ALFALFA HI Content and Star Formation in Virgo Cluster Early-Type Dwarfs

Early-type dwarfs dominate cluster environments, yet their formation and evolutionary histories remain unclear. The ALFALFA (Arecibo Legacy Fast ALFA) blind survey is providing a census of HI in galaxies of all types in a range of environments. Here we report on ALFALFA results for Virgo Cluster earlytype dwarfs between declinations of 4 and 16 degrees. Less than 2% of the Virgo early-type dwarf population is detected, compared to 70-80% of the Im/BCD dwarf population. Most of the dwarfs detected in HI show evidence for ongoing or recent star formation. Early-type galaxies with HI tend to be located in the outer regions of the cluster and to be brighter. Early-type dwarfs with HI may be undergoing morphological transition due to cluster environmental effects.