Part 12: The taxonomic research of the polychaetes of the antiboreal coast of South Australia continues with material collected in the area between Wallaroo and Port MacDonnell in December 8 to 19, 1975. 88 species were found; 70 of them were already known to science. 65 of the known species were already found by the author farther west and northwest at the coasts between Derby (W. A.) and Port Augusta (S.A.) (Parts 2, 4, 6, 8, 9, 10, 11). 8 species (
Anaitides diversiantennata,
Astreptosyllis similiseta,
Sphaerosyllis rnagnoculata,
Armandia bilobata,
Lanicola lobata,
Augeneriella bansei,
Oriopsis cincta,
O. denticollis), 1 subspecies (
Sphaerosyllis capensis lateropapillata), and 1 genus (
Lanicola, Terebellidae) are new and will be described. 9 species could not be determined to species level because of incompletement. One of the already known species is new to Australia:
Hyboscolex longiseta. 15 of the already known species are recorded from South Australia for the first time: ?
Genetyllis castanea, ?
Protomystides uschakovi,
Micropodarke trilobata,
Sphaerosyllis centroamericana,
Exogone sexoculata,
Australonereis ehlersi,
Nereis (N.) maxillodentata,
Goniada eremita,
Proscoloplos confusus,
Polydora (Pseudopolydora) antennata, ?
Axiothella australis,
Idanthyrsus armatus,
Amphiglena mediterranea,
Branchiomma nigromaculata,
Protula (P.) palliata.