Taxonomic inflation

Taxonomic inflation is the rapid accumulation of scientific names due to processes other than new discoveries of taxa. The main processes are "splitting", elevation of taxa to a higher level (creating inflation at the higher level) or taxonomic error of some sort.  For a report on the effect of the phylogenetic species concept (PSC) on taxonomic inflation, and its implications for biodiversity studies, conservation and macroecology, see:
See also:
Origins of the term "taxonomic inflation", and its various uses today

1) Inflation of species due to taxonomic error (overdescription)

Used by John Alroy in: Taxonomic inflation and body mass distributions in north american fossil mammals.  Journal of Mammalogy, 84(2):431-443, 2003.  Available at:

N.B. This is the only use of the phrase that came up using Web of Knowledge/ISI (but see earlier scientific journal uses below).  Intriguing use of a dynamic equilbrium model (proposal vs. synonymization) to estimate equilibrium value of the numbers of species.  He doesn't mention any recent upsurge in the numbers of species considered valid (c.f. use 3), which perhaps has not happened to the fossil taxa with which he is dealing.

See also somewhat similar use of taxonomic inflation via synonymy by P. Venu (2002), in "Current Science":

Another paper in the same journal critiques the "biodiversity hotspot" for herpetofauna in Sri Lanka, and argues that this is due to overdescription, particularly via molecular data:

Chaitra MS, Vasudevan K & Shanker K. (2004) The biodiversity bandwagon: the splitters have it.  Current Science 86 (7): 897-899.

See also inflation used in this sense of synonymy, an argument for use of type specimens to avoid this:

Berendsohn, Walter G. (1998). Names, taxa, and information.  Proceedings of the Taxonomic Authority Files Workshop, Washington, DC, June 22-23: (used to be at:

2) Inflation of rank to higher categories in systematics = taxonomic elevation

See:  Alex Kaslev and Toby White's "Palaeos" site. (dated 12 Dec 2003)

e.g. "Take the example of the brachiopod family [sic] Cranioidea (a type of marine shelled invertebrate).  As these animals are quite distinct from other members of the phylum Brachiopoda they were given their own superfamily Cranioidea.  This then became a distinct order - Craniida.  Okay, fair enough.  But then in a more recent classification they have been raised to the rank of class, the Craniata (containing the Craniida and two other orders, the Craniopsida and Trimerellida) and even a sub-phylum Craniiformea.  Many other examples can be given, such as classes of micro-organisms (Protista) raised to kingdom and superkingdom rank!"

See also: Henrik Enghoff (2004): Myriapoda.  Unpublished document:

3) Explosion of names due to splitting

Somewhat overlaps with above usage, because taxonomic elevation, sense (2), almost always leads to taxonomic inflation in sense (3).

See: DJ Patterson 1999. The diversity of eukaryotes.  Amer. Nat. 65, supplement: S96-S124. 

p. S99: "Ranks and Hierarchy
The past 30 yr have seen a proliferation of phyla and kingdoms largely among the protists. In 1964, the Society of Protozoologists created a scheme of classification with a single phylum of protozoa (Honigberg et al. 1964). More recent classification schemes that use ranks contain dozens of phyla (e.g., Corliss 1984; Cavalier-Smith 1998) within a variable number of kingdoms. This **taxonomic inflation** and the use of different ranks in a short space of time is disquieting."

See also: Cox, C. Barry 2001.  The biogeographic regions reconsidered.  Journal of Biogeography, 28, 511-523.

p. 517: "A more plausible possibility is that the taxonomic diversity of the Holarctic Kingdom has been artificially inflated. ... The low diversity of the angiosperm flora of the Holarctic Kingdom might well also have tempted the many northern hemisphere botanists to raise the taxonomic rank of the taxa they studied, while the greater diversity of the taxa in the tropics might well have discouraged such a tendency. The suggestion that there may have been **taxonomic inflation** in Takhtajan's data base for the Holarctic Kingdom is supported by comparison of his figures for endemic families with those derived from Heywood's (1978) atlas (compare columns 1 and 3 in Table 1). Although in most of the Kingdoms Heywood's figures are half those of Takhtajan, in the Holarctic Kingdom they are only one quarter those of Takhtajan. All of these observations support the view that the high figure for endemic genera (and therefore also for percentage endemicity) in the Holarctic Kingdom is a taxonomic artefact."

See also usage by Ken Kinman discussing the explosion of higher taxa of protists, somewhat overlapping with (2) above, because both types of taxonomic inflation can be due to the same nomenclatural acts.  (Used to be at:

There is also a slightly different sense of taxonomic inflation by Niklas Wahlberg for oversplitting of butterfly genera.  See:

I would say that this meaning (3) has a long informal history and would be the meaning triggered in most butterfly systematists like Niklas Wahlberg, for example, who argues that overzealous application of incorrect phylogenetic assumptions is at the root of the problem.  I think it is also more or less what we mean in Isaac et al. 2004, only we mean it at the species level.

See also Mallet, J. 2002.  The Taxome Project.  Butterflies. Refers specifically to the effect of the phylogenetic species concept on species inflation.

Jim Mallet, May 2004.

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Last updated: 1 April 2002