Numbers of Living Species in Australia and the World

2nd edition

A.D.Chapman
Australian Biodiversity Information Services, Toowoomba, Australia
A Report for the Australian Biological Resources Study September 2009
ISBN (printed) 978 0 642 56860 1 OUT OF PRINT
ISBN (online) 978 0 642 56861 8

Detailed discussion by Group

Invertebrates

Hemichordata (hemichordates)

Burdon-Jones (1998) stated that there are 94 described species in 16 genera in the world, with many more undescribed, and 12 species in seven genera in Australia. Cameron (2008) lists 108 species for the world in three Classes, seven families and 18 genera. This is an increase of two over his 2004 list cited in the previous report. Groombridge and Jenkins (2002) reported c. 90 or 100 species, whereas Brusca and Brusca (2003) gave only 85 species and Bouchet (2006) gave 106.

DEH (2007) lists 17 species for Australia with an estimated 22 species in total. It would appear from the treatment by Burdon-Jones (1998) that at least three species are endemic to Australia. I have accepted the most recent figures of 108 for the world (Cameron 2008) and 17(22) (DEH 2007) for Australia. The Australian numbers have not increased since the previous report.

There are no listed threatened species for Australia (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
38
  Australia Threatened   Australian Threatened as % of World Threatened
85   108   108   ~110   17   15.7%   22   ~25%   0   0  

Echinodermata (starfish, sea cucumbers, etc)

Estimates of the number of described echinoderms in the world vary from about 6 100 (Tangley 1997, Miyajima 2002) through 6 600 (Mooi pers. comm.40) to 7 000 (Wray 1999, Groombridge and Jenkins 2002, Brusca and Brusca 2003, Mulcrone 2005, Bouchet 2006). Charles Messing’s Crinoid Web (Messing n.dat.) lists 540 for comatulids and ~95 species of stalked crinoids giving a total of ~635 species for Crinoidea. The World Asteroidea database (Mah 2009) gives a current figure of 1 859 species for the Asteroidea. The World Ophiuroidea database (Stöhr and O’Hara 2007) provides a figure of 2 139 for the Opiuroidea. Follo and Fautin (2001) cited 940 for Echinoidea. The Tree of Life (Ker 2000), in a breakdown of Orders, listed 1 430 species of Holuthuroidea—I have found no more recent definitive figures. Adding these figures up gives a total of 7 003.

Estimating the total number of species is a difficult exercise. The main problems appear to be the unknown species of the deep waters, the difficulty in finding and identifying very cryptic species and the enormous potential of molecular studies to ‘discover’ new species39. The figure here is estimated by doubling known numbers for most Classes, and adding an extra 20–25% for the Ophiuroidea and Holothuroidea which are ‘cryptic, diverse, relatively unstudied, and common in the deep sea’40.

The number of Australian described species is placed at around 1 475 (O’Hara pers. comm. 200941). The Australian Faunal Directory (ABRS 2009a) and others (Ponder et al. 2002) predict that there may be up to 2 000 species in Australian waters. O’Hara (pers. comm.) states that the number of species in the Australian Economic Exclusion Zone is still a large unknown. I have seen estimates of endemism in Australia as high as 90% for southern waters and 15% for tropical waters (Ponder et al. 2002), but working through the currently published species (Rowe and Gates 1995), the figure comes out at around 31% for Australia as a whole.

There are no listed threatened species.

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
42
  Australia Threatened   Australian Threatened as % of World Threatened
6 100   7 003   7 003   ~14 000   1 475   21.1%   ~2 000   31%   0   0  

Insecta (insects)

Estimates of the number of described insects in the world vary from about 720 000 (May 2000) through 751 000 (Tangley 1997), 800 000 (Nieuwenhuys 1998, 2008), 948 000 (Brusca and Brusca 2003), 950 000 (IUCN 2004) to more than 1 million (Myers 2001a). Groombridge and Jenkins (2002) provide the figure of 963 000 for insects plus myriapods. Estimates for the total numbers of insects vary widely from around 2 million (Nielsen and Mound 2000), 5–6 million (Raven and Yeates 2007) to around 8 million (Hammond 1995, Groombridge and Jenkins 2002). Calculations based on extrapolations from species of Coleoptera and Lepidoptera in New Guinea by Novotny et al. (2002) produced a figure of between 3.7 and 5.9 million for the total number of arthropods in the world. Some workers have estimated that there could be as many as 100 million beetles alone (Tangley 1997), but this would appear to be a gross over-estimate. In the table below, I have attempted to document the numbers for each of the Orders. This leads to a figure between 965 000 and 1 015 000 so I have adopted a figure here of ~1 million as a mid point. This is consistent with previous estimates, but a little higher than the previous report for the number of described species for the world. I have been unable to get individual estimates for the total number of species by Order except for a few Orders, and have thus accepted the figure of about 5 million as given by Grimaldi and Engel (2005) and Raven and Yeates (2007). This is higher than the 4 million given in the previous report which was based on May (2000). As stated by Miller et al. (2002):

‘Current evidence from the major museum collections of sorted and labeled insect species, whether described or undescribed, does not support larger estimates, and insect taxonomists broadly concur from this that although there may be up to five million species of insect in the world, there are probably less than 10 million (Nielsen and Mound 2000).’

