Apseudes grossimanus Norman & Stebbing, 1886

Błażewicz-Paszkowycz, Magdalena, Bamber, Roger N. & Cunha, Marina R., 2011, Apseudomorph tanaidaceans (Crustacea: Peracarida) from mud-volcanoes in the Gulf of Cadiz (North-east Atlantic), Zootaxa 2919, pp. 1-36 : 9-16

Apseudes grossimanus Norman & Stebbing, 1886

( Fig. 5 )

Apseudes grossimanus Norman & Stebbing, 1886: 93 –95, pl. 19.

Material examined. 13, and fragments of male including chelipeds ( BMNH.2010.439),Cruise TTR14, Station AT541, Meknès mud volcano, 34°59.103'N 07°04.435'W, 703 m depth, mud breccia and H2S, TV-grab, 0 5.08.2004. Coll. MRC.

Other GoC records. 1 specimen, Cruise TTR12, Station AT416, TTR mud volcano, 35°21.87'N 06°52.00'W, 695 m depth, mud and corals, TV-grab, 17.07.2002; 2 specimens, Cruise TTR14, Station AT524, Yuma mud volcano, 35°24.973'N 07°05.461'W, 960 m depth, marl and mud breccia, TV-grab, 02.08.2004; 3 specimens, Station AT 560, Kidd mud volcano, 35°25.306'N 06°43.976'W, 498 m depth, mud breccia, boxcore, 08.08.2004; 1 specimen, Cruise TTR15, Station AT 581, Meknès mud volcano, 34°59.178'N 07°04.353'W, 700 m depth, mud breccia, TV-grab, 28.07.2005; 2 specimens, Station AT 586, Meknès mud volcano, 34°59.146'N 07°04.380'W, 701 m depth, mud breccia, TV-grab, 28.07.2005; all coll. MRC.

Remarks. This species was figured by both Norman & Stebbing (1886) and Lang (1955, 1968), although neither gave a figure of the habitus from dorsal view (see Fig. 5 ) ( Lang 1955, included a photograph).

Apseudes grossimanus , with its characteristic tridentate rostrum, is the only apseudomorphan species recorded previously from deep-sea chemosynthetic habitats, on the Mid-Atlantic Ridge ( Larsen et al. 2006); it is otherwise widespread in the north-east Atlantic, to which distribution the present records add nothing new. Records of A. grossimanus from off South Africa and in the Mediterranean (see Sieg 1983) must be regarded with some suspicion. Neither this species nor A. setiferus (see above) shows any particular morphological adaptation to the conditions found at chemosynthetic habitats.

Genus Atlantapseudes B ă cescu, 1978(a)

Atlantapseudes nigrichela B ă cescu, 1978a ( Figs 6–9 )

Atlantapseudes nigrichela Bäcescu, 1978a: 317 –322: fig. 1. A. nigrichela . — Santos & Hansknecht, 2007: 38 (key).

Material examined. 13 ( BMNH.2010.440), 1Ƥ, 3 juveniles, 7 mancae, fragments of another male ( BMNH.2010.441–450), Cruise TTR14, Station AT 560, Kidd mud volcano, 35°25.306'N 06°43.976'W, 498 m depth, mud breccia, boxcore, 08.08.2004; 2ƤƤ, 13 subadult ( BMNH.2010.451-453), Cruise TTR15, AT 576, Mercator mud volcano, 35°17.657'N 06°39.129'W, 428 m depth, mud, boxcore, 26.07.2005.

