Deep-sea spider crabs of the families Epialtidae MacLeay , 1838 and Inachidae MacLeay , 1838 , from the South China Sea , with descriptions of two new species ( Decapoda , Brachyura , Majoidea )

Recent expeditions (NANHAI 2014, DONGSHA 2014 and ZHONGSHA 2015) conducted in deep waters of the South China Sea obtained interesting material of various spider crabs (Majoidea) including several new records for the area, and two new species of epialtids of the genera Oxypleurodon Miers, 1885 and Stegopleurodon Richer de Forges & Ng, 2009. Two poorly known species, previously only known from their types, Rochinia strangeri Serène & Lohavanijaya, 1973 and R. kagoshimensis (Rathbun, 1932) comb. nov., are redescribed, refi gured, and their taxonomy discussed.

However, the diversity in this large area remains poorly understood.We here report on the material collected from three recent expeditions (NANHAI 2014, DONGSHA 2014and ZHONGSHA 2015), which add two new species of epialtid crabs, one in the genus Oxypleurodon Miers, 1886 andanother in Stegopleurodon Richer de Forges &Ng, 2009, to the fauna of the SCS.The re-descriptions of two poorly known species, Rochinia strangeri Serène & Lohavanijaya, 1973 and Rochinia kagoshimensis (Rathbun, 1932) comb. nov., are also included based on fresh material as well as the types.
The four island groups within the SCS -Macclesfi eld Bank (also known as Zhongsha Islands), Pratas Islands (also known as Dongsha or Tungsha Islands), Spratly Islands (also known as Nansha Islands) and Paracel Islands (also known as Xisha Islands) -are known by several different names.This refl ects the complex history of the islands in a dynamic geopolitical situation with uncertainties regarding their ownership.For convenience and in the context of the actual expeditions conducted, the names as used by the collectors will be followed.

Material and methods
Specimens examined are deposited in: National Taiwan Ocean University (NTOU), Keelung, Taiwan; Zoological Reference Collection (ZRC), Lee Kong Chian Natural History Museum (previously known as the Raffl es Museum of Biodiversity Research), National University of Singapore (NUS), Singapore; National Museum of Natural History (USNM), Smithsonian Institution, Washington D.C., USA; Senckenberg Museum Frankfurt (SMF), Frankfurt, Germany and Muséum national d'Histoire naturelle (MNHN), Paris, France.
Measurements provided, in millimetres, are of maximum carapace length (excluding pseudorostral spines) and maximum carapace width (measured across the base of the lateral spine).The following abbreviations are used:

G1
= male fi rst gonopod P2 and P4 = second and fourth walking legs respectively stn = station SCS = South China Sea

Remarks
There are currently two species in this genus, of which Goniopugettia tanakae Sakai, 1986, is the type species (subsequent designation by Ng et al. 2008: 103).Little is known of the type species, Goniopugettia tanakae, and the original description is brief, in Japanese (see Sakai 1986: 2), and with only a single fi gure (Sakai 1986: frontispiece fi g. 3).Moreover, this species has not been reported again since its description.There is a need to examine the type material of Sakai (1986) to re-defi ne the genus and type species more accurately.

Remarks
The species was fi rst briefl y described as Pugettia sagamiensis by Gordon (1930), followed by a more detailed description by Gordon (1931).This species was transferred to Goniopugettia by Sakai (1986).
In the same year, however, Griffi n & Tranter published a large revision on all the Indo-West Pacifi c Majoidea and placed this species in Rochinia (Griffi n & Tranter 1986a: 187).Ng et al. (2001) was the next to recognise Goniopugettia and used this name for the Taiwanese material.
The specimen caught during the DONGSHA cruise within the South China Sea is the most southern known record.

