, J. (1878) Anatomical and zoological research; comprising an account of zoological results of two expeditions to western Yunnan in 1868 and 1875. Available

Beasley, I et al. (2005) Description of a new dolphin, the Australian snubfin dolphin Orcaella heinsohni sp. n. (Cetacea, Delphinidae). Marine Mammal Science 21(3) 365—400. Available

Brownell, R. et al. (2009) Behavior of Melon-Headed Whales, Peponocephala electra, Near Oceanic Islands. Marine Mammal Science. Available

de Blainville, H. (1838) Sur les cachalots. Ann. fr. étrang. Anat. Physiol. 2 :335—337. Available

Catalog of Living Whales. http://www.ubio.org/apps/Hershkovitz/index.php?func=s&ID=2&t=s

Dalebout, M. et al. (2002) A new species of beaked whale Mesoplodon perrini sp. n. (Cetacea: Ziphiidae) discovered through phylogenetic analyses of mitochondrial DNA sequences. Marine Mammal Science 18, 577-608. Available

Cuvier, G. (1812). Rapport fait à la classe des Sciences mathématiques et physiques, sur divers Cétacés pris sur les côtes de France, pricipalement sur ceux qui sont échoués près de Paimpol, le 7 janvier 1812. Annales du Muséum d’Histoire naturelle 19 13—14. Available

Flower, W. (1882) On the cranium of a new species of Hyperoodon from the Australian seas. Proceedings of The Zoological Society of London 1882 392—396. Available

Gervais, P. (1855) Histoire naturelle des Mamifères. Available

Gray J. (1866) Catalogue of seals and whales in the British Museum. Available

Gray, J. (1865). Notes on the whales of the Cape; by E. L. Layard, Esq., of Cape-Town, Corr. Memb. with descriptions of two new species. Proceedings of the Zoological Society of London 1865 357—359. Available

Gray, J. (1846) Zoology of the voyage of H.M.S. Erebus and Terror. Available

Gray, J. (1828). Spicilegia Zoologica Or Original Figures and Short Systematic Descriptions of New and Unfigured Animals. Available

Helgen, K. & McFadden, T. (2001) Type specimens of recent mammals in the Museum of Comparative Zoology. Bulletin of the Museum of Comparative Zoology 157(2) 93—181. Available

de Lacépède, B. (1804). Histoire naturelle des cétacées. Available

Lahille, F. (1912) Nota preliminar sobre una nueva especie de Marsopa del rio dela Plata. (Phocaena dioptrica). Anales del Museo Nacional de Historia Natural de Buenos Aires (23) 269—278. Available

Mignucci-Giannoni, A. et al. (1999) New records of Fraser’s dolphin (Lagenodelphis hosei) for the
Caribbean. Aquatic Mammals 25(1) 15—19. Available

Owen, R. (1866) On some Indian Cetacea collected by Walter Elliot, Esq. Transactions of the Zoological Society 6(1) 10—14. Available

Owen, R. (1846) A history of British fossil mammals, and birds. Available

Peale, T. (1848) United States Exploring Expedition during the years 1838, 1839, 1840, 1841, 1842. VIII. Mammalia and ornithology. Available

Pitman, R. & Lynn, M. (2001) Biological observations of an unidentified mesoplodont whale in the Eastern Tropical Pacific and probable identity: Mesoplodon peruvianus. Marine Mammal Science 17 648—657. Available

Quoy, J. & Gaimard, J. (1824) Voyage autour du monde […] l’Oranie et la Physicienne […] Zoologie. Available

Raynal, M. (2001) Cryptocetology and Mathematics: How Many Cetaceans Remain To Be Discovered? Dracontology 81—96. Available.

Raynal, M. & Sylvestre, J.-P. (1991) Cetaceans with two dorsal fins. Aquatic Mammals 17(1) 31—36. Available

Reyes, J. et al. (1991) A new species of Beaked Whale Mesoplodon peruvianus sp. n. (Cetacea: Ziphiidae) from Peru. Marine Mammal Science 7(1) 1—24.

Rudulph, P. & Smeenk, C. (2009) Indo-West Pacific Marine Mammals IN: Perrin, W. et al. (eds.) Encyclopedia of Marine Mammals.

