Glypturus ferox, Sato & Komai & Shimizu, 2024

Sato, Taigi, Komai, Tomoyuki & Shimizu, Naoto, 2024, Glypturus ferox, a new species of ghost shrimp (Decapoda: Axiidea: Callichiridae) from the Ryukyu Islands, southwestern Japan, Zootaxa 5432 (3), pp. 379-397 : 382-393

Glypturus ferox n. sp.

[New Japanese name: Toge-toge-sunamoguri]

( Figs. 1–7 )

Type material. Holotype: RUMF-ZC-7575, male (cl 27.9 mm), Yoshihara beach, Kabira, Ishigaki Island, intertidal, 3 May 2023, collected by N. Shimizu, DNA voucher.

Paratypes: RUMF-ZC-7576, 1 juvenile (cl 8.1 mm), Sunabe, Chatan, Okinawa Island , intertidal, 1 June 2022 , collected by T. Sato; CBM-ZC 17534, 1 ovigerous female (cl 27.2 mm), Sukuji beach, Kabira , Ishigaki Island , intertidal, 30 July 2023, collected by N. Shimizu ; CBM-ZC 17532, 1 male (cl 15.8 mm), Hoshizuna beach, Uehara, Iriomote Island , intertidal, 14 January 2023 , collected by T. Sato, DNA voucher; CBM-ZC 17533, 1 female (cl 15.5 mm), same data, DNA voucher; RUMF-ZC-7577, 1 ovigerous female (cl 30.1 mm), Hoshizuna beach, Uehara , Iriomote Island , intertidal, 15 July 2023, collected by N. Shimizu.

Other material examined. RUMF-ZC-7578, right cheliped only, same data as CBM-ZC 17532, 17533.

Description. Rostrum ( Figs. 2A , 4A, B ) triangular in dorsal view, terminating in acute spine, overreaching midlength of eyestalks, but not reaching their apices, directed forward or slightly upward; dorsal surface non-carinate, with pair of tufts of short setae slightly proximal to midlength, lateral surface with short carina merging into orbital margin, ventral surface bluntly carinate in proximal half, abruptly becoming deep proximally. Carapace ( Figs. 2A , 3A, B , 4A, B ) frontal margin with sharp anterolateral spine on either side of rostrum, reaching to level of midlength of rostrum, directed forward. Orbital margin between rostrum and anterolateral spine slightly concave. Anterior part of dorsum gently sloping to rostral base; dorsal oval marked posteriorly by deep cervical groove at 0.7 of carapace length and sharp carina slightly posterior to cervical groove; cardiac region posterior to cervical groove slightly sloping posteriorly, nearly as high as dorsal oval; posterodorsal margin fringed with short setae. Linea thalassinica running over entire length of carapace.Anterolateral notch very deep, broadly V-shaped. Branchiostegite anteriorly with low, calcified plate, bearing 2 low elevations, lower elevation having one granule; this calcified part extending posteriorly as narrow band to level of midlength to posterior one-fourth of carapace along linea thalassinica; remainder part membranous, without any sclerite, but with irregularly reticulate pattern of sutures.

Shield on thoracic sternite 7 ( Fig. 3G ) strongly calcified; main part subrhomboidal, posterolateral margins strongly rimmed with tufts of short setae; ventral surface with shallow groove along each posterolateral rim, merging into median groove posteriorly; anterior prolongation also subrhomboidal.

