Periclimenes polynesiensis, Li, 2008

Li, Xinzheng, 2008, Report on some species of Palaemonidae (Crustacea, Decapoda) from French Polynesia, Zoosystema 30 (1), pp. 203-252 : 236-242

Periclimenes polynesiensis n. sp.

( Figs 20-23 )

TYPE MATERIAL. — Marquesas Is. Nuku Hiva, MUS- ORSTOM 9, stn CP 1177, 8°45.1’S, 140°15.1’W, 108-112 m, 25.VIII.1997, ovig. ♀ holotype (cl 3.80 mm) (MNHN-Na 15608).

TYPE LOCALITY. — French Polynesia (Marquesas Is ); 108-112 m depth .

ETYMOLOGY. — The specific name is derived from the type locality, French Polynesia.

DISTRIBUTION. — Only known from the type locality.

DESCRIPTION

A small sized pontoniine shrimp of subcylindrical body form.

Carapace smooth, glabrous. Rostrum well developed, horizontal, compressed, tapered distally, extending slightly beyond distal margin of scaphocerite, subequal to carapace length; dorsal margin nearly straight, with 8 acute teeth, subequal, evenly distributed along whole rostral length, all proper to rostrum, posteriormost tooth with obscure basal suture; lateral carinae feebly developed; ventral margin with distinct basal arch, distally straight, with 3 acute teeth from 0.46 to 0.80 of rostral length, anteriormost ventral tooth just behind anteriormost dorsal tooth; interdental spaces and proximal ventral carina feebly setose. Supraorbital spine absent; epigastric spine acute, smaller than dorsal rostral tooth, situated at anterior 0.29 of carapace length, with distinct basal suture; orbit with middle part strongly concave, parts of dorsal and ventral to the concave part nearly straight, inferior orbital angle strongly produced as subovate lobe, tip rounded; antennal spine acute, marginal, distant to inferior orbital angle, extending to tip of inferior orbital angle; hepatic spine slightly larger than antennal spine, slender, 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 normal, without dorsal compressed process; sixth segment subequal to carapace length, 2.44 times length of fifth, compressed, 2.40 times longer than deep, posterolateral and posteroventral angles blunt; pleura of first 3 segments broadly rounded, fourth and fifth posteriorly produced, posterolateral angles bluntly rounded. Telson about 0.79 of sixth abdominal segment length, 4.85 times longer than anterior width, with 2 pairs of small dorsolateral spines at 0.50 and 0.78 of telson length; posterior margin rounded, without

Palaemonidae ( Crustacea, Decapoda ) from French Polynesia posterior median point, with 3 pairs of posterior spines, lateral spines small, similar to dorsal spines, intermediate spines long, robust, about 0.10 of telson length, submedian spines about half of intermediate spine length.

Eye well developed, with globular cornea, diameter of cornea 0.18 of postorbital carapace length, with distinct accessory pigment spot; stalk long, slightly tapering distally with constriction at distal conjunction with cornea, 1.11 times of corneal diameter, 1.14 times of proximal width.

Antennular peduncle reaching to level of anterior ventral rostral tooth; proximal segment depressed, medial length 0.40 times as long as carapace, 2.32 times longer than its central width, lateral margin distinctly convex, with long slender acute distolateral tooth, reaching level of produced anterolateral margin, medial margin with small ventromedial tooth at about 0.5 of proximal segment length; stylocerite acute, reaching to 0.49 of proximal segment length; intermediate segment 0.40 of proximal segment length, 1.85 times of maximum width, lateral margin expanded laterally, setose; distal segment cylindrical, slender, 0.49 times as long as proximal segment length, 2.80 times as long as wide; upper flagellum biramous, with 8 proximal segments fused, shorter free ramus with 6 segments, 0.67 of fused portion length, total length about 0.56 of carapace length, with 16 groups of aesthetascs; longer ramus slender, filiform, 0.56 times of carapace length; lower flagellum slender, filiform, 1.11 times of carapace length.

