Notes. The columns are: (1) the group name; (2) whether the X-ray emission is on group scales (G) or galaxy halo scales (H), taken from Osmond & Ponman (2004); (3) the richness of the sample: L = low richness, H = high richness, from O’Sullivan et al. (2017); (4) the distance to the group in Mpc, (5) projected virial radius in Mpc and (6) dynamical mass from Kourkchi & Tully (2017); (7) the fraction of the area within R covered by the MATLAS footprint; (8) the number of UDGs identified within R_vir – for two groups, we increased the search radius by 0.15 Mpc in order to catch the UDGs just outside the cluster bounds, which are included in brackets; (9) the number of predicted UDGs using the dynamical mass in Col. 6 and the relation described in van der Burg et al. (2017) – we note that this N_UDG, pred value is nearly identical to the value returned by the relation in Janssens et al. (2019); (10) the number of MATLAS dwarfs (including UDGs) within R_vir – the numbers in brackets include the additional dwarfs found in a search radius increased by 0.15 Mpc; (11) the fraction of early-type galaxies in the group. For consistency, this fraction was calculated using the group membership and morphologies from Kourkchi & Tully (2017). The groups are ordered by increasing mass.