At rest the flatworm is broadest in the middle, tapering to each end. In cross-section, the back is gently convex and the belly is flat. Mature live specimens are approximately 40 mm long and 4 to 5 mm wide. Some specimens may attain a length of 70 mm. The mouth is just behind the mid-point of the belly, with a genital pore about half-way between the mouth and hind end. Two large prominent eyes are situated back from the tip of the elongate snout-like head. The back is light to dark olive-brown, and darkest on either side of the pale creamish-white stripe that runs along the mid-back and at the margins. The olive-brown colour grades to grey at the head end. A thin creamish-white stripe with fine greyish margins runs the length of the body along each side. The belly is creamish-white, with a white mid-ventral stripe. A pale sensory zone passes around the underside of the front end.
Newly emerged hatchlings are up to 8 mm long, with a pale brownish-grey colour extending dorsally and submarginally, a thin pale median dorsal stripe, white ventral surface, and prominent eyes.
A general account of the anatomy of a terrestrial flatworm is provided by Winsor et al. (2004), and detailed anatomical data for P. manokwari are provided by Winsor (1990, 1998d), and Kawakatsu et al. (1992).
Terrestrial flatworms are normally detected by day by hand picking in moist microhabitats. Flatworms emerge at night to hunt and can be found with the aid of a spotlight or headlamp. Trapping methods for flatworms include laying plantain leaves or small boards directly on the ground;wetting areas of dry soil and covering these with a damp board (Ogren, 1955);or using a ceramic tile backed with 5 mm of polystyrene placed tile-down on the ground (Blackshaw, 1990). Polythene bags, 22 cm², and each filled with 1.5 kg of sand, were used to provide an artificial habitat to trap flatworms in New Zealand (Yeates et al., 1998), and conventional pitfall traps were successfully used in Tasmania to trap flatworms in a button grass habitat. Terricola can be extracted from soil samples using a 100 watt light bulb as a heat source (Ogren, 1955), but generally are not collected from soil or litter using dry extraction methods such as Berlese-funnel extractors. Extracting Terricola from soil samples using wet extractors such as those of Macfayden or Kempson (in Southwood, 1966) have potential, but appear not to have been reported. On-site formalin extraction (application rate of 4.5 litres of 0.2% formaldehyde per 1.2 m² quadrat, after Raw, 1959) was effective to a depth of at least 30 cm;the irritant bringing to the surface all specimens of a soil-dwelling flatworm species (Blackshaw and Stewart, 1992).
Bait traps can be useful for the detection of P. manokwari. Sugiura et al. (2006) placed land snails in 2-mm mesh nylon bags (approximately 30 x 25 cm) that allowed the entry of P. manokwari but not the escape of the snails. Five live land snails were placed as bait in each bag. When they checked bags three days after placement, they could find P. manokwari invading bags.
Related invasive species
- Platydemus manokwari
Related Farm Practice
- Light
- Rest
P. manokwari is a large predatory flatworm, originally discovered in New Guinea, which has been deliberately introduced into some Pacific islands in an attempt to control an invasion of the Giant East African Snail (Barker, 2002), but which has also been accidentally introduced to the soil of other Pacific countries. It has had a significant negative impact on the rare endemic land snail faunas of some Pacific islands, and has become established in a wide variety of habitats.
The species occurs naturally on Mt Wilhelm at 3625 metres altitude and at Kainantu in the eastern highlands of New Guinea, Irian Jaya. The natural range of this upland species has not yet been determined.
In addition to hosts listed in the Host table of this datasheet, P. manokwari has been reported to prey on the following in the laboratory: Acusta despecta sieboldiana, Bradybaena similaris, Euhadra amaliae callizona, Euhadra peliomphala, Euhadra quaesita, Trishoplita conospira, Satsuma japonica, Euphaedusa tau, Pinguiphaedusa hakonensis, Zaptychopsis buschi, Discus pauper, Helicarion sp., Pythia scarabaeus, Zonitides arboreus (Kaneda et al., 1990), and Partula radiolata (Hopper and Smith, 1992). P. manokwari also preys on a pheretimoid earthworm in north Queensland, Australia.
P. manokwari feeds on live land snails of an endemic species of the Ogasawara Islands, Japan (Mandarina aureola) under laboratory conditions (Okochi et al., 2004). P. manokwari also feeds on live snails of the predatory species Euglandina rosea as well as other snail and slug species (Ohbayashi et al., 2005). Furthermore, P. manokwari feeds on dead earthworms, and thus can survive in areas where snails have been absent since their invasion (Ohbayashi et al., 2005;Sugiura et al., 2006). P. manokwari feeds on live flatworms of other species (Ohbayashi et al., 2005).