Periclimenes crosnieri, Li & Bruce, 2006

Li, Xinzheng & Bruce, Alexander J., 2006, Further Indo-West Pacific palaemonoid shrimps (Crustacea: Decapoda: Palaemonoidea), principally from the New Caledonian region, Journal of Natural History 40 (11 - 12), pp. 611-738 : 681-686

Periclimenes crosnieri sp. nov.

( Figures 16–18 )

Material examined

Indonesia: KARUBAR, Tanimbar Islands , stn CP45, 7 ° 549S, 132 ° 479E, 302–305 m, 29 October 1991, ♀ holotype (cl 5.81 mm); ♀ paratype (cl 5.68 mm) (MNHN-Na 14943) .

Description

Holotype. A medium body size pontoniine shrimp of subcylindrical body form.

Carapace smooth, glabrous. Rostrum well developed, moderately deep, compressed, extending beyond antennular peduncle, about 0.67 of carapace length, not reaching distal margin of scaphocerite, anteroventrad proximally, upcurved distally; dorsal carina deep, with seven subequal, evenly distributed along whole length, teeth acute, first tooth situated just above posterior orbital margin; lateral carinae feebly developed, slightly upcurved distally; ventral carina deep distal half, with two low acute teeth on distal third, smaller than dorsal teeth; interdental spaces and proximal ventral carina feebly setose. Supraorbital spine absent, epigastric spine situated at anterior 0.25 of the carapace length; orbit feebly developed, inferior orbital angle strongly produced, bluntly round in dorsal view; antennal spine small slender marginal, distinctly below inferior orbital angle, not exceeding inferior orbital angle; hepatic spine larger than antennal spine, slender, below level of antennal spine, below and between epigastric spine and first dorsal rostral tooth in lateral view; anterolateral angle of carapace not produced, bluntly rounded.

Abdominal segments smooth, glabrous; sixth segment about 1.57 times length of fifth, subcylindrical, about 1.53 times longer than deep, subuniform, posterolateral angle acute, posteroventral angle rounded; pleura of first three segments small, broadly rounded, fourth and fifth posteriorly produced, bluntly rounded. Telson about 1.64 times sixth segment length, about 3.6 times longer than anterior width, lateral margins with anterior third curved ventrally, posterior two-thirds straight, convergent, posterior margin about 0.36 of anterior margin width, rounded, without posterior median point; dorsal surface with sparse long setae, with four pairs of small but well-developed dorsolateral spines at 0.41, 0.59, 0.76, and 0.88 of telson length; three pairs of posterior spines, lateral spines short, similar to dorsal spines, about 0.02 of telson length, intermediate spines long, robust, about 0.08 of telson length, submedian spines robust, about 0.43 of intermediate spine length.

Eye small, with feebly pigmented globular cornea, diameter of cornea 0.14 of posterior orbital carapace length, without accessory pigment spot; stalk subequal to corneal diameter, subequal to its width.

Antennular peduncle overreaching to seventh dorsal rostral tooth; proximal segment about 2.0 times longer than central width, with slender acute stylocerite laterally, reaching to about 0.7 of segment length, anterolateral margin feebly produced, setose, with long slender acute lateral tooth reaching to the end of dorsal margin of intermediate segment; statocyst small; medial margin setose, with ventromedial tooth at about 0.5 of length; intermediate segment obliquely articulated with distal segment, dorsal length about 0.25 of proximal segment length, 0.7 of width, lateral margin expanded, setose; distal segment about 2.1 times intermediate segment length, 0.46 of proximal segment length, slender, about 1.9 times longer than distal width; upper flagellum biramous, with eight proximal segments of rami fused, shorter free ramus with five segments, length about 0.46 of fused portion, total length about 0.38 of carapace length, with about 17 groups of aesthetascs; longer ramus, slender, filiform, about 0.45 times carapace length; lower flagellum slender, filiform, about 0.73 times carapace length.

Antennal basicerite robust, with acute lateral tooth; carpocerite about 0.45 of length of lateral margin of scaphocerite, about 3.8 times longer than width, subcylindrical, reaching about 0.42 of total length of scaphocerite; flagellum well developed, slender, about 2.6 times postorbital carapace length; scaphocerite well developed, distinctly exceeding tip of rostrum, broad, about 2.1 times longer than wide, greatest width at about 0.4 of length, distal margin bluntly rounded, lateral margin feebly convex, with strong acute distolateral tooth, reaching near to distal lamella.

