Dubinectes acutitelson

Dubinectes acutitelson (Menzies, 1962)

(Figs 5 and 6)

Eurycope acutitelson Menzies, 1962: 143, Figure 36 A – E.

Material examined

Holotype (AMNH 12096), male (3.4 mm), allotype (AMNH 12097), female (3.2 mm), paratypes (AMNH 12098): 7 specimens (2.1 – 3.0 mm): Biotrawl No 52, Vema –14 – 28, 28 March 1958, south­western flank of the Schmidt­Ott Rise southwest of Cape Town, 41°03.5’S, 07°49’E, 4960 m.

Additional material from ANDEEP III.—Male natasome (2.5 mm) (ZMH 41146), Stn. 16 – 10, 26 January 2005, 41°07.55’S, 09°55.94’W, 4720 m; 2 juveniles (2.4 and 1.9 mm), (ZMH 41147), Stn. 59­5, 14 February 2005, 67°30.75’S, 00°00.23’W, 4651 m; 1 damaged specimen (~ 4 mm) (ZMH 41148), Stn. 88 – 8, 27 February 2005, 68°03.84’S, 20°31.39’W, 4928 m.

Diagnosis

Body with strong cuticule; rostrum thick, by volume dorsally, as long as four basal articles of antenna 2, with distal notch; head lateral ledge smooth; natasome approximately as long as anterior part of body; anterolateral margins of pereonites 6 and 7 and pleotelson greatly extended anterodorsally; posteroventral process of pleotelson thick, triangular, about half as long as pleotelson, uropod protopod angled at 90º, medial angle extended.

Redescription of holotype

Body length (Fig. 5a – c) 2.7 times width, height 0.8 times the width. Head length 0.7 times width; anterolateral ledge smooth; rostrum from tip to level of antennal sockets 1.5 times as long as remainder of head, with distal hollow; clypeus twice as broad and 0.4 times length of labrum.

Pereonite 1 as wide and long as head posterior to antennal sockets, pereonite 4 0.4 times length of pereonite 1. Natasome nearly as long as anterior body part. Pereonite 7 length 0.7 times length of pereonite 5; anterolateral margins of pereonites 6 and 7 and pleotelson greatly extended anterodorsally. Pleotelson length 0.7 times width, slightly longer than medial portion of head; posteroventral projection triangular, robust, 0.6 times length of pleotelson, preanal ridge with two projections near uropod insertions.

Antenna 1 (Fig. 5a, b) article 1 length 1.1 times width, distolateral projection reaching two third of article 2 with 2 or 3 broom setae dorsally and 3 simple setae distomedially; article 2 0.6 times length of article 1, with 2 or 3 broom distal setae; articles 3 as long as article 1, flagellum of 16 articles, article 4 (first flagellar article) length 0.1 times length of article 3, following articles subequal in length to article 4, some with aesthetasc.

Pereopod 2 (Fig. 6): length ratios of ischium­propodus to basis: 0.55, 0.3, 1.1, 0.8; basis and ischium with sparse, small, simple setae, merus with 2 distodorsal simple setae and 1 small, simple ventral seta; carpus with 14 stout flagellate ventral and 5 small, simple dorsal setae; propodus with 6 stout, flagellate ventral setae and tuft of long, whip distal setae; dactylus broken off.

Pereopod 7 (Fig. 6) about 0.5 times length of pereopod 2, length ratios of ischiumdactylus to basis: 1.0, 0.6, 1.2, 1.1, 0.7; ischium and merus each with 4 ventral plumose setae, carpus length 0.9 times width; propodus length 1.9 times width and 0.4 times width of carpus, both articles with distodorsal stout seta, dactylus longer than propodus width.

Pleopod 1 (Fig. 6) length 2.1 times basal width; distolateral lobes length 0.1 pleopod length, each with 4 simple distal setae; distomedial lobes half as wide and 0.3 times length of distolateral lobes.

Pleopod 2 (Fig. 6) protopod length 1.6 times width, with 4 lateral submarginal, plumose setae; stylet of endopod 1.6 times length of protopod; exopod medial hook as long as projected distal part.

Uropod (Fig. 6) length 0.5 times length of pleotelson; protopod angled at 90º, distal part of equal length to proximal, medial angle projected, with 6 long, whip setae; endopod length 0.5 times width and 0.8 times length of protopod, with 1 broom and 6 whip distal setae; exopod length 0.42 times length and 0.5 times width of endopod, with 1 broom and 3 simple distal setae.

Female, paratypes. Similar to male (Fig. 5d–h), but body slightly stouter than in male, length 2.5 times width; antenna 1 shorter and from articles 2 more slender, pleopod 2 approximately as long as wide.

Remarks

This species is similar to D. acutirostrum sp. nov., see comparison under the description of D. acutirostrum. Both species differ from D. nodosus and D. intermedius sp. nov. in having strong, calcified body with long, thick anterior and posterior projections; stout, long rostrum and strong, long posteroventral process of pleotelson.

Distribution

South­eastern Atlantic, Cape Basin, depth 4720–4960 m; western sector of the Southern Ocean: Weddell Sea, depth 4651 – 4928 m.