Sphyrapus malleolus Norman & Stebbing 1886

Sphyrapus malleolus Norman & Stebbing, 1886

(Figs 13–16)

Sphyrapus malleolus Norman & Stebbing, 1886: 98 –99, pl. 22.

Type material examined. 1Ƥ, syntype (now lectotype) (BMNH.1911.11.8.7191), “Porcupine” Station 24, 56°26'N 14°28'W, 199 m depth, 1869 (dredging 2 of Norman & Stebbing 1886); 13, 1Ƥ, syntypes (now paralectotypes) (BMNH.1911.11.8.7189-7190), “Porcupine” Station 17a, 39°39'N 09°39'W, 1353 m depth, 1870 (dredging 3 of Norman & Stebbing 1886), Alfred Merle Norman Collection, The Natural History Museum, London.

Material examined. 1Ƥ, (BMNH.2010.464), 1 fragmented 3, Cruise TTR15, Station AT575, Mercator mud volcano, 35°17.903’N 06°38.715’W, 355 m depth, mud breccia, boxcore, 26.07.2005; 1 fragmented 3, (BMNH.2010.465), Cruise TTR14, Station AT541, Meknès mud volcano, 34°59.103’N 07°04.435’W, 703 m depth, mud breccia and H2S, TV-grab, 05.08.2004; 233, (BMNH.2010.466-467), Cruise TTR15, Station AT581, Meknès mud volcano, 34°59.178’N 07°04.353’W, 700 m depth, mud breccia, TV-grab, 28.07.2005; all coll. MRC.

Other GoC material. 2 specimens, Cruise TTR14, Station AT559, Kidd mud volcano, 35°24.777'N 06°43.782'W, 552 m depth, mud, boxcore, 08.08.2004; 1 specimen, Station AT560, Kidd mud volcano, 35°25.306'N 06°43.976'W, 498 m depth, mud breccia, boxcore, 08.08.2004; 1 specimen, Station AT561, Kidd mud volcano, 35°25.602'N 06°44.099'W, 526 m depth, mud, boxcore, 08.08.2004; 2 specimens, Station AT566, Fiúza mud volcano, 35°15.510'N 06°41.702'W, 414 m depth, mud breccia, TV-grab, 09.08.2004; 1 specimen, Cruise TTR15, Station AT577, Mercator, 35°17.305'N 06°39.672'W, 485 m depth, reference, off MV hemipelagic mud, USNEL boxcore, 26.07.2005; 4 specimens, Cruise TTR15, Station AT585, Meknès mud volcano, 34°59.137'N 07°04.343'W, 701 m depth, crater top, mud breccia, Kasten boxcore, 28.07.2005; 5 specimens, Station AT586, Meknès mud volcano, 34°59.146'N 07°04.380'W, 701 m depth, mud breccia, TV-grab, 28.07.2005; 3 specimens, Station AT597, Bonjardim mud volcano, 35°27.563'N 09°00.030'W, 3061 m depth, mud breccia, TV-grab, 02.08.2005; all coll. MRC.

Remarks. This species has hardly been re-described since the original description of Norman and Stebbing (1886), in which there were few detailed figures, and the reference of those authors to male and female were incorrect, their female being a male, and vice versa. The type-locality is the north-east Atlantic south of Rockall (for the lectotype listed above) and to the west of Portugal (for the paralectotypes listed above); other syntypes listed by Norman and Stebbing (loc. cit.) were from Cape Farewell, off Greenland, but this material cannot be found for confirmation of con-specificity. Bonnier (1896) refigured the species in a somewhat stylized fashion, based on material from the Bay of Biscay at 410 and 650 m.

In the light of the unlikelihood of the wide distribution recorded for this species (including in the Mediterranean, Lo Bianco 1903; off North America, Richardson 1905; off South Africa, Barnard 1920; off Equatorial West Africa, Bamber 2000), based almost entirely only on the presence of “wing-like” lateral apophyses on pleonite 2, a full description is necessary to allow detailed comparison of other aspects of the morphology of “winged” Sphyrapus recorded elsewhere, in order to determine whether this species is really widespread, or rather one of a group of sibling deep-sea taxa. In addition to providing such a description from the Gulf of Cadiz material available to us (which is morphologically consistent with the type-material), we have re-examined syntypes held in the collections of the Natural History Museum, London; of these, we herein designate a female (BMNH.1911.11.8.7191) as the lectotype, and the remaining two specimens, a male and a female (BMNH.1911.11.8.7189-7190), as paralectotypes.

