Tobias (1980a, 1980b) argues that the Laetoli and Hadar samples are not distinct at the species level from Australopithecus africanus and that they should be designated as two separate subspecies, for which he proposed Australopithecus africanus tanzanensis for the Laetoli sample (Tobias, 1980a) and Australopithecus africanus aethiopicus for the Hadar sample (Tobias, 1980b).
Tobias (1980b) establshed the name Australopithecus africanus aethiopicus with no holotype fixed, though in Figure 3 (p. 6) he does explictily indicate specimen A.L. 200-1a as belonging to the newly named taxon. Generally, he regarded all the Hadar material as belonging to this taxon. Tobias (1980a; 1980b) also indicated that the name Au. africanus tanzaniensis is better than Au. afarensis because the former does not match the Ethiopian place name "afar" with a type from Tanzania.
In the years following the taxonomic proposals laid out in Tobias (1980b) there has been controversy regarding the availability of the name Au. africanus aethiopicus. The resolution of this controversy affects the validity of other taxonomic names proposed afterwards including Homo antiquus Ferguson, 1987 and Australopithecus aethiopicus (Arambourg and Coppens, 1968; Walker, 1986; Cela-Conde and Altaba 2002).
The abstract of Tobias (1980b) stated, "Since 'A. afarensis' is tied to a Laetoli specimen as holotype, only the Laetoli specimens should be designated A. africanus afarensis (though A. africanus tanzaniensis suggested by the author in 1978 would have been a more appropriate nomen) and the Hadar fossils A. africanus aethiopicus."
Tobias (1980b p. 14) states, "If further close morphological and statistcal analysts confirms the presence of these small marks of distinction, it may be necessary to recognize and name a separate subspecies within the evolving and polytypic lineage of A. africanus. As the name afarensis would be preoccupied by the Laetoli fossils: then it would be most appropnate to suggest an alternative regional or territorial soubriquet: I propose Australopithecus africanus aethiopicus as a suitable name for this Ethiopian taxon."
Olson (1985) argued that Australopithecus africanus aethiopicus is available, and Olson applied the name as Homo (Australopithecus) aethiopicus. The "If" at the begining of the quote from Tobias (1980b) does suggest a conditional proposal of the name. However Olson (1985) argued that the final clause of the statement and the wording in the abstract both indicate a definitive and non-conditional proposal. Furthermore, Olson (1985) noted that Tobias (1980b) did not fix a holotype. and Olson fixes A.L. 288-1 Lucy as the lectotype.
Ferguson (1987) presented a case for two Pliocene hominid species at Hadar, Homo antiquus Ferguson, 1984 and Au. africanus miodentatus Ferguson, 1987. In naming the latter Ferguson accepted Tobias's argument that at least a portion of the Hadar material is indistinguishable at the species level from Au. africanus. Ferguson (1987) however argued that Tobias's subspecies designation of Au. africanus aethiopicus for the Hadar material is proposed conditionally and therefore unavailable.
Groves (1989) concluded that Au. africanus aethiopicus Tobias, 1980 is conditionally proposed and unavailable. Later however, Groves (1999) reversed himself, and provides an argument favoring the availability of Au. africanus aethiopicus Tobias, 1980. Groves (1999) discussed potential homonymy with Paraustralopithecus aethiopicus Arambourg, 1968 when that taxon is transfered to the genus Australopithecus and then conflicts with Australopithecus africanus aethiopicus Tobias, 1980.
Harrison (2011, Table 7.1 p. 142) listed Au. africanus aethiopicus as "nomen nudum, conditionally proposed," but did not discuss the prior determinations by Olson (1985) nor Groves (1999). Harrision (2011) also noted that Homo aethiopicus is pre-occupied by Bory de Saint-Vincent (1825 p. 314).
Much hinges on the avaiability of Au. africanus aethiopicus Tobias, 1980. If the name is available, then it precludes the combination Australopithecus aethiopicus (but does not preclude the combination Paranthropus aethiopicus) for robust australopiths such as KNM WT 17000. If available it would also precede Homo antiquus Ferguson, 1984 relegating the latter to an objective junior synonym since both use A.L. 288-1 as a type. The latter (H. antiquus) is further invalid because it is a secondary junior homonym of Homo antiquus Adloff, 1908.
We agree with the determination of Harrison (2011) and Groves (1989) that the name "Australopithecus africanus aethiopicus" is conditionally proposed and unavailable.