Other GoC records. 8 specimens, Cruise TTR12, Station AT395, Aveiro, 35°52.226'N 07°26.282'W, 1094 m depth, marl with clasts, TV-grab, 11.07.2002; 7 specimens, Cruise TTR12, Station AT399, Captain Arutyunov, 35°39.805'N 07°19.997'W, 1339 m depth, crater outer part, mud breccia, TV-grab, 13.07.2002; 1 specimen, Cruise TTR12, Station AT407, Pen Duick Escarpment, 35°17.695'N 06°47.082'W, 560 m depth, dead scleractinean framework, TV-grab, 15.07.2002; 1 specimen and fragments of 1Ƥ, 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; 1 specimen, Station AT546, Captain Arutyunov mud volcano, 35°39.692'N 0 7°20.046'W, 1345 m depth, mud breccia and gas-hydrate, TV-grab, 06.08.2004; 14 specimens, Station AT559, Kidd mud volcano, 35°24.777'N 06°43.782'W, 552 m depth, mud, boxcore, 08.08.2004; 9 specimens, Station AT561, Kidd mud volcano, 35°25.602’N 06°44.099'W, 526 m depth, mud, boxcore, 08.08.2004; 5 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 AT581, Meknès mud volcano, 34°59.178’N 07°04.353'W, 700 m depth, mud breccia, TV-grab, 28.07.2005; 3 specimens, Cruise TTR15, Station AT599, Portimão canyon, 36°06.379'N 07°53.564'W – 36°06.538'N 07°53.942'W, 1418– 1275 m depth, carbonate chimneys, Geology dredge, 0 2.08.2005. All coll. MRC.

Other material examined. 2ƤƤ ( BMNH.1989.539.2), CENTOB: Calgim CP63, 35°30.6'N 07°42.1'W, 1510 m depth, 4.06.1984, beam trawl (det. G.J. Bird).

Description of male. Body ( Fig. 6 B), dorsoventrally flattened, elongate, 4.7 mm long, 6.5 times as long as wide, narrower posteriorly. Cephalothorax subrectangular, 1.2 times as long as wide, anterior margin with conspicuous pointed rostrum with slight “shoulders” at base. Eyes absent; eyelobes modified to prominent, curved spinelike apophyses directed anterolaterally; lateral spiniform apophyses at anterior margin of branchial chambers. Six free pereonites; pereonite 1 shortest, 0.3 times as long as cephalothorax, with convex lateral margins without apophyses; pereonite 2 1.3 times as long as pereonite 1, lateral margins convex with dorsolateral spine-like apophysis directed anterolaterally; pereonite 3 with laterally-oriented dorsolateral spine-like apophyses, 1.7 times as long as pereonite 1, expanded anterolaterally over coxal attachments; pereonites 4 and 5 subequal in length, 2.1 times as long as pereonite 1, otherwise similar to pereonite 3; pereonite 6 shorter, 1.5 times as long as pereonite 1, otherwise similar to pereonite 3 (all pereonites respectively 3.3, 2.2, 1.5, 1.2, 1.2 and 1.5 times as wide as long); small ventral hyposphenia present on pereonites 1 to 5, penial tubercle on pereonite 6. Pleon twice as long as pereonite 4, of five free subequal pleonites bearing pleopods; pleonites dorsally convex, about three times as wide as long, laterally expanded by spiniform apophyses, with ventral hyposphenia. Pleotelson long and slender, 0.4 times length of whole pleon, 1.5 times as long as wide.

Antennule ( Fig. 7 A) peduncle 4-articled, proximal article elongate, six times as long as wide, with sparse inner simple and outer penicillate setae; second article one-third as long as article 1, with outer distal tuft of simple and penicillate setae, single mesial and inner distal setae; third article one-quarter as long as second, fourth article as long as third, both with outer penicillate setae. Main flagellum of eight segments, distal segment with aesthetasc; accessory flagellum of four segments.

Antenna ( Fig. 7 B) proximal peduncle article simple, as long as wide, naked; article 2 three-times as long as wide, bearing elongate squama with two unequal simple distal setae; peduncle article 3 as long as wide, 0.25 times as long as article 2, with one seta; article 4 as long as article 2, with inner penicillate setae; article 5 longest, 1.3 times as long as article 4, with inner distal group of penicillate setae. Flagellum of five segments.

