Sphyrapus meknes, Błażewicz-Paszkowycz, Magdalena, Bamber, Roger N. & Cunha, Marina R., 2011

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 : 29-33

Sphyrapus meknes sp. nov.

( Figs 17–19 )

Material. 1 brooding Ƥ, holotype ( BMNH.2010.468), 1 subadult Ƥ, dissected on three microscope slides, paratype ( BMNH.2010.469), Cruise TTR14, Station AT541, Meknès mud volcano, 34°59.103’N 07°04.435’W, 703 m depth, mud breccia and H2S, TV-grab, Cruise TTR14, 0 5.08.2004. Coll. MRC.

Description of female. Body ( Fig. 17 ), dorsoventrally flattened, elongate, holotype 2.3 mm long, 4.8 times as long as wide, narrowing posteriorly. Cephalothorax subrectangular, slightly longer than wide, anterior margin with conspicuous rounded rostrum. Eyes absent; eyelobes very small; single fine seta posterior to anterolateral corners. Pereonite 1 fused to cephalothorax, one third as long as cephalothorax, laterally rounded, naked. Five free pereonites lateral margins uniformly convex, with three (pereonites 2 to 4), two (pereonite 5) or one (pereonite 6) lateral setae; pereonite 2 as long as but narrower than pereonite 1; pereonites 3 and 5 subequal in length, just longer than pereonite 1; pereonite 4 slightly longer and wider; pereonite 6 shortest, half as long as pereonite 4 (all pereonites respectively 2.8, 2.5, 2.1, 2.1, 2.0 and 3.1 times as wide as long). Pleon three times as long as pereonite 1, of five free subequal pleonites bearing pleopods, and pleotelson; pleonites dorsally convex, narrower posteriorly, pleonite 1 three times as wide as long, pleonite 5 2.3 times as wide as long; each pleonite with two lateral setae, all laterally rounded with no lateral spine-like apophyses. Pleotelson oval, one-third of length of whole pleon, as long as wide, laterally expanded at attachment of uropods and with long distal spine 0.8 times as long as pleotelson.

Antennule ( Fig. 18 A, A’) peduncle 3-articled, proximal article robust, 3.3 times as long as wide, setose along inner and outer margins; second article one-quarter as long as article 1, with inner and outer subdistal pair of simple setae; third article 0.65 times as long as second, with single inner subdistal and distal setae, longer outer medial seta. Accessory flagellum absent. Main flagellum of four segments, proximal segment three-quarters as long as whole flagellum, distal three segments subequal in length, segments 1 and 2 bearing convoluted or annulated aesthetascs.

Antenna ( Fig. 18 B) peduncle 3-articled, squama absent; proximal article with outer expansion with slightly denticulated, setulose margin; article 2 with inner rounded apophysis and mesial seta, 0.6 times as long as article 1; peduncle article 3 elongate, three times as long as article 2, with two penicillate setae at mid-length and distal crown of two simple and two penicillate setae. Flagellum of three segments.

Mouth parts. Labrum rounded, distally concave and marginally setose. Left mandible ( Fig. 18 C) pars incisiva and lacinia mobilis with sharp distal teeth, setiferous lobe with six robust setae, pars molaris short, distally with curved denticulations and plumose marginal setae; mandibular palp absent. Right mandible ( Fig. 18 D) as left but without lacinia mobilis, lacinia teeth more rounded. Maxillule ( Fig. 18 E) inner endite with four finely setulate distal setae, outer distal margin with seta; outer endite with ten distal spines and two subdistal setae, distal margins finely setose; palp ( Fig. 18 E’) of two articles, distally with one setulose seta. Maxilla ( Fig. 18 F) with microtrichia on margins; outer lobe of moveable endite with denticulate outer margin, five finely denticulate setae distally; inner lobe of movable endite with three finely denticulate and three simple setae; outer lobe of inner endite with three finely-denticulate spines and three trifurcate spines; inner lobe of fixed endite with rostral row of 17 setae guarding one longer seta. Labium ( Fig. 18 G) marginally naked, palp with fine lateral setules and one distal laterally-setulose spine. Maxilliped ( Fig. 18 H) basis not recovered; palp article 1 with single short seta on outer margin; palp article 2 longer than wide, with nine inner setae mainly in two rows and one longer proximal seta, single outer distal spine; palp article 3 with four simple and three distally-tapering setae along inner margin; palp article 4 with six distal setae; endite not recovered. Epignath ( Fig. 18 I) large, cup-shaped, with inner lobes and setulose distal seta.

Cheliped ( Fig. 19 A) hammer-like. Basis 1.2 times as long as wide, glabrous; exopodite present, 3-articled, distal article with four setae. Merus subrectangular, ventrally with single distal seta. Carpus 1.5 times as long as wide, with two simple setae along ventral margin, one submarginal mid-dorsal seta. Propodus massive, proximally overhanging carpus, 1.3 times as long as wide; fixed finger 0.6 times as long as palm, ventral margin with four setae, two setae in axis of chela, cutting edge of fixed finger with blunt denticulations and six adjacent setae, distal claw robust; dactylus with two fine setae and distal lamella on cutting edge, three subdistal setae, distal claw robust.

Pereopods: Pereopod 1 ( Fig. 19 B) much larger than remaining pereopods. Basis stout, 2.2 times as long as wide, with one ventrodistal seta and penicillate seta and two setules dorsoproximally; exopodite present, 3-articled, distal article with five distal plumose setae. Merus 0.6 times as long as basis, with four ventral setae and ventrodistal spine. Carpus 1.5 times as long as merus, with five setae along dorsal margin and four spines and one seta along ventral margin. Propodus 0.7 times as long as carpus, with 12 dorsal marginal setae, including one dendritic seta, ventral margin with four spines, single distal seta. Dactylus slender, curved, unguis short, both together 0.7 times as long as propodus.

