So who was responsible for the Theraphosidae?

Jason Dunlop

Tarantulas belong in the spider family given the scientific name Theraphosidae. But ,who first came up with that name and why? To answer this you must take a trip into the treacherous world of spider systematics, where science meets history in the often difficult quest to track down who said ,what and why.

Anyway it turns out that Theraphosidae was first proposed as a family name back in 1870 by the eminent Swedish arachnologist, Tord Tamerlan Teodor Thorell (1830-1901), professor of zoology in the University of Upsala. One possible source of confusion is that he created Theraphosidae in a weighty book about European spiders, which is not the first place you'd go looking for tarantula names. Anyway, the full reference is as follows:-

Thorell, T. 1870. On European spiders. Part 1. Review of some European genera of spiders preceded by some observations on zoological nomenclature. Nova Acta Regiae Societatis Scientiarum Upsaliensis, Series 3, Volume 7, 1-242.

Now at this time there was some debate about the best name to use for what we would now call mygalomorph spiders. The problem went something like this. Way back in 1800 the great French natural historian Baron George Cuvier created the name Mygale, which is ancient Greek for 'shrew. Knowing this, Cuvier intended Mygale to be a name for small, furry mammals. All well and good, until in 1802 another French naturalist, Baron Charles Athanasie Walckenaer, also used the name Mygale for a large, furry, perhaps vaguely shrew-like spider from South America which he called Mygale blondii. Of course 'mygalomorph' is taken directly from the name Mygale.

Walckenaer was a little bit naughty in that he shouldn't have used the name Mygale, because it was already in use somewhere else. However the rules of taxonomy were a brand new idea back in the early 1800's and not everyone followed them as strictly as they do today. Aynway, some people tried to get round the confusion by changing the spider name Mygale to Myogale or Myogalea. But this didn't address the real problem, i.e. that Mygale was a name first used for mammals and so shouldn't have been used for spiders. Someone had to find a replacement for Mygale.

Meanwhile in 1805 Walckenaer made the problem he had created worse by renaming Mygale blondii as Theraphosa blondii. This spider is of course the Goliath bird-eating tarantula. the largest spider and a popular pet today (the modern spelling leaves out the last 'i'). Anyway natural historians could now chose to use either Mygale or Theraphosa for big hairy. spiders since both names had the same definition. Most went for Mlygale and new species of large spiders were Generally put in this genus. The only dissenting voice,was a chap called Eichwald whlo in 1830 thought that Thieraphosa, not Mygale, was the correct name. Now it's important to realise that back in the early 1800's the taxonomic hierarchy of species - genus - family - order, etc. was not quite as rigid as today and the early arachnologists often talked about 'groups' or 'tribes' of spiders. The point is that Mygale could mean both a genus and a family in a modern sense, depending on who was using it.

Now, if things weren't confusing enough there were soon to be a couple more names doing the rounds for big, hairy spiders. In 1811 another Frenchman, Antoine Guillaume Oliver. divided Walckenaer's Mygale spiders into two groups which he called 'les Arignees aviculaires' and 'les Arignees mineuses'. In 1818 the celebrated French naturalist, Jean Baptiste de Lamark, more famous for a theory of evolution that predated Darwin, created a new name for 'les Arignees aviculaires'. This was the genus Avicularia (the name means bird keeper or bird catcher) and was based on another of today's most popular tarantulas, the South American pink-toe, Avicularia avicularia. Then in 1825 yet another French naturalist, Pierre Latrielle came up with a genus name for 'les Arignees mineuses' -,which he probably called Ctenize, though amid some confusion this was subsequently changed to Cteniza. Some of these spiders are now in a separate family, the Ctenizdae.

Anyway, by the middle of the last century the names Mygale, Theraphosa, Avicularia and Cteniza could all be used for the group of spiders that we would call mygalomorphs today. Enter Thorell in 1870 trying to bring some order to the general chaos among spider taxonomy. Thorell realised that Mygale was a popular name and that many arachnologists wanted to keep it, even though it was wrong. However, he also knew that as more species of hairy spiders were being described the genus name Mygale was becoming less common and was restricted to only a few spiders.

Thorell argued that Cteniza was essentially the same group of spiders as the troublesome Mygale and that furthermore Theraphosa would form a better group name than Avicularia as Walckenaer's Theraphosa was the older name. The rules of taxonomy suggest you should always use the oldest available name, Mygale was wrong so Theraphosa became next in line. Thorell therefore decided that he was justified in proposing a new name, now a formal family name, for all the large, hairy spiders and went for Theraphosidae, taking the name from Theraphosa. That is where the current name Theraphosidae comes from.

© Copyright 'The British Tarantula Society', 1996,2007

Last Updated: April 04, 2007