Periclimenes vicinus, Li, 2008

Li, Xinzheng, 2008, Report on some species of Palaemonidae (Crustacea, Decapoda) from French Polynesia, Zoosystema 30 (1), pp. 203-252 : 242-248

Periclimenes vicinus n. sp.

( Figs 24-27 )

TYPE MATERIAL. — AustralIs. Tubuai,BENTHAUS, stnCP 1967, 23°21.4’S, 149°34.2’W, 600-1200 m, 19.XI.2002, ♀ holotype (cl 4.0 mm) (MNHN-Na 15987).

TYPE LOCALITY. — French Polynesia (Austral Is); 600- 1200 m depth .

ETYMOLOGY. — “Vicin”, Latin for close, near to, as the new species very closely resembles Periclimenes uniunguiculatus, Bruce, 1990 .

DISTRIBUTION. — Only known from the type locality.

Palaemonidae ( Crustacea, Decapoda ) from French Polynesia

DESCRIPTION

A small sized pontoniine shrimp of subcylindrical body form.

Carapace smooth, glabrous. Rostrum well developed, horizontal, compressed, moderately slen- der, extending slightly beyond distal margin of scaphocerite, subequal to carapace length; dorsal margin near straight, with 12 long, acute teeth (not including epigastric spine), subequal, evenly distributed along whole rostral length, except for 2 smaller distal teeth, posteriormost tooth on carapace posterior to posterior orbital margin, second tooth just above the posterior orbital margin; lateral carina distinct, sharp, extending anteriorly to level of anterior fourth dorsal rostral tooth; ventral margin feebly convex, with 3 acute teeth from 0.47 to 0.71 of rostral length, anteriormost ventral tooth below fourth dorsal tooth from tip. Supraorbital spine absent; epigastric spine acute, smaller than posteriormost dorsal rostral tooth, situated at anterior 0.28 of carapace length, with distinct basal suture; orbital margin evenly concave, inferior orbital angle produced, rounded; antennal spine acute, just below inferior orbital angle, extending beyond tip of inferior orbital angle; hepatic spine long, slender, and much larger than antennal spine, extending near to anterior margin of carapace, arising below level of antennal spine, anterior to level of epigastric spine; anterolateral angle of carapace not produced, bluntly rounded.

Abdominal segments smooth, glabrous; third segment with tergum distinctly gibbous, without dorsal compressed process, posterior margin entire; sixth segment long, slender, subcylindrical, 0.82 of carapace length, 2.42 times of fifth segment length, 2.87 times longer than deep, posterolateral angle acute, posteroventral angle blunt; pleura of first 3 segments broadly rounded, fourth and fifth posteriorly produced, posterolateral angles bluntly rounded.Telson long, narrow, 1.03 of sixth segment length, 4.64 times longer than anterior width, with two pairs of dorsolateral spines at 0.46 and 0.74 of telson length, spines 0.05 of telson length; posterior margin rounded, without acute posterior median

A

B

point, with 3 pairs of posterior spines, lateral spines small, similar to dorsal spines, intermediate spines long, slender, 0.22 of telson length, submedian spines about 0.33 of intermediate spine length.

Eye well developed, with globular cornea, diameter of cornea 0.23 of postorbital carapace length, without accessory pigment spot; stalk short, robust, subcylindrical, subuniform, 0.63 times of width, width slightly narrower than diameter of cornea.

Antennular peduncle reaching to level of anterior third dorsal rostral tooth; proximal segment depressed, medial length 0.46 times as long as carapace, 2.16 times longer than central width, lateral margin distinctly convex, with long, slender, acute, slightly medially curved distolateral tooth, extending beyond level of produced anterolateral margin, medial margin with small ventromedial tooth at proximal 0.45 of proximal segment length; stylocerite acute, reaching to 0.63 of proximal segment length; intermediate segment short, dorsal length 0.26 times of proximal segment length, slightly depressed, 1.01 times of width; distal segment cylindrical, slender, 0.38 times as long as proximal segment length, 1.89 times as long as wide; upper flagellum biramous, with 6 proximal segments fused, shorter free ramus with 5 segments, 0.91 times of fused portion length, total length about 0.69 times of carapace length, with 18 groups of aesthetascs; longer ramus slender, filiform; lower flagellum slender, filiform.

