1 INTRODUCTION

Recent studies suggested that the most speciose genus of Pontoniinae,Periclimenes Costa, 1844,is a polyphyletic taxon(Bruce, 2004,2007; Bruce et al., 2005; Li,2009). This st and point is supported by subsequent molecular study results(Kou et al., 2013). According to Kou et al.(2013),a part of deep-sea Periclimenes species,particularly some members of the “ P . alcocki ” group form a separate clade from those shallow water Periclimenes species. Furthermore,it is speculated that the ancestor of the current deep-sea Periclimenes species inhabited shallow water, and probably for the sake of evading predators or following their initial hosts they gradually migrated to deeper water. Thus,in the long-term evolutionary process,to acclimate to the deep water environment,the body structures of deep-sea Periclimenes species became specialized,making them distinct from those shallow water species in appearance.

So far,over 40 Periclimenes species have been found at depths greater than 200 m, and about 85% are reported from the Indo-West Pacifi c region(De Grave and Fransen, 2011). Among all these deep-sea Periclimenes species,the ‘ alcock species group’ is characteristic in having more than two pairs of dorsolateral spines on the telson,the usually reduced cornea,the dactylus of the major second chela being generally fl anged and the palm covered with fi ne granules, and the biunguiculate dactyli of the ambulatory pereiopods. The combination of these morphological characters is unique,not only in other Periclimenes species but also in other genera of the Pontoniinae. With the addition of the recent molecular evidence,we consider that this species group should be separated from the genus Periclimenes and elevated to full generic status. Therefore,we establish a new genus,Bathymenes,for the ‘ P . alcocki species group’ in this paper. A total of fi fteen species previously considered belonging to this species group are presently assigned to Bathymenes gen. nov.

The abbreviations st and ing for the museums in which the produced samples are deposited are listed as following: MNHN-Na: Muséum National d’Histoire Naturelle,Paris; NMCR: Philippines National Museum,Manila; NMNZ: National Museum of New Zeal and ,Wellington; NTM: Northern Territory Museum,Darwin; NTOU: National Taiwan Ocean University,Keelung; QM: Queensl and Museum,Brisbane; RMNH: Nationaal Natuurhistorisch Museum-Naturalis,Leiden(formerly Rijksmuseum van Natuurlijke Historie); USNM: National Museum of Natural History,Washington,D. C.(formerly United States National Museum); ZRC: Raffl es Museum of Biodiversity Research,National Museum of Singapore,Singapore.

2 TAXONOMY

Palaemonidae Rafi nesque,1815

Pontoniinae Kingsley,1878

Bathymenes gen. nov.

Diagnosis . Moderate to large sized pontoniine shrimps of robust subcylindrical body form. Carapace smooth,glabrous,posteriormost tooth of dorsal rostral series clearly separated from other teeth,epigastric in position; hepatic and antennal spines present,hepatic spine larger than antennal spine,located at same level as or slightly inferior to that,with tip not overreaching anterior margin of carapace; supraorbital spines absent,orbit feebly developed,inferior orbital angle distinct,without inner ventral fl ange. Rostrum generally short and deep,laterally compressed,horizontal or directed slightly anteroventrally,slightly upcurved distally,dorsally and ventrally dentate. Abdomen smooth,third segment not posterodorsally produced,pleura of fi rst three somites enlarged,broadly rounded,fourth and fi fth not posteroventrally acute. Telson with more than two pairs of small dorsolateral spines,three pairs of posterior spines. Eyes with globular cornea,generally reduced,without accessory pigment spot. Antennule well developed. Antenna with basicerite armed with large lateral tooth,scaphocerite short and broad. Epistome unarmed. M and ible without palp,molar process and incisor process well developed; maxillula with bilobed palp,laciniae usually stout; maxilla with simple palp,basal endite slender,scaphognathite large and broad; fi rst maxilliped with simple palp,exopod with large and broad caridean lobe,epipod generally large and bilobed,triangular; second maxilliped with normal endopod,exopod similar to fi rst maxilliped,without podobranch; third maxilliped with slender endopod,ischiomerus distinct from or fused to basis,exopod as in second maxilliped,arthrobranch small or well developed. Thoracic sternites not elongate,fourth thoracic sternite without median process. First pereiopods moderately slender,with fi ngers simple or feebly subspatulate. Second pereiopods robust,usually unequal,similar or dissimilar,sparsely or densely covered with small granules,fi ngers shorter than palm,with strong or feeble lateral fl ange,without molar process or fossae,cutting edge with blunt tooth,carpus and merus unarmed. Ambulatory pereiopods slender,meri distoventral unarmed,dactyli biunguiculate. Uropod distinctly exceeding telson,protopodite with distolateral lobe broadly rounded; exopod broad,lateral margin feebly convex,nonsetose,with small acute distal tooth and mobile spine medially.

