A review of the Pagurixus boninensis species group, with descriptions of six new species (Crustacea: Decapoda: Anomura: Paguridae) Author Komai, Tomoyuki Natural History Museum and Institute, Chiba, 955 - 2 Aoba-cho, Chuo-ku, Chiba 260 - 8682, Japan. Author Osawa, Masayuki text Zootaxa 2006 2006-05-26 1214 1 1 107 https://biotaxa.org/Zootaxa/article/view/zootaxa.1214.1.1 journal article 10.11646/zootaxa.1214.1.1 1175­5334 5064559 6FAE48F8-3ABE-4D62-B4D9-4CDF1BDFF6FB Pagurixus ruber n. sp. ( Figs. 40–43 , 46B , 48 ) Pagurixus boninensis .— McLaughlin & Haig, 1984: 124 (in part), fig. 1a, c, d, f, g.— Paulay et al., 2003: 490 . Type material HOLOTYPE : CBM­ZC 7862, male (SL 2.4 mm ), Ahra beach, Kume­jima Island , Ryukyu Islands , intertidal reef flat, coll. T . Komai and M. Osawa , 15 June 1995 . PARATYPES . Izu Islands , Japan : CMNH­ZC 1863 , 1 male (SL 2.2 mm ), Akinohama , Izu­oshima Island , 4 m , SCUBA diving, coll. H. Arima , 10 November 2004 ; CMNH­ZC 1864 , 1 ovigerous female (SL 2.4 mm ) , same locality, SCUBA diving, coll. H. Arima , 18 November 2004 ; CMNH­ZC 1873 , 1 male (SL 2.3 mm ) , same locality, SCUBA diving, coll. H. Arima , 14 January 2005 . Ryukyu Islands : CBM­ZC 7863, 2 male (SL 1.7, 1.7 mm ), 2 females (SL 1.3, 2.0 mm) , same data as holotype; CBM­ZC 8485, 1 female (SL 2.6 mm ), Naze , Amami­Oshima Island , coll. M. Osawa ; CBM­ZC 8486, 1 male (SL 2.2 mm ), Saneku , Amami­Oshima Island , under dead coral, 1–2 m , coll. M. Osawa , 27 May 2001 ; CBM­ZC 8487, 1 male (SL 2.1 mm ), Maeda­misaki , Okinawa Island , Ryukyu Islands , coral reef, 2.9 m , SCUBA diving, coll. Y. Fujita , 28 April 2002 ; CBM­ZC 8488, 1 male (SL 2.7 mm ), Ahra beach, Kume­jima Island , Ryukyu Islands , under dead corals, subtidal, coll. M. Osawa , 3 July 2000 ; CBM­ZC 8489, 1 male (SL 2.4 mm ), near Yaeyama Marine Park Research Station , Kuro­shima Island , Yaeyama Group , Ryukyu Islands , dead coral, coll. M. Osawa , 7 September 1992 . Taiwan : UF 3768 , 1 male (SL 1.7 mm ), Shiangjianwan , Kenting , fore reef of nearshore fringing reef, 3–8 m , 29 October 2000 , coll. G. Paulay. Guam : UF 31 b, 1 male (SL 2.0 mm), Agat Bay , north of Aluton Island , fore reef, 5 m , coral rubble , 15 November 2000 , coll. H. Conley; UF 308 , 1 male (SL 2.0 mm), 1 female (SL 1.6 mm ), Haputo , 0–18 m , 27 June 2000 , coll. L. Kirkendale; UF 1403 , 1 male (SL 2.3 mm ), Double Reef , 3–6 m , under rubble , 7 May 2001 , coll. V . Bonito ; UF 7305 , 1 male (SL 2.1 mm ), 1 ovigerous female (SL 2.0 mm), labeled as BGUAM­81; UF 7304 , 1 ovigerous female (SL 1.9 mm ), south of Haputo , 6–9 m , 16 August 2000 , coll. R Chang et al. Society Islands : UF 1761 , 3 females (SL 1.4–2.0 mm), Point Faapuo , Moorea , 0–2 m , under rocks , 21 October 2001 , coll. G. Paulay; UF 1856 , 1 female (SL 1.5 mm ) , same data; UF 1860 , 1 male (SL 2.0 mm) , same data. Tuamotu Archipelago : UF 1862 , 1 ovigerous female (SL 1.7 mm ), 14°92.87’S, 147°85.78’W, 6–12 m , under rocks , 10 November 2001 , coll. G. Paulay. Maldives : CBM­ZC 8345, 1 male (SL 1.5 mm ), 1 female (SL 1.9 mm ), 2 ovigerous females (SL 1.8, 2.0 mm), Vadoo , south reef, 10 m , 19 April 1996 , coll. K. Nomura. FIGURE 40. Pagurixus ruber n. sp. A–C, G–I, holotype male (SL 2.4 mm) from Kume­jima Island (CBM­ZC 7862); D–F, paratype male (SL 2.1 mm) from Guam (UF 7305). A, shield and cephalic appendages, dorsal view; B, left antennule, lateral view; C, ultimate segment of left antennular peduncle, ventral view; D, left fourth pereopod, dactylus and propodus, lateral view; E, same, mesial view; F, right fourth pereopod, dactylus and propodus, lateral view; G, sixth thoracic sternite, ventral view; H, coxae of fifth pereopods and eighth thoracic sternite, ventral view; I, telson, dorsal view. Scale bars: 1 mm for A; 0.5 mm for B–I. Other material. Guam : UF 7305 , 1 ovigerous female (SL 1.6 mm ), 1 juvenile (SL 1.3 mm ), Pago Bay , reef front, under rubble in surge channels, 4–8 m , 14 August 2000 , coll. G. Paulay ; UF 7306 , 7 ovigerous females (SL 1.6–1.9 mm ), Cocos, SW side, outer barrier reef, under rubble, 1–2 m , 20 August 2000 , coll. G. Paulay. Description FIGURE 41. Pagurixus ruber n. sp. A, C, D, holotype male (SL 2.4 mm) from Kume­jima Island (CBM­ZC 7862); B, E, paratype male (SL 1.5 mm) from Vadoo, Maldives (CBM­ZC 8345). Right cheliped. A, B, chela, dorsal view; C, entire right cheliped, mesial view (carpus damaged); D, same, lateral view; E, carpus, dorsal view. Scale bar: 1 mm. Shield ( Fig. 40A ) 1.1–1.2 times longer than broad; anterior margin between rostrum and lateral projections slightly concave; anterolateral margins sloping; dorsal surface flat, with few tufts of short setae laterally. Rostrum triangular, not reaching level of midlength of ocular acicles, moderately broad, terminating acutely. Lateral projections slightly produced, with submarginal spinule. FIGURE 42. Pagurixus ruber n. sp. Paratype female (SL 2.6 mm) from Amami­oshima Island (CBM­ZC 8485). Right cheliped. A, chela, dorsal view; B, entire right cheliped, mesial view; C, same, lateral view; D, carpus, dorsal view. Scale bar: 0.5 mm. FIGURE 43. Pagurixus ruber n. sp. Holotype male (SL 2.4 mm) from Kume­jima Island (CBM­ ZC 7862). A, left cheliped, chela and carpus, dorsal view; B, entire left 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. Ocular peduncle ( Fig. 40A ) moderately long and stout, 0.6–0.7 length of shield, each with row of tufts of short setae on dorsal surface mesially; corneas slightly dilated, corneal width about 0.3 of peduncular length; basal part somewhat inflated, slightly broader than corneal width. Ocular acicles subtriangular or subovate, with small submarginal spine. Antennular peduncle ( Fig. 40A, B ) overreaching distal margin of cornea by 0.3–0.5 length of ultimate segment. Ultimate segment with tufts of long setae at dorsolateral angle; ventral surface with 2 longitudinal rows of tufts of short setae ( Fig. 40C ). Basal segment with small lateral spine on statocyst lobe. Ventral flagellum with numerous long setae on lateral and mesial margins. Antennal peduncle ( Fig. 40A ) overreaching distal margin of cornea by 0.3–0.5 length of fifth segment. Second segment with very small spine at dorsomesial distal angle; laterodistal projection short, not reaching midlength of fourth segment, terminating in simple or bifid spine. First segment with small laterodistal spine; ventromesial distal margin produced, unarmed or with spinule just lateral to antennal gland opening. Antennal acicle relatively