Mouth parts. Labrum rounded, simple, with stout, sharp epistome. Left mandible ( Fig. 7 D) with strong, crenulated pars incisiva, slender crenulated lacinia mobilis, setiferous lobe ( Fig. 7 Dʹ) with six stout or trifurcate and one tapering setae, pars molaris tapering, distally setulose (as on right mandible, see Fig, 7Cʹ); mandibular palp ( Fig. 7 Dʹʹ) of three articles, proximal article slender with one small medial seta, article 2 nearly three times as long as article 1 with five simple inner distal setae; article 3 as long as article 1 with eight inner simple setae, distal seta almost as long as article. Right mandible ( Fig. 7 C) as left but without lacinia mobilis, setae on setiferous lobe more robust. Maxillule ( Fig. 7 E) inner endite with finely setose outer margin and four finely setulate distal setae; outer endite with eight unequal distal spines and two subdistal setae, outer margin finely setose; palp of two relativelystout articles, distally with four setae each with setulose tip. Maxilla ( Fig. 7 F) with microtrichia on margins; outer lobe of movable endite with two simple setae on outer margin and six mesially pinnate, distally finely-setulose setae on distal margin; inner lobe of movable endite with four distally finely-setulose and four mesially pinnate setae; outer lobe of inner endite distally with four simple and two mesially pinnate setae, one trifurcate and one multi-furcate spines, and one mesially pinnate subdistal seta; inner lobe of fixed endite with rostral row of 30 setae guarding five longer setae. Labium ( Fig. 7 G) with setulose distal margin, palp with dense, fine lateral setules and three simple distal setae. Maxilliped ( Fig. 7 I). Basis outer margin densely setulose, distally naked; palp article 1 with single seta on outer margin; palp article 2 longer than wide, with about 16 setae on inner margin; palp article 3 longer than wide, with 11 setae on inner margin; palp article 4 with nine inner-to-distal setae. Endite ( Fig. 7 Iʹ) with pinnate inner caudodistal seta and stout, simple or pinnate distal spines. Epignath ( Fig. 7 H) large, elongate-ovoid, with inner lobes and distally-setulose distal seta.

Cheliped ( Fig. 8 A) basis just over twice as long as wide, mid-dorsally with one simple seta, ventrally with two simple setae in proximal half, slender midventral spine and simple subdistal seta; exopodite absent, but small pointed outer apophysis present proximally. Merus quadrangular, narrowing proximally, with single dorsodistal seta and small seta on shoulder of ventral margin. Carpus 2.4 times as long as wide, with two simple setae on ventral margin, seven shorter setae along dorsal margin mainly in proximal half. Propodus stout, tuft of four setules dorsodistally, chela fingers as long as palm, ventral margin with four setae; cutting edge of fixed finger with row of fine submarginal setae, distal half with rounded crenulations, two triangular tooth-like apophyses in proximal half, distal claw slender; dactylus with sparse setae and proximal triangular tooth-like apophysis on cutting edge.

Pereopods: Pereopod 1 ( Fig. 8 B) basis slender, seven times as long as wide, with paired mid-length simple setae and one penicillate seta, fine ventrodistal seta; exopodite absent. Ischium with simple ventrodistal seta. Merus 0.4 times as long as basis, with ventral tuft of three longer setae in proximal half, ventrodistal spine and longer seta, and two dorsodistal simple setae. Carpus slightly shorter than merus, with rows of dorsal and ventral marginal longer setae, distal margin with fine shorter setae, two ventrodistal spines and one dorsodistal spine. Propodus 0.6 times as long as carpus, dorsal margin with two setae and two spines alternating, ventral margin with five spines becoming progressively larger towards distal end; fine seta and small spine adjacent to dactylus insertion. Dactylus with fine dorsal seta and three ventral denticulations; unguis half as long as dactylus, both together just longer than propodus.

Pereopod 2 ( Fig. 8 C) more slender overall than pereopod 1, basis 5.7 times as long as wide with sparse ventral setae. Merus 1.2 times as long as carpus, with one mid-ventral and two ventrodistal elongate setae. Carpus elongate, with rows of six ventral and four dorsal setae in distal two-thirds. Propodus just shorter than carpus, similarly setose. Dactylus slender with fine dorsal and ventral proximal setae, unguis slender, almost as long as dactylus, the two together longer than propodus.

Pereopod 3 ( Fig. 8 D) similar to pereopod 2, but basis with penicillate seta; merus proportionately shorter.

