  HI observations of the Virgo Cluster pair NGC 4532/DDO 137, conducted as part
of the Arecibo Legacy Fast ALFA Survey (ALFALFA), reveal an HI feature
extending ~500 kpc to the southwest. The structure has a total mass of up to 7
x 10^8 solar masses, equivalent to 10% of the pair HI mass. Optical R imaging
reveals no counterparts to a level of 26.5 magnitudes per square arcsec. The
structure is likely the result of galaxy harassment.