long, arcuate, reaching or slightly overreaching distal margin of cornea; mesial margin with row of tufts of stiff setae. Flagellum moderately long, exceeding 4.0 length of shield. Right cheliped of males ( Fig. 41A–E ) not particularly elongate, stout. Chela subovate in dorsal view, 1.6–1.8 times longer than broad. Dactylus 0.6–0.8 of palm length; dorsomesial margin not delimited; surfaces granular to nearly smooth; cutting edge with row of small calcareous teeth in 0.7–0.8 and row of small corneous teeth in distal 0.2–0.3, terminating in small corneous or calcareous claw. Palm subequal to or slightly longer than carpus; convex dorsal surface minutely granular or nearly smooth; dorsolateral margin not delimited or only faintly delimited, dorsomesial margin not delimited; lateral, mesial and ventral surfaces minutely granular or nearly smooth, and occasionally with few tufts of short setae on ventral surface. Cutting edge of fixed finger with row of unequal calcareous teeth (middle one largest), terminating in small calcareous claw. Carpus subequal to or slightly longer than merus; dorsal surface granular (granules strongest mesially), frequently with few small dorsomesial spines; dorsolateral margin not delimited; lateral, mesial and ventral surfaces minutely granular or nearly smooth, lateral surface lacking longitudinal median ridge; mesial face with several short to long setae. Meral­carpal articulation lacking any pronounced clockwise rotation; dorsal surface of merus with trace of transverse ridges in distal half, nearly smooth in proximal half, dorsodistal margin with row of short bristles; lateral face minutely granular, ventrolateral margin with 1 subdistal spine; mesial face smooth, with few stiff setae, ventromesial margin with 1 subdistal spine and row of small tubercles or unarmed; ventral surface with scattered granules and long setae. Ischium with faintly denticulate or smooth ventromesial margin; surfaces unarmed. Right cheliped of females ( Fig. 42A–C ) moderately stout for genus. Chela 2.0–2.3 times longer than broad. Dactylus subequal to or slightly longer than palm; cutting edge with row of small, blunt calcareous teeth in proximal 0.6 and row of small corneous teeth in distal 0.4, terminating in small corneous claw. Palm distinctly shorter than carpus. Cutting edge of fixed finger with row of small calcareous teeth in proximal 0.8–0.9, distal teeth subacute and interspersed by row of small corneous teeth, terminating in small corneous claw. Carpus subequal in length to merus; dorsolateral and dorsomesial margins not delimited; surfaces granular (granules on dorsomesial part particularly conspicuous), with few small spines distomesially; lateral face nearly perpendicular, devoid of longitudinal median ridge. Merus with row of very low protuberances on dorsal surface; ventrolateral margin with 1 subdistal tooth, otherwise almost smooth; ventromesial margin faintly tuberculate but with 1 small subdistal spine. Ischium unarmed on ventromesial margin. Left cheliped ( Fig. 43A–C ) moderately slender, similar between male and female. Chela 2.7–2.9 times longer than broad. Dactylus longer than palm, with sparse tufts of setae on surfaces (setae on ventral surface longest); dorsal surface unarmed; cutting