In yesterday's post on the sperm whales, I alluded to the long and reprehensible debate over the name of the great sperm whale Physeter macrocephalus. Reprehensible because for at least the last hundred years there has been absolutely no disagreement over the nature of the animal concerned; the conflict has purely been concerned with what to call it.
When Linnaeus discussed the genus Physeter in the 1758 Systema Naturae, he referred to four species: P. macrocephalus, P. catodon, P. tursio and P. microps. Most authors now treat these names as synonyms of the great sperm whale*. Normally, when two or more names are available for the one species, the oldest name automatically becomes the correct one. However, because Linnaeus' 1758 publication is the official starting point for zoological nomenclature, none of these names count as the oldest. In such a case, the general rule is that the first person to treat the names as synonymous and pick one of them to be the correct name establishes which has priority (the principle of the First Reviser).
*Physeter tursio and P. microps were both described as having high dorsal fins, something the great sperm whale completely lacks, leading to considerable confusion over the identity of the animals concerned. Modern authors tend to assume they were based on distorted or mistaken accounts of ordinary sperm whales; this is not really a satisfactory explanation, but the true identity will probably never be establishable (killer or pilot whales seem not entirely unlikely to me), and there would be little to be gained from trying.
During the 19th Century, most authors knew the great sperm whale as Physeter macrocephalus while the name P. catodon was less often referred to (and sometimes thought to refer to something like the beluga or pilot whale). It wasn't until the beginning of the 20th Century that Oldfield Thomas (1911) asserted the synonymy of the species and selected P. catodon as the correct name. However, in 1938 Hilbrand Boschma noted that Murray had treated the names as synonymous in 1866 and selected P. macrocephalus, pre-dating Thomas' selection. This was countered in 1966 by Philip Hershkovitz who claimed that Murray's selection was invalid.
The most detailed discussion of the matter was by Husson & Holthuis (1974) who discussed each of the records cited by Linnaeus for the names Physeter catodon and P. macrocephalus, selecting a lectotype for the former and a neotype for the latter that confirmed both as sperm whales. They also established that Blasius had treated the names as synonyms in 1857 and selected P. macrocephalus as the valid name, meaning that P. macrocephalus had priority even if Murray was disqualified as an authority.
However, the validity of Physeter catodon was again championed by Schevill (1986) on the basis that P. macrocephalus was supposedly invalid from the get-go. Linnaeus had distinguished the two species on the basis that P. macrocephalus supposedly had its blowhole on its neck while P. catodon had it at the front of the head; the correct position in the sperm whale is, of course, the latter. Schevill claimed that Husson & Holthuis' examination of the earlier records to correct Linnaeus' description was invalid as the concept of type specimens did not exist in Linnaeus' time, making the printed description the only judge of the species identity. Because the description of P. macrocephalus did not agree with a real sperm whale, it could not be used as the valid name.
As pointed out by Holthuis (1987), Schevill's latter argument was simply wrong. If the original author did not explicitly nominate a type specimen for a new species, then all specimens considered in the original description automatically become the type series*. To claim that the concept of types is inapplicable to Linnaeus is to ignore a fundamental aspect of the nature of the Systema Naturae, which did not spring ex nihilo but was in many places an index to the work of earlier naturalists, tying their descriptions into Linnaeus' new nomenclatural system. In the case of the sperm whale, Linnaeus was mislead by the faulty descriptions provided by others (Linnaeus himself had never seen a sperm whale). Examination of these earlier records allows the error to be recognised. Husson & Holthuis (1974) chose as lectotype of P. macrocephalus a specimen stranded in the Netherlands in 1598; while the specimen has not been preserved anywhere, illustrations of it leave no doubt that it was a sperm whale.
*Though it is true that the type specimen did not exist as a formal concept in 1758, it was not long afterwards that naturalists were finding it useful to examine earlier authors' specimens to determine their intention. Exactly when the type concept became formalised, I'm not sure.
So, in summary, both P. catodon and P. macrocephalus are available names for the great sperm whale; Blasius as First Reviser established the priority of the latter in 1857. The correct name for the great sperm whale is therefore Physeter macrocephalus.
Holthuis, L. B. 1987. The scientific name of the sperm whale. Marine Mammal Science 3 (1): 87-88 (reply by W. E. Schevill, pp. 89-90).
Husson, A. M., & L. B. Holthuis. 1974. Physeter macrocephalus Linnaeus, 1758, the valid name for the sperm whale. Zoologische Mededelingen 48 (19): 205-217, pl. 1-3.
Schevill, W. E. 1986. The International Code of Zoological Nomenclature and a paradigm: the name Physeter catodon Linnaeus 1758. Marine Mammal Science 2 (2): 153-157.