A new species of hermit crab of the family Parapaguridae (Decapoda, Anomura) from French Polynesia

Rafaël LEMAITRE Smithsonian Institution, National Muséum of Natural History, Department of Invertebrate Zoology, Washington, D. C. 20560 (United States)

Lemaitre R. 1998. — A new species of hermit crab of the family Parapaguridae (Decapoda, Anomura) from French Polynesia. Zoosystema 20 (1) : 101-107.

ABSTRACT A new deep-water hermit crab species of the family Parapaguridae, Oncopagurus oimos, is described from Moruroa (French Polynesia, Tuamotu Archipelago). The new species is distinguished primarily by its distinctive colour pattern (still visible in alcohol-preserved spécimens after one year), and consisting of broad stripes on the left cheliped and ambulatory legs. Other diagnostic characters of the new species are: (1) maies lacking first KF.YWORDS pleopods and having reduced unpaired left second pleopods; (2) slender left deep-water hermit crab, new species, cheliped; (3) rounded mesial face of the right chela. The new species is com- Parapaguridae, pared to another congeneric species, O. tuamotu Lemaitre, 1994 that also Oncopagurus, French Polynesia, occurs in French Polynesia, as well as to other species of the genus in which Tuamotu Archipelago. maies lack fitst pleopods.

RÉSUMÉ Une espèce nouvelle de pagure de la famille des Parapaguridae (Decapoda, Anomura) de Polynésie française.Un e espèce nouvelle de pagure d'eau profonde, appartenant à la famille des Parapaguridae, Oncopagurus oimos, est déctite de Motutoa (Polynésie française, archipel des Tuamotu). Cette espèce nouvelle se distingue en patticulier par la couleur (encore visible après un an de conservation en alcool) des bandes longitudinales sur le chélipède gauche et les pattes ambulatoires. D'autres caractères distinctifs sont : (1) la présence, MOTS CLÉS chez les mâles, d'un seul deuxième pléopode gauche ; (2) le chélipède gauche pagure d'eau profonde, nouvelle espèce, grêle ; (3) la face mésiale de la pince droite arrondie. Cette nouvelle espèce Parapaguridae, est comparée à une autre espèce du genre, O. tuamotu Lemaitte, 1994 qui se Oncopagurus, Polynésie française, trouve également en Polynésie française, ainsi qu'aux autres espèces du genre archipel des Tuamotu. dont les mâles n'ont pas de premiers pléopodes.