Pleon ( Fig. 3C–F ) generally glabrous dorsally, about 2.2–2.3 times as long as carapace; length ratio of pleomeres 1–6 and telson measured along midline, 1.0: 1.3: 1.0: 0.9: 1.0: 1.5: 0.7; pleomeres 1 and 2 combined distinctly shorter than pleomeres 3–5 combined (2.3: 2.9). Pleomere 1 slightly narrowing anteriorly in dorsal view, slightly wider than long, clearly bisected by transverse carina running at anterior two-fifths of dorsal length of somite; pleuron with faintly defined ventral margin, continuous with chitinous frame defining posterior part of sternite; no longitudinal setal row on lateral surface. Pleomere 2 not particularly elongate, becoming slightly wider posteriorly; pleuron having posterolateral margin slightly expanded, lateral surface with distinct groove running along anterolateral to ventral margin on anterior part and crossing obliquely surface on posterior part, and with vertical row of setose punctae at posterior 0.8 and small tuft of setae adjacent to posteroventral angle. Pleomeres 3–5 each with short longitudinal sulcus posterolaterally on either side; pleura 3–5 each with patch of soft plumose setae, position of setal patch becoming more anterior in posterior somites; posterolateral margins slightly expanded; third pleuron with distinct excavation ventrally in anterior half to accommodate posterior margin of pleuron 2. Pleomere 6 roundly subrectangular in dorsal view, almost as long as wide; tergite strongly convex longitudinally and transversely, with submedian tufts of setae on posterior one-third and laterally with short transverse groove at posterior one-fourth; lateral surfaces each with field of setation anterior to transverse groove, extending anteriorly to about midlength of pleomere; posterior margin separated by short median groove, with 2 pairs of tufts of long setae laterally.

Telson ( Fig. 4G, H ) small, much narrower than pleomere 6, about 1.3 times wider than long, subrectangular with slightly convex lateral margins in dorsal view, merging into unarmed, nearly straight posterior margin, posterolateral angles faintly delimited, but indicated by tuft of long setae; posterior margin without median spine; dorsal surface anteriorly with low, rounded elevation delimited posteriorly by distinct transverse carina, this transverse carina bearing row of long setae flanked by 1 pair of spiniform setae.

Eyestalks ( Fig. 4A, B ) stout, somewhat depressed dorsoventrally, contiguous, narrowing distally; distomesial projection distinct, almost reaching distal end of first article of antennular peduncle; cornea located dorsolaterally and subterminally, dome-like, darkly pigmented, occupying less than half length of eyestalk. Length of exposed eyestalk in dorsal view not exceeding twice of basal width.

Antennular peduncle ( Figs. 2A , 4A, B ) shorter and slightly stouter than antennal peduncle, 0.3–0.4 times as long as carapace. Article 1 stout, dorsolateral margin distinctly carinate. Article 2 stout, 1.2 times as long as wide. Article 3 about twice as long as article 2, reaching proximal 0.3–0.5 of article 5 of antennal peduncle, narrowing distally. Distal 2 articles with ventromesial and ventrolateral rows of long setae; rows of setae continued onto ventral flagellum. Lower flagellum proximal segments bearing very long midventral setae. Upper flagellum about half length of carapace, slightly shorter than lower flagellum; segments in distal half bearing aesthetascs becoming longer and denser distally.

Antennal peduncle ( Figs. 2A , 4A, B ) about half length of carapace. Article 1 short, forming slightly produced, sparsely setose lobe above laterally produced excretory pore.Articles 2 and 3 obliquely jointed; article 2 distolaterally with single tuft of setae; article 3 with partially fused condylar process articulated to distolateral extreme of article 2, with ventrolateral row of long setae. Article 4 as wide as article 5, with row of sparse long setae on lateral face. Article 5 0.8–0.9 times as long as article 4. Scaphocerite small but well differentiated, showing as subcircular plate. Flagellum about 3.0 times as long as upper antennular flagellum, with 2 or 3 long setae every 2 or 3 articles.

Mouthparts not dissected. Maxilliped 3 ( Fig. 4C ) without exopod. Endopod with long setae on ventral margins of ischium-merus, distal 3 articles also with long setae on extensor and flexor margins. Merus-ischium about 2.5 times width, with distinct notch on lower margin at joint between these 2 articles; ischium subrectangular, longer than broad, proximoventral margin broadly rounded, not produced, mesial surface with well-developed crista dentata ( Fig. 5H ) consisting of 2 parts, distal part longitudinally oriented elevation bearing row of sharp, closely spaced denticles, proximal part with 4 or 5 spiniform denticles; merus roundly subrectangular, approximately as wide as long, upper margin slightly convex, lower margin more strongly convex; mesial surface with longitudinal row of setae medially in distal half. Carpus subequal in length to merus, abruptly narrowing in proximal half, jointed at distodorsal portion of merus; lateral surface with shallow excavation proximoventrally; mesial surface with dense field of fine setae distally. Propodus large, subquadrate with nearly straight extensor margin and strongly convex flexor margin, height subequal to or slightly exceeding length; distal margin inferior to base of dactylus slightly concave, forming rounded flexor distal angle, with prominent tuft of setae medially; mesial surface with patch of dense setae proximally. Dactylus narrow, slightly curved, tapering distally, terminating in small corneous claw, subequal in length to propodus.