Type species . Periclimenes alcocki Kemp, 1922,by present designation.

Included species .

Periclimenes albatrossae Chace and Bruce, 1993

Periclimenes alcocki Kemp,1922

Periclimenes aleator Bruce,1991

Periclimenes brevirostris Bruce,1991

Periclimenes forgesi Li and Bruce, 2006

Periclimenes loyautensis Li and Bruce, 2006

Periclimenes manihine Bruce,2006

Periclimenes ngi Li et al., 2008

Periclimenes panglaonis Li et al., 2008

Periclimenes paralcocki Li and Bruce, 2006

Periclimenes paraleator Li and Bruce, 2006

Periclimenes poupini Bruce,1989

Periclimenes pseudalcocki Li and Bruce, 2006

Periclimenes takedai Mitsuhashi et al., 2012

Periclimenes tangeroa Bruce,2005

Etymology . From Greek word bathus meaning deep, and part of the generic name Periclimenes,indicating the deep water habitat of the members of the genus. Gender: masculine.

Distribution . Tropical to warm-temperate waters of the Indo-West Pacifi c and Eastern Pacifi c Ocean,recorded depths from 187 to 824 m.

Systematic position . Bathymenes gen. nov. is closely related to Periclimenes sensu stricto,in which the species were formerly included. Bathymenes gen. nov. can be distinguished from it by the morphological combination of the posteriormost dorsal rostral tooth remote from other teeth,situated in the epigastric position,telson having more than two pairs of dorsolateral spines,the usually reduced cornea,the dactylus of the major second chela being generally fl anged and the palm covered with fi ne granules.

Except for Periclimenes,among the other pontoniine genera,Bathymenes gen. nov. is most close to the newly established deep-sea genus Echinopericlimenes Marin and Chan, 2014. Both of them are alike in body form,body colour and the shape of the second pereiopods. However,they can be immediately distinguished by two pairs of dorsolateral telson spines,the dactyli of ambulatory pereiopods armed with a number of small teeth at the distoventral margin,the large hepatic spine distinctly overreaching the anterior margin of the carapace and several other characters.

Bathymenes gen. nov. also resembles the monotypic genus,Plesiopontonia Bruce,1985. Plesiopontonia is recorded to be found at depth from 242 to 436 m(Bruce,1985; Li et al., 2008),having the same deep water habitat as Bathymenes gen. nov. In addition,morphologically,they share the subcylindrical body form,well-developed rostrum,similar mouthparts structure and the most important feature of telson with more than two pairs of dorsolateral spines. The most signifi cant diff erentiation between them is the absence(Plesiopontonia)or presence(Bathymenes gen. nov.)of the epigastric posteriormost rostral tooth and hepatic spine. Notabley,unlike most of the Bathymenes gen. nov. species,Plesiopontonia has the corpus of the third ambulatory pereiopod with only an inconspicuous subdistal accessory tooth,making the dactylus look obscurely biunguiculate. However,such a parallel can be found in B . tangeroa or B . pseudalcocki, and the length of the accessory tooth varies from 0.2(B . alcocki ,see Bruce,1991)to almost as long as the unguis(B . poupini ,see Bruce,1989)in other members of the genus. Such an interspecifi c variation pattern of the dactylus might reveal the diff erent hosts they commensally associated with,although the information about their host is largely unconfi rmed or remain absolutely unknown.

Remarks.

The present study gives a group of specifi c morphological characters to delineate the new genus Bathymenes gen. nov.,which is considered to include all the species reported yet. However,currently the molecular data is not suffi cient to prove the monophyly of the members assigned to the new genus. Additionally,several deep-sea Periclimenes species which are excluded from Bathymenes gen. nov. for lacking the diagnostic characters are indicated to share close relationships with the new genus by the recent molecular phylogeny analyses(i.e. P . boucheti Li et al., 2008,P . leptunguis Li et al., 2008 and P . sandybruce Mitsuhashi and Chan, 2009,see Kou et al., 2013). Therefore,to accurately demarcate the extension of the new genus and reveal its systematic status,a robust molecular phylogenetic study is required in the near future, and perhaps more species with diff erent characters will be included in Bathymenes gen. nov. when the analyses are performed.

In conclusion,totally fi fteen Indo-Pacifi c species are now placed in the new genus. The key to the species of Bathymenes gen. nov. is provided below.