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Study of parapagutid samples, obtained from margins sloping; posterior margin broadly roun­ Ftench Polynesia since Lemaitte's (1994) report ded. Rostrum broadly rounded, weakly produ- on the species of this family from the area, has ced, and with shott mid-dotsal ridge. revealed the existence of an undescribed species. Venttolateral margins of shield each with small This new species belongs in the recenrly propo- spine (not visible in dorsal view, and often only sed genus Oncopagurus Lemaitre, 1996, the spe­ on one side). Anterodistal matgin of branchioste- cies of which are characterized primarily by: gite rounded, unarmed, serose. (1) présence of upward curved epistomial spine; Ocular peduncles more than half length of (2) phyllobtanch gills; (3) operculate right chela; shield, with dorsal row of setae. Cotnea weakly (4) maies having pootly to modetately developed dilated. Ocular acicles subttiangular, terminating fitst and second pleopods, with first sometimes in strong spine; separated basally by less than absent (Lemaitte 1996). basai width of one acicle. In the material examined section, the length of Antennulat peduncle long, slender, exceeding the shield of the spécimens is indicated in paren- distal margin of cornea by enrire length of ulti- thesis, measured (to the nearest 0.1 mm) ftom mate segment; venttal flagellum with five to six the tip of the tostrum to the midpoint of the articles. Ultimate segment twice as long as penul- postetiot région of the shield. The term "semi- timate segment, with scatteted setae. Basai seg­ chelate" is used for the foutth peteopod in accor- ment with strong ventromesial spine; latéral face dance with the définition ptovided by with distal subtectangular lobe armed with one McLaughlin (1997). The spelling of the island or two small spines, and strong spine proximally. locality whete this new species was found is Antennal peduncle (Fig. 1B) exceeding distal accotding to Mottelet (1986). A summaty of margin of cornea by about one thitd length of deep-water collecting activities in Ftench fifth segment. Flagellum long, exceeding exten- Polynesia, including a list of ctustacean species ded tight cheliped and ambulatoty legs, articles and station data, can be found in Poupin (1996). with setae less than one to two flagellar articles in length (Fig. 1C). Fifth segment unatmed, but with scatteted setae. Fourth segment with strong Oncopagurus oimos n.sp. spine on dotsolateral distal angle. Thitd segment (Figs 1-3) with strong ventromesial distal spine. Second MATERIAL EXAMINED. — French Polynesia. segment with dotsolatetal distal angle ptoduced, Tuamotu Archipelago, Moruroa atoll, Marara, terminating in strong, simple spine; mesial mar­ stn 499, 21°47,6'S - 138°55,7'W, trapped, 200 m, gin with spine on dorsolatetal distal angle. First 5.V.1996: holotype $ (2.8 mm) MNHN-Pg 5505; segment with unarmed latetal face; ventromesial paratypes, 1 d (2.4 mm), 1 2 (2.7 mm) MNHN- angle ptoduced, with three to four small spines Pg 5506; 1 d (2.9 mm) USNM 276085. latetally. Antennal acicle slightly curved outward ETYMOLOGY. — The spécifie name is from the Greek (in dorsal view), at most slightly exceeding distal oimos, meaning stripe, used as a noun in apposition, matgin of cornea, terminating in strong spine; and refers to rhe distinctive colour pattern of this spe­ mesial margin with row of eight to thirteen cies. spines, setose. DISTRIBUTION. — Known so far only from Moruroa Mandible (Fig. 2A) with three-segmented palp. atoll, on the Tuamotu Archipelago, French Polynesia. Maxillule (Fig. 2B) with extetnal lobe of endo- Depth: 200 m. pod weakly developed, internai lobe with long HABITAT. — Gastropod shells. tetminal seta. Maxilla (Fig. 2C) with endopod exceeding distal maigin of scaphognathite. Fiist maxilliped (Fig. 2D) with endopod exceeding DESCRIPTION exopod in distal extension. Second maxilliped Shield (Fig. 1A) as broad as long; dorsal surface (Fig. 2E) with exopod about seven times as long evenly calcified, with scatteted short setae; ante­ as broad. Thitd maxilliped (Fig. 2F) with distal rior margins weakly concave; latéral projections rwo segments each twice as long as wide; crista subttiangulat, tetminating acutely; anterolateral

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dentata with about twelve corneous-tipped teeth; (Fig. 1D-F) massive, with sparse setation. Fingers coxa and basis each .with one tooth mesially. curved ventromesially, each terminating in cor- Sternite of third maxillipeds with small spine on neous claw; cutting edges with irregularly-sized

FIG. 1. — Oncopagurus oimos n.sp., Marara, stn 499, Moruroa atoll: A-H, holotype S (2.8 mm) (MNHN-Pg 5505); I, paratype S (2.9 mm) (USNM 276085). A, shield and cephalic appendages; B, right antennal peduncle (latéral view); C, proximal portion of fla­ gellum of same; D, right cheliped (dorsal view); E, right chela of same (ventral view); F, merus and carpus of same (mesial view); G, left cheliped; H, left second pleopod (arrow) and portion of pleuron (latéral view); I, left second pleopod (latéral view). Stippled areas on shield (A), merus and carpus of right cheliped (F), and left cheliped (G) indicate reddish colour pattern. Scales bars- A D-G 1 mm; B, C, H, I, 0.5 mm.