Pereopods 1 (chelipeds) unequal and dissimilar, strongly calcified, major cheliped (right ones in all type specimens) strongly compressed laterally; coxae each with prominent process at ventromesial distal angle, bearing tuft of stiff setae. Male major cheliped ( Figs. 5A–D , 7A, B ) ischium slender, slightly widened distally; upper margin gently sinuous, non-carinate; lower margin with row of 8–12 obliquely erect spines noticeably increasing in size distally, distal end of lower margin slightly produced ventrally. Merus 1.8–2.0 times as long as wide; upper margin slightly convex, bluntly carinate, armed with 3 or 4 spines; lower margin also with 2–4 sharp, forwardly directed spines and 6 or 7 minute denticles, proximalmost spine located distinctly lateral to other spines; lateral surface elevated along midline into blunt ridge; mesial surface slightly uneven. Carpus subrectangular, length 1.1 times distal width; upper margin nearly straight, forming sharp keel terminating in blunt distal corner; lower margin also sharply keeled, terminating distally in spine, rounded in general outline, but armed with 3 or 4 spines; lateral surface evenly convex transversely; mesial surface with upturned ventral margin, weakly convex medially. Chela heavy, length (including fixed finger) about 1.8 times width, width greatest at about midlength of palm; palm as long as wide; upper margin of palm distinctly carinate in proximal half, rounded in distal half, armed with 4 distally directed spines (including distal spine); lower margin proximal to base of fixed finger armed with 4–8 spines and spiniform denticles, and with row of tufts of long stiff setae extending onto tip of fixed finger; lateral surface of palm evenly convex transversely, mostly glabrous; mesial surface very slightly convex medially, lower mesial margin slightly upturned. Fixed finger feebly curved in distal half, terminating in acute or subacute tip; occlusal margin with prominent blunt tooth over proximal two-fifths, remainder smooth; lateral surface with row of tufts of stiff setae along occlusal margin. Dactylus subequal to or slightly shorter than palm, slightly curving mesially in dorsal view, strongly curving ventrally in distal part in lateral view, terminating in blunt to acute tip; upper surface non-carinate, with row of tufts of long stiff setae; lateral surface also non-carinate, with row of tufts of stiff setae adjacent to occlusal margin; occlusal margin with 2 low, broad teeth slightly proximal to midlength, distal half forming sharp, smooth edge.

Female major cheliped ( Fig. 7C ) generally similar to that of males, but relatively more slender. Carpus subtriangular, 1.1–1.4 times as long as wide. Chela (including fixed finger) about twice as long as wide.

Male minor cheliped ( Fig. 5E–G ) similar to major cheliped in general setation and structure, but distinctly more slender. Ischium widened distally; upper margin slightly sinuous, non-carinate, unarmed; lower margin with 7–12 spines noticeably increasing in size distally, distal end slightly produced on lower margin. Merus subrectangular, length about 1.8–2.0 times width; upper margin distinctly carinate in distal half, armed with 3 or 4 spines including 1 at distal end; lower margin armed with 2 or 3 distally directed spines, proximalmost spine located distinctly lateral to other spines; lateral surface convex transversely, without ridge. Carpus subrectangular, narrowing proximally, subequal in length to merus, 1.3–1.5 times as long as wide, 1.1–1.3 times as long as palm, widest at distal end; upper and lower margins sharply keeled, latter armed with distal spine and 3–6 small spines. Chela as wide as carpus, length (including fixed finger) about twice width; palm subrectangular, 1.2 times as long as wide; upper margin sharply keeled in proximal half and rounded in distal half, armed with 2 or 3 small spines in distal half; lower margin with 5 spines or spinules; fixed finger subequal in length to palm, gradually tapering to acute or subacute tip, occlusal margin sharply edged entirely, with prominent blunt tooth at proximal 0.4; narrow hiatus between fingers; dactylus slightly longer than fixed finger, gently curving, terminating in acute or subacute tip, occlusal margin sharply edged, without conspicuous teeth.