Remarks
Oxypleurodon stimpsoni Miers, 1885, is the type species of the genus.Miers (1885) fi rst mentioned the species in a narrative, followed by a detailed description and fi gures of the species based on material in the "Challenger" expedition, collected from Indonesia and the Philippines in 1886.The fi rst description of the genus and species by Miers (1885) was not known to Tavares (1991), when he revised the genus (Froglia & Clark 2011: 51).Specimens from Indonesia were measured and fi gured by Miers (1886: 39, pl. 6 fi g. 1).This species appears to be common in the depth range of 250 to 580 m in the tropical West Pacifi c and Indo-Malayan archipelago.3B).Interestingly, the morphology of the only specimen collected by the AURORA cruise on the east coast of Luzon is closer to the SCS material than those from the Bohol Sea.With regards to the specimen from the Kai Islands in Indonesia, which is closer to the type locality, the dorsal plates look relatively more infl ated and the branchial plates are more elongated (Figs 2A, 3A) compared to the SCS specimens (Figs 2C, 3C); and the meri of the ambulatory legs are also weakly carinate.The variation observed here is diffi cult to explain and suggests that we are dealing with a species-complex.To resolve this matter, all the available specimens from across its wide range   Ng 2009), Japan (Sakai 1938) and South China Sea (Lee et al. 2015).

Distribution
This species was recorded from the Philippines (Rathbun 1916), Japan (Takeda & Nagai 1979) and South China Sea (Lee et al. 2015).

Remarks
Oxypleurodon forte was collected on seamounts in the middle of the SCS during the NANHAI 2014 cruise (Lee et al. 2015).The new series of small specimens collected during ZHONGSHA shows that the species has a wider distribution in the SCS.

Distribution
This species is known only from the South China Sea.

Etymology
The species name is dedicated to our colleague and friend Professor Leo Tan, who is actively encouraging a multitude of biodiversity studies in Singapore.The name is used as a noun in apposition.
Antennae at same level of pseudorostral spines.Antennules completely retractable in deep fossae.Basal antennal article fused to carapace, slightly curved, with smooth fl attened surface, slightly rounded external distal angle; distinct tubercle at base of basal antennal article (Fig. 5B).Squarish epistome.Pterygostomial region enlarged into plate with rounded edge (Fig. 5B).Buccal frame totally covered by third maxillipeds when closed.

Colouration
In the fresh specimens of O. leonis sp.nov., the carapace is slightly pink and covered by a layer of white tomentum; chelipeds bright white, ambulatory legs pinkish (Fig. 4B).

Remarks
The material from the ZHONGSHA cruise is superfi cially close to O. bipartitum (Fig. 4A), which was originally described from material collected off the western coast of Luzon, the Philippines.Oxypleurodon bipartitum s. str.was collected in large numbers by fi shermen using tangle nets in Balicasag Island, central Philippines (Richer de Forges & Ng 2009b), which makes it possible for us to directly compare the two species.In typical O. bipartitum (Fig. 4A), the pseudorostrum is proportionately longer and the carapace not as wide as the SCS material.In O. leonis sp.nov., the supraocular eave is narrow and forms a thin "overhang" (Figs 4B, 5A) as compared to O. bipartitum in which the same structure is thick (Fig. 4A).The shape of the branchial plate is also different, being distinctly more fl attened in O. bipartitum rather than more convex and slightly curved in O. leonis sp.nov.( Figs 4B, 5A).In O. bipartitum, the lateral plates (postocular, hepatic, and lateral branchial) are relatively larger and more foliose (Fig. 4A) compared to those in O. leonis sp.nov.(Figs 4B,5A).The pattern of setal arrangement on both species is very different as well; in O. leonis sp.nov., there is a distinct, even tomentum of short setae on the cardiac, gastric, and epibranchial regions (Figs 4B, 5A) whereas in O. bipartitum, the same regions have groups of long and stout setae instead.In O. leonis sp.nov., the posterior border of the carapace is slightly carinate (Figs 4B, 5A) while in O. bipartitum, it forms a large curved carina (Fig. 4A).

Distribution
Only known from South China Sea.  . Milne-Edwards, 1975, by monotypy. Garth (1958) mentioned that the group formed by Rochinia and Scyramathia is not monophyletic due to the form of the male fi rst gonopod.Thus far, despite new species being described from this genus (see Ng

