Pagurixus nomurai Komai & Asakura, 1995

Komai, Tomoyuki & Osawa, Masayuki, 2006, A review of the Pagurixus boninensis species group, with descriptions of six new species (Crustacea: Decapoda: Anomura: Paguridae), Zootaxa 1214 (1), pp. 1-107 : 32-40

Pagurixus nomurai Komai & Asakura, 1995

( Figs. 12–14 , 44C , 47 )

Pagurixus nomurai Komai & Asakura, 1995: 341 , figs. 1–3 [type locality: Kuroishi, Kume­jima Island, Ryukyus, 5 m].— Nomura et al., 1996: 14.— Hoover, 1998: 261, unnumbered fig.— Kato & Okuno, 2001: 85, 146, unnumbered figs.— Kawamoto & Okuno, 2003: 89, unnumbered fig.— Osawa & Takeda, 2004: 1109 .— Okuno & Arima, 2004: 60, Fig. 3D .

Pagurixus sp. 2 (n. sp. fast purple).— Paulay et al., 2003: 490.

Not Pagurixus nomurai .—Asakura, 2002: 452, fig. 4. [right = Pagurixus boninensis ( Melin, 1939) ; left = Catapagurus hirayamai ( Asakura, 2001) ]. See ’Remarks.’

Type material

HOLOTYPE: CBM­ZC 378, female (SL 4.0 mm), Kuroishi , Kume­jima Island, Ryukyus, 5 m, SCUBA, coll. K. Nomura, 24 November 1992 . PARATYPE: CBM­ZC 379, 1 male (SL 3.3 mm), Nakanohama , Kume­jima Island, 10 m, SCUBA diving, coll. S. Hirayama, 22 September 1993 .