edge with row of small corneous teeth, terminating in small corneous claw. Palm 0.5–0.6 length of carpus; dorsal surface slightly elevated in mid­line and bearing scattered tiny tubercles or granules, dorsolateral and dorsomesial margins not delimited; lateral, mesial and ventral surfaces with granules or low protuberances; scattered tufts of long setae present on mesial and ventral surfaces. Cutting edge of fixed finger with row of small calcareous teeth interspersed with corneous teeth. Carpus relatively slender, 0.8–0.9 length of chela and subequal in length to merus; length 2.7–2.9 of distal width and 2.3–2.5 greatest height; dorsal surface with spines at dorsolateral distal and dorsomesial distal angles, dorsolateral and dorsomesial margins each faintly delimited by row of small tubercles; surfaces with few granules; lateral face nearly perpendicular, without longitudinal median ridge; ventrodistal margin unarmed; sparse long setae present on mesial and ventral surfaces. Merus nearly smooth on dorsal surface, dorsodistal margin unarmed; lateral and mesial faces nearly smooth; ventrolateral distal margin with 1 or 2 small subdistal spines and small protuberances, otherwise smooth; ventromesial margin weakly tuberculate; ventral surface nearly smooth, with scattered long stiff setae. Ischium with row of tiny denticles on ventromesial margin, otherwise unarmed. Ambulatory legs ( Fig. 43D, E ) moderately long and slender, similar from right to left. Dactyli ( Fig. 43F, G ) 0.9–1.1 length of propodi, 6.5–7.0 times longer than high, terminating in large corneous claws; dorsal surfaces each with row of sparse short setae; lateral and mesial faces each with few tufts of short setae, mesial faces unarmed (second) or each armed with row of corneous spinules adjacent to dorsal margin (third); ventral margins each with 7–9 long corneous spines notably increasing in size distally. Propodi not tapering distally, 5.0–6.5 times longer than high; dorsal surfaces nearly smooth, with short to moderately long stiff setae; lateral faces nearly smooth; ventral margins each with 2–4 corneous spinules, ventrodistal margins each with paired corneous spines. Carpi each usually with small dorsodistal spine, dorsal surface smooth, with row of sparse setae; lateral faces nearly smooth. Meri nearly smooth on dorsal surfaces, with sparse moderately long setae; lateral surfaces smooth; ventrolateral distal margins each with small subdistal spine (second) or unarmed (third), ventral surfaces faintly tuberculate (second) or smooth (third), all with few short setae. Fourth pereopods ( Fig. 40D–F ) slightly to markedly unequal in both males and females. Dactyli terminating in very small corneous claws, with numerous, dense long setae on dorsal margins (setae much longer and more numerous in left than in right); left dactylus much broader than right. Propodi with tuft of several setae on mesial face at base of ventrodistal extremity; mesial faces nearly flat, with several long setae dorsally. Carpi each with tuft of setae on mesial face near ventrodistal angle (setae longer and more numerous in left than in right). TABLE 3. Comparison among P. festinus McLaughlin & Haig, 1984 , P. boninensis ( Melin, 1939 ) , P. ruber n. sp. and P. paulayi n. sp.

