Normanion chevreuxi Diviacco& Vader, 1988

Kilgallen, Niamh M., Myers, Alan A. & Grath, David M, 2006, A revision of the North Atlantic amphipod genus Normanion (Crustacea: Amphipoda: Lysianassoidea), Zootaxa 1363, pp. 1-21 : 5-11

Normanion chevreuxi Diviacco& Vader, 1988

Figures 4–6

Normanion chevreuxi Diviacco and Vader, 1988: 118 , figs 1–2. — Diviacco and Ruffo, 1989: 514, fig. 350.

Normanion quadrimanus . — Chevreux, 1920: 75, fig. 1. — Chevreux and Fage, 1925: 35, figs 14–15. – Ledoyer, 1968, 180. — Bellan-Santini and Ledoyer, 1973: 920. — Ledoyer, 1977: 379, fig. 19A. – Barnard and Karaman, 1991: 505.

Non Opis quadrimana Bate and Westwood, 1868: 503 .

Type material. HOLOTYPE: Ovigerous female, 3 mm, MSNV No. 774–777.

Type locality. Marseille.

Material examined. Holotype, 1 specimen on a slide, 3 mm, from Marseille, 90 m, dendritic bottom, MSNV 774–777; 1 specimen in alcohol, 2.5 mm, from Marseille, 80 m, MSNV FVP 25; 2 specimens in alcohol, both 3 mm, from Marseille, 90 m, dendritic bottom, MSNV FVP 33.

Description. Lateral cephalic lobes subacute. Eyes present. Antenna 1 subequal to antenna 2, flagellum 6-articulate, article 1 slightly longer than article 2; callynophore present; accessory flagellum 4-articulate. Antenna 2 flagellum 4-articulate; calceoli absent. Mandible palp attached proximal to molar, molar setose. Maxilliped palp 3- articulate, palp reaching to tip of inner plate.

Gnathopod 1 subchelate; coxa 1 slightly shorter than coxa 2, rounded distally; ischium elongate, more than twice as long as broad; carpus more or less subequal in length to propodus; propodus slightly longer than broad, palm transverse, denticulate, and posterodistally delimited by 2 robust setae; inner margin of dactylus may be smooth or have small, blunt serrations. Gnathopod 2 minutely chelate; carpus twice as long as propodus. Pereopods 3–4 dactylus small. Coxa 5 produced into a posterior lobe; pereopod 5 basis twice as long as broad, produced beyond ischium; dactylus extremely long and slender. Coxa 6 produced into a posterior lobe; pereopod 6 basis twice as long as broad, not produced beyond ischium. Pereopod 7 basis subrectangular, slightly longer than broad, and not produced beyond ischium.

Epimeron 1 anterodistal corner acute; epimeron 3 posterodistal corner rounded. Urosomite 1 with dorsal depression. Uropod 1 rami subequal; uropod 2 rami distinctly unequal, with inner ramus longer than outer ramus; uropod 3 rami subequal. Telson emarginate.

Distribution. Mediterranean and Atlantic coast of France (Brittany). 35– 130 m.

Remarks. N. chevreuxi differs from other Normanion species in the denticulate form of the gnathopod 1 palm. Due to the misleading description and drawings of Bate and Westwood (1868), this species had previously been confused by some authors [ Chevreux (1920); Ledoyer (1977)] with N. quadrimanus . However, in light of the re-description of N. quadrimanus as having a striated palm, the coarsely denticulated gnathopod 1 palm of N. chevreuxi makes it a highly distinctive species.

The examined material exhibited variation in the form of the inner margin of the dactylus. While the dactylus of some specimens is perfectly smooth, others show tiny, blunt serrations. However, these serrations are far less conspicuous than those of some specimens of either N. quadrimanus or N. ruffoi .

Figures

FIGURE 4. Normanion chevreuxi Diviacco & Vader, 1988, female, 3 mm (holotype): (A) pereopod 4; (B) pereopod 7; (C) pereopod 5; (D) pereopod 6; (E) gnathopod 1 dactylus; (F) gnathopod 2; (G) gnathopod 1. Scale bars: 1 = 0.1 mm (E); 2 = 0.2 mm (A – D); 3 = 0.1 mm (F – G).

FIGURE 5. Normanion chevreuxi Diviacco & Vader, 1988, female, 3 mm (holotype): (A) epimera 1 – 2; (B) maxilliped; (C) uropod 3; (D) uropod 2; (E) uropod 1; (F) right mandible. Scale bar = 0.2 mm (A); 0.1 mm (B – F).

FIGURE 6. Normanion chevreuxi Diviacco & Vader, 1988, female, 2.5 mm (MSNV FVP 25): (A) habitus; (B) head and antennae. Scale bar: 0.4 mm (A); 0.2 mm (B).