Remarks
Rochinia kotakae is characterised by its long divergent pseudorostral spines, very long and sharp branchial spines pointing outward, and distinctly fl attened postocular and hepatic spines.This species was described based on a single female specimen collected from Tosa Bay, Japan (Takeda 2001).Ho et al. (2004) later gave a more detailed description of a male specimen that was collected from Taiwan.Richer de Forges & Ng (2013) provided photographs of specimens of R. kotakae, from the Philippines European Journal of Taxonomy 358: 1-37 (2017) and Taiwan (Richer de Forges & Ng 2013: fi g. 7).The present specimen from the SCS agrees well with the earlier material.
The only other species of Rochinia known to have this type of carapace pattern, with the fl attened hepatic spine and very long branchial spines, is R. sibogae Griffi n & Tranter, 1986, described from the Ceram Sea, Indonesia.However, in R. sibogae, the post-ocular and the hepatic foliated spine are fused (Griffi n & Tranter 1986b: fi g. 12b).In R. kotakae, these two spines are clearly separated (Fig. 8A).

Distribution
This species was recorded from Japan (Takeda 2001), Taiwan (Ho et al. 2004) and the Philippines (Richer de Forges & Ng 2007).This is a new record for the South China Sea.

Colouration
In the fresh SCS specimens of R. strangeri, the carapace is pale pink while the pseudorostral spines, supraorbital eave, postorbital spine and hepatic spine are pale orange; the cheliped is pinkish orange while the ambulatory legs are pale pink with the distal sections white (Fig. 7B).

Remarks
Little is known of this species, and the original description for Rochinia strangeri by Serène & Lohavanijaya (1973) was relatively brief.Therefore, the species is re-diagnosed here.The species is characterised by the anterior border of the carapace bearing a series of three prominent spine-like plates on the supraocular, postocular and hepatic regions (cf.Serène & Lohavanijaya 1973)  European Journal of Taxonomy 358: 1-37 ( 2017) Poore (2008: 69, fi g. 2d) as R. strangeri, is a different species, morphologically more similar to R. soela; which will have to be re-examined to ascertain its true identity.

Distribution
Only known from South China Sea.

Colouration
In the fresh SCS specimen of R. kagoshimensis, the carapace is white, with the pseudorostral spines orange-pink, and the ambulatory legs orange with the dactylus and distal part of propodus white (Fig. 7C).

Remarks
Little is known of this species.The species was originally described as Pugettia kagoshimensis by Rathbun (1932) from Japan, with no fi gures illustrated.Sakai (1976) provided a rather schematic line drawing of the holotype specimen (Sakai 1976: text-fi g. 105).The holotype is shown in Fig. 10A-C.The overall carapace morphology shows long hepatic spines that are not typically seen in Pugettia Dana, 1851 (Figs 7C, 10A, D).The G1 morphology (Fig. 11) is also unlike typical Pugettia, which is scyriform shape with three angles at the G1 tip.This species is therefore transferred to Rochinia sensu lato on the basis of the G1 morphology.This species was previously known only from Japan from the holotype specimen.
The specimen collected from the SCS is very similar to the type of R. kagoshimensis (Rathbun, 1932) comb.nov., although there are some differences.For the holotype of R. kagoshimensis, the pseudorostral spines are straight and diverging (Fig. 10A), whereas for the SCS specimen, the pseudorostral spines are distinctly curved outwards (Fig. 10D).On the carapace of the specimens, the hepatic and branchial spines of the holotype are pointed in a more upward direction (Fig. 10A, C) while in the SCS specimen, it is pointed more outwards (Fig. 10D, F).The strong and blunt cardiac spine on the carapace is relatively thicker on the SCS specimen (Fig. 10F) compared to the holotype (Fig. 10C).On the pterygostomial region, the holotype of R. kagoshimensis has two small granules on the edge (Fig. 10B) whereas on the SCS specimen, there are three small granules instead (Fig. 10E).As there is only one male specimen collected from SCS, it is uncertain if both are conspecifi c or these differences are only the result of variation.Both specimens are treated as the same species for the time being.
Rochinia kagoshimensis has a similar general carapace shape (Fig. 10A, E) to R. debilis Rathbun, 1932 (Fig. 12) due to both having similar pseudorostral spines, large and diverge branchial spines; and dorsal surface of the carapace is covered by a tomentum of short setae.The main differences are on the cardiac spine: wide and blunt in R. kagoshimensis (Fig. 10C, F), while in R. debilis, it is reduced to a small swelling (Fig. 12).In R. kagoshimensis, the hepatic spines are proportionately longer compared to R. debilis, which is reduced to a short spine on a convexity (Fig. 8A).Rochinia debilis is currently known only from Japan (Sakai 1976).