Based on the table below, the number of described species in Australia would appear to be around 62 000 with the total number of species varying from about 195 000 to 215 000. I have accepted the figure of nearly 205 000 given by Yeates et al. (2003) and Raven and Yeates (2007). The difference between the numbers is due to the variation in estimates for Coleoptera of 80 000 and 100 000 (Yeates et al. 2003).

Little appears to have been written on endemism in Australian insects, however Ridsdill-Smith (2004) stated that ‘up to 70% of insects are endemic to Australia.’

There are eight listed threatened species of insect in Australia and one undescribed subspecies. Three are listed as Critically Endangered, four as Endangered, and one as Vulnerable with the subspecies listed as Endangered (DEWHA 2009a).

Order World Described/
Accepted
  Reference   World Estimate   Australia Described/
Accepted
  Reference Australia Estimate   Reference
Archaeognatha 470   Hallan (2003)       10   ABRS (2009a) 14   Yeates et al. (2003)
Blattodea 3 684–4 000   Hallan (2003), 
ABRS (2009a)
      534   ABRS (2009a) 587   Yeates et al. (2003)
Coleoptera 360 000–~400 000   CSIRO43, Oberprieler44   1 100 000   22 901   Yeates et al. (2003) 80 000–100 000   Yeates et al. (2003), Oberprieler45
Dermaptera 1 816   Hallan (2003)       91   ABRS (2009a) 121   Yeates et al. (2003)
Diptera 152 956   Thompson 2008   240 00046   7 482   ABRS (2009a) 30 000   Yeates et al. (2003), Austin et al. (2004)
Embioptera 200–300   ABRS (2009a), Wikipedia47   2 000   26   ABRS (2009a) 28   Yeates et al. (2003)
Ephemeroptera 2 500–   Wikipedia48,
ABRS (2009a)
      113   ABRS (2009a) 333   Yeates et al. (2003)
Grylloblattaria 24   Hallan (2003)       0     0    
Hemiptera 80 000–88 000   Discover Life49,
Hallan (2003)
      5 150–~6 000   ABRS (2009a) 11 580   Yeates et al. (2003)
Hymenoptera 115 000   Hymenoptera Online Database50   >300 000   9 155   ABRS (2009a) 44 000   Yeates et al. (2003), Austin et al. (2004)
Isoptera 2 600–2 800   Wikipedia51,
Hallan (2003)
  4 00051   26352   ABRS (2009a) 455   Yeates et al. (2003)
Lepidoptera 174 250   Lepidoptera Taxome Project53   300 000–500 00054   10 586   Yeates et al. (2003) 20 000   Yeates et al. (2003)
Mantodea 2 200   Encyclopedia Britannica55       105   ABRS (2009a) 114–160   Yeates et al. (2003),
ABRS (2009a)
Mecoptera 481   Hallan (2003)       30   ABRS (2009a) 30   Yeates et al. (2003)
Megaloptera 250–300   Hallan (2003),
ABRS (2009a)
      26   ABRS (2009a) 26   Yeates et al. (2003)
Neuroptera ~5 000   ABRS (2009a)       553–>600   ABRS (2009a) 800   Yeates et al. (2003)
Odonata 6 500   Trueman & Rowe (2008)       321   ABRS (2009a) 330   Yeates et al. (2003)
Orthoptera 24 380   Eades & Otte (2009)       1 835   Yeates et al. (2003) 2 800   Yeates et al. (2003)
Phasmatodea (Phasmida) 2 50056–3 300   ABRS (2009a),
Hallan (2003)
      105   ABRS (2009a) 115–150   Yeates et al. (2003),
ABRS (2009a)
Phthiraptera >3 000–~3 200   Smith & Page (1997),
ABRS (2009a)
      465   ABRS (2009a) 648   Yeates et al. (2003)
Plecoptera 2 274   Hallan (2003)       192   ABRS (2009a) 196   Yeates et al. (2003)
Psocoptera 3 200–~3 500   Hallan (2003),
ABRS (2009a)
      293   ABRS (2009a) 293 plus many more   ABRS (2009a)
Siphonaptera 2 525   ABRS (2009a)       84   ABRS (2009a) 92   Yeates et al. (2003)
Strepsiptera 596   Kathirithamby (2002)       42   ABRS (2009a) 58–159   Yeates et al. (2003),
ABRS (2009a)
Thysanoptera ~6 000   ABRS (2009a)       750   ABRS (2009a) ~1 500   ABRS (2009a)
Trichoptera 12 627   Trichoptera World Checklist57       719   ABRS (2009a) 800   Yeates et al. (2003)
Zoraptera 28   Hallan (2003)       1   ABRS (2009a)58 1  
Zygentoma (Thysanura) 370   Mendes (2002)       36   ABRS (2009a) 38   Yeates et al. (2003)
TOTAL 965 431–1 015 897           61 868–62 765     ~194 959–215 141    
World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
59
  Australia Threatened   Australian Threatened as % of World Threatened
720 000   1 000 000   ~1 000 000   ~5 000 000   ~62 000   6.2%   ~205 000   up to 70%   626 
(0.06%)
  8
(0.01%)
  1.2%

