Dubinectes nodosus ( Menzies, 1962 )

Malyutina, Marina & Brandt, Angelika, 2006, A revaluation of the Eurycopinae (Crustacea, Isopoda, Munnopsidae) with a description of Dubinectes gen. nov. from the southern Atlantic deep sea, Zootaxa 1272 (1), pp. 1-44 : 27-37

Dubinectes nodosus ( Menzies, 1962)

( Figs 12–18 )

Eurycope nodosa Menzies, 1962: 145 , Figure 36 F–H

Material examined

Holotype ( AMNH 12106 ), female (4.6 mm), Biotrawl No. 53, Vema –14 – 31, 4 April 1958, Lower Continental Rise southwest of Cape Town, 36°34’S, 14°08’E, 4885 m; paratype ( AMNH 12107 ), badly damaged specimen, the same locality.

Additional material.—ANDEEP II: 3 females (2.8 – 3.2 mm) ( ZMH 41150), Stn. 131­ 3, 05 March 2002, 65°20’S, 51°31.61’W, 3053 m ; 1 juv. (1.8 mm) ( ZMH 41151), Stn. 133­ 3, 07 February 2002, 65°20.17’S, 54°14.30’W, 1121 m ; 5 males, 11 females (2.0 – 4.1 mm) ( ZMH 41152); Stn. 134 – 4, 09 March 2002, 65°19.20’S, 48°03.77’W, 4069 m ; 3 males, 10 females (1.8 – 3.8 mm) ( ZMH 41153), Stn.135–4, 10 March 2002, 65°00.05’S, 43°03’W, 4678 m ; 7 females (2.5 – 3.4 mm) ( ZMH 41154), Stn. 136 – 4, 12 March 2002, 64°01.54’S, 39°06.88’W, 4747 m ; 2 mancas (1.5, 1.7) ( ZMH 41155), Stn. 137 – 4, 14 March 2002, 63°44.98’S, 38°47.75’W, 4976 m ; 1 male, 3 females (2.3 – 3.6 mm), ( ZMH 41156), Stn. 138 – 6, 17 March 2002, 62°58.08’S, 27°54.10’W, 4542 m . ANDEEP III: 2 males, 4 females (2.8 – 4.1 mm) ( ZMH 41157), Stn. 16 – 10, 26 January 2005, 41°07.55’S, 09°55.94’W, 4720 m ; 3 specimens ( ZMH 41158), Stn. 21 – 7, 29 January 2005, 47°39.87’S, 04°15.79’W, 2923 m ; 3 females (2.6 – 3.2 mm) ( ZMH 41159), Stn. 59 – 5, 14 February 2005, 67°30.75’S, 00°00.23’W, 4651 m ; 1 male, 1 female (3.9, 4.0 mm), ( ZMH 41160), Stn. 88 – 8, 27 February 2005, 68°03.84’S, 20°31.39’W, 4928 m .

Diagnosis

Body cuticle relatively thin. Rostrum only slightly longer than article 1 of antenna 1; natasome about 1.5 times anterior body part length, outline of natasome is almost smooth; posterior rim narrow, almost lacking ventral process, 0.15–0.2 times pleotelson length.

Redescription. Body ( Figs 12 and 13 ) length 2.5 times pereonite 5 width (2.3–2.5). Head length 0.7 width (0.6–0.7); anterolateral ledge sloping, rostrum length 0.9 times rest of head (0.7–0.9), concave distally, rostrum in females broader than in males; clypeus twice as broad and 0.5 times length of labrum.

Pereonite 1 slightly wider (1.08) than head, pereonite 4 length 0.4 times pereonite 1 length. Natasome 1.4 times length of anterior body (1.2–1.6); lateral outline almost uninterrupted; pereonite 7 0.9 times length of pereonite 5 (0.75–0.9). Pleotelson slightly longer than head, posterior rim narrow, ventral projection 0.15 times pleotelson length (0.15–0.2), preanal ventral ridge low.

Antenna 1 of male ( Fig. 15 ) article 1 length equals width, distolateral projection reaching two thirds of article 2, setation: 3 dorsal broom setae, lateral row of small, simple setae and 2 distomedial simple setae; article 2 length 0.6 times article 1, with 3 broom distal setae; article 3 subequal to article 1, article 4 0.1 times length of article 3, with 2 distal broom setae, the other 8 flagellar articles (the last broken off) longer than article 4, all articles after 7 each with simple seta. Antenna 1 of female ( Fig. 12 ) 0.2 times body length, articles more slender than in male.

