Pagurixus anceps ( Forest, 1954 )

Komai, Tomoyuki, 2010, New species and new records of the hermit crab genus Pagurixus Melin, 1939 (Crustacea: Decapoda: Anomura: Paguridae) from the Indo-West Pacific, Journal of Natural History 44 (21 - 22), pp. 1269-1342 : 1271-1279

publication ID	https://doi.org/ 10.1080/00222931003624812
persistent identifier	https://treatment.plazi.org/id/754C8783-FFE7-FFAE-FDCE-FE87FDF1FB33
treatment provided by	Felipe
scientific name	Pagurixus anceps ( Forest, 1954 )
status

Treatment

Pagurixus anceps ( Forest, 1954) View in CoL

( Figures 1–3 View Figure 1 View Figure 2 View Figure 3 )

Eupagurus (Pagurixus) anceps Forest 1954, p 72 View in CoL , figures 15–19 [type locality: Hikuéru Island, Tuamotu Archipelago]; Forest 1956, p 52; 1957, p 1067.

Pagurus (Pagurixus) anceps Dechancé 1964, p 38 ; Ball and Haig 1972, p 103; Lewinsohn 1982, p 58.

Pagurus boninensis Lewinsohn 1969, p 64 , figure 11; Lewinsohn 1982, p 58. Not

Pagurus boninensis (Melin, 1939) .

Pagurus anceps Baba 1982, p 66 , figure 1.

Pagurixus anceps McLaughlin and Haig 1984, p 135 View in CoL (in part?), figure 5; Asakura 1995, p 364, figures 21–277; Poupin 1996, p 19; Davie 2002, p 81.

Pagurixus laevimanus Asakura 1995, p 365 View in CoL , figures 21–279. Not Pagurixus laevimanus (Ortmann, 1892) View in CoL .

Material examined

Syntypes. Hikueru Atoll, Tuamotu, 7 males SL 1.1 mm (MNHN-Pg 577); 1 male SL 1.3 mm (MNHN-Pg 578); 11 males SL 1.1–1.4 mm, 1 female SL 1.1 mm, 1 juvenile (not measured) (MNHN-Pg 581).