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Arachnida (spiders, scorpions, etc)

Estimates of the number of described arachnids vary from 60 000 (Myers 2001a, Brusca and Brusca 2003) through 70 000 species (Nieuwenhuys 1999), 74 000 (Groombridge and Jenkins 2002), 75 000 (Hawksworth and Kalin-Arroyo 1995, May 2000), 98 000 (Chapman 2006) to 102 248 (this report). There do not seem to be many estimates for the total numbers of spiders in the world, however Coddington and Levi (1991) predicted that there may be as many as 170 000 species. Perhaps the best way to determine the number of described arachnid species is to make a breakdown of the various Orders. Spiders are probably the best known, and Nieuwenhuys (2008) gives 40 462 species while Platnick (2008) lists 40 700 described species in The World Spider Catalog. One of the largest of the arachnid groups includes the mites and ticks (Acarina) and here the numbers vary greatly. Hickman et al. (2004) estimated 40 000 described species with a total of 500 000 to 1 million. Halliday et al. (2000) estimated that there were 48 200 described species of Acarina and a total fauna of about 0.5 million. Walter et al. (1996) on the Tree of Life website estimated 45 000 described species and suggested that that may only be about 5% of the total species alive today. Other estimates from the 1960s and 1970s (see Halliday et al. 2000) varied from 17 500 to 30 000. Other Orders include Amblypygi (136 (Harvey 2003)), Opiliones (around 5 000 species (Myers 2001a), 6 400 (Pinto-da-Rocha et al. 2007)), Palpigradi (c. 78 (Harvey 2003), to 80 species60), Pseudoscorpionida (>3 300 species61), Ricinulei (57 species (Amrine 2005)), Schizomida (>23062), Scorpionida (1 764 (Rein 2009)), Solifugae (1 095 (Savary 2006)) and Uropygi (286 (Fox 2006)). Summation of these figures gives a total of over 102 248 described species, considerably higher than the estimates cited above, with estimates of the total number of species varying between 160 000 and about 1 million (Hawksworth and Kalin-Arroyo 1995). Hawksworth and Kalin-Arroyo (1995) accepted a working figure of 750 000 species.

Halliday et al. (2000) conducted an extensive literature survey of mites in Australia and concluded that there were about 2 700 described species and by extrapolating from recent revisions estimated that the total mite fauna in Australia may be in the order of 7 800. They then further suggested that this may be a gross under-estimation as many of the lesser known groups are likely to include many more species. Their final estimate for the total Australian mite species was in excess of 20 000 species.

ABRS (ABRS 2009a) reports numbers of described and estimated Australian species as shown in the following table, except for the number of 10 000 for the estimated Araneae which comes from Raven (pers. comm.63) who stated that the figure of 20 000 in Yeates et al. (2003) was a gross over-estimate. Raven also supplied an updated figure of 3 300 for the number of described species of Araneae. Estimates for the total number of the described Australian Arachnid fauna varies from 5 666 (DEH 2001) through 5 711 (DEH 2007) to 6 615 (this publication) and for the total number of Arachnid fauna from 20 937 (using Halliday’s number for the Acarina) through 22 838 (this publication) to 27 837 (using the ABRS figure for the Acarina) and 27 960 (previous report). Harvey (pers. comm.64) agrees that this is a good summary of current knowledge. No estimates of the percentage of Australian endemics has been found.

There are no species of spider listed as threatened for Australia (DEWHA 2009a).

Order World Described World Estimated Australian Described Australian Estimated
Acarina 48 200 ~100 000–500 000 2 851 20 000
Amblypygi 136 150 5 10
Araneae 40 700 80 00065 3 300 10 000
Opiliones 6 400 10 000 199 500
Palpigradi unknown 3 3
Pseudoscorpionida ~3 300 unknown 161 600
Ricinulei 57 unknown 0 0
Scorpionida 1 764 ~2 400 43 150
Schizomida >230 unknown 53 75
Solifugae 1 095 unknown 0 0
Uropygi 286 unknown 0 0
TOTAL ~102 248 ~200 000–600 000 6 615 31 338
World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World
Estimate
  Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
66
  Australia Threatened   Australian Threatened as % of World Threatened
60 000   102 248   102 248   200 000–600 000   6 615   6.5%   31 338   unknown   18
(0.02%)
  0   0%

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Pycnogonida (sea spiders)

There are around 1 340 described species of Pycnogonida in the world (Arango pers. comm.67). Bamber and Nagar (2009) list 1 308 species (as of early April 2009), but this does not include the recently described Australian species.

A recent study by Arango at the Queensland Museum (Arango pers. comm.67) has identified 215 species for Australia, and predicts that this number will increase rapidly with many newly discovered species. Examining the species listed in the Australian Faunal Directory (ABRS 2009a), just under 50% are identified as endemic. This figure will increase with the addition of the newly described species.