Epistome unarmed. Fourth thoracic sternite without slender median process, with low transverse ridge with shallow median notch; posterior sternites narrow.

Mouthparts typical of the genus. Mandible with corpus moderately robust, without palp; molar process normal, with four strong blunt teeth, lower inner tooth bilobed; incisor process robust, obliquely truncate distally with three stout acute teeth, central tooth smaller than outer teeth. Maxilla with short simple non-setose palp; basal endite deeply bilobed, upper lobe stouter than lower, with simple setae distally; coxal endite obsolete, medial margin convex; scaphognathite well developed, about 3.2 times longer than central width, posterior lobe about 0.34 of scaphocerite length, 1.5 times longer than wide, anterior lobe with median margin concave, about 1.7 times longer than wide. Second maxilliped with normal endopod, dactylar segment about 4.0 times longer than broad, with numerous serrulate spines medially; propodal segment broad, with distal margin with numerous long finely serrulate spiniform setae; carpus, ischiomerus and basis without special features; coxa angularly produced medially, with four to five simple setae; exopod with slender flagellum with eight to nine plumose setae distally; epipod simple, without podobrach. Third maxilliped with slender endopod, extending distally to the middle of the carpocerite, ischiomerus and basis fused incompletely, basal portion medially expanded, convex, combined segment length about 5.0 times central width, compressed, setose medially, with submarginal row of 15–17 very short small spines on proximal medial ischial portion; intermediate segment about 0.45 of combined proximal segment length, 3.2 times longer than central width, with several groups of long finely serrulate spiniform setae medially; terminal segment about 0.3 of combined proximal segment length, distally tapering, about 3.2 times longer than proximal width, with sparse spiniform setae medially, with long distal spines; exopod with slender flagellum with 12–14 plumose setae distally; coxa feebly produced medially, with oval lateral plate; arthrobranch distinct.

First pereiopods moderately slender, exceeding tip of rostrum by length of chela; chela with palm subcylindrical, slightly compressed, about 2.0 times longer than maximal depth, at about proximal 0.4 of length with several tranverse rows of short cleaning setae proximoventrally; finger subequal to palm length, slender, tapering, cutting edges sharp, entire, tips hooked, base slightly expanded, surrounded by palisade of short curved setae medially and laterally, carpus about 1.3 of chela length, 5.0 times longer than distal width, tapering proximally, with seven to eight serrulate cleaning setae distoventrally; merus about 1.4 times chela length, 5.4 times longer than central width; ichium 1.1 of palm length, 2.75 times longer than distal width, not strongly carinate distoventrally, obliquely articulated with basis; basis about 0.34 of carpus length; coxa without ventromedial process.

Second pereiopods well developed, generally similar, unequal. Major (right) second pereiopod exceeding carpocerite by chela and carpus; chela about 1.33 times carapace length, palm subcylindrical, subuniform, with small tubercles, some of the tubercles with short and fine setae on tip, about 3.4 times longer than maximal depth, fingers about 0.45 of palm length, with stout hooked tips and both with well-developed lateral flanges, lateral surfaces with small tubercles similar to those of palm; dactyl about 3.8 times longer than proximal depth, with developed lateral flange, 0.6 distal cutting edge entire, large triangular acute tooth at proximal quarter, notch present distal to and proximal to tooth, respectively; fixed finger stouter than dactyl, with well-developed lateral flange, cutting edge with large pit at base, large tooth with rounded tip present in pit, distal three-quarters cutting edge entire; carpus about 0.22 of palm length, 1.1 times longer than distal width, cup-like, feebly excavate distally, proximally tapered, armed with small tubercles similar to palm; merus about 0.5 of palm length, subuniform, about 3.65 times longer than distal depth, armed with sparse small tubercles, without distoventral tooth; ischium about 0.5 of palm length, subequal to merus length, 3.66 times longer than distal width, slightly dorsoventrally compressed, slightly proximally tapered, armed with sparse small tubercles; basis and coxa normal. Minor (left) pereiopod exceeding carpocerite by chela and distal two-thirds of carpus; chela about 0.81 times postorbital carapace length, 0.62 times length of major chela; palm about 3.5 times longer than maximal depth, with very sparse small tubercles; fingers about 0.5 of palm length, with strongly hooked tips, cutting edges entire, sharp, with feebly dentition proximally; dactyl about 4.8 times longer than proximal depth, with feebly developed lateral flange; carpus cup-like, about 0.33 of palm length, 1.2 times the distal width, with scattered small tubercles; merus about 0.84 of palm length, subequal to ischium, with tubercles ventrally; basis and coxa normal.