Other material. Madagascar. Stn 4/1, Tulear , 1976 , coll. P. Galenon, 1 ovigerous female SL 1.4 mm (MNHN-Pg 8259); same data, 3 males SL 1.8–1.9 mm, 1 female SL 1.8 mm (MNHN-Pg 8260); stn 6/05, Tulear , 1976 , coll. P. Galenon, 7 specimens (including 1 male, 1 ovigerous female), not measured (MNHN-Pg 8261); stn 7/15, Tulear , 1976 , coll. P. Galenon, 1 male SL 1.59 mm, 1 female SL 1.1 mm (MNHN-Pg 8262); stn 22/25, Tulear , 1976 , coll. P. Galenon, 1 male SL 1.4 mm (MNHN-Pg 8263); stn 25/0.5, Tulear , 1976 , coll. P. Galenon, 1 male SL 1.8 mm (MNHN-Pg 8264); stn 27/0.5, Tulear , 1976 , coll. P. Galenon, 2 males SL 1.6, 1.7 mm (MNHN-Pg 8265); stn 29/0.5, Tulear , 1976 , coll. P. Galenon, 1 male SL 1.8 mm, 1 female SL 1.2 mm (MNHN-Pg 8266); stn 30/0.5, Tulear , 1976 , coll. P. Galenon, 1 female not measured (MNHN-Pg 8267); stn 32/05, Tulear, 1976, 3 males SL 1.5–1.6 mm, 3 specimens not sexed nor measured (MNHN-Pg 8268); stn 33/0.5, 1 male SL 1.9 mm, 1 ovigerous female SL 1.8 mm (MNHN-Pg 8269); stn 34/15, Tulear, 1976, 2 males SL 1.8, 1.9 mm, 2 ovigerous females SL 1.4, 1.9 mm (MNHN-Pg 8270); stn 34/015, Tulear , 1976 , coll. P. Galenon, 2 males SL 1.5, 1.7 mm, 9 specimens not measured nor sexed (once dried) (MNHN-Pg 8271); stn 36/15, Tulear, 1976, 1 female SL 1.6 mm, 1 ovigerous female SL 1.2 mm (MNHN-Pg 8272); stn 40/05, Tulear , 1976 , coll. P. Galenon, 1 male SL 1.7 mm (MNHN-Pg 8273); stn 41/15, Tulear , 1976 , coll. P. Galenon, 1 male SL 1.7 mm (MNHN-Pg 8274); stn 42/15, Tulear , 1976 , coll. P. Galenon, 1 male SL 1.5 mm, 2 females SL 1.4, 1.7 mm, 1 ovigerous female SL 1.72 mm (MNHN-Pg 8275); stn 45/0.22, Tulear , 1976 , coll. P. Galenon, 3 ovigerous females SL 1.3–1.7 mm, 1 juv. not measured (MNHN-Pg 8276). Reunion. Marée Reef, Saint Gilles, 17 September 1982, coll. M. de Saint Laurent, 1 male SL 1.2 mm (MNHN-Pg 8277) . Thailand. Cape Promthep, Phuket, intertidal, 7 November 1995, coll. T . Komai, 1 male SL 0.9 mm, 4 ovigerous females SL 0.9–1.1 mm ( CBM-ZC 9561 ) . Japan. Kurio, Yakushima Island , Ohsumi Islands, tide pool, 3 June 1996, coll. T . Komai, 1 ovigerous female SL 1.4 mm ( CBM-ZC 8342 ); Henza Island, Okinawa Islands, Ryukyu Archipelago , intertidal, coral rock, March 1998, coll. T . Komai, 2 males SL 1.5, 1.7 mm ( CBM-ZC 8169 ); Bise-zaki, Motobu, Okinawa Island , intertidal reef flat, coral rock, 10 June 1995, coll. T . Komai, 1 male SL 1.1 mm ( CBM-ZC 8343 ); same locality, 21 May 2005, coll. T . Komai, 1 male SL 1.5 mm, 7 ovigerous females SL 1.1–1.2 mm ( CBM-ZC 9571 ); Zanpa-misaki, Okinawa Island , intertidal, coral reef, July 1996 , coll. E. Nishi, 1 male SL 1.29 mm, 1 ovigerous female SL 1.4 mm ( CBM-ZC 8347 ); near Tokashiki Port, Tokashiki Island, Kerama Group , intertidal, reef flat, 19 May 1998, coll. T . Komai, 1 male SL 1.3 mm ( CBM-ZC 5792 ); Ahra beach, Kumejima Island, Ryukyu Archipelago , intertidal, June 1995, coll. T . Komai, 1 male SL 1.6 mm ( CBM-ZC 5854 ); Iko, Kuroshima Island, Yaeyama Islands, Ryukyu Archipelago , intertidal, coral rubble, 11 July 1998 , coll. K. Nomura, 6 males SL 1.5–1.8 mm, 1 female SL 1.4 mm, 3 ovigerous females SL 1.5–1.7 mm ( CBM-ZC 8408 ); similar locality, reef flat, 9 May 1998, coll. T . Komai, 4 males SL 1.6–1.7 mm, 1 ovigerous female SL 1.7 mm ( CBM-ZC 8414 ); Sonai, Iriomote Island , Yaeyama Islands, intertidal, coral rock, 9 July 1999, coll. T . Komai, 1 male SL 1.2 mm ( CBM-ZC 8171 ); Hoshizuna beach, Iriomote Island , reef flat, intertidal, 14 July 2000, coll. T . Komai, 1 male SL 1.2 mm ( CBM-ZC 8172 ); Uehara beach, Iriomote Island, Ryukyu Archipelago , intertidal, reef flat, 13 July 2003, coll. T . Komai, 1 male SL 1.0 mm, 1 ovigerous female SL 1.0 mm ( CBM-ZC 8346 ); Miyano-hama beach, Chichi-jima Island , Ogasawara Islands, intertidal, 10 December 2005, coll. T . Komai, 9 males SL 1.3–1.6 mm ( CBM-ZC 9570 ) . Palau. Ngchesau reef, 07°11.6′N, 134°27.11′E, 0–3 m, reef top and back reef, 7 March 2003, coll. G. Paulay, 1 male SL 1.2 mm ( FMNH 3895 About FMNH ) GoogleMaps . Indonesia. Marsegu Island, Ceram , intertidal, 16 September 1993 , coll. D. L. Rahayu, 1 male SL 1.4 mm, 1 female SL 1.5 mm, 2 ovigerous females SL 1.5, 1.7 mm ( CBM-ZC 337 ) . New Caledonia. LIFOU 2000 , stn 1429, Santal Bay, Lifou Island , Loyalty Islands, 20°47.5′S, 167°07.7′E, 8–18 m, 24 November 2000, 2 males SL 1.0, 1.1 mm (MNHN-Pg 8278) GoogleMaps .