No species are identified as threatened in Australia at this stage (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
68
  Australia Threatened   Australian Threatened as % of World Threatened
1 300   1 340   1 340   unknown   215   16.0%   unknown   ~50%   0   0  

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Myriapoda (millipedes, centipedes)

Brusca and Brusca (2003) gave an estimate of 11 460 described species of Myriapoda in the world. Yeates et al. (2003) estimated the total number of described myriapod species in Australia at 2 539. This is lower than the ABRS estimate of 2 800 (DEH 2007).

There are no myriapod species listed as threatened in Australia (DEWHA 2009a).

Chilopoda (centipedes)

Estimates of the number of described species of Chilopoda vary from 2 500 (Hoffman 1982, Myers 2001c) through 2 800 (Brusca and Brusca 2003) to about 5 000 (Nieuwenhuys 2008). I have accepted the figure of 3 149 in 429 genera for the world as cited in Chilobase (Bonato et al. 2006). ABRS (2009a) lists 131 species of Chilopoda for Australia and a number have been added recently (Edgecombe pers. comm.69). Yeates et al. (2003) provided an estimate of about 446 for total species in Australia. Calculations from ABRS (2009a) and Edgecombe (pers. comm.69) lead to a figure of around 81.4% endemism.

Diplopoda (millipedes)

Estimates of the number of described species of Diplopoda vary from 5 000 (Nieuwenhuys 2008) through 8 000 (Myers 2001b, Brusca and Brusca 2003), 10 000 (Geoffroy 2001) to 12 000 (Sierwald and Bond 2007). I have accepted the figure of 12 000 as given by Sierwald and Bond (2007) as this appears to be ‘very solid’ (Mesibov pers. comm.70). Geoffroy (2001) estimated the total number of species at betweeen 80 000 and 90 000. These figures appear to be based on Hoffman (1980) and are regarded as probably an under-estimate (Mesibov pers. comm.70). Mesibov (2008 and pers. comm.70) provides figures of 366 species for Australia and an estimate of around 2 000 in total. Endemism in the 230 species listed in ABRS (2009a) is 91.3%.

Pauropoda (centipede-like arthropods)

The number of described Pauropoda of the world is between 500 (Brusca and Brusca 2003) and 715 (ABRS 2009a), with 18 species described for Australia (55% of which are endemic), but with an estimated total number of >500 (ABRS 2009a). I have accepted the ABRS figure of 715 for the world.

Symphyla (glasshouse symphylans)

Although little information could be obtained on this group, it would appear that there are about 200 described species of Symphyla in the world (ABRS 2009a). Brusca and Brusca (2003) estimated that there are 160 species and Hallan (2003) gave 208 species.

ABRS (2009a) listed 26 species for Australia, of which 24 are endemic, and estimates about 150 species in total. Yeates et al. (2003) provided a figure of 29 described species with 200 for the total number of species.

  World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
71
  Australia Threatened   Australian Threatened as % of World Threatened
Chilopoda 2 500   5 000   3 149   unknown   140   4.0%   446   81.4%       0    
Diplopoda 5 000   12 000   12 000   80 000–90 000   366   2.9%   2 000   91.3%       0    
Pauropoda 500   715   715   unknown   18   2.5%   >500   55.5%       0    
Symphyla 160   208   208   unknown   29   13.9%   150   92.3%       0    
Total 8 160   17 923   16 072   ~90 000   553   3.4%   ~3 100   86.0%   15 (0.1%)   0   0%

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Crustacea (crabs, lobsters, etc)

The estimated number of described species of Crustacea in the world varies from 25 000 (Nieuwenhuys 2008), 30 000 (Myers 2001d), >30 000 (Ponder et al. 2002), 38 732 (Hallan 2003), 40 000 (with 38 000 marine species) (Hawksworth and Kalin-Arroyo 1995, May 2000, Groombridge and Jenkins 2002), 44 950 marine species (Bouchet 2006), 52 000+ (Martin and Davis 2001, Wikipedia72) to 68 171 (Brusca and Brusca 2003). I have accepted a figure of approximately 47 000 described species based on the detailed breakdown given by Bouchet (2006), and adding the approximate 2 000 non-marine species (including 1 608 Ostracoda). One of the big increases since the previous report appears to be with the Ostracoda where Bouchet gives 6 400 marine species plus 1 608 non-marine species as opposed to 5 650 given by Abele (1982) and 10 000–15 000 by Martin and Davis (2001). The recently published checklist of Brachyuran Crabs (Ng et al. 2008) gives a figure of 6 793 (species and subspecies) for the crabs. It would appear, however, that there are very few accepted subspecies in the list so 6 793 is fairly close to the number of species. Wilson (2008) states that there are about 950 described species of freshwater isopod crustaceans with another possible 1 400 species remaining to be described out of a total of about 10 300 in all habitats. Further information on individual taxa can be found in Crustacea.net coordinated by the Australian Museum (Lowry et al. 1999 onwards). The World List of Marine, Freshwater and Terrestrial Isopod Crustaceans lists 5 300 species of marine and freshwater isopod crustaceans from 10 659 names (Schotte et al. 2009).