Antenna 2 ( Fig. 12 ) 1.5 times body length. Article 5 2.4 times length of articles 1–4, with 4 stout, medial setae and many small, simple lateral setae, article 6 1.5 times length of article 5, with many sparse, simple setae along article. Flagellum 1.6 times longer than article 6, article 1 elongate, the following, about 30, articles almost half as the length of article 1.

Mandibles ( Fig. 14 ): incisor process with 3 weak cusps; lacinia mobilis of left mandible stout, 0.9 times length of incisor process, with 8 teeth; spine row with 4 and 5 spines respectively; palp article 2 2.5 times longer than article 1, with 1 stout distal seta and small marginal seta, article 3 with row of marginal setulose setae.

Maxilla 1 ( Fig. 14 ) lateral endite 1.4 times width of mesial endite.

Maxilliped ( Fig. 14 ) basis 2.5 times longer than wide, endite with 4 coupling hooks, distal margin with 4 large fan setae and numerous simple, slender setae; palp article 2 lateral margin slightly convex, serrated, 1.3 times longer than straight medial margin, with 8 simple setae; article 3 medial margin slightly convex, 1.2 times longer than medial margin of article 2, with dense row of setulose setae; article 4 laterally 2.3 times length of articles 3, medial lobe half as the length of article 5, with 5 distal setae, article 5 with 6 distal setae. Epipod length 1.5 times width, and 0.9 times basis length, distal angle acute.

Pereopods of mature male ( Fig. 16 ): pereopod 1 0.3 times body length, length ratios of ischium­propodus to basis: 0.5, 0.3, 1.0, 0.75, 0.2; basis with sparse small setae; merus with 4 stout flagellate ventral setae, carpus with 17 stout ventral and 2 simple distodorsal setae; basis­carpus of the same width, propodus 0.5 times carpus width, with small marginal setae. Pereopods 2–4 bases subequal in size, more than half basis 1 width, basis 3 slightly shorter than or equal to 2 and 4. Pereopod 5 0.7 times pereopod 2 length, length ratios of ischium­dactylus to basis: 1.4, 0.6, 1.6, 1.4, 0.7; ischium with 4 broom and 1 plumose dorsal setae and 2 small simple ventral setae; merus with 2 plumose dorsal setae; carpus 1.2 times width; propodus 1.6 times width; dactylus with stout dorsal claw that is half length of slender ventral seta. Pereopod 6 length ratios of ischium­dactylus to basis: 0.9, 0.5, 1.3, 1.0, 0.4; basis with 3 dorsal setae; ischium with 5 long dorsal and 5 shorter ventral setae; merus with 2 ventral setae; carpus 1.1 times width; propodus 2 times width. Pereopod 7 length ratio of ischium­dactylus to basis: 1.1, 0.5, 1.4, 1.2, 0.6; basis with 1 ventral seta; ischium with long 4 dorsal and 5 simple ventral setae; merus with 4 ventral setae; carpus 1.2 times width; propodus 1.7 times width.

Pereopods of immature male ( Fig. 17 ): pereopod 2 length ratios of ischium­dactylus to basis: 05, 0.2, 1.0, 0.7, 0.5; basis with sparse small ventral setae; ischium with 2 ventral setae; merus with 2 ventral and 2 dorsal setae; carpus with 14 ventral stout setae, 5 slender flagellate dorsal and 3 distodorsal simple setae; propodus with 7 long ventral flagellate, some simple dorsal setae and 8 distal whip long setae; dactylus twice length of propodus distal setae. Pereopod 3 shorter than pereopods 2 and 4; length ratios of ischium­dactylus to basis: 0.4, 0.3, 0.9, 0.7, 0.5; basis with small simple ventral setae; ischium with 1 dorsal seta; merus with 3 distal setae; carpus with 7 stout ventral setae and 4 simple small dorsal setae; propodus with 1 stout and 3 slender simple setae ventrally, 5 distal whip setae. Pereopod 4 length ratios of ischium­dactylus to basis: 0.4, 0.2, 0.9, 0.9, 0.4; all articles with only simple sparse setae; carpus and propodus avoiding stout flagellate setae, propodus narrowest and longest among pereopods 1–4, with some small simple setae along article and 4 distal long setae.