Description of female. Body (Fig. 13 A, B), dorsoventrally flattened, holotype 1.6 mm long, 4.4 times as long as wide, narrower posteriorly. Cephalothorax subrectangular, as long as wide, anterior margin with conspicuous rounded rostrum. Eyes absent; eyelobes small. Pereonite 1 fused to cephalothorax, one third as long as cephalothorax, laterally rounded, with single fine anterolateral and posterolateral setae. Five free pereonites lateral margins uniformly convex, with single (pereonites 2 to 4) or paired (pereonites 5 and 6) lateral setae; pereonite 2 as long as but narrower than pereonite 1; pereonites 3 and 4 subequal in length, 1.2 times as long as pereonite 1; pereonite 5 shorter, 0.8 times as long as pereonite 1; pereonite 6 shortest, 0.7 times as long as pereonite 1 (all pereonites respectively 3.3, 2.7, 2.2, 2.5, 3.3 and 3.6 times as wide as long). Pleon four times as long as pereonite 5, of five free subequal pleonites bearing pleopods, and pleotelson; pleonites dorsally convex, 1.5 times as wide as long, with two lateral setae, mostly laterally rounded but pleonite 2 with curved, sharp lateral spine-like apophyses. Pleotelson subrectangular, 0.3 times length of whole pleon, as long as wide, laterally expanded at attachment of uropods and with long distal spine 0.7 times as long as pleotelson.

Antennule (Fig. 14 A, A’) peduncle 4-articled, proximal article robust, 3.5 times as long as wide, setose along inner and outer margins; second article, apparently the fusion of two articles, one-quarter as long as article 1, with outer subdistal tuft of three setae, inner subdistal pair of penicillate setae, and inner distal pair of unequal setae; third and fourth articles indistinctly articulated, subequal in length, together 0.2 times as long as second, with outer distal seta, ventral array of penicillate setae, inner margin extended distally with paired setae and fused to accessory flagellum. Accessory flagellum a partially-segmented fused extension of the peduncle with three distal setae. Main flagellum of five segments, proximal segment two-thirds as long as whole flagellum, distal four segments subequal in length, segments 2 and 3 bearing convoluted aesthetascs.

Antenna (Fig. 14 B) peduncle 4-articled, squama absent; proximal article with outer expansion with crenulated margin, proximally setulose; articles 2 and 3 indistinctly articulated, often appearing fused, subequal in length, article 2 naked or with ventral seta, article 3 naked, together 0.7 times as long as article 1; peduncle article 4 elongate, 2.4 times as long as article 2, with penicillate seta at midlength and distal crown of five shorter and one longer setae. Flagellum of three segments.

Mouth parts. Labrum (Fig. 14 C) rounded, distally concave and marginally setose. Left mandible (Fig. 14 D) pars incisiva and lacinia mobilis with sharp distal teeth, setiferous lobe with six mainly bifurcate setae, pars molaris (Fig. 14 D’) robust, distally with complex crenulations and plumose marginal setae; mandibular palp absent. Right mandible as left but without lacinia mobilis. Maxillule (Fig. 14 E) inner endite with four finely setulate distal setae, outer distal margin with sparse setules; outer endite with ten distal spines and two subdistal setae, distal margins finely setose; palp of two articles, distally with five setae. Maxilla (Fig. 14 F) with microtrichia on margins; outer lobe of moveable endite with five finely denticulate setae; inner lobe of movable endite with two finely denticulate, three plumose and four simple setae; outer lobe of inner endite with one simple seta, four sickle-shaped finely-denticulate spines, and three trifurcate spines; inner lobe of fixed endite with rostral row of 30 setae guarding five longer finely-denticulate setae. Labium (Fig. 14 G) marginally naked, palp with fine lateral setules and one distal spine. Maxilliped (Fig. 14 H) basis with one long distal seta; palp article 1 with single short seta on outer margin, and long plumose seta on inner margin; palp article 2 longer than wide, with 11 inner setae mainly in two rows, single outer distal spine; palp article 3 with six distally-tapering setae along inner margin; palp article 4 with six distal setae. Endite (Fig. 14 H’) distally with four stout plumose setae and three stout spines; two coupling hooks. Epignath not retrieved.

Cheliped (Fig. 15 A) hammer-like. Basis 1.3 times as long as wide, dorsally with two small proximal setae, ventrally with two distal setae; exopodite (not figured) present, 3-articled, distal article with four plumose setae. Merus subrectangular, ventrally with single proximal and distal setae. Carpus almost twice as long as wide, with three simple setae along dorsal margin, one midventral seta. Propodus massive, proximally overhanging carpus; fixed finger half as long as palm, ventral margin with four setae, three setae in axis of chela, cutting edge of fixed finger finely denticulate with row of eight adjacent setae, distal claw robust; dactylus with fine setae but no apophyses on cutting edge, one subdistal seta, distal claw robust.

