Projected spatial distribution of UCDs within the inner  ≃ 100 kpc of the Hydra, Centaurus and Fornax clusters (Misgeld et al. 2009, 2011; Mieske et al. 2004). UCDs are in this context defined as compact stellar systems with M_V <  −11 mag. Left panel: UCDs color coded according to host cluster. Red triangles are Hydra UCDs, blue squares are Centaurus UCDs, and green circles are Fornax UCDs. Right panel: the same sample of UCDs is shown as black dots, with the brightest UCDs (M_V <  −12 mag) marked by large open circles. There are 54 UCDs known within the central 50 kpc of Hydra, Centaurus, and Fornax. Large filled circles indicate the projected positions of canonical dwarf galaxies (see text for references), restricted to a magnitude range  −20.5 < M_V <  −16 mag, which corresponds to the assumed luminosity range for possible UCD progenitor galaxies (see text for details). To allow a direct comparison of the number counts between UCDs and progenitors, we show only 62% of the dwarf galaxies, given that the UCD searches are on average complete to  ~62% in the central 50 kpc radius (see text for details).