Oedicerina ingolfi Stephensen, 1931

Coleman, Charles Oliver & Thurston, Michael H., 2014, A redescription of the type species of Oedicerina Stephensen, 1931 (Crustacea, Amphipoda, Oedicerotidae) and the description of two new species, Zoosystematics and Evolution 90 (2), pp. 225-247 : 227

Taxon classification Animalia Amphipoda Oedicerotidae

Oedicerina ingolfi Stephensen, 1931 Figs 1, 2, 3, 4, 5

Oedicerina ingolfi Stephensen, 1931, p. 250, fig. 72.

Oedicerotidae gen. et sp. n. Dahl 1979, p. 60 (ecology).

Material examined.

3 ovig. females, 6 females, 3 males, 2 unknown sex, 4 juveniles, ZMBN 95143, St. 81.08.14.5, 64°16.9'N, 00°11.7'W, 2630 m, F/F Håkon Mosby, RP-sledge, T. Brattegard, 14 August 1981.

1 female, 1 male, 1 juvenile, ZMBN 95144, St. 81.08.14.1, 65°19.7'N 01°02.7'E, 2908 m, F/F Håkon Mosby, RP-sledge, T. Brattegard, 14 August 1981.

1 ovig. female, 4 females, 7 males, 3 unknown sex, 12 juveniles, ZMBN 95145, St. 82.11.24.1 64°48.2'N 01°33.0'W, 3000 m, F/F Håkon Mosby, RP-sledge, T. Brattegard, 24 November 1982.

1 male, 1 juvenile, ZMBN 95146, St. 81.06.03.5, 67°47.0'N 07°43.9'E, 2025 m, F/F Håkon Mosby, RP-sledge, T. Brattegard, 3 June 1981.

1 female, ZMBN 95147, St. 86.07.26.1, 69°36.4'N 09°54.6'W; 2212 m, F/F Håkon Mosby, RP-sledge, T. Brattegard, 26 July 1986.

2 adult females, 1 female, 2 juveniles, NORBI St. 2, DS05, 65°22.9'N 00°02.1'E - 65°22.4'N 00°02.2'E; 2970 m, N.O. Jean Charcot, 21 July 1975.

1 ovig. female, 1 adult male, NORBI St. 6, DS12, 76°54.4'N 01°44.6'E - 76°54.0'N 01°46.3'E; 3200 m, N.O. Jean Charcot, 2 August 1975.

Description.

Based on ovigerous female, 10.3 mm, St. 81.08.14.5.

Head (Fig. 1a): longer than high, longer than pereonites 1-2 combined; no eyes or ocular pigment visible; rostrum strongly deflexed, ventral margin weakly convex. Antenna 1 (Fig. 1b): about as long as antenna 2; length ratios of peduncle articles 1-3 1:0.9:0.6; flagellum 10-articulate; accessory flagellum 1-articulate, minute, slender, less than half length of first flagellum article. Antenna 2 (Fig. 1c): peduncle setose; length of article 4 1.6 × article 5; flagellum shorter than peduncle article 5, 7-articulate. Upper lip (labrum) (Fig. 1d): wider than long, rounded apically. Mandible: molar triturative, with one associated seta; incisors and laciniae mobiles 5-dentate; palp (Fig. 1i) 3-articulate, article 2 swollen proximally, article 3 tapered, length ratios of articles 1-3 1:4.1:4.5. Lower lip: inner lobes prominent and broad, hypopharyngeal gap wide, outer lobe mandibular processes short and rounded. Maxilla 1 (Fig. 1e, f, g): inner fig oval, with two distal setae; outer fig with nine acute setal-teeth; palp 2-articulate, article 2 3.6 × length of article 1. Maxilla 2 (Fig. 2a): inner fig 1.2 × wider than outer fig; both figs with relatively sparse apical setation. Maxilliped (Fig. 2b): inner fig short, extending just beyond base of palp article 1; outer fig extending 50% along palp article 2, concave medially; palp 4-articulate; article 1 tapered; article 2 broad, strongly expanded medially, lobe subtriangular; article 3 narrow proximally,expanded mediodistally; article 4 acute, weakly falcate: length ratios of articles 1-4 1:1.7:0.7:1.3.

