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First 'common' earthworm found in Tasmania
Invertebrata 9, November 1997

The European earthworm Lumbricus terrestris Linneaus, 1758 has been found in a suburban garden in Launceston - the first authenticated record of this species in Australia.

Studies on L. terrestris have a long history as it was one of the species considered by Charles Darwin in his famous treatise on earthworms (Darwin 1881). In the past, various species of earthworms introduced into Australia have been misidentified as L. terrestris. An unfortunate consequence of earlier unsubstantiated accounts of its presence here is that it has been erroneously listed as an introduced species in the scientific literature. Here I describe the animal, give details of the Launceston find and comment on earlier accounts of its distribution. A formal scientific note on L. terrestris in Tasmania will appear elsewhere.

Description. Lumbricus terrestris (see illustration) is a fairly stout-bodied earthworm about 250 mm long and 12 mm wide. The posterior third of the body flattens and assumes a spade-like shape shape when the worm is disturbed. In life, the top of the worm is gunmetal gray with a blue iridescence, while the underside is pink and the clitellum ('saddle') is yellowish. There are 136 segments, with the clitellum on segments 32-37. There are eight setae per segment, closely paired in regular rows. Dorsal pores: 7/8 small, from 8/9 larger. Nephropores: large at anterior margin of segment just lateral of the 'b' setal line on many segments (e.g. on right-hand side on 11-15, 20, 22-25, 28, 30-36, 39-44, etc.), irregularly alternating to between the 'd' line and mid-dorsum (e.g. on right-hand side seen in dorsal position on 3-7, 9, 17-19, 21, 26-27, 29, 33-34, 37-39, 44-45). (Note: see illustration for location of 'a', 'b', 'c' and 'd' setal lines. It is not known why in some segments the nephropores appear to be in both positions on one side.) Spermathecal pores: in 9/10/11 in 'cd', nearer to 'c' lines. Female pores: paired, just lateral of 'b' setae on 14. Male pores: towards lateral extremity of equatorial slits within tumid lips between 'a' and 'c' setal lines, confined to 15; distinct mound tract (formed by parallel seminal grooves?) extends from male pores (or female pores?) to clitellum between 'b' and 'c' line on both sides. Genital markings: ventral setal couples within slightly tumid pads, especially 8, 9-11, 25, 31-32 and 37-38; tubercula pubertatis as elongate smooth pad just median of 'c' line in 33-36 on both sides. Details of the internal anatomy of L. terrestris are readily available in zoology textbooks (e.g. Sims and Gerard 1985, figs 4 & 6). In order to avoid excessive damage to the single available specimen, I have not dissected it. The description agrees with that of Sims and Gerard (1985; pp. 106-108, figs 1, 37 & 38), who for internal anatomy only remark on the septa and seminal vesicles, and also with descriptions by Gates (1972; pp. 118-123) and Lee (1959; pp. 365-368).

Biology. I found the animal (QVM registration number 14:3648) on the soil surface while I was digging to 1 m depth in black clay in a suburban garden at 145 Holbrook Street, Invermay, Launceston on 29 June 1997. The specimen is mature and compete; it was fixed in 10% formalin and preserved in 80% ethanol. ).

The characteristic spade-shaped tail is believed to enhance gripping of the burrow walls, as the worm's foraging behaviour is to anchor the tail in the mouth of the burrow and to drag leaves and twigs back down for feeding. The burrow may extend to 3 m depth, and the entrance is often marked by a small midden of pebbles and twigs as well as a plug of leaves, etc (Gates 1972, Sims and Gerard 1985). L. terrestris is usually described as being nocturnally active (e.g. Linnaeus 1758; p. 647; 'adscendit noctu'), and its above-ground wandering and copulation have earned it the common name in North America of the 'European Nightcrawler' (in French Canada, 'ver nocture rampant'). However, its dark pigmentation indicates a need for protection from sunlight and the present specimen was rapidly escaping over the soil surface in daytime. This escape response may have been excited by my digging; perhaps I reminded the worm of a European mole (Talpa sp.) for which L. terrestris is a favourite food! Such an escape response is exploited by predatory birds like lapwings (Vanellus spp.) that mimic the mole-digging vibrations by stamping on the soil surface (Darwin 1881; p. 28).

