Acidostoma neglectum Dahl, 1964

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 : 18-19

Acidostoma neglectum Dahl, 1964

( Figs 15–17 )

Acidostoma neglectum Dahl, 1964: 50 (key), 53, figs 12–18. ― Ansell, 1969: 345.

Acidostoma laticorne . ― Della Valle, 1893: 782, pl. 6 fig. 12, pl. 28 figs 1–21. ― Chevreux & Fage, 1925: 30, figs 7, 8.

Acidostoma obesum . ― Lincoln, 1979: 56 (key), 58, figs 19e–g, 20a–f. ― Moore, 1984: 32 (at least in part). ― Vader, 1984: 144. ― Diviacco & Ruffo, 1989: 471, fig. 318. ― Palerud & Vader, 1991: 32.

? Acidostoma obesum . Meinert, 1890: 157 (in part). ― Poxton et al., 1983: 323, table 2. ― Keegan et al., 1987: 13. ― Costello et al., 1990: 32. ― Dauvin & Gentil, 1990: 127 (table 2). ― Vallet & Dauvin, 1996: 481. ― O'Reilly et al., 2001: 36 ― Dauvin & Bellan-Santini, 2002: 315.

? Acidostoma laticorne . ― Stephensen, 1923b: 10. ― Stephensen, 1929: 52, fig. 14/15. ― Clark & Milne, 1955: 178 (list). ― Harmelin, 1964: 59. ―Toulmond, 1964: 321. ― Toulmond & Truchot, 1964: 5. ― Bellan-Santini & Ledoyer, 1973: 918. ― Ledoyer, 1977: 372. ― Macquart-Moulin, 1984: 185.

Material examined. One immature female, 4 mm, ZMO F14282b, Christiansand, Norway, [approx. 58°10’N 8°00’E]. – 2 males, ZMO F13363b, western Norway, G.O. Sars collection . – 12 males, BMNH 1911.11.8: 12534-46, Scotland, A.M. Norman collection .

At the time of writing, the type material of this species could not be located. We have used Dahl's original description and the material listed here, which was originally identified as A. obesum , for our assessment of the species.

Diagnostic description. Mandible molar vestigial, a low ridge. 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 about as long as broad. 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 subequal in length to peduncle, without plumose setae; outer ramus article 2 small. Telson broader than long, notched.

Remarks. Dahl (1964) assigned the A. laticorne records of Della Valle (1893) and Chevreux & Fage (1925) to his new species A. neglectum . Neither of these authors show or record any molar on the mandible. However, the molar of A. neglectum we have examined is so reduced it could easily be overlooked. Della Valle's A. laticorne also appears to differ from A. neglectum in the uropod 3 not extending as far along uropod 2 and the telson being about as broad as long rather than slightly broader than long. The difference in these latter two characters is slight and could be an artefact of the illustrations.

Distribution. North Sea, eastern North Atlantic Ocean, Mediterranean Sea; 1–200 m depth.

Figures

FIGURE 15. Acidostoma neglectum Dahl, female, 4 mm, ZMO F14282b, Christiansand, Norway.

FIGURE 16. Acidostoma neglectum Dahl, female, 4 mm, ZMO F14282b, Christiansand, Norway. Scales represent 0.1 mm.

FIGURE 17. Acidostoma neglectum Dahl, female, 4 mm, ZMO F14282b, Christiansand, Norway. Scales for U1–3, T represent 0.1 mm; remainder represent 0.2 mm.