Pereopods: Pereopod 1 (Fig. 15 B) much larger than remaining pereopods. Basis stout, 2.2 times as long as wide, with four ventrodistal setae; exopodite present, 3-articled, distal article with five distal plumose setae. Merus 0.8 times as long as basis, with three ventral setae and ventrodistal spine. Carpus 1.2 times as long as merus, with six setae along dorsal margin and five spines along ventral margin. Propodus 0.7 times as long as carpus, with dense row of dorsal marginal setae, ventral margin with four spines, single distal seta. Dactylus stout, curved, unguis short, both together 0.65 times as long as propodus.

Pereopod 2 (Fig. 15 C) smaller than pereopod 1; basis 3.4 times as long as wide with two dorsal penicillate setae and tuft of five ventrodistal setae. Ischium with one ventral seta. Merus 0.8 times as long as carpus, with four ventral setae. Carpus with rows of six dorsal and five ventral marginal setae. Propodus 1.5 times as long as carpus, dorsal margin with nine long setae, ventral margin with seven setae and five short spines, distal seta adjacent to dactylus. Dactylus slender, curved, unguis short, the two together half as long as propodus.

Pereopod 3 (Fig. 15 D) similar to pereopod 2, but ischium with two setae, remaining articles with fewer setae.

Pereopod 4 (Fig. 15 E) basis 4.6 times as long as wide, with mid-dorsal plumose seta and four ventrodistal setae; ischium with one ventral seta; merus 0.6 times as long as carpus, with three distal setae; carpus with seven plumose ventral setae and two ventral spines, dorsally with five simple setae; propodus 0.73 times as long as carpus, with three ventral spines, distally with crown of ten finely-denticulate setae and one longer simple seta; dactylus plus claw 0.6 times as long as propodus and shorter than longest dorsodistal propodal setae.

Pereopod 5 (Fig. 15 F) basis 3.3 times as long as wide with two penicillate setae and three ventrodistal setae; ischium with one long ventral seta; merus more than half length of carpus, with five dorsal and four ventral plumose setae; carpus with four dorsal and six ventral plumose setae; propodus just over half as long as carpus, with ventral row of 16 short leaf-like, bilaterally-setulose spines, strong distal seta exceeding length of dactylus plus unguis; dactylus and short unguis curved, together just longer than propodus.

Pereopod 6 (Fig. 15 G) similar to pereopod 5, but basis with eight simple and one plumose setae along ventral margin, mesial row of four plumose setae, dorsally with three simple and five plumose setae.

Pleopods (Fig. 15 H) all alike. Basis elongate, with three outer plumose setae. Endopod shorter than exopod with proximal articulation bearing plumose seta; both rami oar-shaped, with plumose marginal setae.

Uropod (Fig. 15 I) biramous, both rami filiform. Basis with two setae on inner margin; exopod of two segments, nearly reaching distal end of third endopod segment; endopod elongate, three times as long as pleotelson, with 12 segments.

Distinctions of male. Generally as female. Antennule (Fig. 16 A) peduncle of four distinct articles, first article more attenuate than that of female, 6.2 times as long as wide, third and fourth articles distinctly articulated, subequal in length; flagellum with single aesthetascs on each of four proximal segments. Antenna (Fig. 16 B) with twosegmented flagellum. Cheliped (Fig. 16 C) dimorphic, proportionately larger than that of female; carpus curved, distal on merus, with ventral proximal apophysis, three ventral marginal setae; propodus not overhanging carpus proximally, chela forcipate, fixed finger with squared distal tip bearing six inner setae; gap between fingers with setulose rounded apophysis and tuft of four setae; dactylus with four rounded apophyses along cutting edge, three distal setae. Pereopod 1 (Fig. 16 D) proportionately longer and more slender than that of female, carpus only sparsely setose dorsally, ventral propodal spines more slender; dactylus and unguis more slender, together just longer than propodus. Other pereopods (e.g. Fig. 16 E) more slender than those of female, dactyli and ungues proportionately longer.

Remarks. Subtle variation exists in the articulation of the peduncle of the antennules and the antennae. The third and fourth articles of the antennular peduncle in the female show partial fusion in the lectotype, as does the small tubercle-like accessory flagellum: in neither case is the line of articulation complete; in the figured specimen from the Gulf of Cadiz, these lines of articulation are completely absent. Similarly, the second and third articles of the peduncle of the antenna in both sexes are fused in the Gulf of Cadiz specimens, while retaining a slight line of articulation in the lectotype.

The present material extends the depth range for this species to 199 to 3061 m.