Confusion. A number of references note that other earthworm species have frequently been confused with L. terrestris in the past, possibly due partly to its inaccurate characterisation in school texts as 'the common earthworm', an expression rejected for this species by, amongst others, Stephenson (1930) in a preface to his great mnograph. Gates (1972; p. 123) remarks that 'A belief that almost any earthworm is Lumbricus terrestris is not entirely restricted to high-school graduates who have had an elementary course in biology (cf. Stephenson, 1930: p. xi). The species used in a recent electron-microscope study of sperm cytology was said to be L. terrestris but actually was Allolobophora [= Aporrectodea] tuberculata'.

A species that has often been confused with L. terrestris, until relatively recently, is Aporrectodea longa (Ude). The distribution of this latter species given by Sims and Gerard (1985; p. 64) extends to 'Australia (including Tasmania)'. A. longa has been frequently reported from Australia; see Blakemore (1997; p. 607) for a list of records of this and for 15 other introduced lumbricid species. For example, Wood (1974), while acknowledging Professor Jamieson for identifying the earthworms, recorded this species as Allolobophora terrestris f. longa (Ude) from Kosciusko National Park. Gates (1972; pp. 75-76), who had earlier shown that this latter name is illegitimate, went on to state that 'A. longa is not known to have been sold or used for bait in North America but the species may have occasionally been mistaken for [L.] terrestris, unless anglers are more careful than university professors'.

Distribution. According to Sims and Gerard (1985; p. 108) the Southern Hemisphere distribution of L. terrestris includes 'Holarctic and temperate regions of South America, Australia, New Zealand, several temperate oceanic and other southern islands'. It is said to be found 'in many undisturbed, terrestrial habitats, most numerous in grasslands (including lawns) and orchards, less common in woodland, arable soil and river banks. Found in alkaline soils of pH 6.2-10.0; especially abundant in clay'. In New Zealand, Lee (1959; pp. 367-368) regarded this species as 'quite common in garden soils in Auckland, Hamilton, and probably in other nearby towns'. However, the record of this species in 'Australia' in Sims and Gerard (1985) is unauthenticated, although these authors cite Gates (1972) in their references and Gates (1972; p. 119) lists this species in Australia, again without reference. The only earlier report that I can find for this species in Australia is by Jamieson (1965; p. 40) where, after explaining how 'essential' it was not to confuse species, he proclaims: 'The British "Common Earthworm", Lumbricus terrestris, has been found to flourish in Australian earthworm farms and is of value'. Reynolds (1977; pp. 7 & 101) explains how L. terrestris, although routinely collected at night for fishing bait and study in North America, cannot be commercially cultured economically because of its long life cycle, low reproductive rate, and large spatial requirements. Jamieson's report of this species in Australian worm farms is therefore highly dubious. Furthermore, since no specimens of L. terrestris are known in any reference collection in Australia, and since Jamieson (1981; pp. 898-899) fails to mention this species amongst the six lumbricids he does report from Australia, then Jamieson's earlier claim is most likely erroneous.

The finding of L. terrestris brings to about 60 the author's (unpublished) tally of introduced earthworms in Australia.

Dr R.J. Blakemore
Queen Victoria Museum and Art Gallery



Ventrolateral view of Lumbricus terrestris Linnaeus, 1758, and dorsal view of prostomium (QVM specimen 14:3648)

References:

Blakemore, R.J. 1997. Agronomic potential of earthworms in brigalow soils of south-east Queensland. Soil Biology Biochemistry 29(3/4): 603-608.

Darwin, C.R. 1881. The Formation of Vegetable Mould through the Action of Worms, with Observations on Their Habits. London: John Murray.

Gates, G.E. 1972. Burmese earthworms, an introduction to the systematics and biology of megadrile oligochaetes with special reference to southeast Asia. Transactions of the American Philosophical Society 62(7): 1-326.

Jamieson, B.G.M. 1965. Recognising Australian earthworms. Australian Natural History 15(2): 39-43 (June 15, 1965).

Jamieson, B.G.M. 1981. Historical biogeography of Australian Oligochaeta. In Keast, A. (ed.), Ecological Biogeography of Australia, vol. 2, part 3. The Hague: Dr W. Junk.