Pereopods of female ( Fig. 17 ) similar to those in small males. Pereopod 1 of female length ratios of ischium­dactylus to basis: 0.4, 0.2, 1.0, 0.7, 0.25; basis with many small setae; ischium with 1 ventral seta, merus with 3 ventral and 2 dorsal setae; basis­merus of the same width, carpus 0.6 times as wide as basis, with 5 small ventral and 2 simple dorsal setae; propodus 0.6 times as wide as carpus, with 5 ventral and 9 dorsal small setae.

Pleopods ( Fig. 18 ): pleopod 1 of male 2.4 times width, with small ventral setae on distal third; distal margin: lateral lobes 0.1 times length of total pleopod, each with acute lateral projections and several distal small setae; medial lobes almost as wide and 0.5 times length of lateral lobes, each with two small distal setae. Pleopod 2 of male protopod 1.6 times width, and 1.1 times width of pleopod 1, with 2 lateral submarginal setae, stylet of endopod 2.2 times longer than protopod, distal part of exopod wider in ventral view before tapering medial hook. Pleopod 2 of female ( Fig. 15 ) 0.8 times width. Pleopod 3 endopod 1.3 times width, exopod 1.2 times endopod length, reaching its distal margin, basal article 0.4 times width of endopod, distal article 0.4 times length and 0.3 times width of basal article, with 1 distal simple seta and dense row of long hair­like lateral setae. Pleopod 4 endopod 1.4 times width, exopod 0.4 times width and 0.9 times length of endopod, with dense row of long hair­like lateral setae. Pleopod 5 endopod 1.4 times width.

Uropod ( Fig. 15 ) 0.3 times pleotelson length; protopod proximal part shorter than distal part, medial projection with 7–8 long whip setae, endopod 0.4 times width and almost equal protopod length, with about 10 distal setae (1 or 2 broom and 8 simple); exopod 0.5 (male) and 0.4 (female) times length and width of endopod, with 4 distal setae. Remarks

The body habitus of this species closest to Eurycope , because the natasome outline is almost smooth, the rostrum, especially in females, is not as extremely long and thick as in D. acutitelson and D. acutirostrum . The rostrum is almost the same width and slightly longer than the article 1 of antenna 1. D. nodosus is similar to D. intermedius sp. nov. The main characters which differentiate D. nodosus are: 1. the narrow posterior rim, 0.15–0.2 times the pleotelson length; 2. the ventral process is almost absent. D. nodosus is widely distributed and was collected at almost every station during ANDEEP.

Distribution

South­eastern Atlantic: Cape Basin at a depth 4574–4960 m; western sector of the Southern Ocean: Weddell Sea from the 0 meridian to the Antarctic Peninsula at a depth 1121–4976 m.

Figures

FIGURE 12. Dubinectes nodosus (Menzies, 1962). a, b, female, holotype, AMNH 12106, body dorsal and lateral views, with attached pleotelson ventral view; c, female, Stn. 135–4, dorsal view with attached natasome lateral view; d, immature male, Stn. 138–6, dorsal view; e, f, females, Stn. 136–4, dorsal views with attached pleotelson ventral view, dotted line shows oostegites.

FIGURE 13. Dubinectes nodosus (Menzies, 1962). a–f, male, Stn. 137–4, a b, body dorsal and lateral views; c, pleotelson, ventral view; d, natasome, oblique ventral view; e, head, frontal view; f, head, lateral view; g–j, female from the same station, g, h, body dorsal and lateral view; i, natasome, ventral view with attached oblique ventral view of pleotelson; j, head, lateral view.

FIGURE 14. Dubinectes nodosus (Menzies, 1962). Male, Stn. 137–4, mouthparts.

FIGURE 15. Dubinectes nodosus (Menzies, 1962). Male and female, Stn. 137–4, antenna 1, pleopods 3–5 and uropods.

FIGURE 16. Dubinectes nodosus (Menzies, 1962). Male, Stn. 137–4, pereopods 1, 5–7; pereopods 2–4 bases.

FIGURE 17. Dubinectes nodosus (Menzies, 1962). Male and female, Stn. 137–4, pereopods.

FIGURE 18. Dubinectes nodosus (Menzies, 1962). Male and female, Stn. 135–4, pleopods 1 and 2.