Distribution
This species was recorded from Japan (Rathbun 1932).This is a new record for the South China Sea.

Diagnosis
Small species, pyriform carapace, smooth surface.Short diverging pseudorostral spines.One supraocular spine formed at anterior angle of supraocular eave.One postocular spine, 1 hepatic spine of same length.
European Journal of Taxonomy 358: 1-37 ( 2017) No distinct spine on dorsal surface of carapace.Gastric and cardiac regions slightly raised.Dorsal surface of carapace covered by tomentum of thick short setae.Basal antennal article fused with carapace, smooth, distal external angle forming blunt spine.

Remarks
What is here referred to as Rochinia sp., is probably a new species.However, as there are only two female specimens, one of which is in poor condition, it is not formally described here.This species is closest in morphology to R. daiyuae Takeda & Komatsu, 2005.However, in this species the hepatic spine is fl attened and pointing upwards (Fig. 8B-C), whereas in R. daiyuae, the fl attened hepatic spine is pointed anteriorly (Takeda & Komatsu 2005: fi g. 3A).

Distribution
Only known from South China Sea.

Remarks
The type species of this genus is Stegopleurodon planirostrum Richer de Forges & Ng, 2009, from New Caledonia.Until the discovery of the new species from the present SCS expeditions, the genus was monotypic.

Diagnosis
Carapace surface smooth, with 2 large lateral lobes; 1 postocular lobe with sharp anterior angle, 1 branchial lobe (Fig. 16A).Outer lateral border of branchial lobe thin, expanded above lateral border, forming wing-like structure.Dorsal surface with 2 convex regions: 1 small gastric swelling, 1 large cardiac one.Posterior part of cardiac convexity forms ridge joining posterior border of carapace.Male cheliped with propodus infl ated, carinate on upper border; carpus squarish in cross-section with each angle carinate; merus triangular in cross-section, with each angle carinate.Ambulatory legs with merus, carpus, propodus enlarged, carinate on upper border; lower border of merus of P2-P5 each with 2 crested carinae with margin bearing setae-like spines; dactylus curved, sharp.

Etymology
The name 'pteridion' means 'with wings' in Greek.The name is treated as a Latin noun in apposition.

Description
Small size species.Carapace pyriform.Pseudorostrum composed of 2 short dorsoventrally fl attened parallel teeth with rounded edge.Supraorbital eave narrow, forming rounded anterior and posterior angles.Carapace surface smooth, with 2 large lateral lobes; 1 postocular lobe with sharp anterior angle, and 1 branchial lobe (Figs 13F,14A).Outer lateral border of branchial lobe thin, expanded above lateral border, forming wing-like structure.Dorsal surface with 2 convex regions: 1 small gastric swelling, 1 large cardiac one (Figs 13F,14A).Posterior part of cardiac convexity forms ridge joining posterior border of carapace.
Antennae shorter than pseudorostrum.Antennule retractable in deep fossae.Eyes with short cornea, rounded; anterior region of eye protected by supraorbital eave; postorbital plate forms a cavity protecting posterior region of eye.On lateral side of carapace, behind postocular plate, a series of long hooked European Journal of Taxonomy 358: 1-37 (2017) setae.Basal antennal article fl at, curved on proximal edge; distinct tubercle at base of basal antennal article (Fig. 14B).Epistome small.Pterygostomial region relatively large, smooth, with 2 distinct plates present (Fig. 14B).Buccal frame quadrangular, completely closed by third maxillipeds.Male cheliped with propodus infl ated, carinate on upper border; carpus squarish in cross-section with each angle carinate; merus triangular in cross-section, with each angle carinate.Ambulatory legs with merus, carpus, propodus enlarged, carinate on borders; merus triangular in cross-section, lower border of merus of P2-P5 each with 2 crested carinae with margin bearing spine-like setae; carpus with 2 carinae on anterior region, posterior region covered with setae; propodus with single carina on anterior region, posterior region covered with setae; dactylus curved, sharp, covered with setae except at tip.Male thoracic sternum anteriorly deeply depressed, covered with setae, smooth when denuded; sternites 1-3 fused (Fig. 14B).Male abdomen with triangular telson and 6 free somites, widest at third.G1 straight, constricted distally (Fig. 15).

