Acidostoma namibiensis, Stoddart & Lowry, 2012

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 : 15-17

Acidostoma namibiensis sp. nov.

( Figs 11–14 )

Acidostoma obesum . ―K.H. Barnard, 1925: 322. ―Griffiths, 1975: 143. ― Griffiths, 1976: 56, fig. 31I.

Type material. HOLOTYPE, female, 5 mm, SAM A6050 , Duminy Point , off Saldanha Bay, South Africa, eastern South Atlantic Ocean, [approx. 33°S 18°E], 160 m, S.S. Pieter Faure, 17 March 1902 . PARATYPES: 1 female, 4.5

mm, SAM A42050 , same data as Holotype (material recorded by K.H. Barnard, 1925 as A. obesum ). — 2 males, 4.5 mm, AM P.46667, off Cape Cross , Namibia, eastern South Atlantic Ocean, 21°08'S 12°33'E, 450–460 m, 8 September 1980, E. Macpherson, BENGUELA II, stn P-63 .

Diagnostic description. Mandible molar absent. Maxilla 1 palp absent. 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, subacute. Uropod 1 peduncle dorsolateral margin without robust setae. Uropod 2 peduncle dorsolateral margin not castellate, without setae. Uropod 3 reaching to about the end of uropod 2; rami shorter than peduncle, without plumose setae; outer ramus article 2 small. Telson about as long as broad, moderately cleft (about 50%).

Etymology. Named for Namibia, the geographic area of origin.

Remarks. Acidostoma namibiensis is very similar to A. obesum . It differs from that species in lacking a vestigial palp on maxilla 1 and having a better developed article 2 on the outer ramus of uropod 3.

Both species have nine setal-teeth on the outer plate of maxilla 1 and the arrangement is similar, but in A. namibiensis STC and STD are distinctly on the inner row whereas in A. obesum they have migrated into a more proximal position on the plate which obscures their origin as inner-row setal-teeth.

Distribution. West coast of southern Africa, eastern South Atlantic Ocean; 160–460 m depth.

Figures

FIGURE 11. Acidostoma namibiensis sp. nov., paratype female, 4.5 mm, SAM A42050, off Saldanha Bay, South Africa.

FIGURE 12. Acidostoma namibiensis sp. nov., paratype male, 4.5 mm, AM P.46667, off Cape Cross, Namibia.

FIGURE 13. Acidostoma namibiensis sp. nov., holotype female, 5 mm, SAM A6050, off Saldanha Bay, South Africa; paratype male, 4.5 mm, AM P.46667, off Cape Cross, Namibia. Scales represent 0.1 mm.

FIGURE 14. Acidostoma namibiensis sp. nov., holotype female, 5 mm, SAM A6050, off Saldanha Bay, South Africa; paratype male, 4.5 mm, AM P.46667, off Cape Cross, Namibia. Scales represent 0.2 mm.