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oblique angle to longitudinal axis of palm; mesial of about ten to fourteen corneous spines; latéral margin broadly curved, well defined by row of and mesial faces with shallow, longitudinal sulcus spines (corneous-tipped on distal half); dorsal on proximal half (deeper on mesial face). face with scattered small spines proximally; ven­ Propodus with row of setae on dotsal and ventral tral face smooth; venttomesial face concave. margins. Carpus with small dorsodistal spine and Fixed finger broad at base; latéral margin well setae dorsally and ventrally. Merus unarmed, defined by row of spines (corneous-tipped on with setae on dorsal and ventral margins. distal half); dorsal face with scattered small Ischium and coxa unarmed. Anterior lobe of spines or tubercles; ventral face smooth. Palm sternite of third pereopods setose, subsemicircu- broader than long; latéral margin broadly roun­ lar, armed with simple terminal spine. ded, well delimited by row of blunt to sharp Fourth pereopod (Fig. 3E) semichelate. Dactyl spines; dorsomesial margin marked by row of terminating in sharp corneous claw; with ventro­ small spines; mesial face rounded, with small lateral row of small corneous spinules. Propodus spines or tubercles; dorsal surface smooth except longer than dorsoventral width, rasp formed of for scattered small tubercles; ventral surface one row of rounded scales. Carpus with long smooth. Carpus with latéral margin well delimi­ setae on dotsal margin. Merus with rows of long ted by row of spines; dorsal face with numerous setae on dorsal and venttal margins. small spines; dorsodistal margin with row of Fifth pereopod (Fig. 3F) chelate. Propodal rasp spines; ventromesial distal margin slightly expan­ extending to mid-length of segment. ded mesially, with row of spines; venttal face Uropods and telson (Fig. 3G-I) markedly asym­ with scattered small tubercles. Merus with dorsal metrical. Telson lacking ttansverse suture; dorsal row of small spines; ventromesial margin with surface with scatteted setae; terminal margin row of spines. Ischium with ventromesial row of with shallow médian cleft separating left and small spines. Coxa with one or two small spines tight lobes, each with sevetal marginal corneous on ventromesial and ventrolateral margins, and spines. ventromesial row of setae. Maie lacking first pleopods; with unpaired redu- Left cheliped (Fig. 1G) slender, with chela as ced second left pleopod (Fig. 1H, I) consisting of long as carpus; well calcified. Fingers terminating minute bud or very short segment with few ter­ in small corneous claws; dorsal and ventral sur­ minal setae. Female lacking vestigial second right faces unarmed except for scattered tufts of setae; pleopod. cutting edge of dactyl and fixed finger each with row of minute corneous teeth. Dactyl subequal Colourpattern (Figs 1A, F, G, 3A, B) to palm in length. Palm unarmed or at most with No observations of colour in life were made of this inconspicuous tubercle on dorsomesial angle, species. Howevet, after approximately one year in and scattered setae; ventral face smooth except alcohol, a distinctive reddish colour pattern was for scattered setae. Carpus with strong dorsodis­ still visible in the spécimens. The shield has two tal spine; dorsal margin with moderate setation; small reddish spots (Fig. 1A) on the anterior half, ventral face smooth. Merus with setae on dorsal one just behind each latéral projection. On both margin; ventrolateral distal matgin with row of chelipeds (Fig. 1F, G), the dorsodistal portions of spines; ventral face smooth. Ischium unarmed, the meri are reddish. The carpus of the right cheli­ with setose ventral face. Coxa with one spine on ped has a reddish area on the proximal portion of ventromesial and ventrolateral distal margins, the latéral and mesial faces. The carpus of the left and ventromesial row of setae. cheliped has a distinctive broad reddish stripe on Ambulatory legs (Fig. 3A-C) similar from right the dorsolateral and mesial faces; the dotsomesial to left, teaching approximately to, or just margin of the palm is light reddish; the dactyl is beyond, tip of extended right cheliped. Dactyl reddish. The ambulatory legs (Fig. 3A, B) have a slightly less than twice as long-as propodus, ter­ reddish colour dorsodistally on the meri; the carpi minating in sharp corneous claw; with dotsal and each have a reddish stripe on the latéral and mesial dorsomesial rows of setae, and venttomesial tow faces, and the stripes of the carpi continue on the

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meri but only on the latéral faces; the dactyls The othet four are O. haigae de Saint Laurent, have teddish dorsal faces. 1972 (Eastern Pacific); O. orientalis de Saint Lautent, 1972 (Indo-Pacific); O. tuamotu REMARKS Lemaitre, 1994 (known only from the Tuamotu This new species is the fifth in the genus Atchipelago); and O. cidaris Lemaitte, 1996 Oncopagurus in which maies lack first gonopods. (known only from Austtalia). The maies of thèse

FIG. 3 — Oncopagurus oimos n.sp., Marara, stn 499, Moruroa atoll: holotype d (2.8 mm) (MNHN-Pg 5505). A, left second pereopod (latéral view); B, lett third pereopod (latéral view); C, dactyl of same (mesial view); D, sternite of third pereopods (ventral view); E, left fourth pereopod (latéral view); F, propodus and dactyl of left fifth pereopod (latéral view); G, exopod of left uropod (dorsal view); H, telson (dorsal view); I, exopod of right uropod (dorsal view). Stippled areas on second (A) and third (B) pereopods indicate reddish colour pattern. Scale bars: A-D, 1 mm; E-l, 0.5 mm.