Colouration
In the fresh specimen, the carapace is orange with the chelipeds pinkish-orange; the fi rst three pairs of ambulatory legs are pale orange, with the last pair entirely white (Fig. 13F).14A).In S. planirostrum, there are strong ridges on the carapace: one longitudinal and two transverse, forming a cross on the gastric and another on the cardiac region (cf.Richer de Forges & Ng 2009b: fi g. 8A).In S. pteridion sp.nov., only one ridge is present on the posterior part of the carapace between the cardiac region and the posterior margin of the carapace (Fig. 14A, C).

Distribution
Only known from South China Sea.

Remarks
There are currently 29 species in this genus (Ng et al. 2008

Distribution
This species seems common in relatively shallower waters, between 150 and 250 m in Indonesia, the Philippines, Japan (Richer de Forges & Ng 2007) and Taiwan (Ng & Huang 1997).The species has also been recorded from East Africa, western Australia and South China Sea (Griffi n & Tranter 1986a).

Remarks
This deep-sea species was fi rst described from the Bohol Sea in the Philippines, and is believed to be associated with glass-sponges (Richer de Forges & Ng 2007).The species is characterized by the two pseudorostral spines, which are tightly appressed along most of their length.

Distribution
Besides the type locality in the Phillipines, this species has previously been recorded in Taiwan by Richer de Forges et al. (2009).This is a new record for the South China Sea.
The present large female specimen from the SCS material has a granulated carapace.On the interior border of the branchial region, there is a series of three strongly curved spines (Fig. 16A), whereas the Taiwanese specimen has a series of fi ve weak spines (Fig. 16B).On the thoracic sternum, there is a line of sharp spines adjacent to the margins of the abdomen.Compared to the material from Taiwan, which typically has granulation on thoracic sternum, all the specimens examined in this study possess spination that is similar to those from the Philippines (from PANGLAO 2005 expedition).This collection of Platymaia aff.remifera should be compared to the type material of P. remifera Rathbun, 1916, that was collected from the central Philippines, and P. alcocki Rathbun, 1916, that was collected from the Indian Ocean.Unfortunately, P. alcocki, was described on the basis of a juvenile specimen; hence certain morphological characteristics of the adult might not be obvious.

Distribution
This species seems to be very common in the northern Taiwanese waters (Ng & Huang 1997), as well as the Philippines (Guinot & Richer de Forges 1986;Ng & Huang 1997), and has been reported from the SCS by Serène & Lohavanijaya (1973).