Lee, K.E. 1959. The Earthworm Fauna of New Zealand. New Zealand Department of Scientific and Industrial Research, Wellington, Bulletin 130.

Linnaeus, C. 1758. Systema naturae... (10th ed.). Holmiae: Salvii.

Reynolds, J.W. 1977. The Earthworms (Lumbricidae and Sparganophilidae) of Ontario. Life Sciences Miscellaneous Publications, Royal Ontario Museum.

Sims, R.W. and Gerard, B.M. 1985. Earthworms, Keys and Notes for the Identification and Study of the Species. Synopses of the British Fauna (New Series) No. 31. London: Brill/Backhuys.

Stephenson, J. 1930. The Oligochaeta. Oxford: Oxford University Press.

Wood, T.G. 1974. The distribution of earthworms (Megascolecidae) in relation to soils, vegetation and altitude on the slopes of Mt Kosciusko, Australia. Journal of Animal Ecology 43: 87-106.

Cats and toxoplasmosis
Invertebrata 9, November 1997

Members of the cat family (Felidae) are the definitive hosts of the protozoan parasite Toxoplasma gondii. Toxoplasmosis, a disease associated with this parasite, can be contracted by Australian marsupials through indirect contact with our only felid, the domestic cat Felis domesticus.

The eastern barred bandicoot, Perameles gunnii, appears to be particularly susceptible to toxoplasmosis. The disease is recognised as an important threat to the long-term survival of this bandicoot, both in its relict population in Victoria and in its more secure stronghold on the island of Tasmania. A recently completed field study of P. gunnii in Tasmania found no serological evidence for exposure to Toxoplasma in free-range bandicoots. Once exposed, however, bandicoots rapidly develop an acute and fatal infection (Obendorf et al. 1996).

Coprophagic (feces-eating) invertebrates such as earthworms, snails, flies and ground beetles were already known to act as mechanical transport hosts for Toxoplasma oocysts, either through ingestion of cat droppings or of soil contaminated with cat fecal material. Oocysts ppass through the gut of these invertebrates and are dispersed in their excreta. T. gondii oocysts on grasses and other edible groundcovers are a recognised source of infection for grazing herbivores and omnivores.

As earthworms and beetles make up a significant proportion of the diet of P. gunnii, these soil invertebrates seemed to be highly likely sources of Toxoplasma for bandicoots. A three-year study in the Huon Valley found numerous earthworm chaetae (bristles) in bandicoot feces, and as might be expected the proportion of fecal samples with chaetae was higher in winter than summer (51% vs. 28%; data from Mallick et al. 1996).

Under experimental conditions two eastern barred bandicoots were fed earthworms exposed to soil containing oocysts (Bettiol et al., in press). The animals developed clinical signs of toxoplasmosis and died 11 and 14 days, respectively, afetr feeding. Histopathological examination of various tissues from the two bandicoots suggested that the animals were overwhelmed by acute, generalised Toxoplasma infection. The study confirmed that P. gunnii can contract toxoplasmosis by eating earthworms exposed to oocyst-contaminated soil, and it was further demonstrated that oocysts in the alimentary tract of the worms, rather than infective stages in the body tissues, were responsible for the infection.

Dr Sylvana Bettiol and Dr David Obendorf
Department of Pathology
University of Tasmania

References:

Bettiol, S.S., Obendorf, D.L., Nowarkowski, M. Goldsmid, J. and Milstein, T. The role of earthworms in the transmission of Toxoplasma gondii infection to eastern barred bandicoots (Perameles gunnii). (In press)

Mallick, S.M., Driessen, M. and Hocking, G. 1996. Biology and Conservation of the Eastern Barred Bandicoot (Perameles gunnii) in Tasmania. Wildlife Report No. 97/1 to Environment Australia. Parks & Wildlife Service, Tasmania.

Obendorf, D.L., Statham, P. and Driessen, M. 1996. Detection of agglutinating antibodies to Toxoplasma gondii in sera from free-ranging Eastern Barred Bandicoots (Perameles gunnii). Journal of Wildlife Diseases 32: 623-626.

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