The estimated total number of world species is 150 000 (May 2000, Groombridge and Jenkins 2002) with a range of 75 000 to 200 000 (Hammond 1995, Hawksworth and Kalin-Arroyo 1995). Brusca and Brusca (2003) stated that there could be from 5–10 times the number of described species, giving a figure of 300 000–600 000 for their estimate.

In 2007, DEH gave an estimate of 7 130 described species for Australia and a total number of 9 500 species. The number given by ABRS (2009a) is 6 467 excluding barnacles and a further 799 species are now known for the Australian fauna. This brings the total number of accepted described species to 7 266.

Overall endemism is unknown, however a count of the Decapoda produced a figure of 25.9% endemism for Australia; and some 69% of Branchiopoda are endemic.

Nine crustacea are listed as threatened species in Australia—two are listed as Critically Endangered, three as Endangered and four as Vulnerable (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
74
  Australia Threatened   Australian Threatened as % of World Threatened
25 000   68 171   47 000   150 000   7 266   15.5%   ~9 500   unknown   606
(1.3%)
  9
(0.1%)
  1.5%

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Onychophora (velvet worms)

The number of described species of Onychophora would appear to be around 165, with estimates varying from about 70 (Hickman et al. 2004), 100 (Groombridge and Jenkins 2002), 110 (Brusca and Brusca 2003, Hallan 2003, Peripatus Web75), about 120 (Monge-Najera 2000), 155 (Wikipedia76) to about 200 (Geoffroy and Ruhberg 2006). Reid in the Australian Faunal Directory (ABRS 2009a) states that there are 75 species in the Peripatidae and 90 in the Peripatopsidae, making a total world described fauna of 165 species. This is the figure I have used here, even though it is considerably higher than many of the other estimates. Estimates for the total fauna include about 200 (Geoffroy 2001), 220 (Brusca and Brusca 2003) and 300 (Wikipedia84).

In Australia, ABRS (DEH 2007, ABRS 2009a) estimated that there are about 71 described species with perhaps another nine undescribed species. It appears that all 71 are endemic to Australia (ABRS 2009a).

There are no species of Onychophora listed as threatened for Australia (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
77
  Australia Threatened   Australian Threatened as % of World Threatened
70   200   165   ~220   71   43.0%   ~80   100%   9
(5.5%)
  0   0%

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Hexapoda (proturans, springtails)

The three Classes covered here include Protura, Collembola and Diplura. Yeates et al. (2003) estimated the total number of species in Australia at between about 2 000 and 3 000, with 382 species described. By far the greatest number of these are the Springtails—Collembola. In the previous report this group was inadvertantly omitted.

Collembola

ABRS (2009a) identifies 357 described species of which about 78 are introduced, and an estimated total fauna of about 2 000 species. Bellinger et al. (2009) state that there are about 7 900 described species in the world, however Greenslade (ABRS 2009a) suggests that this figure may include many synonyms. Janssens (pers. comm.78), one of the managers of the website Collembola.org (Bellinger et al. 2009), suggests a more conservative figure of c. 7 500. Hallan (2003) gives a figure of 6 000 species. Hopkin (1997) suggested the total number of species in the world is about 50 000.

Diplura

ABRS (2009a) identifies 28 species for Australia and 800 for the world. There is little further information currently available. Yeates et al. (2003) gave a figure of 38 for the estimated number of species for Australia.

Protura

Szeptycki (2007) listed 31 described species for Australia one of which appeared dubious, whereas ABRS (2009a) lists 32—four of which are probably introduced. Szeptycki (2007) listed 748 species for the world. Twenty-five of the 31 species listed by Szeptycki (2007) are endemic.

There are no species currently listed as threatened in Australia (DEWHA 2009a).

  World Described/
Accepted
World Estimate Australia Described/
Accepted
Australia Percentage Australia Estimate Australia Endemic World Threatened
79
Australia Threatened Australian Threatened as % of World Threatened
Collembola ~7 500 50 000 279 34.7% ~2 000 6.1% 0 0
Diplura 800 unknown 28 3.5% 38 92.8% 0 0
Protura 748 unknown 31 4.1% 32 80.6% 0 0
 
ALL HEXAPODA ~9 048 52 000 338 3.7% ~2 070 ~17.6% 0 0

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Mollusca (molluscs, shellfish)

Estimates of the number of described species of molluscs in the world vary from nearly 50 000 living species (Tangley 1997, Hickman et al. 2004) through 52 525 marine species (Bouchet 2006), ?70 000 (Hawksworth and Kalin-Arroyo 1995), 70 000–75 000 (with possibly more than 100 000) (Groombridge and Jenkins 2002), 81 000 (IUCN 2009b), 93 195 (Brusca and Brusca 2003), 110 000 (Hallan 2003) to 120 000 (Ponder et al. 2002). Hawksworth and Kalin-Arroyo (1995), Groombridge and Jenkins (2002) and Rosenberg (pers. comm.80) estimated a possible total of around 200 000 species, and May (2000) provided an estimate of about 120 000. I have accepted a figure for the world of c. 85 000 described species based on 52 525 marine (Bouchet 2006), and 24 000 terrestrial molluscs and 7 000 freshwater molluscs (Lydeard et al. 2004), with a total world estimate of 200 000 species (Rosenberg pers. comm.80).