Discussion
Overall, a total of 11 species from the family Epialtidae MacLeay, 1838, and fi ve species from the family Inachidae MacLeay, 1838, are reported from the SCS.Of these, two are new to science, Oxypleurodon leonis sp.nov.and Stegopleurodon pteridion sp.nov., while four are new records for SCS.Species that are not well known, Rochinia kagoshimensis (Rathbun, 1932) comb. nov. andRochinia strangeri Serène &Lohavanijaya, 1973, are redescribed and re-fi gured with fresh materials and type materials.
LEE B.Y. et al., Epialtidae and Inachidae from South China Sea Genus Rochinia A. Milne-Edwards, 1875 Remarks There are currently 39 recognised species in this genus (Ng et al. 2008; Richer de Forges & Ng 2013; Takeda & Marumura 2014; Tavares et al. 2016), with the species distributed across the Indo-Pacifi c and Atlantic Oceans (Griffi n & Tranter 1986a; Ng & Richer de Forges 2007).The type species of Rochinia is R. gracilipes A
Lee et al. 2015)tly 30 recognised species within this genus (Richer de Forges & Ng 2009a, b; Richer de Forges 2010; Richer de Forges & Corbari 2012;Lee et al. 2015).The type species of this genus is Oxypleurodon stimpsoni Miers, 1885, by monotypy.With the description of another new species from the SCS, there are now 31 species in Oxypleurodon.
The specimens examined from the South China Sea (SCS) have dorsal plates on carapace with rounded angles, and the articles of the ambulatory legs are cylindrical and slightly carinate (Figs 2C, 3C).The large series of specimens from Balicasag Island, the Philippines, LEE B.Y. et al., Epialtidae and Inachidae from South China Sea LEE B.Y. et al., Epialtidae and Inachidae from South China Sea (including the types) will need to be examined.At present, only one species is recognised, O. stimpsoni sensu lato.
Richer de Forges & Ng, 2009 Fig. 13E Oxypleurodon sanctaeclausi Richer de Forges & Ng, 2009a: 2-5, fi gs 1A-C, 3A, B, 11A (type locality: Bohol Sea, the Philippines).Oxypleurodon sanctaeclausi -Richer de Forges & Ng 2009b: 248 (table).-Lee et al. 2015: 1261.(For the complete synonymy of this species, see Richer de Forges & Ng 2009a: 2.) Material examined SOUTH CHINA SEA: 1 ♀ (16.6 × 11.5 mm) (ZRC 2016.0074),northwest of Dongsha, stn CP4160, 20°48.88′N, 116°43.15′E to 20°47.29′N, 116°42.06′E, 251-195 m, coll.ZHONGSHA 2015 Expedition, 30 Jul. 2015.Remarks Richer de Forges & Poore (2008) recognised a new species, O. wilsoni, from south of the Western Australian coast (ca 30° S).They separated it from the allied O. luzonicum (Rathbun, 1916) by a number of characters but based this on material they had from the northern part of the Western Australian coast (ca 15° S).Richer de Forges & Ng (2009a) clarifi ed the identity of O. luzonicum s. str. on the basis of topotypic material and recognised a new species, O. sanctaeclausi Richer de Forges & Ng, 2009, from the Bohol Sea, east of the Philippines.Species identifi ed as "O.luzonicum" from the Indonesian archipelago and the Philippines by Richer de Forges (1995) are now all referred to O. sanctaeclausi as well (Richer de Forges & Ng 2009a: 4).The South China Sea is now added to the range of O. sanctaeclausi.LEE B.Y. et al., (Rathbun, 1932)ges 2007, 2013; Richer de Forges & Poore 2008; Richer de Forges & Ng 2013), the genus has not been revised as a whole.Some genera, which were once synonymised under Rochinia, such as Sphenocarcinus A. Milne-Edwards, 1875 and Oxypleurodon Miers, 1885, have been resurrected and redefi ned (Tavares 1991; Richer de Forges & Ng 2009b).New genera have also been established: Goniopugettia Sakai, 1986, Laubierinia Richer de Forges & Ng, 2009, Guinotinia Richer de Forges & Ng, 2009, Garthinia Richer de Forges & Ng, 2009 and Samadinia Ng & Richer de Forges, 2013, all of which are related to Rochinia.It has been discussed by various authors (see Ng & Richer de Forges 2007, 2013; Richer de Forges & Poore 2008) that Rochinia is not homogeneous.However, splitting the genus into distinct groups is not a simple task.Ng & Richer de Forges (2013) recognised a new genus, Samadinia Ng & Richer de Forges, 2013 and also listed four possible groups within Rochinia.The diagnosis of the genus as provided by previous authors, such as Griffi n &Tranter (1986a, b)is no longer useful given the signifi cant changes in species composition since 1986.The authors of the present paper are currently revising this genus.With the new combination for one species, Rochinia kagoshimensis(Rathbun, 1932)comb.nov., a total of 40 species are now recognised in this genus.
European Journal of Taxonomy 358: 1-37(2017) comb.nov.Pugettia kagoshimensisRathbun, 1932: 31 (type locality: Sata Misaki Light, Japan).Supraorbital eave narrow, forming sharp distal angle.Small postorbital angle forming cavity protecting eye.Carapace with distinct spines: 2 long hepatic spines, pointed obliquely outwards; 1 short gastric spine surrounded by hooked setae; 1 strong thick cardiac spine with blunt squarish tip; 2 thick branchial spines long, pointing outward with blunt tips, proximal small spine on each branchial spine and pointing upwards; 1 tooth on posterior margin of carapace, with spine on anterior region of tooth.Long setae along lateral edge of carapace, between hepatic and branchial spines.Epialtidae and Inachidae from South China Sea blunt spine; dactylus slightly curved with sharp tip, proximal region covered with row of setae, short spines on distal third of dactylus.