PROC. BIOL. SOC. WASH. 94(1), 1981, pp. 181-227 ADDITIONAL ACANTHONOTOZOMATID, PARAMPHITHOID, AND STEGOCEPHALID AMPHIPODA FROM THE SOUTHERN OCEAN Les Watling and Heather Holman Abstract. — Odius antarcticus n. sp. is described and 2 new subspecies of Gnathiphimedia sexdentata are named. In addition 14 acanthonotozomatid, 5 paramphithoid, and 4 stegocephalid species are recorded, with most re-described. Iphimediella discoveryi Watling and Holman is herein considered synonymous with Gnathiphimedia macrops. A combined key to Gnathi-phimedia and Iphimediella is given. In the genus Epimeria, E. excisipes is placed into synonymy with E. georgiana and Suhepimeria geodesiae with E. puncticulata. The boreal North Pacific Uschakoviella echinophora is recorded from Antarctic waters for the first time. This paper is the second in a series directed toward the redescription of poorly known or incorrectly described species as well as the description of new species. In the first paper (Watling and Holman, 1980) we described 6 new species and one new genus of Acanthonotozomatidae, 2 new species of Paramphithoidae and one new species of Stegocephalidae, chiefly from the Scotia Sea region. New revisions were also offered for the acanthono-tozomatid genera Acanthonotozomella, Iphimedia, Iphimediella and Pseu-diphimediella, and the paramphithoid genera Epimeria and Parepimeria. The present paper contains one new species (Odius antarcticus), two new subspecies of Gnathiphimedia sexdentata, and redescriptions of 10 acan-thonotozomatids, 5 paramphithoids, and 2 stegocephalids. Several other species are also recorded. Acanthonotozomatidae Acanthonotozomoides Schellenberg Acanthonotozomoides Schellenberg, 1931:124. Type-species. — A. sublit oralis Schellenberg, 1931 (original designation). Diagnosis. — Mandible with narrow, slightly toothed apex; maxilla 1 palp biarticulate, inner plate minute; maxilliped palp exceeding outer plate, 4-ar-ticulate, article 2 slightly produced medially; gnathopods simple; coxa 1 distally acute.