Estimates for Australia are approximately 8 700 described species out of a total of about 12 250 (DEH 2007).

Endemism of about 90% is reported in the 2001 Australian State of the Environment Report (DEH 2001), however Ponder et al. (2002) reported that only about 10% of tropical species (i.e. about of all Australian species) and 95% of temperate species are endemic, making a total of about 38% endemism.

There are 14 listed threatened mollusc species in Australia (one undescribed) and one undescribed subspecies (DEWHA 2009a). Ten (plus the subspecies) are listed as Critically Endangered and four as Endangered.

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
81
  Australia Threatened   Australian Threatened as % of World Threatened
50 000   120 000   ~85 000   ~200 000   ~8 700   10.2%   ~12 250   38%   978
(1.2%)
  14
(0.2%)
  1.4%

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Annelida (segmented worms)

Estimates for the number of described species of Annelida in the world vary from 12 000 (Tangley 1997, Bouchet 2006) through 12 070 (Hallan 2003), 13 000 (with only about 8 000 reliable species) (Hutchings and Fauchald 2000), 13 500 (Myers 2001e), 15 000 (May 1998, Hickman et al. 2004), c. 16 000 (Groombridge and Jenkins 2002), 16 600 (Brusca and Brusca 2003) to 16 763 (this report). Myers (2001e) reported about 10 000 species of Polychaeta, 3 000 species of Oligochaeta and about 500 species of Hirudinea, and a total of about 13 500 species. Wilson and Capa (pers. comm.82) report around 8 350 species in 1 093 genera for Polychaeta, although figures for a number of families are approximate. The figures I have used are c. 8 432 polychaete species, from Beesley et al. (2000) who give a detailed breakdown by family; 147 species of Pogonophora from the Catalogue of Life (Bisby et al. 2009); 7 684 Oligochaeta from Blakemore (2008 and pers. comm.86) and 500 Hirudinea from Myers (2001i)—making a total of 16 763. Glasby (pers. comm.83) suggests that higher figures often given for Polychaetes (i.e. around 13 000) are more related to names than species and don’t take into account synonymy, whereas the lower figures (around 8 000) are more accurate for the number of species.

An estimate for the total number of species is between 25 000 and 30 000 (Snelgrove et al. 1997 as reported by Ponder et al. 2002).

According to DEH (2007), the number of described Australian species is about 2 300 out of an estimated total of about 4 230. Adding up the species in each Order, however, gives a figure of about 2 192 made up of 1 139 polychaetes (ABRS 2009a, Wilson and Capa pers. comm.82), 22 Myzostomida (ABRS 2009a), 10 Pogonophora (which should now be included in the Polychaete family Siboglinidae)84, 962 oligochaetes85 and 59 Hirudinea (ABRS 2009a). Many of these figures do, however, appear to be quite fuzzy. The percentage of endemics is unknown, but it is reported that southern Australia has about 67% endemism (Poore 1995). Blakemore (pers. comm.86) states that there are probably around 2 000 endemic species of megadriles in Australia, of which 650 are currently described.

There is one listed threatened worm species in Australia, listed as Vulnerable (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
87
  Australia Threatened   Australian Threatened as % of World Threatened
12 000   16 763   16 763   25 000–30 000   2 192   13.1%   ~4 230   67%   6
(0.04%)
  1
(0.05%)
  16.7%

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Nematoda (nematodes, roundworms)

Estimates for the number of described species of Nematoda vary from around 12 000 (Myers 2001f, Hickman et al. 2004) through 20 000 (Hodda 2000), 20 000–25 000 (Groombridge and Jenkins 2002), fewer than 25 000 (Baldwin et al. 2000), 25 000 (Hawksworth and Kalin-Arroyo 1995, Brusca and Brusca 2003), over 80 000 of which over 15 000 are parasitic (Wikipedia88). Bouchet (2006) accepted a figure of 12 000 for marine species based largely on Hugot et al. (2001). Estimates for the total numbers of species, however, are much larger, ranging from 400 000 (Hawksworth and Kalin-Arroyo 1995, Groombridge and Jenkins 2002) through about 500 000 (Myers 2001f, Hickman et al. 2004) to 500 000–1 million (Baldwin et al. 2000) and ‘several times’ their estimate of 25 000 (Brusca and Brusca 2003). Baldwin et al. (2000) stated that ‘Although 4 000–5 000 marine nematode species have been named and described, full surveys of marine habitats probably will reveal many millions of previously unknown species’. They also provided references to estimates for the total number varying from 100 000 (Hawksworth and Kalin-Arroyo 1995) to as many as 10 million.

Estimates for the numbers of described Australian species vary from 1 200 (ABRS 2005) to about 2 060 (DEH 2007). The current version of the Australian Faunal Directory (ABRS 2009a) lists just 358 species, but I am informed that this is very incomplete and includes mostly just the free-living nematodes. Estimates for the total number of species are around 30 000 (DEH 2007). I have found no published estimates for the percentage of endemics.