Other material. Japan: CBM­ZC 560, 1 female (SL 3.9 mm), Chiyogahama , Hachijo Island, Izu Islands, 12 m , SCUBA diving, coll. H. Takasu, 8 July 1994 ; CBM­ZC 2389, 1 male (SL 3.0 mm), Kuroshima Island , Yaeyama Islands, Ryukyu Islands, intertidal, coll. M. Osawa, 2 September 1992 ; CBM­ZC 3115, 1 female (SL 3.1 mm), Madomari Port , Kume­jima Island, 8–10 m , SCUBA diving, coll. K. Nomura, 11 June 1995 ; CBM­ZC 3423, 1 female (SL 3.2 mm), Akihohama , Izu­Oshima Island, Izu Islands, 10 m , SCUBA diving, coll. M. Mitsuhashi, 19 October 1996 ; CBM­ZC 5015, 1 ovigerous female (SL 4.8 mm), Kuroshima Island , Yaeyama Islands, 5 m , SCUBA diving, coll. K. Nomura, 1 June 1999 . CBM­ZC 7859, 1 female (SL 3.8 mm), Sabiura , Kushimoto, Kii Peninsula, 5–6 m , SCUBA diving, coll. K. Nomura, 24 January 2004 ; CBM­ZC 8256, 1 female (SL 3.2 mm), Fuki Beach , Kuroshima Island, Yaeyama Islands, lagoon, 2 m, coll. K. Nomura, 3 September 1998 ; CBM­ZC 8258, 1 female (SL 2.6 mm), Sabiura , Kushimoto, Kii Peninsula, 6 m , SCUBA diving, coll. K. Nomura, 5 March 1995 . Guam: UF 31 , 2 males (SL 2.2, 3.1 mm), Agat Bay , north of Aluton Island, fore reef, 5 m, coral rubble, coll. H. Conley, 15 November 2000 ; UF 274 , 1 male (SL 3.3 mm), similar locality, 2–60 m, date not indicated, coll. H. Conley ; UF 432 , 1 male (SL 3.6 mm), Gun Beach , 10–15 m, fore reef, under rubble, coll. G. Paulay, 1 July 1999 ; UF 485 , 1 female (SL 4.9 mm), Apra Harbor , 15–35 m, among rocks, coll. H. Conley, 1 June 2001 ; UF 1395 , 1 male (SL 3.8 mm), Haputo , 8–10 m, rubble field, under rock, coll . V. Bonito & R. Riston­Williams , 29 March 2001 ; UF 7078 , 1 female (SL 3.5 mm), Piti lagoon, 1.2–2.4 m, coll. H . T. Conley , 23 April 1994 ; UF 7079 , Piti lagoon, 1.2–3.2 m, coll. H . T. Conley , 3 June 1996 ; UF 7080 , 1 ovigerous female (SL 3.6 mm), Cocos Barrier Reef , rubble field, coll. G. Paulay, 19 May 1997 ; UF 7293 , 1 male (SL 3.3 mm), outer end of Orote Peninsula , reef slope, 20–25 m, coll. G. Paulay, 27 November 1998 ; UF 7294 , 1 ovigerous female (SL 3.7 mm), Tepungan channel on floor, 3–5 m, coll. L. Kirkendale, 3 June 1999 ; UF 7295 , 1 ovigerous female (SL 2.0 mm), Lace Coral Cave , 10 m, coll. L. Kirkendale, 14 January 2000 ; UF 7296 , 1 male (SL 5.1 mm), 1 ovigerous female (SL 4.8 mm), Barracuda rock, in crevices, 15 m, coll. G. Paulay, 27 April 2000 ; UF 7297 , 1 male (SL 4.2 mm), 1 ovigerous female (SL 4.2 mm), south of Orote Peninsula , Shark Pit, 15 m, coll. G. Paulay, 31 May 2000 ; UF 7288 , south of Haputo fore reef, 6–9 m, coll. G. Paulay, 1 August 2000 ; UF 7289 , 1 ovigerous female (SL 2.3 mm), Anae Cave , 5–8 m, coll. G. Paulay, 18 August 2000 ; UF 7290 , 1 male (SL 2.5 mm), 1 ovigerous female (SL 3.1 mm), 1 juvenile (SL 1.8 mm), Agat Bay , north of Alutan Island fore reef, 3–8 m, coll. H . T. Conley , June–August 2000 ; UF 7291 , 1 ovigerous female (SL 4.6 mm), same locality, 3–5 m, coll. H . T. Conley , 14–17 August 2000 . Cook Islands: UF 1366 , 1 female (SL 3.4 mm), Avarua Pass , Rarotonga, subtidal, coll. C. Meyer, 27 October 2001 . Tuamotu Archipelago : UF 1746 , 4 ovigerous females (SL 2.4–3.5 mm), Rangiroa Atoll , 14°92.87’S, 147°85.78’W, 3–12 m, outer reef slope, coll. G. Paulay, 10 February 2001 ; UF 1754 , 2 males (SL 2.1, 3.0 mm), 2 ovigerous females (SL 3.1, 3.5 mm), Avatoru Motu , Rangiroa Atoll, intertidal, reef flat, coll. G. Paulay, 10 January 2001 ; UF 1814 , 1 ovigerous female (SL 1.6 mm), Rangiroa Atoll , 14°92.87’S, 147°85.78’W, 6–12 m, outer reef slope, under rock, coll. G. Paulay, 10 November 2001 ; UF 1855 , 1 male (SL 2.3 mm), same data ; UF 1859 , 1 female (SL 2.4 mm), off Hotua Ura Motu , Rangiroa Atoll, 14°93.12’S, 147°72.6’W, 5–12 m, outer reef slope, coll. G. Paulay, 10 October 2001 . Society Islands : UF 1341 , 1 male (SL 2.9 mm), Passe Taotai , Moorea, 0–2 m, barrier reef, under rocks, coll. G. Paulay, 22 October 2001 . Samoa: UF 3248 , 1 male (SL 3.4 mm), Tuituilia Island , American Samoa, 9–18 m, coll . V. Bonito , 16 October 2002 .

Description

Shield 1.0–1.1 ( Fig. 12A ) times as long as broad; anterior margin between rostrum and lateral projections concave; anterolateral margins sloping; dorsal surface with several pairs of tufts of short to long setae. Rostrum triangular, distinctly overreaching lateral projections and reaching nearly to level of midlength of ocular acicles. Lateral projections obtusely triangular, weakly produced, with small submarginal spine.

Ocular peduncle ( Fig. 12A ) moderately long but comparatively stout, 0.7–0.8 of shield length, each with row of tufts of short setae on dorsal surface mesially; cornea distinctly dilated, corneal width 0.4–0.5 of peduncular length; basal part not inflated, narrower than corneal width. Ocular acicles subovate or subtriangular, with small submarginal spine.

Antennular peduncle ( Fig. 12A ) overreaching distal margin of cornea by 0.2–0.3 length of ultimate segment. Ultimate segment with tufts of long setae at dorsolateral distal angle; 2 longitudinal lines of setae each consisting of scattered numerous short setae ( Fig. 12B ). Basal segment with small lateral spine on statocyst lobe. Ventral flagellum with numerous long setae on lateral and mesial margins ( Fig. 12B ).

