Pagurapseudes inquilinus, Bamber, 2007

Bamber, Roger N., 2007, New apseudomorph tanaidaceans (Crustacea, Peracarida, Tanaidacea) from the bathyal slope off New Caledonia, Zoosystema 29 (1), pp. 51-81 : 75-80

Pagurapseudes inquilinus n. sp.

( Figs 13-15 )

TYPE MATERIAL. — Holotype: New Caledonia, BIO- CAL, stn DW 44, 22°47.35’S, 167°14.50’E- 23°47.34’S,

167°14.80’E, 440-450 m depth, 30.VIII.1985, 1 ♀ with brood pouch (MNHN-Ta931).

Paratypes: same data as holotype, 1 brooding ♀, 1 subadult ♂, 1 ♂, dissected (MNHN-Ta932) ; 1 brooding ♀, 1 subadult ♂ (NHM.2005.2716-2717).

TYPE LOCALITY. — Off New Caledonia, 22°47.35’S, 167°14.50’E- 23°47.34’S, 167°14.80’E.

ETYMOLOGY. — From the Latin “ inquilinus ”, a tenant or lodger.

DESCRIPTION

Female

Body ( Fig. 13A ) typical of a pagurapseudid, pleon skewed to the right and curved under pereon; small, holotype about 1.15 mm long. Cephalothorax narrowing anteriorly, 0.9 times as long as wide, with straight denticulate anterior margin, the outer teeth largest; scattered dorsal setae and posterolateral setae all plumose. Eyelobes distinguished, eyes present as sparse group of ocelli, unpigmented in preserved material. Epistome small. Six free pereonites, all with paired anterior and lateral plumose setae; pereonite 1 shortest, 0.6 times as long as pereonite 2; pereonites 2 to 6 subequal, pereonites 4 and 5 just longest. Pleon of five free subequal pleonites, pleonites 1, 2 and 3 only bearing pleopods, each pleonite about half as long and 0.7 times as wide as pereonite 6. Pleotelson ( Fig. 13B ) pentagonal, longer than last two pleonites together, 1.14 times as wide as long; with numerous plumose lateral, dorsal and posterior setae as figured.

Antennule similar to that of male ( Fig. 13C ), proximal peduncle article 7 times as long as wide, with conspicuous inner and outer apophyses, mostly accompanied by plumose setae, and blunt distal apophysis; second and third articles subequal, 0.15 times as long as first, fourth peduncle article 1/3 length of third. Main flagellum of seven segments, with single aesthetascs on segments 4, 6 and 7; accessory flagellum of two segments, distally reaching to half length of fourth segment of main flagellum.

Antenna ( Fig. 13D ) with wide proximal peduncle article bearing two spine-like apophyses and four plumose setae in distal half, and inner proximal apophysis and simple seta; second article as long as wide; third and fourth peduncle articles subequal, twice as long as second, both with plumose distal sensory setae. Flagellum of two segments, distal segment with three distal setae.

Labrum ( Fig. 14A ) bilobed, sparsely setose. Left mandible ( Fig. 14B ) with tricuspid pars incisiva, lacinia mobilis inconspicuous, setiferous lobe with four variously crenulate setae, pars molaris round, blunt, simple; palp of three articles, proximal article with long, plumose distal seta, second article longest, four times as long as proximal article, with five pairs of inner setae in distal half; third article 3/4 as long as second, with nine progressively longer setae in distal half, distal pair as long as article. Right mandible as left but without lacinia mobilis. Labium ( Fig. 14G ) typically marginally setose, palp with two distal setae. Maxillule ( Fig. 14D ) inner endite with four finely plumose distal setae, outer endite with nine distal spines, outer margins sparsely setose; palp of two articles with indistinct articulation, distally with five finely-setulose setae with expanded tips and single longer simple seta. Maxilla ( Fig. 14C ) with rostral row of about 20 simple setae, fixed endite with trifurcate, simple and bifurcate setal groups and serrate margin; moveable endite lobes fused and with simple setae. Maxilliped ( Fig. 14E, F ) endite with five slender outer distal setae, four inner distal bilobed spines and innermost plumose seta; proximal palp article with denticulate outer margin with one plumose seta, and three plumose sensory setae on ventral face; second article with three long plumose setae on denticulate outer margin, five shorter simple inner spines and six plumose setae along inner margin; third article with two dorsal and four inner marginal simple setae, inner and outer margins crenulate; distal article with eleven finely denticulate inner-marginal and distal setae, and dorsal row of five similar setae.

Chelipeds ( Fig. 14H ) showing no conspicuous dimorphism. Compact basis 1.6 times as long as wide, with subdistal, ventral plumose seta and three ventral marginal spines, and dorsoproximal denticulation; exopodite absent. Merus triangular, ventral margin with membranous spine-like apophyses, plumose seta in distal half with two adjacent outer small spines. Carpus elongate, just more than twice as long as wide, widening distally, with groups of short proximal spines, ventral margin with membranous spine-like apophyses in distal half. Propodus slender, twice as long as wide, setose as figured, fixed finger with row of small teeth and five small spines distally on cutting edge; moveable finger slender, curved.