Sasaki, T. et al. (2006) Balaenoptera omurai is a newly discovered baleen whale that represents an ancient evolutionary lineage. Molecular Phylogenetics and Evolution 41 40—52. Available

True, F. (1885) On a new species of porpoise, Phocoena dalli, from Alaska. Proceedings of the United States National Museum 8(7) 95—98. Available

von Haast, J. (1876) On Oulodon: a new genus of Ziphioid Whales. Transactions of the Royal Society of New Zealand 9 450—458. Available

Weir C. (2010) A review of cetacean occurrence in West African waters from the Gulf of Guinea to Angola. Mammal Review 40(1) 2—39. Available

WoRMS (2012). Cetacea. IN: Perrin, W. (2012) World Cetacea Database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=2688 on 2013-01-05

Species Description “Discovery” Notes – Sources
Balaena mysticetus 1758 1758 No Holotype (based on earlier descriptions) – WoRMS
Eubalaena australis 1822 1818 Lectotype – WoRMS
Eubalaena glacialis 1776 1742 No Holotype, date for earlier description – WoRMS
Eubalaena japonica 1818 1818 Holotype is a drawing! – WoRMS
Balaenoptera acutorostrata 1804 1791 No Holotype, early stranded individual – WoRMS
Balaenoptera bonaerensis 1867 1867 Cannot find original source
Balaenoptera borealis 1828 1819 Holotype – WoRMS
Balaenoptera edeni 1878 1852 Holotype – Anderson (1878)
Balaenoptera musculus 1758 1738 No Holotype, date for earlier description – WoRMS
Balaenoptera omurai 2003 1976 Earliest specimens – Rudolph & Smeenk (2009)
Balaenoptera physalus 1758 1675 No Holotype, date for earlier description – WoRMS
Megaptera novaeangliae 1781 1741 No Holotype, date for earlier description – Catalog of Whales
Eschrichtius robustus 1861 1725 Date for earlier, invalid description – Catalog of Whales
Caperea marginata 1846 1846 No date for Holotype – Gray (1846)
Cephalorhynchus commersonii 1804 1804 No holotype (sighting), no date – Lacépède (1804)
Cephalorhynchus eutropia 1846 1846 No date for Holotype – Gray (1846)
Cephalorhynchus heavisidii 1828 1828 No date for Holotype – Gray (1828)
Cephalorhynchus hectori 1881 1873 Date for earlier, invalid description – Catalog of Whales
Delphinus delphis 1758 1738 No Holotype, date for earlier description – Catalog of Whales
Delphinus capensis 1828 1828 No date for Holotype – Gray (1828)
Feresa attenuata 1874 1827 Early invalid synonym – WoRMS
Globicephala macrorhynchus 1846 1846 No date for Holotype – Gray (1846)
Globicephala melas 1809 1806 Lectotype – WoRMS
Grampus griseus 1812 1811 Date for holotype being received – Cuvier (1812)
Lagenodelphis hosei 1956 1895 Holotype purchased in 1895, found prior -Mignucci-Giannoni et al. (1999)
Lagenorhynchus acutus 1828 1828 No date for Holotype – Gray (1828)
Lagenorhynchus albirostris 1846 1846 No date for Holotype – Gray (1846)
Lagenorhynchus australis 1848 1848 Cannot find original source
Lagenorhynchus cruciger 1824 1820 No Holotype, date for observation – Quoy & Gaimard (1824)
Lagenorhynchus obliquidens 1865 1855 Date Holotype was cataloged – WoRMS
Lagenorhynchus obscurus 1828 1828 No date for Holotype – Gray (1828)
Lissodelphis borealis 1848 1848 No Holotype, no date for earliest encounter – Peale (1848)
Lissodelphis peronii 1804 1802 Date may or may not be for type specimen – WoRMS
Orcaella brevirostris 1866 1866 No date for Holotype – Owen in Gray (1866)
Orcaella heinsohni 2005 1948 Paratype – Beasley et al. (2005)