Redescription

Shield ( Figures 2A View Figure 2 , 4A View Figure 4 ) 1.0–1.1 times as long as broad; anterior margin between rostrum and lateral projections concave; anterolateral margins sloping; posterior margin roundly truncate; dorsal surface with few short setae anterolaterally. Rostrum triangular, moderately broad, distinctly overreaching lateral projections, terminating in acute tip. Lateral projections obtuse, each with small submarginal spinule or unarmed.

Ocular peduncles ( Figures 2A View Figure 2 , 4A View Figure 4 ) moderately stout, 0.6–0.7 length of shield, slightly widened proximally, each with few tufts of short setae on dorsomesial surface; corneas not dilated, corneal width 0.3–0.4 of peduncular length. Ocular acicles subovate, each with small submarginal spine or unarmed.

Antennular peduncles ( Figures 2A View Figure 2 , 4A View Figure 4 ) overreaching distal corneal margins by about 0.2 lengths of ultimate segments. Ultimate segment ( Figure 4B View Figure 4 ) about 2.2 times longer than high, with one short seta on dorsolateral distal portion; ventral surface naked. Basal segment with one small spine on distal margin of statocyst lobe. Ventral flagellum with few short setae on lateral and mesial margins.

Antennal peduncles ( Figure 1A View Figure 1 , 4A View Figure 4 ) slightly overreaching distal corneal margins. Second segment with spinule at dorsomesial distal angle; laterodistal projection not reaching midlength of fourth segment, terminating in simple spine. First segment unarmed on lateral face; ventromesial distal margin strongly produced but unarmed. Antennal acicle arcuate, terminating in slender spine, overreaching base of cornea but not reaching distal margin; mesial margin with few setae. Flagellum moderately long, more than 3.0 times as long as shield.

Male right cheliped ( Figure 3A–C View Figure 3 ) massive, not particularly elongate. Chela 1.5–1.7 times longer than wide. Dactylus subequal in length to palm, terminating in calcareous claw; dorsomesial margin not delimited; surfaces minutely granular; cutting edge with few obtuse calcareous teeth. Palm slightly widened distally, subtrapezoidal in general outline, subequal in length to or slightly longer than carpus; dorsal surface convex, dorsolateral and dorsomesial margins not delimited; all surfaces minutely granular. Fixed finger terminating in calcareous claw; cutting edge with row of low, blunt calcareous teeth. Carpus slightly longer than merus; length 1.2–1.4 times distal width; dorsal surface lacking conspicuous spines or tubercles or spiniform setae, dorsolateral and dorsomesial margins not delimited; all surfaces minutely granular, lateral surface without trace of division; ventral surface convex, naked. Meral–carpal articulation lacking any pronounced clockwise rotation; dorsal surface of merus nearly smooth, dorsodistal margin with few short setae (setae missing in illustrated syntype); lateral face finely or minutely granular, ventrolateral margin without conspicuous spines but crenulate or granular at least in distal part; mesial face smooth, convex ventromesial margin weakly produced, smooth or faintly crenulate or denticulate; ventral surface smooth, only with few long setae. Ischium with smooth ventromesial margin; surfaces smooth.

Female chelipeds distinctly unequal with right stouter than left. Chela ( Figure 4C–E View Figure 4 ) subovate in dorsal view, 1.3–1.7 times longer than broad, lateral margin moderately to strongly arcuate. Dactylus slightly longer than palm, terminating in small corneous claw; dorsomesial margin not delimited; dorsal surface with sparse coarse granules; mesial face with some short, vertical or oblique, granular ridges; ventral surface nearly smooth, with few tufts of short setae; cutting edge with row of small corneous teeth in distal half. Palm shorter than carpus; convex dorsal surface finely granular, with sparse coarse granules; dorsolateral margin delimited by distinct, granular ridge extending to midlength of fixed finger; dorsomesial margin delimited by row of granules or small tubercles; lateral face with coarse granules; mesial and ventral surfaces smooth. Fixed finger terminating in small corneous claw; cutting edge with few small calcareous teeth and row of small corneous teeth in distal 0.7–0.8. Carpus subequal in length to merus; length 1.3–1.6 times distal width; dorsal surface with coarse granules (occasionally forming transverse rows) and few short spiniform setae mesially, dorsomesial and dorsolateral margins not delimited; sloping lateral face with coarse granules, devoid of longitudinal ridge, ventrolateral margin smooth or faintly granular; mesial surface with coarse granules distally, but otherwise nearly smooth, ventromesial margin smooth; ventral surface strongly convex. Merus smooth on dorsal surface; lateral face weakly granular, mesial face smooth; ventrolateral and ventromesial margins unarmed. Ischium unarmed.