Pereopod 1 ( Fig. 15A ) longest pereopod, with stout basis twice as long as wide, dorsal margin bearing nine plumose setae, ventral margin with numerous small, simple setae and single distal plumose seta; exopodite present, large, distal article with 13 plumose setae. Ischium 0.4 times as long as basis, with dorsal and ventral simple distal setae and single ventrodistal plumose seta. Merus as long as basis, ventral margin with short plumose setae, and spines mainly in distal half. Carpus shorter than merus, with short ventral spines and simple setae, single ventrodistal and paired dorsodistal setae plumose. Propodus longer than merus, with short ventral spines and simple setae. Dactylus curved, 1.1 times as long as propodus, with ventral flagellated blunt apophyses, unguis slender, blunt, 0.4 times as long as dactylus.

Pereopods 2 to 6 ( Fig. 15 ) similar to each other, progressively shorter, each about 1/3 as long as pereopod 1; bases 3 times (pereopod 2) to twice (pereopod 6) as long as wide, with subdistal, ventral plumose seta, and rows of dorsal plumose setae numbering 7, 2, 3, 2 and 1 on pereopods 2 to 6 respectively; ischium with paired ventrodistal setae, both plumose on pereopod 2, one simple on pereopods 3 to 6. Merus, carpus and propodus bearing “sucker-like” spines and plumose setae as figured. Merus about as long as carpus on pereopods 2 to 4; on pereopods 5 and 6 carpus 3 times as long as merus. Propodus of pereopod 2 with simple distal seta; propodus of pereopod 6 with distal denticulate spine and adjacent simple spine. Dactylus and unguis not fused into claw, with minute inner seta on pereopods 4 to 6.

Pleopods ( Fig. 13E ) all alike, biramous, the rami slender, as long as basis, and bearing plumose setae; basis with single dorsal and ventral plumose setae. Uropod ( Fig. 13B ) biramous, basis with three small outer and one longer mesial distal setae; endopod longer than basis, of three segments increasing in length, second segment distally with two simple setae, third segment with three stout distal setae; exopod of one segment, just longer than proximal endopod segment, with two stout distal setae.

Male closely similar to female, but antennule ( Fig. 13C ) with more aesthetascs on main flagellum (one each on segments 2 to 7).

REMARKS

Pagurapseudes inquilinus n. sp. is morphologically and geographically close to the type species of the genus, P. spinipes Whitelegge, 1901 , recorded from New South Wales, Australia, at depths of 37 to 108 m ( Whitelegge 1901); indeed, it keys out to that species in the key to the nine species known previously of Guţu (1997). The gross morphology of both animals is quite similar. The present species is distinguished in that pereonites 2 to 4 are subequal in P. inquilinus n. sp., without posterior “incisions” (2 <3 <4 in P. spinipes , with posterior “submedian incisions”), the rostral margin is more coarsely denticulate (“minutely spinulose” in P. spinipes ), the pleonites are subequal (pereonite 1 “rather longer” in P. spinipes ), the main and accessory flagella of the antennule have seven and two segments respectively (four and one in P. spinipes ; note that, in his text, Whitelegge [1901] included the distal peduncle article in both flagella), the basal apophysis on the antenna is much smaller in P. inquilinus n. sp., and the basis of pereopod 1 has long, plumose setae, while Whitelegge (1901) describes and figures only “a few small denticles on the anterior border”. The segmentation of the antennular flagella serves as a ready character to distinguish these species without dissection.

Pagurapseudes abrucei Băcescu, 1981 , from Heron island, Queensland, at 30 m depth, is the only other species described from this region. That species has four and two articles in the main and accessory flagella of the antennule respectively, and a prominent triangular rostrum without denticulation ( Băcescu 1981).

Figures

FIG. 13. — Pagurapseudes inquilinus n. sp., ♀: A, holotype ♀, entire; B, pleotelson,dorsal;C, right antennule of male;D, right antenna; E, pleopod (plumose nature of setae not shown). Scale bar: A, 1 mm; B-E, 0.5 mm.

FIG. 14. — Pagurapseudes inquilinus n. sp., ♂: A, labrum;B, left mandible; C, maxilla;D, maxillule,with distal detail of palp seta;E, left maxilliped palp, showing inner and ventral setae only; F, right maxilliped, showing outer and dorsal setae of palp only; G, labium; H, right cheliped. Scale bar: A-G, 0.3 mm; H, 0.5 mm.

FIG. 15. — Pagurapseudes inquilinus n. sp., ♂: A-F, pereopods 1-6 respectively. Scale bar: A, 0.45 mm; B-F, 0.3 mm.