Ituglanis australis can be diagnosed from all its congeners, with the exception ofI. parahybae andItuglaniscahyensis, by its color pattern consisting of three well-defined dark brown stripes running along each body flank (vs. dark pigmentation either absent, uniform or forming regular or irregular spots). It can be distinguished from I. parahybae and I. cahyensis in having i,4 pelvic-fin rays (vs. i,3 when pelvic fin is present), modally i,5 pectoral-finrays (vs. i,4) and pores i1 and i3 of the infraorbital branch of the cephalic laterosensory system usually present (vs. pores i1 and i3 always absent). It further differs from I. parahybae by having pores s3 and s6 of the supraorbital branch of the cephalic laterosensory system (vs. pores s3 and s6 absent) and from I. cahyensis by having 8 basal radials of the dorsal fin (vs. 7) (Ref. 95054).