Key to the species of Bathymenes gen. nov .(Based on the key to the species of the ‘ Periclimenes alcock species group’ in Li et al.(2008) and the modifi cation given by Mitsuhashi et al.,(2012))

1. Telson with seven pairs of dorsolateral spines; rostrum overreaching scaphocerite; third pereiopod with dactylus truncate subdistally,propodus without spines on fl exor margin ……………………………………………. B . albatrossae(Chace and Bruce, 1993)comb. nov. – Telson with three to fi ve pairs of dorsolateral spines ……………………………………………………. 2

2. Telson with three pairs of dorsolateral spines; rostrum not overreaching scaphocerite; corneal diameter about 0.12 of carapace length,eye-stalk not distinctly narrower than cornea; dorsal rostral margin concave; propodus of third pereiopod with spines along fl exor margin,rows of transverse setae distally and pairs of distoventral and sub-distoventral spines ………… B . paralcocki (Li and Bruce, 2006)comb. nov. – Telson with four to fi ve pairs of dorsolateral spines …….…………………………………………… 3

3. Rostrum overreaching scaphocerite; hepatic spine normal; corneal diameter about 0.16 of carapace length; dorsal rostral margin concave; propodus of third pereiopod with pair of distoventral spines and four spinules on fl exor margin ……………………… B . paraleator (Li and Bruce, 2006)comb. nov. – Rostrum not overreaching scaphocerite ……… 4

4. Cornea markedly reduced,diameter about 0.10 of carapace length; dorsolateral telson spines minute ……………………………………………………… 5 – Cornea not markedly reduced,diameter more than 0.13 of carapace length; dorsolateral telson spines not minute ……………………………………………………… 9

5. Propodus of third ambulatory pereiopod without distoventral or ventral spines,dactylus with accessory tooth minute,at most 0.11 length of unguis; rostrum relatively deep,distally with strong upward curve; dorsolateral telson spines relatively large,0.045 of telson length ………………… B . pseudalcocki (Li and Bruce, 2006)comb. nov. – Propodus of third ambulatory pereiopod with distoventral and ventral spines ……………………… 6

6. Accessory tooth of dactylus of third pereiopod about 0.45 length of unguis ………………… …………………… B . ngi (Li et al., 2008)comb. nov . – Accessory tooth of dactylus of third pereiopod 0.08–0.30 length of unguis …………………….…… 7

7. Corneal diameter less than 0.08 of carapace length; hepatic spine at about same level as posteriormost tooth of dorsal rostral series; dactylus of third pereiopod 0.17 of propodal length,accessory tooth about 0.20 length of unguis …………… ……. …………… B . alcocki (Kemp,1922)comb. nov . – Hepatic spine anterior to level of posteriormost tooth of dorsal rostral series …………………….…… 8

8. Corneal diameter 0.10 of carapace length; dactylus of third pereiopod 0.28 of propodal length,accessory tooth 0.07 length of unguis; dorsolateral telson spines 0.04 length of telson … ………………… B . tangeroa (Bruce,2005)comb. nov. – Corneal diameter 0.08 of carapace length; dactylus of third pereiopod 0.15 of propodal length,accessory tooth 0.30 length of unguis; dorsolateral telson spines 0.02 length of telson ……… …… B . takedai (Mitsuhashi et al., 2012)comb. nov.

9. Accessory tooth of dactylus of third pereiopod almost as long as unguis,laterally twisted …… …………………… B . poupini (Bruce,1989)comb. nov . – Accessory tooth of dactylus of third pereiopod not unusually long or twisted ……………………….……10

10. Rostrum distinctly exceeding antennular peduncle …………….…………………………… 11 – Rostrum not reaching end of antennular peduncle; pigmented cornea large,diameter about 0.16–0.18 of carapace length …………………………………………… 13

11. Hepatic spine located distinctly inferior to antennal spine ………………………… ……………… B . aleator (Bruce,1991)comb. nov . – Hepatic spine at about same level as antennal spine …………………………………………….………… 12

12. Hepatic spine normal; rostral teeth long ………………… … B . loyautensis (Li and Bruce, 2006)comb. nov. – Hepatic spine infl ated at base; rostral teeth short ………………… ………… B . panglaonis (Li et al., 2008)comb. nov .