Female minor cheliped generally similar to male minor cheliped, but carpus relatively more slender than that of male, 1.3–1.7 times as long as wide. Upper margin of palm with 3–5 spines.

Pereopod 2 ( Fig. 4D ) chelate, strongly compressed laterally, numerous long setae on lower margins of ischium to chela, tufts of setae on upper margins of carpus, palm and dactylus. Coxa with concave mesial face, unarmed. Ischium with upper margin slightly sinuous, lower margin strongly sinuous, terminating in small, well-marked tubercle. Merus with upper margin slightly sinuous, with tuft of setae at distal margin; lateral surface with several tufts of setae arranged longitudinally; lower margin sinuous, forming narrow facet. Carpus triangular, with transverse row of tufts of short setae adjacent to distal margin on lateral surface. Chela triangular; palm upper margin convex, lateral surface with several tufts of short setae; fingers straight, each terminating in small corneous tip, occlusal margins microscopically pectinate with row of corneous spinules; dactylus 2.3 times as long as palm.

Pereopod 3 ( Fig. 4E, F ) with coxa having flattish mesial face. Ischium with upper margin nearly straight, lower margin also straight, terminating in small tubercle. Merus widest at distal one-third, length exceeding 3 times width; margins with sparse setae; lateral surface glabrous. Carpus subtriangular, more than twice as long as distal width, distally with patches of stiff setae. Propodus subrectangular, with proximally-directed lobe of lower margin (heel) not reaching beyond broadest part of carpus, lobe terminally with dense, long distally-directed setae; lower distal margin faintly concave, with row of tufts of shorter setae; upper margin with fields of long setae grading to small patterned tufts of shorter setae on lateral face. Dactylus tear-shaped, densely setose on lateral surface, terminating in minute corneous tip.

Pereopod 4 ( Fig. 6A ) semichelate. Coxa enlarged, subovate, weakly flattened dorsoventrally, armed with small, outwardly directed spine on mesial face. Ischium with upper and lower margins nearly straight, latter terminating in minute tubercle. Merus wider and longer than carpus. Carpus elongate, slightly widened distally, length less than 4 times distal width. Propodus shorter than carpus; upper margin nearly straight, lower margin slightly sinuous, distal corner produced into short fixed finger bearing stout, microscopically serrate setae on external side and short bristles at truncate tip; dense setation on outer surface of propodus and dactylus, that of propodus divided into upper and lower fields, densest in lower field and continuing onto lower half of inner surface; dactylus terminating in minute corneous tip directed toward external side.

Pereopod 5 ( Fig. 6B ) chelate. Coxa with well-defined lateral facet. Ischium short, lower distal margin terminating in minute tubercle. Merus longest, gently arcuate. Carpus longer than propodus, greatest width at about distal one-third; dorsal margin convex distally. Propodus slightly widened distally; opposable surfaces of propodus and small dactylus excavate, spooned, terminally rounded, forming beak-like chela obscured by dense fields of setation on distal half of propodus and upper surface of dactylus; distal margins of tips of fingers microscopically pectinate.

Pleopod 1 uniramous in both male and female, composed of 2 articles. In male ( Fig. 6C ), ramus subrectangular, subequal in length to peduncle, bearing long stiff setae marginally and submarginally distally, terminally subdivided into 2 rounded lobes by U-shaped notch; superior lobe slightly exceeding inferior lobe. In female ( Fig. 6D ), both articles moderately slender and elongate; peduncle gently curved; ramus with weakly produced shoulder on proximal one-fourth.