Ambulatory pereiopods robust. Third pereiopod exceeds carpocerite by dactyl, propod, and distal quarter of carpus; dactyl compressed, curved, about 0.22 of propod length, unguis distinct, about 0.75 of dorsal length of corpus, corpus about 2.5 times longer than proximal depth, ventral margin unarmed, without distal accessory tooth, with two distolateral sensory setae; propod about 0.51 of carapace length, 6.8 times longer than maximum wide, slightly tapered distally, with pair of short slender simple distoventral spines, three single spines distributed on ventral margin, and transverse rows of long setae distolaterally; carpus about 0.52 of propod length, 3.65 times longer than distal width, unarmed; merus 1.08 of propod length, 6.5 times longer than wide, uniform, unarmed; ischium subequal to carpus length, 0.5 of merus length, 3.45 times longer than distal width, slightly tapered proximally; basis and coxa without special features. Fourth and fifth pereiopods similar to third, fourth propod subequal, fifth propod 1.1 times third propod length, less strongly spinose distoventrally; fifth exceeds carpocerite by dactyl and distal three-fifths propod, with propod with transverse rows of cleaning setae distolaterally.

Uropod distinctly exceeding telson; protopodite with posterolateral angle short, rounded; exopod 2.4 times longer than central width, lateral border distinctly convex, with small acute distal tooth, with large mobile spine medially, diaeresis distinct; endopod about 0.9 of exopod length, 3.0 times longer than wide.

Paratype. Similar to holotype. Rostrum longer than that of the holotype, 0.77 of carapace length, but not reaching the distal end of scaphocerite, lower than that of holotype, dorsal margin slightly concave, with eight dorsal and four ventral teeth, interdental spaces and with distinct short setas. Telson regenerated and soft except the extreme base, the four dorsolateral spines distinct along right margin, obscure along left margin.

Measurements (mm)

Holotype. Female, carapace length, 5.81; carapace and rostrum, 10.19; second pereiopod, major chela, 7.74; minor chela, 4.80.

Paratype. Female, carapace length, 5.68; carapace and rostrum, 10.03; second pereiopod, major chela, 8.47; minor chela, 5.57.

Systematic position

In its general morphology, particularly the telson with four pairs of dorsolateral spines, major second pereiopods with lateral flange on the fingers and palms covered with fine tubercles, and shape of the rostrum, Periclimenes crosnieri sp. n. shows a close resemblance to P. aleator Bruce, 1991 and other species of the ‘‘ P. alcocki species group’’. It can immediately be distinguished from these species by the presence of a simple nonbiunguiculate dactyl on the ambulatory pereiopods. It is similar to P. uniunguiculatus Bruce, 1990 , P. granuloides Hayashi, 1986 , P. foresti Bruce, 1981 , or other deep-water species with a simple dactyl on the ambulatory pereiopods. It can easily be distinguished from those species by the telson with four pairs of dorsolateral spines, and also the well-developed lateral flange on the major second pereiopod.

Etymology

The specific name is given in honour of the French carcinologist, Alain Crosnier.

Remarks

Telson with four pairs of dorsolateral spines may show that Periclimenes crosnieri n. sp. belongs to the ‘‘ Periclimenes alcocki species group’’, but the simple dactyl on the ambulatory pereiopods indicates that it is separated from the other members of the group. Captured at a depth of 302–305 m, occurs in shallower depth than P. alcocki and P. aleator , but at similar depth with P. albatrossae Chace and Bruce, 1993 , which has seven pairs of dorsolateral spines on telson.

Figures

Figure 16. Periclimenes crosnieri, new species, holotype female (MNHN-Na 14943), body, lateral view.

Figure 17. Periclimenes crosnieri, new species. (a, c–k) Holotype female; (b) paratype female (MNHN-Na 14943). (a) Anterior carapace; (b) carapace; (c) right eye, lateral view; (d) telson; (e) right antennule; (f) same, peduncle, medial view; (g) right antenna; (h) mandible; (i) maxilla; (j) second maxilliped; (k) third maxilliped.

Figure 18. Periclimenes crosnieri, new species. (a–f, i) Holotype female; (g, h) paratype female (MNHN-Na 14943). (a) First pereiopod; (b) same, chela; (c) major second pereiopod; (d) same, fingers; (e) minor second pereiopod; (f) third pereiopod; (g) same, propod and dactyl; (h) same, distal propod and dactyl; (i) uropod.