Antennal peduncle ( Fig. 12A ) overreaching distal margin of cornea by 0.3–0.5 length of fifth segment. Second segment with conspicuous spine at dorsomesial distal angle; laterodistal projection not reaching midlength of fourth segment, terminating in simple or bifid spine. Antennal acicle moderately long, reaching or overreaching distal margin of cornea; mesial margin with row of tufts of stiff setae. Flagellum extremely long, exceeding 8.0 length of shield.

Right cheliped of males ( Fig. 13A–D ) elongate. Chela subovate in dorsal view, 2.3–2.6 times longer than wide. Dactylus 0.5–0.6 length of palm; dorsomesial margin not delimited; surfaces coarsely granular; cutting edge with 1 or 2 prominent calcareous teeth and row of short corneous teeth in distal 0.2, terminating in very small corneous claw. Palm slightly longer than carpus; convex dorsal surface with covering of small granules, dorsolateral margin weakly delimited by granular ridge becoming obsolete proximally, dorsomesial margin not delimited; lateral, mesial and ventral surfaces granular (granules on ventral surface larger), with some tufts of short to long setae. Fixed finger with crenulate cutting edge bearing 1 low, but distinct calcareous tooth, terminating in very small corneal tooth or small calcareous tooth. Carpus slightly shorter than or subequal to merus; dorsolateral and dorsomesial margins each faintly delimited by row of small, often spinulose tubercles; all surfaces granular, lateral surface divided into oblique dorsal and perpendicular ventral sections by distinct, tuberculate longitudinal ridge. Meral­carpal articulation lacking any pronounced clockwise rotation; dorsal surface of merus with row of low transverse ridges, dorsodistal margin unarmed; lateral and ventral faces with minute vertical ridges and small granules; ventrolateral margin with 1 distal spine and row of small spinulose tubercles; ventromesial margin with row of spinulose tubercles; ventral surface slightly concave, with scattered granules and few short setae. Ischium with row of minute denticles on ventromesial margin; posterolateral angle with few tiny tubercles.

Right cheliped of females ( Fig. 14A–C ) comparatively slender for genus, length substantially variable. Chela subovate in dorsal view, 2.4–2.7 times longer than broad. Dactylus about 0.8 length of palm, with low longitudinal ridge on dorsal midline; cutting edge with row of unequal calcareous teeth and row of long corneous teeth in distal 0.3, terminating in small corneous claw. Palm about half length of carpus; convex dorsal surface covered with minute granules, dorsolateral margin clearly delimited by granular ridge, dorsomesial margin not delimited; lateral, mesial and ventral surfaces granular; tufts of long setae present on ventral surface. Cutting edge of fixed finger with row of small calcareous teeth, terminating in small calcareous claw. Carpus 2.5–3.0 times longer than distal width, slightly shorter than or subequal to merus; dorsal surface with long setae (number of setae variable) and longitudinal row of small tubercles mesially; dorsolateral margin weakly delimited by row of small spinulose tubercles, dorsomesial margin not delimited; all surfaces with sparse granules, lateral surface divided into two sections (oblique dorsal and perpendicular ventral sections) by distinct, granular or tuberculate ridge. Merus with row of low transverse ridges and tufts of long setae on dorsal surface, dorsodistal margin unarmed or with 1 small spine; lateral face with numerous minute vertical ridges, ventrolateral margin with 1 subdistal spine but otherwise nearly smooth; mesial surface also with minute or short vertical ridges, ventromesial margin with row of small granules. Ischium with row of minute denticles on ventromesial margin, otherwise unarmed.

