New Zealand Flatworm

A. triangulates, also known as the New Zealand flatworm, is a free-living terrestrial flatworm native to New Zealand. This species of flatworm is considered to be an invasive species in several areas of Europe. It is considered an invasive species because of its predation over native earthworms leading to the decline of soil fertility. The leading vector of introduction for this invasive species is thought to be the horticulture and agriculture trade (Blackshaw and Stewart, 1992).

Life cycle of the New Zealand Flatworm. [Wikipedia]

Scientific Classification

New Zealand Flatworm. [Wikipedia]

   Domain: Eukaryota
    Kingdom: Metazoa
     Phylum: Platyhelminthes
      Class: Turbellaria
       Order: Tricladida
        Family: Geoplanidae
         Genus: Arthurdendyus
          Species: Arthurdendyus triangulates

Description

Mature Arthurdendyus triangulates can vary in size from 5 to 20cm based on the extension of the body. It has a flattened body that narrows toward the anterior, with no segmentation [2]. (Data Report). The back or dorsal side of the flatworm is a darker brown color and the underside or ventral part of the flatworm is a pale tan color. The body of the flatworm is covered in a mucus that is sticky to the touch [3] (Willis and Edward 1977). These flatworms can be found on the surface of the soil, under debris and other objects that are in contact with the soil, or found beneath the soil when hunting for food. the species has the ability to survive without food for long durations of time (Christensen & Mather, 1995).

The species can move up to 17 meter per hour utilizing trails previously made by earthworms (Christensen & Mather 1995). They move using circular muscles located beneath the epidermal cells and longitudinal muscles that contract throughout the body.

Reproduction

This species of flatworm is a hermaphrodite where adults reproduce following mutual fertilization [4] (Baird et al., 2005). Following fertilization A. triangulates produces a single egg capsule that starts as a red color before turning black. The capsule itself is shiny, flexible and around 8mm in size containing numerous juvenile flatworms [1]. Studies show that a single flatworm can produce an egg capsule once every 2 weeks[4][5]. (Christensen & Mather, 2001)

Native range

The native range of Arthurdendyus triangulates is the South Island in New Zealand. Its native ecosystem is the southern beech forest soils. In its native range there is no documented effects on native earthworm populations [1] (Blackshaw & Stewart, 1992). This species of flatworms can also be found in horticulture soils within its native range such as gardens and plant nurseries [6] (Johns et al.,1998).

Invasive Species

Arthurdendyus triangulates was first found outside its native range in Belfast, Northern Ireland in the early 1960s. It was thought to have been spread through the ornamental plant trade in both the adult and egg form (willis and Edwards, 1977). The species can now be found in areas of England, Norther Ireland, Scoland and the Faroe Islands. Modeling suggests that this flatworm species could thrive if their invasive range were to spread into areas of German, Poland and Sweden (Boag et al. 1995). Once introduced into this new range Arthurdendyus triangulates is shown to reduce the population size and diversity of native earth worm species, specifically Lumbricus terrestris(Blackshaw, 1990). This depletion of earthworm biodiversity reduces the soil quality by eliminating the decomposition service provided by the earthworms. This has an impact on agricultural services by reducing soil fertility.