Pereon. Pereonite 1 (Fig. 1a): longer than 2; pereonites 3-5 successively longer; pereonites 6 and 7 subequal in length to 5. Gnathopod 1 (Fig. 2c): coxa subtriangular, posterior margin straight, anterodistal corner rounded, posterodistal corner rectangular, distal margin straight, strongly setose; basis straight, weakly expanded, posterior margin with a row of plumose setae; merus, posterodistal lobe rounded, setose; carpus strongly expanded, subacute posterior lobe with posterior and distal margins setose; propodus strongly expanded, as long and wide as carpus, anterior margin convex, palm transverse, convex, crenellate and setose; dactylus curved, just longer than palm. Gnathopod 2 (Fig. 3a): coxa as long as coxa 1, weakly tapering distally, apex rounded, setose; basis subrectangular, with a row of plumose setae near posterior margin; merus, posterodistal lobe narrow, setose; carpus strongly expanded, wider than propodus, posterodistal lobe subacute, distal margin oblique; propodus shorter than carpus, expanded distally, palm strongly convex, crenellate; dactylus slender, falcate, as long as palm. Pereopod 3 (Fig. 3b): coxa subequal to coxa 2; basis shorter than coxa, with very long slender setae on posterior margin and plumose setae close to anterior margin; merus weakly expanded distally; carpus 1.3 × length and about as wide as merus, posterior margin setose; propodus oval, setose; dactylus 1.2 × length of propodus. Pereopod 4 (Fig. 4a): coxa wider than long, distal margin rounded, posterodistal lobe very strong, subrectangular; basis shorter than coxa; merus weakly expanded; carpus shorter than merus, but subequal in width, setose posteriorly and anterodistally; propodus with anteromarginal rows of slender setae; dactylus rather stout, short and straight. Pereopod 5 (Fig. 4b): coxa about as deep as coxa 4, bilobed, posterior lobe expanded distally, distal margin straight, anterior lobe 0.7 × length of posterior lobe, rounded distally; basis shorter than coxa; merus as long as basis, carpus 0.5 × length of merus; propodus slender, subrectangular, 0.8 × length of merus, about as long as straight lanceolate dactylus; articles 2-6 variously setose. Pereopod 6 (Fig. 5a): coxa almost as deep as coxa 5, bilobed, posterior lobe long, distal margin straight, oblique, anterior lobe short, rounded distally; basis subrectangular; merus posterior margin weakly convex; carpus tapering weakly, 0.5 × length of merus; propodus with several rows of setae along anterior margin, 0.9 × length of merus; dactylus lanceolate; articles 2-6 variously setose. Pereopod 7 (Fig. 5b): long, exceeding apices of uropods; coxa wider than long, posterodistal corner subrectangular; basis, posterior margin weakly sinuous, anterior margin strongly convex; merus and carpus with groups of short slender setae on anterior and posterior margins; carpus 1.2 × length of merus; propodus narrow, subrectangular, 0.6 × length of merus; [dactylus unknown].

Pleon. Pleonites 1-2 (Fig. 1a) with mid-dorsal, relatively long posteriorly directed carinate teeth; pleonite 3 with short, slender, upright tooth. Epimera: 1 and 3 evenly rounded; epimeron 2 subrectangular. Pleopod 1 (Fig. 5c): peduncle stout, 0.8 × length of rami.

Urosome. Urosomite 1 (Fig. 1a) longest, with an inconspicuous boss close to the posterior margin; urosomite 3 longer than 2, with short, acute mid-dorsal projection. Uropod 1 (Fig. 5e): peduncle about as long as outer ramus, margins with short setae; inner ramus 1.3 × length of outer ramus, with small setae on both margins; outer ramus with setae on lateral margin only. Uropod 2 (Fig. 5f): peduncle slightly tapering, with short setae on both margins; inner ramus 1.7 × length of outer ramus, with short setae on both margins; outer ramus with setae on lateral margin only. Uropod 3 (Fig. 5g) peduncle short, about as long as telson, with ventral subacute projection; rami subequal, plumose setae on lateral margins. Telson (Fig. 1h) tapered, notched 30%.

Sexual dimorphism.

Male antenna 1 with shorter peduncle articles in the ratio 1:0.7:0.3 and more numerous flagellum articles compared to female. Article 1 of the flagellum is elongate, about as long as peduncle article 3. Subsequent proximal articles are shorter than wide. The 1-articulate slender accessory flagellum is about 1/3 as long as article 1 of the primary flagellum.

Distribution.

Between the Faroes and Jan Mayen ( Stephensen 1931); Norwegian Sea, Greenland Sea (this study), 1802-3200 m.

Remarks.

Stephensen’s (1931) specimen was damaged and incomplete. Only the head and pereonites 1-4, pereopods 3-4 and coxae and bases of pereonites 1-2 on one side were available for study. The material from the Bergen Museum used for this description consists of numerous specimens of all sizes, both female and male, and was collected relatively close to the type locality of Oedicerina ingolfi , but nevertheless we cannot be absolutely sure that our material represents Stephensen‘s species (see discussion below).