Paratanais pseudomartinsi, Larsen, Kim, 2012

Larsen, Kim, 2012, Tanaidacea (Crustacea) from Macaronesia II. The deep-water fauna from the Azores archipelago, Portugal, Zootaxa 3250, pp. 26-42 : 38-41

Paratanais pseudomartinsi n. sp.

( Figs 6–7 )

Material examined. Holotype non-ovigerous Ƥ. Body length 2.0 mm. MMF 42246, Station L09D20RS01, 37º43'1536"N. 25º48'5290"W. South of S. Miguel Island 312 m depth.

Paratype (dissected) MMF 42247 one non-ovigerous Ƥ, station L9D17B36(R1), 38º40'123"N. 26º51'463"W, East of Terceira Island, 459 m depth.

Diagnosis. Female. Pleotelson, about 35% the total length of pleon. Left mandible lacinia mobilis upper margin serrated. Antenna article 2 with ventral spiniform seta arising from a process; article 3 dorsal spiniform seta as long as half or article. Maxilliped basis with three small (shorter than palp article 1) distal setae. Cheliped propodus with one pointy and one blunt- broad, flat, setae at dactylus insertion; fixed finger with large blunt inner process with medial depression; terminal spine heavily calcified; dactylus without ventral setae. Pereopods all with one ischial seta; pereopods 5 and 6 dactyli with dorsal serration/spines. Uropods shorter than pleotelson.

Male unknown.

Etymology. Named after the similar-looking Paratanais martinsi Bamber & Costa, 2009

Description. Non-ovigerous female.

Body: ( Fig. 6 A) slender, subcylindrical, about nine times longer than broad. Carapace slightly shorter than pereonite 1 and 2 together. Eye-lobes prominent, triangular and with visual elements. Pereon, pereonite 1 wider than long, with single dorsoanterior seta. Pereonites 2 to 6 longer than wide. Pleon about 0.2 times as long as body. Pleonite 1 longer than other pleonites. Other pleonites subequal, all with setulated lateral setae on lateral shield. Pleotelson as wide as pleonites, longer than last two pleonites combined.

Antennule ( Fig. 6 B) length 0.8 times as long as cephalothorax. Article 1 shorter than combined length of articles 2–5, 0.4 times as wide as long, with three medial setulated, one simple and one setulated subdistal, and one simple distal setae. Article 2 less than half as long as article 1, 0.8 times as wide as long, with one dissimilar length simple distal seta on each margin. Article 3 longer than half of article 2, with two short simple distal setae. Article 4 longer than half of article 1 but only half as wide, with one simple distal seta. Article 5 minute, with five simple distal setae.

Antenna ( Fig. 6 C) almost as long as antennule. Article 1 narrower and shorter than article 2, naked. Article 2 slightly longer than article 3, with one simple dorsodistal and one spiniform ventro-subdistal setae arising from a process. Article 3 with large dorsal spiniform seta as long as half or article. Article 4 longer than other articles, with three setulated distal setae. Article 5 slightly shorter than article 3, with one distal simple seta. Article 6 length minute, with one short and four setae longer than half of antenna.

Mouthparts. Labrum ( Fig. 6 D) extending ventrally from clypeus, with setae and setules; clypeus with setules and small apical process. Mandibles ( Fig. 6 E,F) molar process broad with heavily calcified, blunt distal apex. Left mandible ( Fig. 6 F) lacinia mobilis as long as- and much wider than incisor, with proximal denticulation on upper margin, incisor simple blunt shaped, smooth. Right mandible ( Fig. 6 E) incisor bluntly bifurcated, with crenulations on upper margin. Labium ( Fig. 6 G) with two lobes, lateral margins and anterior corners with sparse setulation and three setae, inner proximal part of lobes heavily setulose, left side with lateral expansion (not visible on the right but this is probably an artifact). Maxillule ( Fig. 6 H) endite outer margin with regularly spaced setules, with nine spiniform setae and several small simple distal setae. Palp biarticulated, first article twice as long as second, with two distal setae longer than palp. Maxilla ( Fig. 6 I) tapering distally, naked. Maxilliped ( Fig. 6 J) endite lateral and distal margin with regularly spaced setae, with one subdistal seta and two flat, rounded distal setae. Basis with one distal seta. Palp article 1 naked. Article 2 with one outer and three bipinnate inner setae. Article 3 with four bipinnate setae. Article 4 with five bipinnate inner setae and one outer subdistal simple seta. Epignath ( Fig. 6 K) membranous, blunt, naked.

