Acidostoma ortum J.L. Barnard, 1967

Stoddart, H. E. & Lowry, J. K., 2012, Revision of the lysianassoid genera Acidostoma and Shackletonia (Crustacea: Amphipoda: Acidostomatidae fam. nov.), Zootaxa 3307 (1), pp. 1-34 : 25

Acidostoma ortum J.L. Barnard, 1967

Acidostoma obesum ortum J.L. Barnard, 1967: 44 , figs 16–18. ― Barnard & Karaman, 1991: 457. ― García-Madrigal, 2007: 92.

Diagnostic description. Mandible molar a small non-setose triangular flap. Maxilla 1 palp vestigial, 1- articulate, without apical setae. Maxilliped inner plate well developed; outer plate with subapical notch. Gnathopod 2 dactylus vestigial. Pereopods 5 and 6 merus broader than long. Epimeron 3 posteroventral corner produced, rounded. Uropod 1 peduncle dorsolateral margin with less than 10 robust setae. Uropod 2 peduncle dorsolateral margin not castellate, without setae. Uropod 3 reaching to about the end of uropod 2; rami longer than peduncle, without plumose setae; outer ramus article 2 small. Telson about as long as broad, moderately cleft (about 60%).

Remarks. Acidostoma ortum is a deepwater species with a vestigial palp on maxilla 1, a subapical notch on the outer plate of the maxilliped and a small second article on the outer ramus of uropod 3, similar to A. neglectum . It differs from that species in having a small, non-setose mandibular molar, broad merus on pereopods 5 and 6, and moderately cleft telson.

Distribution. Cedros Trench, off Baja California, Mexico, eastern North Pacific Ocean; 2400 m depth.