Antennal basicerite robust, with acute lateral tooth; scaphocerite well developed, extending near tip of rostrum, 0.83 of carapace, 3.08 times longer than wide, distal margin produced, rounded, slightly overreaching tip of distolateral tooth, lateral margin near straight, feebly concave, with strong acute distolateral tooth; carpocerite 0.29 of scaphocerite length, 3.61 times longer than wide; flagellum well developed, slender, filiform.

Epistome unarmed. Fourth thoracic sternite with low transverse ridge with median notch, fifth with low transverse ridge with similar median notch; posterior sternites narrow.

Mouthparts typical of the genus. Mandible without palp; molar process normal, with blunt teeth, lower inner tooth bilobed; incisor process obliquely truncate distally with three stout acute teeth, central tooth smaller than outer teeth. Maxillula with well developed bilobed palp, lower lobe with small ventral tubercle. Maxilla with short simple non-setose palp; basal endite deeply bilobed, upper lobe stouter than lower, with simple setae distally; scaphognathite damaged when dissected. First maxilliped with slender palp with long subterminal setulose seta; exopod well developed, caridean lobe large, broad, flagellum slender with 3 plumose distal setae; epipod large, triangular, bilobed. Second maxilliped with normal endopod, dactylar segment broad, 1.85 times longer than maximum width, with numerous serrulate spines medially; propodal segment broad, distal margin with numerous long finely spiniform setae; coxa produced medially, with 3 simple setae; exopod with slender flagellum with single long simple distal seta; epipod simple, without podobranch. Third maxilliped with endopod slender, extending to proximal 0.33 of carpocerite, ischiomerus and basis fused, basal portion medially expanded, convex, ischiomerus subuniform, compressed, combined segment length 0.39 of carapace length, 5.50 times of central width, setose medially; penultimate segment 0.50 of combined segment length, 3.62 times longer than basal width, setose medially; terminal segment 0.45 of combined segment length, distally tapering, 4.60 times longer than proximal width, with groups of long finely serrulate spiniform setae medially; exopod slender, extending to 0.91 of combined segment length, with 2 terminal and 1 subterminal simple setae; coxa with oval lateral plate; arthrobranch rudimentary.

Pereiopods long. First pereiopods extending near to distal end of scaphocerite, beyond carpocerite by chela and distal half of carpus; palm of chela subcylindrical, 0.22 times of carapace length, 3.22 times as long as maximum depth, ventral margin with 4 transverse rows of short cleaning setae on proximal 0.33 of length; finger 0.78 times of palm length, slender, base slightly expanded, tapered distally, surrounded with 5 (dactyl) or 6 (fixed finger) clusters of long setae outer surface in distal half, cutting edges sharp, entire, tips hooked; carpus slightly swollen distally, 1.70 times of palm length, 5.76 times longer than distal width, with a row of serrulate cleaning setae distoventrally corresponding those on palm; merus 1.95 times of palm length, 7.76 times longer than distal width; ischium 0.79 of palm length, 3.43 times longer than distal width; basis and coxa without special features.

Second pereiopods well developed, similar, unequal. Major (left) second pereiopod smooth, glabrous, exceeding carpocerite by chela and carpus; palm subcylindrical, 0.98 of carapace length, very slightly swollen proximally, 4.14 times longer than maximal depth, fingers 0.46 of palm length, with stout hooked tips; dactyl compressed, uniform except for slenderer tip, 5.37 times longer than deep, lateral flange developed, sharp in distal 0.60 of dactyl length, distal 0.59 of cutting edge entire, sharp, a strong and shallow blunt tooth at proximal 0.28 of cutting edge, 2 shallow notches present respectively proximal and distal to the tooth on cutting edge; fixed finger similar, without lateral flange, distal 0.72 of cutting edge entire, sharp, with 2 teeth at proximal 0.21 and 0.29 of cutting edge, distal tooth shallow, continuing with distal entire cutting edge, proximal tooth developed, rounded, a notch present between the 2 teeth, corresponding to the dactyl tooth; carpus cup-like, 0.23 of palm length, 1.38 times longer than distal width, feebly excavate distally, proximally tapered, unarmed; merus subcylindrical, subuniform, 0.63 of palm length, 5.26 times longer than deep, unarmed; ischium very slightly swollen distally, 0.42 of palm length, 5.22 times longer than distal width, unarmed; basis and coxa normal. Minor (right) second pereiopod slender, smooth, glabrous, exceeding carpocerite by chela and distal 0.75 of carpus; palm subcylindrical, slightly tapering distally, 0.59 of carapace length, 0.60 of major palm, 4.92 times longer than maximal depth; fingers 0.59 of palm length, slightly tapering distally, with strongly hooked tips and long subdistal setae, dactyl 5.65 times longer than proximal depth, with lateral flange over distal 0.60 of dactyl length, cutting edges sharp, with distal 0.71 entire, proximal 0.29 sinuous, fixed finger, with 2 very low blunt teeth at proximal 0.20 and 0.30 of cutting edge, proximal tooth larger than distal; carpus cup-like, 0.39 of palm length, 2.19 times of the distal width, unarmed; merus slightly compressed proximally, 1.04 of palm length, 6.75 of the distal width, unarmed distoventrally; ischium compressed, slightly tapering proximally, 0.68 times of palm length, 5.71 times of distal width; basis and coxa normal.