Pereopod 2 ( Fig. 19 C) smaller than pereopod 1; basis 3.6 times as long as wide with two penicillate setae at mid-length and two ventrodistal setae. Ischium with one ventral seta. Merus 0.9 times as long as carpus, with one simple and one bifurcate ventral setae. Carpus with rows of eight dorsal and five ventral marginal setae. Propodus 1.4 times as long as carpus, dorsal margin with ten long setae, ventral margin with six setae and five shorter spines, distal seta adjacent to dactylus. Dactylus slender, curved, unguis short, the two together just over half as long as propodus. Pereopod 3 ( Fig. 19 D) similar to pereopod 2, but with fewer setae, propodus with four ventral spines.

Pereopod 4 ( Fig. 19 E) basis 3.9 times as long as wide, with two dorsoproximal penicillate seta, fine ventral subdistal seta, and two ventrodistal setae, vestigial exopod present proximally; ischium with one ventral seta; merus half as long as carpus, with three ventrodistal setae; carpus with one ventral seta, submarginal row of seven setae curving to mid-distal margin, and dorsally with two simple setae in distal half; propodus 0.6 times as long as carpus, with two ventral spines, distally with crown of ten finely-denticulate setae and one pectinate spine; dactylus with ventrodistal setule, together with short claw 0.7 times as long as propodus and shorter than longest dorsodistal propodal setae.

Pereopod 5 ( Fig. 19 F) basis 3.5 times as long as wide with two dorsal penicillate setae, fine ventral subdistal seta, and three plumose ventrodistal setae, vestigial exopod present proximally; ischium with one ventral seta; merus just more than half length of carpus, with one simple and four plumose-dendritic dorsal setae, ventrally with one plumose and two plumose-dendritic setae; carpus dorsally with three plumose and one plumose-dendritic setae, ventrally with four plumose and one plumose-dendritic setae plumose setae; propodus just over half as long as carpus, with ventral row of 10 short leaf-like, bilaterally-setulose spines, strong distal seta exceeding length of dactylus plus unguis; dactylus and short unguis curved, together 1.3 times as long as propodus.

Pereopod 6 ( Fig. 19 G) basis with four simple and four dendritic setae along ventral margin, no vestigial exopodite; seta on ischium dendritic; merus almost as long as carpus, with two plumose dorsal setae and three plumose-dendritic ventral setae; carpus with three simple dorsal setae and three finely plumose ventral setae; propodus half as long as carpus, with ventral row of 6 short leaf-like, bilaterally-setulose spines, strong distal seta as long as dactylus plus unguis; dactylus and short unguis straight, together 1.4 times as long as propodus.

Pleopods ( Fig. 19 H) all alike. Basis elongate, with one outer plumose setae. Endopod and exopod subequal in length without proximal articulation; both rami with one proximal and four distal plumose marginal setae.

Uropod ( Fig. 19 I) biramous, both rami filiform. Basis with penicillate seta on outer margin; exopod with two segments; endopod elongate with 12 segments.

Male unknown.

Holotype has 10 eggs in the brood-pouch.

Etymology. Named after the Meknès mud volcano, the type-locality (noun in apposition).

Remarks. The only genus of the Sphyrapinae without a multi-segmented accessory flagellum on the antennule is Sphyrapus , with which genus the morphology of S. meknes sp. nov. is largely consistent. The only previouslydescribed species of Sphyrapus sensu stricto, S. malleolus (see above) has spine-like lateral apophyses on pleonite 2; S. meknes is thus immediately distinguished as not having these apophyses. Further, while the accessory flagellum on the antennule is present either as a 1-segmented or unsegmented small setose tubercle in S. malleolus , it is quite absent in the present species.

Other characterizing, and unusual, features of Sphyrapus meknes include the bifurcate-dendritic setae on pereopods (e.g. Fig. 19 F); these are essentially branched setae, which on the posterior pereopods are also plumose, and have not been recorded in any other sphyrapid species. The presence of a vestigial exopod on the basis of each of pereopods 4 and 5 in the adult female is also unprecedented; exopods have been found to be present on these two pereopods in the manca of some sphyrapids, e.g. Pseudosphyrapus quintolongus Kakui et al., 2007 (q.v.) (as also in some kalliapseudids, e.g. Lang 1956), but this is the first time any trace of exopods on posterior pereopods has been found to persist in an adult apseudomorph.

Sphyrapus meknes was only found at the Meknès mud volcano at 703 m depth in sulphurous mud.

Subfamily Pseudosphyrapodinae Gu ţ u, 1980

Genus Pseudosphyrapus Gu ţ u, 1980

Figures

FIGURE 17. Sphyrapus meknes sp. nov., holotype female, dorsal. Scale line = 1 mm

FIGURE 18. Sphyrapus meknes sp. nov., paratype female, A, antennule, with A’, detail of distal articles; B, antenna; C, left mandible; D, right mandible, distal; E, maxillule endites and E’, palp; F, maxilla; G, labium; H, maxilliped palp; I, epignath. Scale lines = 0.1 mm.

FIGURE 19. Sphyrapus meknes sp. nov., paratype female, A, cheliped; B – G, pereopods 1 to 6; H, pleopod; I, uropod. Scale lines = 0.1 mm.