Peponocephala electra 1846 1841 Holotype – Brownell et al. (2009)
Pseudorca crassidens 1846 1843 Holotype – Owen (1846)
Sotalia fluviatilis 1853 1853 Cannot find original source
Sotalia guianensis 1864 1858 Paratypes? – Catalog of Living Whales
Sousa chinensis 1765 1765 No Holotype, date for sighting. Can’t determine date, original text too Swedish – WoRMS
Sousa teuszii 1892 1891 Holotype – Weir (2010)
Stenella attenuata 1846 1846 No date for Holotype – Gray (1846)
Stenella clymene 1850 1846 Earlier date for invalid description – WoRMS
Stenella coeruleoalba 1833 1833 Cannot find original source
Stenella frontalis 1829 1825 Holotype – WoRMS
Stenella longirostris 1828 1828 No date for Holotype – Gray (1828)
Sotalia fluviatilis 1853 1853 Cannot find original source
Sotalia guianensis 1864 1858 Holotype – WoRMS
Steno bredanensis 1828 1817 Date for earlier, invalid description – Catalog of Whales
Tursiops aduncus 1832 1832 Cannot find original source
Tursiops australis 2011 1902 Lectotype – Charlton-Robb et al. (2011)
Tursiops truncatus 1821 1814 Holotype – WoRMS
Inia boliviensis 1834 1790 Holotype – Catalog of Living Whales
Inia geoffrensis 1817 1812 Date for earlier, invalid description – Catalog of Whales
Kogia sima 1866 1853 Holotype – Owen (1866)
Kogia breviceps 1838 1838 No date for Holotype – de Blainville (1938)
Lipotes vexillifer 1918 1916 Holotype – WoRMS
Delphinapterus leucas 1776 1773 Date for earlier, invalid description – Catalog of Whales
Monodon monoceros 1758 1758 No Holotype (based on earlier descriptions) – WoRMS
Neophocaena asiaeorientalis 1972 1922 Holotype – Helgen & McFadden (2001)
Neophocaena phocaenoides 1829 1829 No date for Holotype
Phocoena dioptrica 1912 1912 Holotype – Lahille (1912)
Phocoena phocoena 1758 1758 No Holotype (based on earlier descriptions) – WoRMS
Phocoena sinus 1958 1950 Holotype – WoRMS
Phocoena spinipinnis 1865 1865 Cannot find original source
Phocoenoides dalli 1885 1873 Holotype – True (1885)
Physeter macrocephalus 1758 1758 No Holotype – WoRMS
Platanista gangetica 1801 1797 Holotype – WoRMS
Pontoporia blainvillei 1844 1844 Cannot find original source
Berardius arnuxii 1851 1846 Holotype – WoRMS
Berardius bairdii 1883 1882 Holotype – WoRMS
Hyperoodon ampullatus 1770 1717 No Holotype, early stranded individual – WoRMS
Hyperoodon planifrons 1882 1882 No date for Holotype – Flower (1882)
Indopacetus pacificus 1926 1882 Holotype – WoRMS
Mesoplodon bidens 1804 1800 Holotype – WoRMS
Mesoplodon bowdoini 1908 1904 Holotype – Andrews (1908)
Mesoplodon carlhubbsi 1963 1946 Holotype – WoRMS
Mesoplodon densirostris 1817 1817 Cannot find original source
Mesoplodon europaeus 1855 1850 Approximate date for early, invalid description – Catalog of Living Whales
Mesoplodon ginkgodens 1958 1957 Holotype – WoRMS
Mesoplodon grayi 1876 1875 Holotype – von Haast 1876
Mesoplodon hectori 1871 1866 Holotype – WoRMS
Mesoplodon layardii 1865 1865 No date for Holotype – Gray (1865)
Mesoplodon mirus 1913 1912 Holotype – WoRMS
Mesoplodon perrini 2002 1975 Paratype – Dalebout et al. (2002)
Mesoplodon peruvianus 1991 1955 Individual known only from photographs – Pitman & Lynn (2001)
Mesoplodon stejnegeri 1885 1883 Holotype – WoRMS
Mesoplodon traversii 1874 1872 Holotype – WoRMS
Tasmacetus shepherdi 1937 1933 Holotype – WoRMS
Ziphius cavirostris 1823 1804 Holotype – WoRMS
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