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four species have paired asymmetrical second previously mentioned différences in pleopod gonopods; however, Lemaitre (1996, 1997) has conditions, othet chatacters can also be used to documented intra-specific variation in maies of distinguish O. oimos n.sp. from O. tuamotu. The O. orientalis and O. cidaris, where the second fight mesial face of rhe right palm is rounded in the gonopod is occasionally lacking. The three known new species, with a weak irregular dorsomesial maies of O. oimos n.sp. have only reduced, simple row of spines, whereas the mesial face is expan- unpaired left second pleopods. The segmentation ded distally, and thete is a distinct dorsomesial of the maie second pleopods in thèse five species and venttomesial rows of spines in O. tuamotu. differs. The second pleopods are unsegmented in The left chela is noticeably more slender, as long O. oimos n.sp., O. haigae and O. orientalis; they as the carpus, and the fingers are ser nearly paral­ are two-segmented in O. tuamotu; and one- or lel ro the longitudinal axis of the palm in the two-segmented in O. cidaris. Of ail known species new species; the chela is shorter than the catpus, of Oncopagurus, O. oimos n.sp. is the only one in and the fingets are ser obliquely (pointing ven- which females have only unpaired left second tiolaterally) to the longitudinal axis of the palm pleopods; females of ail othet species have vestigial in O. tuamotu. tight second pleopods as well. The distinctive colout pattern of O. oimos n.sp., Acknowledgements can be used to distinguish it from O. tuamotu, The collecting effot ts of Joseph Poupin in French the only other congeneric species known from Polynesia have been invaluable in documenting French Polynesia. The new species has broad the crusracean fauna from rhis area. His efforts sttipes on the left cheliped and ambulatory legs are gratefully acknowledged. I thank also Alain (Figs 1G, 3A, B), whereas O. tuamotu has red Crosnier for fosteting this and othet studies bands on the cheliped and walking legs (see based on the important matetial gatheted during Lemaitte 1994: 411, fig. 281). In addition to the many récent French expéditions.

REFERENCES Bouchet P. (eds), Résultats des Campagnes MUSORSTOM, Volume 16, Mémoires du Muséum national d'Histoire naturelle 172 : Lemaitre R. 1994. — Crustacea Decapoda: 573-596. Deep-water hermit crabs (Parapaguridae) from McLaughlin P. A. 1997. — Crustacea Decapoda: her­ French Polynesia with descriptions of four new mit crabs of the family Paguridae from rhe Karubar species, in: Crosnier A. (éd.), Résultats des Expédition in Indonesia, in Crosnier A. & Bouchet Campagnes MUSORSTOM, Volume 12, P. (eds), Résultats des Campagnes MUSORS­ Mémoires du Muséum national d'Histoire naturelle TOM, Volume 16 (5), Mémoires du Muséum natio­ 161 : 375-419. nal d'Histoire naturelle 172 : 433-572. — 1996. — Hermit crabs of the family Parapaguridae Motteler L. S. 1986. — Pacific island names. A map (Crustacea: Decapoda: Anomura) from Australia: and name guide to the New Pacific. Bishop species of Strobopagurus Lemaitre, 1989, Muséum Miscellaneous Publication 34: 1-91. Sympagurus Smith, 1883 and two new gênera. Poupin J. 1996. — Atlas des crustacés marins profonds Records of the Australian Muséum 48: 163-221. de Polynésie française. Récoltes du navire Marara — 1997. — Crustacea Decapoda: Parapaguridae (1986/1996). Service Mixte de Surveillance from the Karubar Cruise in Indonesia, with des­ Radiologique et Biologique de l'homme et de criptions of two new species, in Crosnier A. & l'environnement, Montlhéry, 59 p.

Submitted on 30 May 1997; accepted on 8 September 1997.

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