Normanion quadrimanus ( Bate & Westwood, 1868 )

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 : 11-15

Normanion quadrimanus ( Bate & Westwood, 1868)

Figures 7–9

Opis quadrimana Bate and Westwood, 1868: 503 .

Normania quadrimana Boeck, 1871: 120 . — G. O. Sars, 1895: 33, pl. 13, fig. 1. Normanion quadrimanus . — Stebbing, 1906: 42 (in part). — Lincoln, 1979: 44, fig. 13 (in part). —

? Costello et al., 1989: 34. — Barnard and Karaman, 1991: 505. Normanion sarsi Stebbing, 1906: 42 .

Type material. TYPE: NHML 1911. 11. 8. 654.

Type locality. Banffshire, Scotland.

Material examined. Type NHML 1911. 11. 1. 654, 3.2 mm from Banffshire, Scotland; NHML 1911. 11. 8. 1267, 2 specimens on slides, sex unknown, from Cumbrae, Scotland; ZMO F10523, 2 specimens on slides, 3–3.5 mm; ZMO F13172, 15 specimens in alcohol, 2–4 mm, both ZMO collections from Trondhjemsfjord.

Description. Lateral cephalic lobes subquadrate. Eyes present. Antenna 1 subequal to antenna 2, flagellum approximately 5-articulate, article 1 distinctly elongate; callynophore present; accessory flagellum 3-articulate. Antenna 2 flagellum 4-articulate; calceoli absent. Mandible palp attached proximal to molar, molar setose. Maxilliped palp 3- articulate, 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 shorter than propodus; propodus subequal in length and breadth, palm transverse, striated, and posterodistally delimited by 2 robust setae and a central spine; 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 almost twice as long as broad, produced beyond ischium; dactylus extremely long and slender. Coxa 6 produced into a posterior lobe; pereopod 6 basis longer than broad, not produced beyond ischium. Pereopod 7 basis subrectangular, longer than broad, and not produced beyond ischium.

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

Distribution. Northeast Atlantic, from the west coast of Scotland and the Norwegian Sea, 20– 565 m.

Remarks. N. quadrimanus ’ unique combination of characters are the 3-articulate maxilliped palp, the smooth and striated gnathopod 1 palm, and the relative lengths of the uropod 3 rami, which are unequal.

The examined material showed a variety of form of the inner margin if the gnathopod 1 dactylus. While some specimens exhibit a smooth inner margin, others have an uneven surface with small bumps (including the type specimen), while more still have tiny blunt serrations. This appears to be the only variation, as other characters remain stable.

Figures

FIGURE 7. Normanion quadrimanus (Bate & Westwood, 1868), (A) habitus (female, 3.2 mm, holotype); (B) head and antennae (NHML 1911. 11. 8. 1267): (C) right mandible (NHML 1911. 11. 8. 1267); (D) right maxilliped (NHML 1911. 11. 8. 1267); (E) epimeron 3 and urosome (holotype). Scale bars: 1 = 0.4 mm (A); 0.2 mm (B, E): 2 = 0.1 mm (C – D).

FIGURE 8. Normanion quadrimanus (Bate & Westwood, 1868), female, 3.2 mm (holotype): (A) gnathopod 1 dactylus; (B) gnathopod 2; (C) gnathopod 1; (D) uropod 1; (E) uropod 2; (F) uropod 3; (G) telson (non-type—NHML 1911. 11. 8. 1267). Scale bar = 0.1 mm (A); 0.2 mm (B – G).

FIGURE 9. Normanion quadrimanus (Bate & Westwood, 1868), (NHML 1911. 11. 8. 1267): (A) pereopod 6 (B) pereopod 4; (C) pereopod 7; (D) pereopod 5 (holotype). Scale bars: 1 = 0.2 mm (A – C); 2 = 0.2 mm (D).