Left cheliped ( Figure 3D–F View Figure 3 ) similar in male and female, moderately short and stout. Chela 2.2–2.4 times longer than wide, 1.2–1.3 times longer than carpus. Dactylus longer than palm, terminating in small corneous claw, with sparse tufts of setae on surfaces; dorsal surface almost smooth or minutely granular, with few small tubercles mesially; cutting edge with row of small corneous teeth. Palm about 0.6 length of carpus; dorsal surface convex, with scattered small tubercles or coarse granules; dorsolateral and dorsomesial margins not delimited; mesial surface smooth, with few tufts of short setae; ventral surface slightly convex, smooth. Fixed finger terminating in small corneous claw, cutting edge with row of small corneous teeth. Carpus somewhat compressed laterally, shorter than merus; length 1.8–1.9 times distal width and 1.3–1.6 times height; dorsolateral and dorsomesial margins unarmed or each with row of tiny tubercles and few spiniform setae; dorsodistal margin unarmed or with few tiny tubercles; lateral face nearly perpendicular, smooth, with scattered very short setae, ventrolateral margin strongly convex; mesial face also nearly smooth, with short setae dorsally; ventral surface convex, with prominent fringe of long setae on distal margin (male) or naked (female). Merus smooth on dorsal surface, dorsodistal margin unarmed; lateral surface smooth, ventrolateral margin unarmed or minutely denticulate; mesial face also smooth, ventromesial margin unarmed; ventral surface weakly convex, smooth, with few long setae. Ischium unarmed.

Ambulatory legs ( Figures 2B, D View Figure 2 , 4F View Figure 4 ) relatively stout, generally similar on right and left. Dactyli 0.9–1.0 length of propodi, 4.0–5.0 times longer than broad in male ( Figure 2C, E View Figure 2 ), 3.5–4.1 times in female ( Figure 4F View Figure 4 ), terminating in large corneous claws; dorsal surfaces each with few short setae; lateral and mesial faces smooth; ventral margins each with five or six (rarely seven) moderately long corneous spines increasing in size distally. Propodi not tapering distally, 3.2–3.5 times longer than broad in males or 2.5–3.0 times in females; dorsal surfaces smooth, with sparse short setae; lateral faces smooth; ventral margins each with one or two corneous spinules, ventrodistal margins each with paired small corneous spines. Carpi each with small dorsodistal spine, dorsal surface otherwise unarmed; ventrodistal margin of left third pereopod produced as far as dorsodistal margin, occasionally bearing tuft of short stiff setae. Meri with sparse setae on smooth dorsal and ventral margins; lateral surfaces nearly smooth; ventrolateral distal margins unarmed.

Fourth pereopods ( Figure 2F View Figure 2 ) subequal and similar in both male and female. Dactyli moderately broad, straight, terminating in small corneous claws, each with tuft of short setae distally. Propodi with few setae on dorsal margins; mesial faces nearly flat or slightly convex, with few short setae; propodal rasp of single row of corneous scales. Carpi without prominent tufts of setae on mesial faces.

Anterior lobe of sixth thoracic sternite ( Figure 2G View Figure 2 ) subrectangular, with row of short to long setae on anterior margin. Eighth thoracic sternite ( Figure 2H View Figure 2 ) composed of two subequal, closely set, rounded lobes; ventral surface of each lobe flattened.

Coxae of fifth pereopods slightly unequal in male; right with prominent tuft of setae reaching to left coxa ( Figure 2H View Figure 2 ); no development of posteromesial protrusion; no papilla-like protrusion of vas deferens. Left coxa with gonopore partially masked by tuft of short setae; no development of sexual tube or protrusion of vas deference seen. Females with paired gonopores.