13. Rostrum shallow,proximally elevated over orbital region,tapered distally,ventral margin straight,with one tooth; accessory tooth of dactylus of third pereiopod reaching about proximal 0.4 length of unguis …. B . forgesi (Li and Bruce, 2006)comb. nov . – Rostrum deep,proximally not elevated over orbital region ………………………………………………… 14

14. Rostrum tapered distally,carpus of fi rst pereiopod short,distinctly shorter than chela and merus,fi xed fi nger of major second pereiopod feebly bidentate in male ……………… ………. .…… B . brevirostris (Bruce,1991)comb. nov . Rostrum not strongly tapered distally,carpus of fi rst pereiopod long,distinctly longer than chela,subequal to merus,fi xed fi ngers of both second pereiopods deeply bidentate distally … ……………… B . manihine (Bruce,2006)comb. nov .

Checklist of the species of Bathymenes gen. nov.

Bathymenes albatrossae(Chace and Bruce, 1993)comb. nov.

Synonymy:

Periclimenes albatrossae Chace and Bruce, 1993: 100–101,fi g. 20; Bruce,1996: 227–228,fi g.11a; Li,2000: 151,fi g. 183.

Type data . Ovigerous female holotype,USNM 252658.

Distribution . Type locality: Philippines. South China Sea off western Luzon. Also known from Indonesia.

Bathymetric range . 315–452 m.

Host . Unknown.

Bathymenes alcocki(Kemp,1922)comb. nov.

Synonymy:

Palaemon(Brachcarpus)laccadivensis Alcock,1901: 138–139(partim).

Periclimenes(Periclimenes)alcocki Kemp,1922: 154–156,fi gs. 21–24; Kubo,1940: 33,fi gs. 1,2. Periclimenes alcocki : Bruce,1978: 227–228,fi g. 10; Bruce,1981: 190,fi gs. 1,2; Bruce,1985: 231,fi g. 1; Burukovsky,1990: 197; Bruce,1991: 302–308,fi gs. 2–5; Chace and Bruce, 1993: 102; Bruce,1996: 228,fi g. 11b–d; Li,2000: 151,fi g. 184; Davie,2002: 323; Li and Bruce, 2006: 672.

Type data . Ovigerous female holotype,deposited in the Indian Museum(the collections of the Zoological Survey of India,catalogue number 4789/7).

Distribution . Type locality: Laccadive Sea. Also known from Philippines,Indonesia,Australia,New Caledonia,Solomon Isl and s,Fiji Isl and s,Tonga,Japan,Madagascar and Chile.

Bathymetric range . 187–824 m.(erroneously given as 930 m in Bruce,1996 and Li and Bruce, 2006)

Host . In association with sea pens,Virgularia sp. [Pennatulacea: Virgulariidae](see Bruce,1996)

Bathymenes aleator(Bruce,1991)comb. nov.

Synonymy:

Periclimenes aleator Bruce,1991: 315–322,fi gs. 10–14; Li,2000: 152,fi g. 185; Li and Bruce, 2006: 673–674,fi g. 14; Li,2008: 218–219,fi g. 5B; Bruce,2008a: 10–11,fi g.6.

Type data . Ovigerous female holotype,MNHN– Na 12027.

Distribution . Type locality: Loyalty Isl and s,New Caledonia. Also known from Indonesia,Solomon Isl and s,Vanuatu,Fiji Isl and s,French Polynesia and Western Australia.

Bathymetric range . 315–610 m.

Host . In association with sea urchins,Aspidodiadema sp. [Echinoidea,Diadematidae](see Li,2008).

Bathymenes brevirostris(Bruce,1991)comb. nov.

Synonymy:

Periclimenes brevirostris Bruce,1991: 321–330,fi gs. 15–20; Li,2000: 163,fi g. 200; Li & Bruce,2006: 677.

Type data . Female holotype,MNHN–Na 12044; 1 male paratype,MNHN–Na 12045.

Distribution . Type locality: Isle of Pines,New Caledonia. Also known from Solomon Isl and s and Vanuatu.

Bathymetric range. 440–800 m.

Host . Unknown.

Bathymenes forgesi(Li and Bruce, 2006)comb. nov.

Synonymy:

Periclimenes forgesi Li and Bruce, 2006: 686–691,fi gs. 19,20.

Type data . Ovigerous female holotype,MNHN– Na 14928; 1 ovigerous female paratype,MNHN–Na 15869.

Distribution . Type locality: New Caledonia. So far only known from the type locality.

Bathymetric range . 382–514 m.

Host . Unknown.

Bathymenes loyautensis(Li and Bruce, 2006)comb. nov.

Synonymy:

Periclimenes loyautensis Li and Bruce, 2006: 700– 703,fi g. 24.

Type data . Ovigerous female holotype,MNHN– Na 14947.

Distribution . Type locality: Loyalty Isl and s,New Caledonia. So far only known from the type locality.

Bathymetric range . 430 m.