Third pereiopod exceeding carpocerite by dactyl, propod and distal 0.20 of carpus, overreaching distal end of scaphocerite by dactyl and distal 0.20 propod; dactyl short, compressed, strongly curved, 0.15 of propod length, unguis distinct, articulated, slender, 0.70 of dorsal length of corpus, corpus 2.03 times longer than proximal depth, ventral margin straight, unarmed, without distal accessory tooth, with 2 distolateral sensory setae; propod 0.62 of carapace length, uniform, 12.50 times longer than wide, with a single slender distoventral spine, spine 0.06 of propod length, 2 single spines on distal 0.13 of ventral margin, spines largely obscured by accompanying transverse rows of long ventral setae, distoventral-lateral transverse rows of long setae overreaching tip of dactyl, distodorsal margin of propod with long setae; carpus 0.47of propod length, slightly tapering proximally, 5.45 times longer than distal width, unarmed, distodorsally produced lobe distinct; merus 1.06 of propod length, uniform, 10.34 times longer than wide, unarmed; ischium 0.46 of propod length, slightly tapering proximally, 5.04 times longer than distal width; basis and coxa without special features. Both fourth and left fifth pereiopods lost. Right fifth pereiopod similar to third, overreaching carpocerite by propod and dactyl, propod 1.22 times of third propod length.

Uropod distinctly exceeding telson, distolateral tooth of exopod just overreaching tip of telson; protopodite with posterolateral angle short, rounded; exopod 0.87 of carapace length, 3.73 times longer than maximum width, lateral margin near straight, with very small acute distal tooth, and long and slender mobile spine medially, mobile spine about 0.04 of exopod length, diaeresis distinct; endopod narrow, 0.88 of exopod length, 4.09 times longer than maximum wide.

REMARKS

As the etymology above indicates, Periclimenes vicinus n. sp. looks very similar to P.uniunguiculatus ,especially as concerns the pereiopods and tailfan. It can be distinguished from the latter by the noticeably long and slender hepatic spine which extends nearly to the anterior margin of the carapace, instead of distinctly distant to the anterior margin of the carapace in P. uniunguiculatus ; the epigastric spine is widely separated from the rostral series of dorsal teeth, instead of subequal interdental between the posterior rostral series teeth in P.uniunguiculatus ; there are only a single distoventral spine and two ventral spines which are distinctly separated from the ventral border in the third ambulatory propod, instead of a pair of distoventral spines and three ventral spines which are closely adpressed to the ventral border in P.uniunguiculatus ; and the rostrum is horizontal, rather than slightly upcurved distally in P. uniunguiculatus .

Figures

FIG. 24. — Periclimenes vicinus n. sp., holotype ♀ (MNHN-Na 15987), body, lateral view. Scale bar: 1 mm.

FIG. 25. — Periclimenes vicinus n. sp., holotype ♀ (MNHN-Na 15987): A, rostrum and anterior part of carapace,lateral view; B, telson, dorsal view; C, eye; D, antennule; E, antenna; F, uropod. Scale bars: 1 mm.

FIG. 26.— Periclimenes vicinus n. sp.,holotype ♀ (MNHN-Na 15987):A, mandible;B, maxillula;C, maxilla;D, first maxilliped;E, second maxilliped; F, third maxilliped. Scale bars: A-E, 0.5 mm; F, 1 mm.

FIG. 27. — Periclimenes vicinus n. sp., holotype ♀ (MNHN-Na 15987): A, first pereiopod; B, same, chela; C, major second pereiopod; D, same, fingers; E, minor second pereiopod; F, same, fingers; G, third pereiopod; H, same, dactyl and distal part of propod. Scale bars: A, C-G, 1 mm; B, 0.5 mm; H, 0.25 mm.