The Holarctic 'carnea' species group of the green lacewing genus Chrysoperla is a swarm of cryptic species, reproductively isolated from one another by substrate-borne vibrational mating songs. Only one species of the group, Chrysoperla zastrowi, is found south of the equator, in South Africa. Here we describe the courtship/mating song of this species, together with that of an undescribed taxon, 'Cc5-generator', from the Arabian peninsula. Although the songs of these two taxa are measurably different, they are also remarkably similar, suggesting either that (1) the two 'species' are simply clinal end-points of a continuous, vast geographic range spanning the equator, or (2) that the two are sister species, with C. zastrowi likely derived from its northern-hemisphere sibling. Song comparisons, plus morphological analyses of both adults and larvae, are used to resolve the problem.