There are currently no listed threatened species of nematode in Australia (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
89
  Australia Threatened   Australian Threatened as % of World Threatened
12 000   >80 000     ~500 000   ~2 060   8.2%   ~30 000   unknown   0   0  

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Acanthocephala (thorny-headed worms)

Estimates for the number of described species of Acanthocephala in the world vary from more than 500 (Hickman et al. 2004), 842 (Hallan 2003), over 1 000 (of which 600 are marine) (Groombridge and Jenkins 2002, Bouchet 2006), 1 100 (Brusca and Brusca 2003) to 1 150 (Wikipedia90).

Groombridge and Jenkins (2002) suggested that only a low to moderate proportion of the group is known, suggesting perhaps a total of around 1 500 species.

DEH (2007) reports figures of 56 described species for Australia out of a total of about 160.

There are no listed threatened species of Acanthocephala for Australia (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
91
  Australia Threatened   Australian Threatened as % of World Threatened
~500   1 150   1 150   ~1 500   56   4.9%   ~160   unknown   0   0  

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Platyhelminthes (flat worms)

Estimates for the number of described species of flat worms in the world are around 20 000 (Hawksworth and Kalin-Arroyo 1995, Groombridge and Jenkins 2002, Brusca and Brusca 2003), although Hallan (2003) gives an unsubstantiated figure of 25 000. Myers (2001g) reported 3 000 species of Turbellaria, 9 000 species of Trematoda and 5 000 species of Cestoda, while Ponder et al. (2002) provided a figure of 3 000–4 000 Monogenea which would give a total of 20 000–21 000 species. I have accepted the lower of these (20 000) in line with the majority of reports. About 15 000 of these are marine species (Bouchet 2006).

I found one obscure estimate of the total number of species at over 80 000.

Estimates for the number of described Australian species vary from 1 506 (DEH 2001) to 1 593 (DEH 2007) with estimates for total species of around 10 000 (DEH 2007) and 10 806 (DEH 2001) although these estimates appear high (Wells pers. comm.92). The Australian Faunal Directory (ABRS 2009a) lists just 465 species, however this is very incomplete as not all Classes have been covered. Endemism is likely to be low in parasitic forms in birds, marine fishes and in free-living marine forms and high in parasites of marsupials, reptiles and frogs, and in free-living freshwater forms (Wells pers. comm.92).

There are no listed threatened species of Platyhelminthes, however The IUCN Red List of Threatened Species (IUCN 2009b) lists one Extinct species of Turbellaria.

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
93
  Australia Threatened   Australian Threatened as % of World Threatened
20 000   25 000   20 000   (~80 000)   1 593   8%   ~10 000   unknown   0   0  

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Cnidaria (jellyfish, sea anenomes, corals)

Estimates for the number of described species of Cnidaria in the world vary from 9 000 (Groombridge and Jenkins 2002, Hickman et al. 2004) through 9 500 (Hallan 2003), 9 795 (Bouchet 2006), 10 000 (Groombridge and Jenkins 2002) to 10 000–11 000 (Brusca and Brusca 2003). I have accepted the figure of 9 795 as it appears to be the most thoroughly researched and reliable. I am not sure if these include the Myxozoa, which are included here under the Protoctista and of which there are about 1 200 species (Adl et al. 2007). I have accepted that these were most likely not included by Bouchet in his publication.

The number of described Australian species reported varies from 1 270 (DEH 2001) to 1 705 (DEH 2007) with estimates of the total Australian fauna consistent at about 2 200 (DEH 2007), made up of around 1 043 species of Anthozoa, 51 species of Scyphozoa, nine of Cubozoa and perhaps around 600 species of Hydrozoa (Ponder et al. 2002), making a total of around 1 705 described species and around 2 200 species in total.

There are no listed threatened species of Cnidaria in Australia (DEWHA 2009a) but 231 Anthozoa and five Hydrozoa are listed in The IUCN Red List of Threatened Species for the world.

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
94
  Australia Threatened   Australian Threatened as % of World Threatened
9 000   11 000   9 795   unknown   1 705   17.4%   ~2 200   unknown   236
(2.4%)
  0   0%

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Porifera (sponges)

Estimates for the number of described species of Porifera in the world vary from 5 500 (Myers 2001h, Brusca and Brusca 2003, Bouchet 2006) through 5 000–10 000 (Groombridge and Jenkins 2002), 6 000 (ABRS 2009a), to 10 000 (Hallan 2003, Ramel 2009a). ABRS (2009a) also estimates that the figure of 6 000 described species is perhaps only about one-third of the total number of extant species. I have accepted the figure of 6 000 as given by ABRS (2009b).

Described species in Australia number between 1 320 and 1 476. Hooper and Wiedenmayer (1994) provided figures of 1 320–1 335 with 56% endemic and DEH (2001, 2007) estimated that there were 1 416 described species in Australia with the total number of species in Australian waters at about 3 500. The Australian Faunal Directory (ABRS 2009a) has now updated this figure to 1 476. Ponder et al. (2002) stated that about 45% of species on the Great Barrier Reef are endemic.