Host . Unknown.

Bathymenes manihine(Bruce,2006)comb. nov.

Synonymy:

Periclimenes manihine Bruce,2006: 45–54,fi gs. 1–4.

Type data . Male holotype,QM W. 28012; 1 male paratype,RMNH D.51683.

Distribution . Type locality: Off Ras Ngomeni,Kenya. So far only known from the type locality.

Bathymetric range . 245–256 m.

Host . Unknown.

Bathymenes ngi(Li et al., 2008)comb. nov.

Synonymy:

Periclimenes ngi Li et al., 2008: 397–402,fi gs. 9–11,17C,D; Mitsuhashi et al., 2012: 212–214,fi gs. 1A,2.

Type data . Female holotype,deposited at NMCR; 1 female paratype is deposited at ZCR and another female paratype is deposited at MNHN–Na(see Li et al., 2008).

Distribution . Type locality: Philippines. Also reported from northeastern Taiwan Isl and .

Bathymetric range . 273–531 m.

Host . Unknown.

Bathymenes panglaonis(Li et al., 2008)comb. nov.

Synonymy:

Periclimenes panglaonis Li,Mitsuhashi and Chan, 2009: 402–406,fi gs. 12,13,14A–D,17E.

Type data . Female holotype,deposited at NMCR(see Li et al., 2008).

Distribution . Type locality: Philippines. Only known from the type locality.

Bathymetric range . 418–477 m.

Host . Unknown.

Bathymenes paralcocki(Li and Bruce, 2006)comb. nov.

Synonymy:

Periclimenes paralcocki Li and Bruce, 2006: 707– 710,fi g. 27; Li,2008: 230–231,fi g. 15; Bruce,2008a: 12–14,fi g. 7.

Type data . Female holotype,MNHN–Na 14865.

Distribution . Type locality: Bayonnaise Bank,Tuvalu. Also known from French Polynesia and Western Australia.

Bathymetric range . 407–794 m.

Host . Unknown.

Bathymenes paraleator(Li and Bruce, 2006)comb. nov.

Synonymy:

Periclimenes paraleator Li and Bruce, 2006: 711– 714,fi g. 28.

Type data . Ovigerous female holotype,MNHN– Na 14945.

Distribution . Type locality: New Caledonia. Only known from the type locality.

Bathymetric range . 520 m.

Host . Unknown.

Bathymenes poupini Bruce,1989 comb. nov.

Synonymy:

Periclimenes poupini Bruce,1989: 851–863,fi gs. 1–5,6A; Li,2000: 228,fi g. 302.

Type data . Ovigerous female holotype and 3 ovigerous female paratypes,MNHN–Na 11123; 2 ovigerous female paratypes,MNHN–Na 12540/12541; 1 male and 1 ovigerous female paratypes,NTM. Cr. 006714.

Distribution . Type locality: Tubuai,French Polynesia. Only known from French Polynesia.

Bathymetric range . 430–560 m.

Host . Associated with sea anemones,which is present on the gastropod shells occuped by Sympagurus dofl eini(Balss,1912)(identifi ed by J. Poupin,see Bruce,1989)

Bathymenes pseudalcocki(Li and Bruce, 2006)comb. nov.

Synonymy:

Periclimenes alcocki : Burukovsky,1990: 197(partium).

Periclimenes pseudalcocki Li and Bruce, 2006: 716–719,fi g. 30; Bruce,2008b: 1007–1009,fi g.1.

Type data . Female holotype,MNHN–Na 14855.

Distribution . Type locality: Kai Isl and s,Indonesia. Also known from off Sala y Gomez,Chile.

Bathymetric range . 315–485 m.

Host . Unknown.

Bathymenes takedai(Mitsuhashi et al., 2012)comb. nov.

Synonymy:

Periclimenes takedai Mitsuhashi,Li and Chan, 2012: 214–222,fi gs. 1B,3–5.

Type data . Ovigerous female holotype,NTOU M01223.

Distribution . Type locality: Taiwan Isl and . Only known from the type locality.

Bathymetric range . 506–509 m.

Host . Unknown.

Bathymenes tangeroa(Bruce,2005)comb. nov.

Synonymy:

Periclimenes tangeroa Bruce,2005: 12–19,fi gs. 5–7,8D.

Type data . Ovigerous female holotype,NMNZ CR 9997.

Distribution . Type locality: South Norfolk Ridge,Australia. Only known from the type locality.

Bathymetric range . 242–254 m.

Host . Unknown.

3 ACKNOWLEDGEMENT

Thanks are due to the reviewers of the manuscriptfor their valuable comments.