P. festinus	P. boninensis	P. ruber n. sp.	P. paulayi n. sp.
Setal rows of ultimate segment of antennular peduncle	consisting of short transverse rows of setae	consisting of tufts of setae	consisting of tufts of setae	consisting of mixture of short and moderately short setae
Dorsal surface of palm of male right cheliped	granular, but not spinulose	granular, but not spinulose	granular, but not spinulose	spinulose
Dorsolateral margin of palm of female right cheliped	distinctly ridged	distinctly ridged	not delimited	no data
Ventrolateral margin of merus of right cheliped	unarmed	with 1 or 2 spines followed by row of small tubercles	at least with 1 spine	at least with 1 spine
Dorsolateral and dorsomesial margins of carpus of left cheliped	without conspicuous spines or tubercles	each with row of small spines	each with row of very small tubercles or low protuberances	each with row of very small tubercles or low protuberances
Fourth pereopods	subequal	subequal	unequal	no data
Right coxae of fifth pereopod in male	with very short ventromesial protrusion; tuft of setae well developed, reaching to left coxa	with prominent ventromesial protrusion; tuft of setae well developed, reaching to left coxa	without ventromesial protrusion; tuft composed of some short setae, not reaching to left coxa	with prominent ventromesial protrusion, tuft of setae reaching to left coxa
Left gonopore of male	present	present	absent	absent
Coloration in life	unknown	Fig. 45A	Fig. 46B	Generally purple

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. Anterior lobe of sixth thoracic sternite ( Fig. 40G ) subrectangular or subsemicircular, with anterolateral angles rounded, anterior margin with row of short setae. Eighth thoracic sternite ( Fig. 40H ) composed of two unequal, narrowly separated, rounded lobes. Males with coxae of fifth pereopods slightly unequal ( Fig. 40H ). Ventromesial protrusion on right coxa barely differentiated or, if present, very short; setae arising posterolateral to gonopore relatively few, short, not reaching midline; left coxa lacking, or with very small, gonopore. Female with single left gonopore. FIGURE 45. A, Pagurixus boninensis ( Melin, 1939 ) , ovigerous female (SL 2.7 mm) from Hachijo Island, Izu Islands, Japan (CMNH­ZC 1688), photo taken by J. Okuno; B, Pagurixus carinimanus n. sp. , paratype female (SL 1.6 mm) from Okinawa Island, Ryukyu Islands (CBM­ZC 8481), photo taken by Y. Fujita; C, D, Pagurixus brachydactylus n. sp. , male (SL 2.6 mm) from Chichi­jima Island, Ogasawara Islands, photo taken by M. Osawa. Telson ( Fig. 40H ) with terminal margins horizontal, bearing 4 or 5 small spines. Colour in life. ( Fig. 46B ) Shield light pink or purplish red anteriorly and whitish posteriorly, occasionally showing striped pattern anteriorly. Ocular peduncle generally white, with tinge of purplish red distally and proximally. Antennular peduncle with ultimate segment light purplish red; flagella also light purplish red. Antennal peduncle purplish red; flagellum banded with purple red (4–6 articles) and white (1 or 2 articles). Chelipeds and ambulatory legs generally purplish red; distal parts of dactyli and propodi of ambulatory legs white. FIGURE 46. A, Pagurixus pseliophorus n. sp. , paratype male (SL 3.3 mm) from Saga, Kochi Prefecture, Japan (CBM­ZC 8533), photo taken by T. Komai; B, Pagurixus ruber n. sp. , paratype male (SL 2.3 mm) from Izu­oshima Island, Izu Islands, Japan (CMNH­ZC 1873), photo taken by J. Okuno. Distribution Ryukyu Islands , Izu Islands , Taiwan , Guam . Society Islands , Tuamotu Archipelago and Maldives ( Fig. 48 ); subtidal to 8 m . This new species appears to be widely distributed in the Indo­West Pacific . Remarks Pagurixus ruber n. sp. is very similar to P. boninensis and P. paulayi n. sp. Differences among the three species are summarized in Table 3 . In life, this new species is readily recognizable by its coloration; the chelipeds and ambulatory legs are generally purplish red or wine red ( Fig. 46B ). As discussed before, McLaughlin & Haig’s (1984) male specimens referred to P. boninensis most probably represent this new species. During this study, we have examined specimens from Guam , identified by Dr. P. A. McLaughlin as P. boninensis . They actually represent P. ruber n. sp. , instead of P. boninensis . Therefore, we list the reference of P. boninensis from Guam ( Paulay et al., 2003 ) in the synonymy of P. ruber n. sp. , although we have not examined the voucher specimen ( UF 645) identified by Dr. McLaughlin. Etymology From the Latin ruber , meaning red, in reference to the characteristic, vivid lifecoloration of the new species.