Telson ( Figure 2I View Figure 2 ) with terminal margins horizontal, each bearing three to six spinules.

Colouration

In life. Shield generally whitish, with some brown spots anteriorly. Ocular peduncle also whitish, with two brown spots proximal to base of cornea and two spots basally. Antennular peduncle generally transparent; ultimate segment with brown band in proximal 0.3; penultimate segment with brown spot basally; dorsal flagellum pale yellowish-brown. Antennal peduncle also with brown spots on second segment; fifth segment with brown lateral and mesial margins; distal half of antennal acicle brown; antennal flagellum pale brown, without conspicuous markings. Chelipeds generally white, occasionally with tinge of brown on chelae and carpi; meri occasionally with subdistal brown ring. Ambulatory legs white with brown markings; dactyli each with brown ring occupying proximal 0.2–0.3; propodi each with two brown rings, distal one distal to midlength and proximal one at proximal 0.2, rings occasionally combined by longitudinal bar on lateral surface (rings occasionally broken into dorsal and ventral spots); carpi each with two or three brown spots laterally; meri each with brown subdistal ring (occasionally broken into two spots) and one proximal brown spot.

Size

Largest male SL 1.9 mm, largest female SL 1.9 mm, ovigerous females SL 0.9–1.9 mm.

Distribution

Literature records include Central Pacific, Philippines, southern Japan, Palau, Caroline Islands, and Red Sea. Newly recorded herein from Madagascar, Reunion, Phuket, Thailand, Indonesia, and New Caledonia. Intertidal to 18 m.

Remarks

In his original description, Forest (1954) did not specify the number of syntypes of this species. The syntypes in the MNHN collection reexamined in this study include 21 specimens separated in 3 lots (see “Material examined”). None of them is intact; appendages are mostly disarticulated. The illustrated male specimen (SL 1.14 mm; Figure 1 View Figure 1 ) still had right second and left third pereopods attached. There is no doubt that the syntypes all belong to the same species. No designation of a lectotype has been made .

Pagurixus anceps closely resembles P. kermadecensis de Saint Laurent and McLaughlin, 2000 , particularly in the lack of dorsomesial spines on the carpus of the right cheliped in both male and female. However, P. anceps is rather easily recognized among the P. anceps group in having the combination of the following characters: carpus of right cheliped lacking dorsomesial spines in adults; merus of right cheliped without conspicuous spines on ventrolateral margin; merus of left cheliped unarmed on both ventrolateral and ventromesial margins; ambulatory dactyli each with five or six (rarely seven) ventral spines; ventrodistal margin of carpus of left third pereopod distinctly produced, extending as far as dorsodistal projection; fourth pereopods subequal and similar, without prominent tuft of setae on left dactylus; female with paired gonopores; and terminal margins of telson nearly horizontal.

As already noted by McLaughlin and Haig (1984), two descriptions of Pagurixus anceps [as Eupagurus (Pagurixus) ] appear in the literature. The first was presented by J. Forest in a paper given at the Eighth Pacific Science Congress in November 1953. This paper was subsequently published in the Proceedings of that Congress in 1957. Also, Forest (1954) published the same description of the species in the Bulletin du Muséum national d’Histore naturelle, Series 2, Volume 26. The correct publication year of this species is 1954.

McLaughlin and Haig (1984) examined one syntype deposited in the collection of the Bernice P. Bishop Museum (indicated as paratype) and referred additional material from the Marshall Islands, Caroline Islands, the Philippines, Ryukyu Islands, and the Gulf of Aqaba to P. anceps . The given description, however, differs from the specimens examined in this study in the presence of dorsomesial and dorsolateral spines on the carpus of the female right cheliped, and the presence of a row of weak to strong spines on the ventrolateral margin of the merus of the left cheliped. The female gonopores are said to be paired or unpaired (when only the left is present). In the present female specimens, the gonopores are paired. There is little doubt that more than one species was represented in the material studied by McLaughlin and Haig (1984). Asakura (1995) figured a specimen from the Kerama Islands, Ryukyu Islands, which he identified as P. laevimanus sensu McLaughlin and Haig (1984) . The absence of dorsomesial spines on the carpus of the right cheliped and the relatively stout third pereopod with only five or six dactylar spines clearly suggest that his specimen actually represents P. anceps .