Left cheliped ( Fig. 13E–H ) elongate, very slender, similar between male and female. Chela 3.0–3.5 times longer than broad. Dactylus longer than palm, with sparse tufts of setae on surfaces (setae on ventral surface longest); surfaces smooth; cutting edge with fine row of small corneous teeth, terminating in small corneous claw. Palm shorter than half length of carpus; dorsal surface slightly convex, with sparse tiny tubercles, dorsomesial margin faintly delimited by row of tiny tubercles; lateral part of dorsal surface also sloping, dorsolateral and dorsomesial margins not delimited; lateral, mesial, ventral surfaces nearly smooth or with few low protuberances, and with tufts of short to long setae. Carpus elongate, very slender, subcylindrical, 1.1–1.2 length of chela and subequal in length to merus; length 3.0–4.3of distal width and 3.5–4.5 of greatest height; surfaces with minute granules; dorsolateral and dorsomesial margins each with row of small tubercles and stiff setae; lateral surface divided into oblique dorsal section and perpendicular ventral section by distinct, granular or crenulate ridge; mesial surface with tufts of long setae; ventral surface smooth, with some long setae. Merus with row of short transverse ridges on dorsal surface, and tufts of very short setae, dorsodistal margin unarmed, but with several long setae; lateral surface with numerous very small vertical ridges, ventrolateral margin nearly smooth or with few tiny tubercles; mesial face with short vertical ridges, ventromesial margin nearly smooth or with row of small granules. Ischium with row of minute denticles on ventromesial margin, otherwise unarmed.

Ambulatory legs ( Fig. 14D, E ) long and slender, similar from right to left. Dactyli ( Fig. 14F, G ) of second 0.9–1.0 length of propodi, those of third 1.0–1.1, 9.0–11.0 times longer than high; terminating in large corneous claws; dorsal surfaces each with row of sparse long setae; lateral and mesial faces each with few tufts of short setae, mesial faces unarmed (second) or armed with row of corneous spinules adjacent to dorsal margin (third); ventral margins each with 9–12 long corneous spines increasing in size distally. Propodi tapering distally, 5.5–6.5 times longer than high; dorsal surfaces each with row of low protuberances and moderately long stiff setae; lateral faces smooth; ventral margins each with row of 4–6 corneous spinules, ventrodistal margins with paired long corneous spines. Carpi each with dorsodistal spine or tubercle (sometimes rudimentary), dorsal surface with row of low protuberances and tufts of short setae; lateral faces with sparse granules and short setae. Meri each with row of low transverse ridges and short stiff setae on dorsal surface; lateral surfaces minutely granular, with scattered tufts of short setae (granules fewer on third than on second); ventrolateral distal margins each with small subdistal spine on second, unarmed on third; ventral margins each with row of spinules or small spinulose tubercles (second) or smooth (third), and with row of short setae.

Fourth pereopods ( Fig. 12C, D ) similar from right to left in both male and female. Dactyli moderately broad, terminating in small corneous claws; dorsal margins with short setae. Propodi with few tufts of short setae on nearly flat mesial faces.

Anterior lobe of sixth thoracic sternite ( Fig. 12E, F ) transversely oblong, anterolateral angles produced laterally (more prominent in females), each angle occasionally with 1 or 2 small tubercles, anterior margin slightly concave, with row of moderately short setae. Eighth thoracic sternite ( Fig. 12G ) composed of 2 subequal, closely set, rounded lobes.

Males with coxae of fifth pereopods slightly unequal ( Fig. 12G ); right with tuft of long stiff setae directed toward left and reaching left coxa; posteromesial protrusion not developed, but short, papilla­like sexual tube apparent; left coxa with papilla­like sexual tube or protrusion of vas deferens partially masked by tuft of setae directed ventrally. Females with paired gonopores.

Telson ( Fig. 12H ) with terminal margins oblique, each bearing 6–8 very small spines.

Colour in life. ( Fig. 44C ) Appendages generally brown, olive or bluish gray. Shield with white marking on brown background. Antennal flagellum uniformly brown. Meri of chelipeds each with 2 moderately broad white bands; meri of ambulatory legs also with 2 moderately broad white bands.

Variation. Variation in the setation on the shield, chelipeds and ambulatory legs is substantial in P. nomurai . The presence of relatively numerous tufts of stiff setae on the shield and appendages is seen in large specimens, regardless of sex. Variation in length and stoutness of the female right cheliped is appreciable (cf. Komai & Asakura 1995: fig. 2A; this study) and this does not appear to be a function of size.

Distribution

Previously known from southern Japan and Hawaii ; newly recorded from Guam, Cook Islands, Tuamotu Archipelago , Society Islands , Samoa and northwestern Australia (Kimberley) ( Fig. 47 ); subtidal to 60 m. It appears that P. nomurai is widely distributed in tropical and subtropical waters in the western Pacific, and at least in the eastern Indian Ocean .