There are currently no listed threatened Porifera species in Australia (DEWHA 2009a).

World Described/
Accepted minimum
  World Described/
Accepted maximum
  World Described/
Accepted
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic   World Threatened
95
  Australia Threatened   Australian Threatened as % of World Threatened
5 500   10 000   ~6 000   ~18 000   1 476   24.6%   ~3 500   56%   0   0  

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Other Invertebrates

A difficulty in listing this group is determining what belongs here, and what belongs in the Protoctista (see later).

Estimates for the number of described species in the various phyla in the world are given in the next table and are compiled from Groombridge and Jenkins (2002), Brusca and Brusca (2003), Hickman et al. (2004) and Bouchet (2006). Those for Australia are from ABRS (2009a) with the exception of the Rotifera supplied by Shiel (pers. comm.96). The Phylum Monoblastozoa listed in the following table is, according to Meeûs and Renaud (2002), of doubtful existence, and Hickman et al. (2002) stated that the Phylum Chaetognatha was not supported by molecular evidence. They have, however, been included in the table. Guidetti and Bertolani (2005) listed 980 species of tardigrade for the world, of which 147 were marine. Bouchet (2006) stated that there were 212 marine species making a new total of 1 045 species in total.

Information for Australia on Tardigrada (water bears) was supplied by Claxton (pers. comm.97). She reported that an unpublished paper by her and Reinhardt Kristensen listed 46 marine species for Australia in 1998, and that her PhD (submitted in 2004) identified 182 terrestrial species of which 69 have been published in the literature. About 56% of the 182 species are endemic. She suggested that there are at least 500 species in total for Australia.

Most estimates for the world total of described species of Mesozoa are around 90–106, whereas ABRS (2005) stated that there are 100 described species for Australia. I have contacted several researchers around Australia, and all have the view that there is probably no-one in Australia who knows the number of described species in Australia. Similarly, the figure of 100 for the Loricifera reported by Groombridge and Jenkins (2002) does not fit with figures of around 10 reported by other researchers, or 28 supplied by Kristensen (pers. comm.98).

Other figures that differ from those given in the cited papers are 1 200 described species out of a worldwide total of 5 000–10 000 in Nemertea (Ponder et al. 2002).

Ponder et al. (2002) stated that about 87% of the Australian species of Entoprocta are endemic. Other endemism figures are largely determined from ABRS (2009a).

There are two species of Nemertea (ribbon worms) listed as Vulnerable in The IUCN Red List of Threatened Species, but no species are currently listed as threatened in Australia (DEWHA 2009a).

Phylum  Common name  World World Described/
Accepted
  
  World Estimate   Australia Described/
Accepted
  Australia Percentage   Australia Estimate   Australia Endemic
Hickman et al.   Brusca and Brusca
99
  Groombridge and Jenkins   Bouchet (marine only)  
Placozoa   1   1   1     1     0   0%   0   0%
Monoblastozoa     1       1          
Mesozoa (Rhombozoa, Orthonectida) mesozoans accepted?   90   ~90   106   106     100   94%   100  
Ctenophora comb jellies   100   ~100   166   166   200   10   6%   60  
Nemertea (Nemertina) ribbon worms 650   900   ~900   1 180–1 230   1 200   5 000–10 000   81   7%   281   65%
Rotifera rotifers ~1 800   1 800   ~2 000   50 marine   2 180100     683   31%   1 300   45%
Gastrotricha gastrotrichs ~400   450   ~400   390–400   400     45   11%   45  
Kinorhyncha kynorhinchs 75   150   ~150   130   130     8   6%   8  
Nematomorpha horsehair worms 250   320   ~240   5 marine   331101   ~2 000   32   10%   32  
Entoprocta (Kamptozoa) kamptozoans 150   150   ~150   165–170   170   170   16   9%   >16   87%
Gnathostomulida gnathostomulids >80   80   ~80   97   97     8   8%   8  
Priapulida priapulans 18   16   17   8 marine   16     2   12%   2  
Loricifera loriciferans few   10   ~100   18 marine   28102   >100   4   14%   6   50%
Cycliophora cycliophorans ?1   1   accepted?   1   1     0   0%   0  
Sipuncula peanut worms ~330   320   ~150   144   144103     48   33%   48  
Echiura spoon worms 140   135   ~140   176   176     13   7%   13   54%
Tardigrada water bears 300–400   800   ~750   212 marine   1 045104     112 (228)   11–22%   ~500   56%
Phoronida phoronids ~10   20   16   10   10     6   60%   6  
Ectoprocta (Bryozoa) moss animals ~4 000   4 500   ~4 000   5 700   5 700   ~5 000   1 000   18%   ~2 500   50%
Brachiopoda lamp shells ~325   335   ~350   550   550     58   11%   70   ~70%
Pentastomida tongue worms ~90   ~130105   accepted?     100     10   10%   10  
Chaetognatha arrow worms   100   ~70   121   121     19   16%   10   0%
TOTAL   ~8 820   ~10 409   ~9 704   9 229–9 294   12 673   ~20 000   2 255–2 371   18.7%   ~5 015   unknown

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