Invasive Alien Species in Northern Ireland

Australoplana sanguinea, Australian flatworm

Australoplana sanguinea 
The Australian flatworm is a medium–sized strap–like, flattened worm with a brownish–red to buff upper surface tinged deep peach to blood–red towards the narrowly pointed head end, and with a paler buff underside. Unlike earthworms, flatworms have no annulations or rings on the body and are completely smooth.
This animal is a predator of native earthworms. Because of its smaller size and rarity in Northern Ireland, it does not compare with the abundant and voracious New Zealand flatworm in its effect upon earthworm populations. The situation may be very different, however, in the south of Ireland.
Unlike the New Zealand flatworm this species does not form coils in its resting state but is usually laid out lengthwise in the soil. When moving it can be up to 75mm (3”) long but at rest, less than half that. The body is also not so flat as the New Zealand flatworm, being slightly domed in cross–section with only a small part of the middle of the underside contacting the ground when it is moving, as can be seen in the photograph. The body comes to a point at each end and is a buff, peachy or pale reddish colour with more intense blood–red or brownish red shades near the head end.
The head end is slender and more extendible than the hind end. On close examination a row of brownish or blackish dots is visible along the pale margin, being dense and close together near the head but sparse and well separated towards the tail. These are light sensitive organs or ‘eyes’ which help the animal to navigate. The mouth or pharynx is located on the underside about one third the way down from the head. The pharynx is pushed out of the body cavity when feeding and envelops the prey, secreting a digestive fluid on to it.
Country of origin
The Australian flatworm was described by Moseley in 1877 from material collected in south–eastern Australia. Dendy later described a similar but paler species from material collected near Ballarat in Victoria. This was subsequently synonymised with Moseley’s species. The form found in the British Isles is closely similar to Dendy’s animal from Ballarat and is now called Australoplana sanguinea var. alba although Fauna Europea lists it (perhaps more correctly) as Australoplana alba.
Location in Ireland
First recorded from gardens near Belfast in the nineteen–seventies (Jones, 1981), and subsequently found in woods and other wild places across Northern Ireland (Anderson, 1986). However, most records are for urban centres in the east of the Province.
Some thirty years after its discovery it is still uncommon in Northern Ireland and rarely found in more than ones or twos. This is probably connected to the prevalence of Arthurdendyus and the consequent scarcity of earthworm prey.
In southern Ireland this flatworm has a wide but scattered distribution and is clearly much commoner than the larger New Zealand flatworm, the reverse of the situation in N. Ireland (see map). It is particularly common near the south coast in Cork and Waterford (for example, Cawley & Jones, 2001).
Life cycle
As with the New Zealand flatworm developing eggs are detectable in mature flatworms as bulges on the mid line. The egg capsules when laid are proportionately smaller than those of the New Zealand worm and as in that species, are a dull red at first. The chitin of the egg cures shiny black within a few hours.
Egg capsules are rarely encountered in N. Ireland, possibly because they are laid in soil rather than under the heavy objects such as stones usually selected by the New Zealand flatworm. The eggs hatch after several weeks to release one to four small flatworms. The young look like paler miniature versions of the adults.
Adults are usually found between autumn and late spring and are rarely detectable in the summer, probably because they retreat into the soil when the atmosphere is dry.
Wildlife and habitat impacts
The Australian flatworm has been observed predating earthworms both in the field and in the laboratory (O’Meara, 1999; Santoro and Jones, 2001) and when gut contents of wild–collected animals are examined these normally contain earthworm setae (McDowell, 2005). It can occur in gardens and has been flushed from lawns using formalin (Anderson, 1986).
Laboratory observations suggest, however, that its attacks upon earthworms are slower and less successful than is the case with the New Zealand flatworm. Nevertheless it can probably do significant damage to earthworm populations, at least in gardens (O’Meara, 1999; Santoro and Jones, 2001).
Human impacts
None attributable in Northern Ireland but in southern Ireland damage to earthworm populations in gardens is highly probable.
Key vectors
There is no prima facie evidence for transport by human beings, inadvertent or otherwise, but it is likely to be distributed via the movement of plants in the horticultural trade.
What you can do as an individual
If you encounter the Australian flatworm and wish to record the find, CEDaR at the Ulster Museum will accept records (Damian McFerran, CEDaR, Botany Department, Sciences Division, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down BT18 0EU. Tel: 028 9039 5256, email damian.mcFerran[at] as will the author of this article (roy.anderson[at]
Advice to specific groups relevant to this species
None at present.
Management measures
There appears to be little need to control this animal in Northern Ireland. Its distribution is still localised and despite having been in the Province for over thirty years, shows little sign of consolidating. Most likely it will remain a relatively scarce component of the fauna of soils in gardens and woodlands unless Arthurdendyus becomes rarer with climate warming.
Management groups
Research into the biology and potential control measures for flatworms, including this species, is carried out by the Agri–food Biosciences Institute (AFBI), Newforge Lane, Belfast. Contact: Dr Archie Murchie, Applied Plant Science, AFBI.
Further information
HDRA, the organic organisation:
Scottish Executive:
Dr Archie Murchie, AFBI researcher:
Biological and ecological studies by SERAD (Scottish Executive RUral Affaitrs Dept.):
Alford, D.V., Lole, M.J. and Emmett, B.J. (1996). Alien terrestrial planarians in England and Wales, and implications for horticultural trade. UK Crop Conference, November 18-21, 1996, Brighton, England: Pests and diseases, 1996, Vol. 3: 1083-1088.
Anderson, R. (1986). The land planarians of Ireland (Tricladida, Terricola) a summary of distribution records. Irish Naturalists’ Journal 22: 141-146.
Cawley, M. and Jones, H.D. (2001). Kontikia ventrolineata (Dendy, 1882) an alien land planarian (Tricladida: Terricola: Geoplanidae) new to Ireland. Irish Naturalists’ Journal 22: 424-426.
Johns, P.M. and Boag, B. (2003). The spread and distribution of terrestrial planarians (Turbellaria: Tricladida: Geoplanidae) within New Zealand. New Zealand Journal of Ecology 27(2): 201-206.
Jones, H.D. (1981). A specimen of the Australian land planarian Geoplana sanguinea (Moseley) var. alba (Dendy) from the Isles of Scilly. Journal of Natural History 15: 837-843.
McDowell, (2005). Reproduction and survival of invading flatworms, with emphasis on the ‘Australian flatworm’ Australoplana sanguinea var. alba. Ph.D. Thesis, The Queen’s University of Belfast.
O’Meara, M. (1999). The Australian land planarian Australoplana sanguinea (Moseley) var. alba (Dendy) (Tricladida: Terricola) in Waterford. Irish Naturalists’ Journal 26: 204.
Santoro, G. and Jones, H.D. (2001). Comparison of the earthworm population of a garden infested with the Australian land flatworm (Australoplana sanguinea alba) with that of a non-infested garden. Pedobiologia 45(4): 313-328.
Text written by:
Dr Roy Anderson