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New Zealand Flatworm, Arthurdendyus triangulatus


Short description of Arthurdendyus triangulatus, New Zealand Flatworm

Flat (with a more or less pronounced median dorsal ridge), covered in sticky mucus, pointed at both ends, up to 17 cm long when elongated but shape can vary considerably. Upper surface dark brown with a lighter margin, underside also lighter with small dark specks.  It has no annules.

Description of Arthurdendyus triangulatus, New Zealand Flatworm status in GB

The New Zealand flatworm has a widespread distribution and is relatively common in Scotland and Northern Ireland.

Habitat summary: Arthurdendyus triangulatus, New Zealand Flatworm

Most records are from domestic gardens, some still come from garden centres and nurseries with relatively few from farmland.

The New Zealand flatworm requires damp, cool conditions to survive i.e. it cannot live in dry soils or where the temperature is below 0 or above c. 20 degrees Celcius. Its distribution in GB is probably limited to areas which have earthworms  (soils with pH levels above 4). The New Zealand flatworm is nocturnal and probably feeds on the earthworm species which come to the soil surface at night to feed. During the day it takes refuge under stones, pieces of wood and piece of polythene. It itself does not seem to have the ability to make burrows but when conditions are unfavourable it relies on earthworm tunnels, dead root channels or cracks in the soil surface to access the deeper soil horizons where it is cool and damp.  

Overview table

Environment: Terrestrial
Species status: Non-Native
Native range: New Zealand
Functional type: Predator
Status in England: Non-Native
Status in Scotland: Non-Native
Date of first record: 1965

Distribution map

Map of the UK with areas shaded to show the UK distribution of New Zealand Flatworm

GB Distribution from NBN Atlas

Author's name:

Brian Boag

Last updated:

September 26th 2016

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