Pleopod 2 biramous in both male and female. In male ( Fig. 6E ), setation short and sparse overall; protopod widest at midlength; endopod only faintly narrowed, without shoulder on mesial margin, appendix masculina located at distomesial portion of endopod, separated basally by incomplete oblique suture, roundly triangular in general outline, bearing long setae on mesial to terminal margin; appendix interna arising slightly proximal to midlength of appendix masculina; distolateral lobe of endopod separated from appendix masculina by deep V-shaped notch, rounded, bearing long marginal setae; exopod bladelike, slightly narrowed to rounded distal margin, reaching tip of appendix masculina, with transverse shallow grooves. In female ( Fig. 6F ), both rami with long setae on margins; protopod widest at midlength; endopod slightly narrowing distally, part distal to appendix interna gradually tapering; appendix interna slender, located at about 0.7 length of mesial margin of endopod, not reaching terminal margin of distal lobe; exopod overreaching distal margin of endopod, having some transverse shallow grooves.

Pleopods 3–5 forming large, wide, posteriorly cupped fans when cross-linked by cincinnuli of appendices internae on contiguous opposed margins of endopods, margins fringed by dense setae. Each protopod strongly flattened, subrectangular in general outline; anterior (dorsal) surface with blunt median ridge extending from base to joint with endopod; posterior (ventral) surface with median area being membranous. Endopod subtriangular, each with distinct, sinuous submedian keel on anterior surface; distal part with dendritic or reticulate pattern of sutures. Appendix interna located proximal to midlength of endopod, clearly demarcated basally, subtriangular in anterior or posterior views, stubby, basally embedded into mesial margin of endopod; mesial surface oval in outline, flattish, bearing numerous cincinnuli entirely. Exopod attached to lateral margin of protopod, embracing endopod; anterior surface each with median keel running over entire length, lateral and distomesial part with dendritic or reticulate pattern of sutures.

Uropod ( Figs. 3F , 4G ) with protopod roundly subrectangular in general shape, dorsally divided into 3 parts by distinct grooves, with prominent process at posteromesial angle (hidden by telson). Endopod exceeding as far as anterodorsal plate on flexed exopod, suboval in general outline with posteromesial margin more strongly convex than anterolateral margin, about twice as long as wide, tapering to rounded terminus bearing marginal fringe of long setae; margins fringed with thick setae; dorsal surface with distinct submedian carina reaching to posteromesial margin. Exopod roundly subtriangular in general outline, with very thick dorsal plate falling far short of distal margin, posterodistal edge of plate rounded, with short, thick, spiniform setae grading to thinner, dense, elongate setae of exopodal margin; dorsal surface with blunt, arcuate longitudinal carina reaching to posterolateral angle; distal margin of exopod fringed with short spiniform and long plumose setae; proximomesial article well demarcated, with 1 subdistal spine.

Ontogenetic variation. In juvenile specimen (RUMF-ZC-7576), major cheliped ( Fig. 7D, E ) with carpus subtriangular, unarmed on lower margin; upper margin of palm with fewer (3) spines than in adults; lower margin of palm with 4 minute denticles instead of spines; minor cheliped carpus lower margin unarmed, palm lower margin minutely dentate.

Coloration in life. Body generally light brown to light orange; dorsal oval and chelipeds pale orange to orange; antennae and antennules orange, flagella uniformly orange ( Figs. 1 , 2A ).

Distribution. Presently known only from Ryukyu Islands, Japan: Okinawa Island, Ishigaki Island, Iriomote Island; intertidal.

Ecology. All type specimens of Glypturus ferox n. sp. were collected from intertidal sand flats in inner reef lagoons ( Fig. 8A–C ). Mounds and burrow openings were found in seagrass beds, chiefly composed of Halodule pinifolia and Thalassia hemprichii , where the specimens of the new species were collected. Ovigerous females were collected in July.

A commensal mud shrimp, Naushonia carinata Dworschak, Marin & Anker, 2006 (Gebiidea: Laomediidae ), was collected from a burrow of the present new species at Hoshizuna beach, Iriomote Island.

Etymology. The specific epithet is derived from the Latin word “ferox ” (= fierce), by its distinctive spinose major cheliped palm.

