Schebeck (2001:54) lists Gulunggurr (N105) as a sub-group of Ritharrngu N104.
Scarlett et al (1982:159) mentions Gulungurr Ritharrngu. There is also evidence of a homeland called Gulungurr (Dhoyndji) and a surname Gulungurr.
Oates and Oates (1970:218) list Gulunggor as a Wulamba (a name given to the cultural area of N.E. Arnhem Land, called Murngin by Warner) dialect listed in Capell (1963) and recorded by Schebeck, but in her later work, Oates (1975:385) deletes Gulunggor.
For Yolngu languages see also Yolngu Matha N230.
Speaker numbers were measured differently across the censuses and various other sources listed in AUSTLANG. You are encouraged to refer to the sources.
Speaker numbers for ‘NILS 2004’ and ‘2005 estimate’ come from 'Table F.3: Numbers of speakers of Australian Indigenous languages (various surveys)' in 'Appendix F NILS endangerment and absolute number results' in McConvell, Marmion and McNicol 2005, pages 198-230 (PDF, 2.5MB).