Antennal basicerite robust, with small acute lateral tooth; scaphocerite well developed, extending near tip of rostrum, 0.93 of carapace, 3.71 times longer than wide, distal margin strongly produced, rounded, far overreaching distolateral tooth, lateral margin near straight, feebly concave over distal 0.8, with strong acute distolateral tooth; carpocerite 0.31 of scaphocerite length, 2.57 times longer than wide; flagellum well developed, slender, about 5.0 times postorbital carapace length.

Epistome unarmed. Fourth thoracic sternites unarmed; posterior sternites narrow.

Mouthparts typical of the genus. Mandible without palp; molar process normal, with 4 strong blunt teeth, lower inner tooth bilobed; incisor process obliquely truncate distally with 3 stout acute teeth, central tooth smaller than outer teeth. Maxillula normal. Maxilla with short simple non-setose palp; basal endite deeply bilobed, upper lobe stouter than lower, with simple setae distally; scaphognathite well developed, about 2.92 times longer than central width. First maxilliped normal. Second maxilliped with normal endopod, dactylar segment about 2.64 times longer than broad, with numerous serrulate spines medially; propodal segment broad, distal margin with numerous long finely serrulate spiniform setae; coxa produced medially; exopod with 2 long setae distally; epipod simple, without podobranch. Third maxilliped with endopod slender, extending to tip of carpocerite, ischiomerus and basis distinct, ischiomeral segment slightly tapered distally, 0.24 of carapace length, 4.60 as long as proximal width, setose medially; penultimate segment about 0.65 of ischiomerus length, 5.68 times longer than distal width; terminal segment about 0.45 of ischiomeral length, distally tapering, 5.48 times longer than proximal width, with long setae along entire length; exopod slender, with 4 setae distally; coxa with oval lateral plate; arthrobranch distinct.

Pereiopods short and slender. First pereiopods extending to distal end of distal segment of antennular peduncle; palm of chela slightly compressed, 0.15 times of carapace length, 2.80 times as long as maximum depth, ventral margin with 4 transverse rows of short cleaning setae on proximal 0.3 of length; fingers 0.79 times of palm length, slender, base slightly expanded, tapered distally, surrounded with clusters curved setae laterally, cutting edges sharp, entire, tips hooked; carpus elongate, slightly swollen distally, 3.0 times of palm length, 8.21 times longer than distal width, with row of serrulate cleaning setae distoventrally corresponding to those on chela, including 5 long and 7 short setae; merus 2.76 of palm length, 7.43 times longer than distal width; ichium 1.63 of palm length, 5.13 times longer than distal width; basis and coxa without special features.

Left (major?) second pereiopod lost. Right (minor?) second pereiopod slender, smooth, glabrous, exceeding carpocerite by chela and carpus; palm subcylindrical, slightly compressed, expanding distally, 0.39 of carapace length, 3.66 times longer than distal depth; fingers 0.47 of palm length, tapering distally, with strongly hooked tips and long subdistal setae, dactyl 3.73 times longer than proximal depth, cutting edges sharp, with very low tooth at middle of dactyl length, fixed finger slightly more robust, cutting edge with 2 very low teeth at positions just proximal and distal to the tooth on dactyl when fingers closed, and proximal hollow fitting proximal part of dactyl cutting edge; carpus slender, long, 1.14 of palm length, 5.97 of the distal width; merus 1.08 of palm length, 7.50 of distal width, unarmed distoventrally; ischium 1.27 times of palm length, 9.61 times distal width; basis and coxa normal.