Cheliped ( Fig. 7 A) basis divided almost equally by triangular sclerite, shorter than carpus, naked. Merus triangular with one ventral seta. Carpus with two ventral and two dorsal setae, with small ventrodistal process. Propodus ( Figs. 7 B), including fixed finger shorter than basis, with one inner subdistal distal seta, one pointed and one blunt wide, flat, outer distal setae near dactylus insertion. Fixed finger with two ventral setae and three on inner margin; inner margin with large blunt inner process with medial depression; terminal spine heavily calcified. Dactylus stout with one seta on dorsal margin.

Pereopod 1 ( Fig. 7 C) length 1.5 times that of other pereopods. Coxa with one simple seta. Basis with one simple dorsoproximal seta. Ischium with one simple seta. Merus rectangular, longer than carpus with one simple ventrodistal seta. Carpus rectangular with one simple distal seta on each margin. Propodus longer than merus, with one ventro-subdistal simple seta and two dorso-subdistal setae and distal spine. Dactylus and unguis combined about as long as propodus. Dactylus shorter than unguis, with simple proximal seta.

Pereopod 2 ( Fig. 7 D) coxa with one simple seta. Basis naked. Merus shorter than carpus with one spiniform and one simple ventrodistal setae. Carpus shorter than propodus with two short ventrodistal and one longer dorsodistal spiniform setae, with one dorsodistal apparently simple seta. Propodus as long as merus and carpus combined, with one ventro-subdistal simple seta and two dorso-subdistal setae, distal scales and spine. Dactylus and unguis combined shorter than propodus. Dactylus shorter than unguis, with simple proximal seta.

Pereopod 3 ( Fig. 7 E) similar to pereopod 2 except: carpus with bone-shaped seta.

Pereopod 4 ( Fig. 7 F) basis twice as wide as on pereopod 1 to 3, with two dorsoproximal setulated, one ventroproximal simple, and two setulose ventromedial setae. Ischium with one seta. Merus as long as carpus, with two bifurcate ventrodistal spiniform setae and ventral scale pad. Carpus with four bifurcate spiniform and one boneshaped distal setae, and ventral scale pad. Propodus with one dorsomedial, one dorsodistal rigid, and two ventrodistal bipinnate spiniform setae, distal scales, and dorsal spine. Dactylus and unguis combined shorter than propodus. Dactylus apparently naked, twice as long as unguis.

Pereopod 5 ( Fig. 7 G) similar to pereopod 4 except: dactylus with dorsal serration.

Pereopod 6 ( Fig. 7 H) similar to pereopod 5 except: basis with one ventroproximal seta only. Propodus with three rigid bipinnate dorsodistal setae.

Pleopods ( Fig. 7 I) all five pairs similar. Basal article widening distally and naked. Exopod with 15 plumose inner setae, gap between most proximal and other setae. Endopod with one outer and nine inner plumose setae, gap between most proximal and other setae.

Uropods: ( Figs. 6 L) basal article naked. Endopod with two articles; article 1 longer than exopod, with one simple and two setulose distal setae; article 2 with two simple, two as long as uropod, and 1 short circumplumose setae. Exopod uniarticulated with one medial seta, one simple distal seta, and one seta longer than endopod.

Remarks. This species is in most respects similar to P. martinsi ( Bamber & Costa, 2009), also found at the Azores, albeit at the much more shallow depths of 37.8 meters ( Bamber & Costa 2009). The major differences are the large process on the inner side of the cheliped fixed finger and the propodus with one pointed and one blunt, wide, flat, outer distal setae near dactylus insertion; all pereopods with only one ischial seta. More subtle differences are: the larger spiniform seta on the antenna article 3; the proportionally longer pereonite 1, about half as long as carapace and two-thirds as long as pereonite 2 (while about 40% of carapace length and 56% of pereonite 2 length in P. martinsi ); The longer pleotelson, about 35% the total length of pleon (while less than 20% in P. m a rtinsi); the dorsal serration/spines on the dactylus of pereopod 5 & 6. It is still possible that these are only morphological variations associated with depth, but only a genetic analysis can confirm/reject this. Furthermore the genus Paratanais is infamous for its many cryptic species (Larsen 2011). Therefore I have chosen to erect a new species but with a name reflecting the close similarity with P. martinsi .

Figures

FIGURE 6. Paratanais pseudomartinsi n. sp., female. A, holotype, B – L paratype. A, lateral view. scale bar 0.5 mm. B, antennule. C, antenna. D, labrum. E, right mandible. F, left mandible. G, labium. H, maxillule. I, maxilla. J, maxilliped. K, epignath. L, uropod. Scale bars 0.1 mm.

FIGURE 7. Paratanais pseudomartinsi n. sp., paratype, female. A, cheliped. B, same, propodus / dactylus, scale bar 0.1 mm. C, pereopod 1. D, pereopod 2. E, pereopod 3. F, Pereopod 4. G, pereopod 5. H, pereopod 6. I, pleopod, scale bar 0.1 mm. Other scale bars 0.5 mm.