Remarks

The transversely oblong anterior lobe of the sixth thoracic sternite is shared by P. nomurai , P. laevimanus and P.tweediei . Pagurixus nomurai is characterized by the slender left cheliped and the elongate ambulatory dactyli (Table 1). Furthermore, the structure of the setal rows on the ventral surface of the antennular peduncle is different between P. nomurai and the other two species.

In the original description of P. nomurai, Komai & Asakura (1995) reported the species as having a transverse white band on each carpus of the chelipeds, but this is incorrect. In fact, there are no white bands on the carpi of the chelipeds in the specimens examined, in which the color pattern was still preserved.

Asakura (2002) presented two color photographs of living hermit crabs, taken in situ at Hachijo Island, Izu Islands, which he believed to represent P. nomurai . However, the coloration of the hermit crabs depicted in the two photographs is quite different from that of P. nomurai . The coloration of the individual shown in the figure (4A, left) of Asakura (2002) corresponds well to that of P. boninensis , particularly in the striped color of the ambulatory legs. The second, right photograph most probably represents Catapagurus hirayamai (Asakura, 2002) because of the coloration and the shape of the chelipeds ( Okuno & Arima 2004; personal observation). The specimen ( UF 432) listed as Pagurixus sp. 2 (n. sp. fast purple) by Paulay et al. (2003) is identifiable with P. nomurai .

Figures

FIGURE 3. Pagurixus laevimanus (Ortmann, 1892). Holotype male (SL 3.7 mm) from Tahiti (MZS 464, in spirit). A, right second pereopod, lateral view; B, left third pereopod, lateral view; C, right second pereopod, dactylus and distal part of propodus, mesial view; D, left third pereopod, dactylus and distal part of propodus, mesial view. Scale bars: 2 mm for A, B; 2 mm for C, D.

FIGURE 12. Pagurixus nomurai Komai & Asakura, 1995. A–E, G–H, male (SL 3.0 mm) from Rangiroa Atoll, Tuamotu Archipelago (UF 1754); F, female (SL 4.9 mm) from Guam (UF 485). A, shield and cephalic appendages, dorsal view; B, ultimate segment and ventral flagellum of left antennule, ventral view; C, dactylus and propodus of left fourth pereopods, lateral view; D, dactylus and propodus of right fourth pereopod, lateral view; E, sixth thoracic sternite, ventral view; F, same, anterior lobe; G, coxae of fifth pereopods and eighth thoracic sternite, ventral view; H, telson, dorsal view. Scale bars: 1 mm for A, E; 0.5 mm for B–H.

FIGURE 13. Pagurixus nomurai Komai & Asakura, 1995. Male (SL 3.0 mm) from Rangiroa Atoll, Tuamotu Archipelago (UF 1754). A, chela of right cheliped, dorsal view; B, entire right cheliped, mesial view; C, same, lateral view; D, carpus of right cheliped, dorsal view; E, chela of left cheliped, dorsal view; F, entire left cheliped, mesial view; G, same, lateral view; H, carpus of left cheliped, dorsal view. Scale bars: 1 mm.

FIGURE 14. Pagurixus nomurai Komai & Asakura, 1995. A–C, female (SL 4.9 mm) from Guam (UF 485); D–G, male (SL 3.0 mm) from Rangiroa Atoll, Tuamotu Archipelago (UF 1754). A, right cheliped, chela and carpus, dorsal view; B, entire right cheliped, mesial view; C, same, lateral view; D, right second pereopod, lateral view; E, left third pereopod, lateral view; F, right second pereopod, dactylus and distal part of propodus, mesial view; G, left third pereopod, dactylus and distal part of propodus, mesial view. Scale bars: 1 mm.

FIGURE 44. A, Pagurixus maorus (Nobili, 1906), male (SL 3.9 mm) from Kume­jima Island, Ryukyu Islands, photo taken by M. Osawa; B, Pagurixus tweediei (Forest, 1956), male (SL 3.9 mm) from Tahiti, Society Islands, French Polynesia (UF 1731), photo taken by G. Paulay; C, Pagurixus nomurai Komai & Asakura, 1995, ovigerous female from Guam, Mariana Islands (UF), photo taken by G. Paulay; D, Pagurixus concolor n. sp., paratype female (SL 3.2 mm) from Tokashiki Island, Kerama Islands (CBM­ZC 8484), photo taken by M. Osawa.

FIGURE 47. Geographic distribution of Pagurixus laevimanus (), P. maorus (), P. tweediei (), P.nomurai (), P. pulcher () and P. concolor n. sp. ().