Further monthly records (1994 to 2000) of size and abundance in a population of the ``Australian'' flatworm, Australoplana sanguinea alba in the UK

Collections of the ``Australian'' flatworm, Australoplana sanguinea alba, have been made in one garden in the UK three times a week from February 1995 to September 2000. All specimens seen were placed in 70\% alcohol, one jar each month. Flatworms were counted but not collected for some months from March 1992. The first flatworm was seen in December 1991. Rainfall, soil moisture and air and soil temperature (and latterly, the depth of the water table) were recorded. All specimens (5121) were weighed and measured. For some years the maturity of each specimen was also determined. Fewest flatworms are found in July and most in November. Seasonal variation is probably related to soil moisture content. Relatively low rainfall in the winter of 1995-6 apparently led to low numbers of flatworms the following winter. Average size of flatworms is smallest in July and largest in March. Apparent hatchlings are most abundant August to October. 80\% of the specimens were mature. Immature flatworms form the majority only between July and October. Specimens as small as 9.5 mm long are mature. Only four egg capsules have been seen over eight years. Flatworms have been observed undergoing fission and it is suspected that fission may be the main method of reproduction in this population. Body weight varies with the square of body length (exponent = 2.093).