Pereopod 4 ( Fig. 8 E) basis stouter, four times as long as wide, with three dorsoproximal and one mid-ventral penicillate setae. Merus about half as long as carpus, with one dorsodistal and two ventrodistal setae. Carpus with ventrodistal to distal crown of about ten setae. Propodus 0.8 times as long as carpus, with mid-dorsal plumose sensory seta, mid-ventral spine, dorsodistal tuft of three short and three long setae; dactylus plus claw just shorter than propodus and shorter than longest dorsodistal propodal seta.

Pereopod 5 ( Fig. 8 F) similar to pereopod 4, but basis with single dorsoproximal penicillate seta; merus with one dorsodistal and one ventrodistal setae; carpus with ventrodistal spinules rather than setae; propodus just shorter than carpus, with two ventrodistal setae.

Pereopod 6 ( Fig. 8 G) similar to pereopod 5, but basis with two mid-dorsal penicillate setae.

Pleopods ( Fig. 8 H) all alike. Basis elongate, with one simple and one plumose inner distal setae. Exopod of two articles, proximal article with long outer plumose seta; endopod just shorter than exopod without proximal articulation; both rami slender, with about ten plumose setae.

Uropod ( Fig. 8 I) biramous, both rami filiform. Basis with two outer distal setae; exopod about one-quarter as long as endopod, with five segments; endopod with about 19 segments.

Distinctions of female ( Fig. 6 A, 9). Generally as male, but pleopods absent. Cheliped merus with spine-like apophysis on “shoulder”; fingers of chela without tooth-like apophyses. Pereopod 1 ( Fig. 9 B) stouter, basis (for example) 3.4 times as long as wide.

Remarks. Bäcescu (1978a) described this species originally from material taken in the north-east Atlantic off the west of Portugal at 740–1250 m depth, but that description was somewhat incomplete; the present material has allowed us to describe the species fully, including the mature male. The present male appears to be more mature than those of Bäcescu (1978a), as it does show distinct triangular tooth-like apophyses on the fingers of the chela, while Bäcescu (ibid) stated that the male did not differ in the form of its chela. The black pigment on chela, from which the specific epithet is derived, persists in all of this material (in alcohol) only on the distal spines on the chela fingers. While Bäcescu (ibid) states that the carpus of the pereopods is shorter than the merus, it was in fact clearly longer on the posterior pereopods in all the present material. Of other slight differences with the types, Bäcescu’s description and figure show one less segment in both antennular flagella than found in the present material, one more seta on the outer margin of the second article of the maxilliped palp, and a plumose nature to the ventral carpal setae on the cheliped.

While all of the newly recorded material above is from the same region as the type-collection, the depth range for this species has been extended to from 414 to 1510 m.

The most recent study on Atlantapseudes was that of Santos and Hansknecht (2007): they described two new species of the genus, one from off Brazil and one from off Madagascar, and produced a key to the five known species. They sensibly removed Apseudes diversus Lang, 1968 to a new genus, Taraxapseudes , this species having previously been attributed to Atlantapseudes by Guţu (1996). It should be noted that Apseudes coriolis Bamber, 2007 ( Bamber 2007a) should also be moved to Taraxapseudes .

Figures

FIGURE 5. Apseudes grossimanus, A, lateral (male); B, dorsal (female). Scale line = 1 mm.

FIGURE 6. Atlantapseudes nigrichela, female, A, dorsal; B, lateral. Scale line = 2 mm.

FIGURE 7. Atlantapseudes nigrichela, A, antennule; B, antenna; C, right mandible, distal, with Cˏ, pars molaris; D, left mandible with Dˏ, detail of setiferous lobe and Dˏˏ, palp; E, maxillule; F, maxilla; G, labium; H, epignath; I, maxilliped, with Iˏ, endite. Scale lines = 0.1 mm.

FIGURE 8. Atlantapseudes nigrichela, male, A, cheliped; B – G, pereopods 1 – 6 respectively; H, pleopod; I, uropod. Scale lines = 0.5 mm for A – G, I; 0.1 mm for H.

FIGURE 9. Atlantapseudes nigrichela, female, A, cheliped; B – G, pereopods 1 – 6 respectively; H, uropod. Scale lines = 1 mm.