Remarks. Glypturus ferox n. sp. is unique within the genus in having a row of spines on the lower margin of the major cheliped palm. In other four extant congeners, this margin is unarmed ( Rabalais et al. 1981; de Vaugelas & de Saint Laurent 1984; Manning 1987; Klompmaker et al. 2015; Komai et al. 2015). In spite of the unique armature in the major cheliped palm, the new species is morphologically most similar to G. armatus , particularly in the smooth lateral and mesial faces of the major chela, which are devoid of fields of granules. In addition to the different armature of the major cheliped palm, G. ferox n. sp. is distinguished from G. armatus by the following characters: lateral margins of telson nearly straight in G. ferox n. sp. ( Fig. 4G, H ), rather than weakly convex in G. armatus (cf. Komai et al. 2015: fig. 2D, F); lower margin of minor cheliped palm with spines or spinules in adults of G. ferox n. sp. (but no spines in young specimens) ( Fig. 5F, G ), while always unarmed in G. armatus ( Komai et al. 2015: fig. 5D); carpus of pereopod 4 stouter in G. ferox n. sp. than in G. armatus (less than 4 times as long as wide versus about 4.5 times as long; cf. ( Fig. 6A versus Komai et al. 2015: 27, fig. 4G); distolateral lobe of the ramus of the male pleopod 1 rounded ( Fig. 6C ), rather than acuminate in G. armatus (cf. Komai et al. 2015: fig. 6A). The colour of the antennular and antennal flagella is also different between the new species and G. armatus . In the new species, those flagella are uniformly brown ( Figs. 1 , 2A ), whereas in G. armatus there are brown rings on the translucent ground colour (cf. Fig. 2B , Dworschak 2018: fig. 1d).

Habitat preference may be different between Glypturus ferox n. sp. and G. armatus, although these two species were seen sympatrically at Yoshihara beach, Ishigaki Island. As noted above, specimens of G. ferox n. sp. were all collected from intertidal sand flats in inner reef lagoons on relatively open coasts ( Fig. 8A–C ). On the other hand, G. armatus is found intertidally as well as subtidally (to 30 m depth) in diverse conditions ( Poore & Suchanek 1988, as G. motupore ).

The other three species ( G. acanthochirus , G. laurae and G. rabalaisae ) differ further from the new species in having fields of granules on the lateral and mesial faces of the major cheliped palm ( Klompmaker et al. 2015; Felder 2019). Poore (2023) reported that in a small specimen from Saudi Arabia he referred to G. laurae the cheliped palm was devoid of granules on the lateral face, and this suggests that the development of granular fields on the major cheliped palm might vary ontogenetically in G. laurae . In addition, the banded colour of the antennular and antennal flagella in life also differentiates G. acanthochirus and G. rabalaisae from G. ferox n. sp. ( Poore & Ahyong 2023; Felder 2019). No information on the living coloration is available for G. laurae .

As mentioned above, Glypturus is well represented by fossil taxa, although precise comparison with extant species is not easy because of the availability of only major cheliped in fossils (e.g., Klompmaker et al. 2015). Nevertheless, none of those fossil taxa has spines on the major cheliped palm lower margin ( Böhm 1922; Schweitzer et al. 2006; Beschin et al. 2012; Hyžný & Müller 2012; Hyžný et al. 2013; Klompmaker et al. 2015). Furthermore, in all but G. spinosa , the major cheliped palm has fields of granules on the lateral and mesial faces, though the extension varies according to species ( Hyžný & Müller 2012; Hyžný et al. 2013; Klompmaker et al. 2015). As mentioned above, in G. ferox n. sp. and G. armatus, such fields of granules are not seen on the major cheliped palm. Glypturus spinosus is distinctive in having unusually strong spines on the upper margin of the major cheliped palm ( Hyžný & Müller 2012: fig. 7D). Glypturus sp. sensu Klompmaker et al. (2015) is not considered herein because of its uncertain taxonomic status.

