Amphilochus manudens Spence Bate, 1862

Tandberg, Anne Helene S. & Vader, Wim, 2018, On a new species of Amphilochus from deep and cold Atlantic waters, with a note on the genus Amphilochopsis (Amphipoda, Gammaridea, Amphilochidae), ZooKeys 731, pp. 103-134 : 109-111

Amphilochus manudens Spence Bate, 1862

Amphilochus manudens Spence Bate, 1862:107, pl 17 fig 6; Sars 1890-95: 217, pl 74; Chevreux and Fage 1925: 114, fig 109; Lincoln 1979: 150, fig 65 e-f, fig 66 a-d; Krapp-Schickel 1982: 75, fig 51.

Remarks.

Although Amphilochus manudens is one of the best described species within the Amphilochidae ( Sars 1890-95; Lincoln 1979; KrappSchickel 1982), we have included a redescription of material from Iceland, to facilitate direct comparison with the new species.

Material examined.

all drawings are made from specimens found during the BioIce program. For the complete set of drawings (Figs 5-8) we have used specimens IINH37889 (BioIce 2207), IINH37887 (BioIce 2215) and IINH37885 (BioIce 2237). Type material not examined. Additional material of Amphilochidae from a Statoil funded baseline survey of some Faroe waters has been examined, and only Amphilochus anoculus and Amphilochus tenuimanus were found. We have also examined all Amphilochidae from the BioFar program, and only Amphilochus manudens was found (no Amphilochus anoculus sp. n.). During a cruise in the Polar basin in 2005 both Amphilochus manudens and Amphilochus anoculus sp. n. were found, but at different stations (see discussion below). Material from several Norwegian surveys (summarised in the project NorAmph) and the IceAGE project included several Amphilochus manudens . For information about the specific sample-stations, see Table 1.

Description.

Head. Rostrum curved, smaller than peduncle article 1 of antenna 1. Eyes round, no ommatidial framing, small, deep brown-red in colour. Cephalic lobe produced, distally acute. Antenna 1 subequal to antenna 2; peduncle article 1 is longer than article 2, which is longer than article 3; peduncle is longer than six-articulate flagellum; accessory flagellum absent. Antenna 2 peduncle longer than eight-articulate flagellum; peduncle articles have few short setae.

Labrum asymmetrically bilobed. Mandible molar small but triturative, cone-shaped, with a row of short setae around the ridged chewing area; incisor serrate; nine accessory spines; palp slender, 3-articulate; article 1 is shorter than article 2, which is longer than article 3; article 3 with two long setae distally and distal third of margin serrate; lacinia mobilis laterally expanded. Labium symmetric; inner lobes reduced. Maxilla 1 palp 2-articulate, with eight setae; inner plate reduced, with 1 seta; outer plate with six strong setae and two rows with four and three smaller setae. Maxilla 2 inner plate shorter than outer plate, six long setae distally and a row of five short, three long and five short setae; outer plate is long and thin with three distal setae. Maxilliped inner plate is long and thin, well separated, three short and strong setae distally; outer plate reaches just past merus of palp; palp slim, heavily setulated on carpus and propodus.

Mesosome dorsally smooth; length segment 3 is smaller than segment 4. Coxa 1 reduced and covered by coxa 2, which is longer than broad. Coxa 2 distal margin serrate, with setae. Coxa 3 concave; distal margin serrate, without setae. Coxa 4 distal margin serrate; without setae. Coxa 5-7 concave.

Pereopod 1 basis longer than propodus, upper half distally widened, few and short setae on anterior margin, longer setae on posterior margin; carpal lobe well developed, 50% of posterior margin of propodus; propodus subtriangular, proximal half of oblique palm serrate, distal half with short evenly spaced setae, no seta defining palm, anterodistal tooth strong; dactylus longer than palm, narrow and acute, apparently smooth. Pereopod 2 basis longer than propodus, linear, several short setae; one robust seta distally on ischium; merus with small distal ‘hook’; carpal lobe covers 100% of posterior margin of propodus, lined with setae posteriorly, small crown of setae distally; propodus elongate with a regularly convex serrate palm without seta, anterodistal tooth strong; dactylus longer than palm, narrow, apparently smooth. Pereopod 3 coxa elongate, pereopod 4 coxa posteriorly produced, both with basis to propodus anterior edge lined with short setae, dactylus more than half propodus. Pereopod 5 to 7 basis and merus with posterior lobes; carpus shorter than propodus; dactylus longer than half propodus.

Metasome smooth. Epimeral plate 1 with small, blunt posterodistal tooth, distal margin convex; plate 2 angular, distal margin convex; plate 3 with clear posterodistal tooth, distal margin weakly concave. Urosome smooth; segment 1 as long as segments 2 and 3 together. Uropod 1 peduncle and rami subequal; rami subequal; setae on outer ramus. Uropod 2 peduncle subequal to inner ramus; outer ramus about half-length of inner ramus; setation on both rami. Uropod 3 peduncle longer than rami; outer ramus is shorter than inner ramus; rami longer than telson; rami with setae.

Gills on segments 2 to 6. Oostegites on segments 2 to 5. Telson elongate; distal end entire and acute; no setae.

Distribution.

North East Atlantic and Arctic Ocean (Lincoln, 1979); Barents Sea and Murmansk area ( Gurjanova 1951; Vader and Bryazgin 1998; Vader et al. 2001); Spitsbergen ( Stephensen 1935; Vader et al. 2001); Mediterranean (Marseilles, Capri) ( Krapp-Schickel 1982); amphi-Atlantic ( Watling 1979); Gulf of St Lawrence ( Brunel et al. 1998).