Ballistura filifera appears to be native to Central and South America and has clearly been introduced. The only confirmed records are from mushroom and cucumber beds. It was also found by Greenslade and Fletcher (1986) in earthworm-rearing beds at Rothamsted but is now probably extinct there. Ballistura filifera is greyish blue, up to 0.9 mm in length and has a distinctive set of characters shown in Figs. 1 to 5 below including 6+6 ocelli, a very long mucro, and a clear empodial filament. The three specimens in the NHML slide collection were mis-identified as Proisotoma minuta, Ballistura borealis and Pachyotoma ultonica. Ballistura filifera is bound to be present in many more localities where levels of organic matter are high and it is protected from frost.
Fig. 1 (above): Ballistura filifera collected from 'mushroom beds' somewhere in England in November 1932 (locality and name of collector not given on slide). The PAO is almost circular and the eyes each have 6 ocelli (*).
Fig.2 (above): Ballistura filifera collected from a cucumber glasshouse in Terrington St. Clement in February 1971 (collector not stated). The ventral side of the dens is in focus showing the row of three setae (*). There are no ventral setae on the manubrium (man).
Fig.3 (above): The same field of view as shown in Fig. 2 but with the dorsal side of the dens in focus showing the numerous dorsal setae.
Fig.4 (above): Distinctive mucro of Ballistura filifera collected from Felpham, Bognor in October 1937 (collector not known).
Fig.5 (above): Foot of leg 3 of Ballistura filifera collected from 'mushroom beds' somewhere in England in November 1932 (collector not stated).