The phylogenetic relationship among the five species of Glypturus , inferred from partial fragments of the 16S rRNA gene is well consistent with the phylogenetic reconstruction by Robles et al. (2020). Glypturus ferox n. sp. is sister species to G. armatus ( Fig. 9 ), although the pairwise genetic divergence between the two species is considerably high (14.6–16.5%).

Figures

FIGURE 1. Glypturus ferox n. sp., habitus, showing living coloration. A, B, holotype, male (cl 27.9 mm), RUMF-ZC-7575, dorsal and left lateral view; C, left, paratype, male (cl 15.8 mm), CBM-ZC 17532; middle, paratype, female (cl 15.5 mm), CBM- ZC 17533; right, non-type (right cheliped, no owner was collected), RUMF-ZC-7578.

FIGURE 2. Anterior part of carapace and cephalic appendages of Glypturus, dorsal view. A, G. ferox n. sp., paratype, female (cl 30.1 mm), RUMF-ZC-7577; B, G. armatus (A. Milne Edwards, 1870), female (cl 31.0 mm), RUMF-ZC-7579.

FIGURE 3. Glypturus ferox n. sp., holotype, male (cl 27.9 mm), RUMF-ZC-7575.A, B, carapace and cephalic appendages, left lateral and dorsal view; C, pleomeres 1 and 2, dorsal view; D, pleomeres 3–5, dorsal view; E, pleomere 6, dorsal view; F, pleon, telson and pleonal appendages, left lateral view; G, shield on seventh thoracic sternite. Scale bars: 5.0 mm.

FIGURE 4. Glypturus ferox n. sp., holotype, male (cl 27.9 mm), RUMF-ZC-7575. A, B, anterior part of carapace and cephalic appendages, left lateral and dorsal view (antennular flagella omitted); C, left maxilliped 3, lateral view (setae omitted); D, left pereopod 2, lateral view; E, left pereopod 3, lateral view; F, same, propodus and dactylus, lateral view (setae omitted); G, telson and left uropod, dorsal view; H, telson, dorsal view (simple setae omitted). Scales bars: 5.0 mm.

FIGURE 5. Glypturus ferox n. sp., holotype, male (cl 27.9 mm), RUMF-ZC-7575. A–D, major (right) cheliped; E–G, minor (left) cheliped. A, E, ischium, lateral view; B, F, merus to chela, lateral view; C, G, lower margin of palm, lateral view (setae omitted); D, chela, dorsomesial view (setae omitted); H, left maxilliped 3, ischium, ventral view (setae omitted). Scales bars: 5.0 mm.

FIGURE 6. Glypturus ferox n. sp. A–C, E, holotype, male (cl 27.9 mm), RUMF-ZC-7575; D, F, paratype, female (cl 15.5 mm), CBM-ZC 17533. A, left pereopod 4, lateral view (setae omitted); B, left pereopod 5, lateral view (setae omitted); C, left pleopod 1, lateral view; D, left pleopod 1, ventral view; E, F, left pleopod 1, ventral view. Scales bars: A, B, 5.0 mm; C–F, 1.0 mm.

FIGURE 7. Glypturus ferox n. sp., major (right) chelipeds, lateral view (setae omitted). A, body not collected (right cheliped only), RUMF-ZC-7578; B, paratype, male (cl 15.8 mm), CBM-ZC 17532; C, paratype, female (cl 15.5 mm), CBM-ZC 17533; D, E, paratype, juvenile (cl 8.1 mm), RUMF-ZC-7576. A–D, merus to chela; E, chela. Scales bars: A–D, 5.0 mm; E, 1.0 mm.

FIGURE 8. Habitat of Glypturus species in Ryukyu Islands.A, Hoshizuna Beach, Iriomote Island, habitat of G. ferox n. sp.; B, same, mounds; C, same, mound and burrow opening; D, coast of Ikei Island, Okinawa Islands, habitat of G. armatus (A. Milne Edwards, 1870).

FIGURE 9. Maximum likelihood (ML) phylogenetic tree of five species of Glypturus based on 538 bp of partial fragments of the mitochondrial 16S rRNA gene. Bootstrap values (≥ 80%) are shown.