Third pereiopod exceeding carpocerite by dactyl and propod, reaching distal end of scaphocerite; dactyl slender, compressed, simple, 0.25 of propod length, unguis distinct, very slender and elongate, 0.77 of corpus length, corpus 2.74 times longer than proximal depth, ventral margin unarmed, without distal accessory tooth; propod compressed, subuniform, 0.54 of carapace length, 10.1 times longer than deep, with pair of short slender simple distoventral spines, spines 0.04 of propod length, 0.27 of dactyl corpus length, ventral margin with two single spines distributed at distal 0.33 and 0.09 of propod length, of which, distal spine long, 0.32 of dactyl corpus length, proximal tooth very short, 0.45 of distal tooth length, distal margin of propod with 2 distoventral and 2 distodorsal long curved setae, without transverse rows of setae; carpus 0.46 of propod length, 4.5 times longer than distal width, distodorsal margin with produced lobe; merus 1.04 of propod length, 8.6 times longer than wide, uniform, unarmed; ischium 0.42 of propod length, 3.58 times longer than distal width, slightly tapered proximally; basis and coxa without special features. Fourth and fifth pereiopods similar to third, fourth propod 1.06, fifth propod 1.16 times as long as third propod length; fifth exceeds carpocerite by dactyl and distal 0.80 of propod, propod with transverse rows of cleaning setae distolaterally.

Uropod distinctly exceeding telson, exopod exceeds telson by lobe distal to diaeresis; protopodite with posterolateral angle short, rounded; exopod 0.93 of carapace length, 4.11 times longer than central width, lateral border near straight, with very small acute distal tooth, and large mobile spine medially, diaeresis distinct; endopod narrow, 0.77 of exopod length, 4.32 times longer than wide.

Egg with moderate size, maximum length 0.46 mm.

A

REMARKS

Periclimenes polynesiensis n. sp. closely resembles P. uniunguiculatus Bruce,1990 , especially in the form of the rostrum and pereiopods.It can be distinguished from the latter by the epigastric spine being widely separated from the rostral series of dorsal teeth, the hepatic spine being not noticeably larger than antennal spine, the eyestalk being more slender and elongate, the dactyli of ambulatory pereiopods being more slender and longer, 0.25 times as long as the propod of third pereiopod (vs. 0.12 in P. uniunguiculatus ), the third propod lacking transverse rows of long setae distoventrally.The new species is also closely similar to P.fujinoi Bruce, 1990 . It differs from the latter by the epigastric spine not being very posterior (at anterior 0.29 of carapace length, vs. 0.4 in P. fujinoi ), all dorsal rostral teeth being on rostrum (vs. posterior 2 on carapace posterior to orbital margin in P.fujinoi ), the eye having a distinct accessory pigment spot (lacking the spot in P. fujinoi ), the third propod having a pair of distoventral spines (single only in P. fujinoi ). The proximal antennular peduncle segment of P. polynesiensis n. sp. with the distal margin being produced anteriorly, reaching tip of the distolateral tooth, the lateral margin being distinctly convex, is different from those of P. uniunguiculatus and P. fujinoi , too.

The loss of the major second pereiopod of the holotype limits the comparison of the new species with the similar species,however,the combined morphological features of rostrum, eye, and ambulatory pereiopods indicates that it is distinct from the other closely allied species. Captured at a depth of 102-118 m, it occurs in much shallower depth than P. uniunguiculatus (456-1280 m) and P. fujinoi (487-610 m).

Figures

FIG. 20. — Periclimenes polynesiensis n. sp., holotype ovig. ♀ (MNHN-Na 15608), body, lateral view. Scale bar: 1 mm.

FIG. 21. — Periclimenes polynesiensis n. sp., holotype ovig. ♀ (MNHN-Na 15608): A, carapace; B, telson and uropod; C, posterior tip of telson; D, eye; E, antennule; F, scaphocerite. Scale bars: A, B, F, 1 mm; C, 0.25 mm; D, E, 0.5 mm.

FIG. 22.— Periclimenes polynesiensis n. sp.,holotype ovig.♀ (MNHN-Na 15608):A, mandible;B, maxillula;C, maxilla;D, first maxilliped; E, second maxilliped; F, third maxilliped. Scale bars: 0.5 mm.

FIG. 23. — Periclimenes polynesiensis n. sp., holotype ovig. ♀ (MNHN-Na 15608): A, first pereiopod; B, same, chela; C, second pereiopod; D, same, fingers; E, third pereiopod; F, same, dactyl and distal part of propod. Scale bars: A, C, E, 1 mm; B, D, 0.5 mm; F, 0.25 mm.