Paguristes albimaculatus, Komai, 2001

Komai, 2001, review of the north-western Paci ® c species of the genus Paguristes Decapoda: Anomura: Diogenidae), I. Five species initially reported Ortmann (1892) from Japan, Journal of Natural History 35 (3), pp. 357-428 : 369-378

Paguristes albimaculatus n. sp.

(®gures 2A, 7±10)

Paguristes palythophilus: Miyake, 1978: 31 (part), text-®gure 10; Miyake and Imafuku, 1980a: 3 (part); Miyake, 1982: 96, pl. 32, ®gure 4; Takeda, 1982: 58, ®gure 174.

Paguristes kagoshimensis: Baba, 1986: 191 , ®gure 139; Yu and Foo, 1990: 52, unnumbered ®gure Not Paguristes kagoshimensis Ortmann, 1892 [5 Paguristes digitalis Stimpson, 1858 ].

Material examined. HOLOTYPE. OOE Kochi, Tosa Bay , 33ss16.02¾N, 133ss40.02¾E, 189±190 m; 9.iv.1993; RV Toyohata-maru, beam trawl; coll. K. Sasaki; male (SL 5.9 mm); CBM-ZC 4906.

PARATYPES. OOE Kochi, Tosa Bay, 190 m; 10 August 1991; RV Toyohata-maru, beam trawl; coll. K. Sasaki; two males (SL 6.1, 6.3 mm); CBM-ZC 180. OOE Shionomisaki, Kii Peninsula, 200 m; 19 December 1992; dredge; coll. S. Nagai; one male (SL 5.5 mm), one female (SL 3.9 mm); CBM-ZC 1183. OOE Kochi, Tosa Bay , 110±190 m; 2 October 1989; RV Toyohata-maru, beam trawl; coll. K. Sasaki; three males (SL 5.0 ± 6.8 mm), one female (SL 4.7 mm), one ovigerous (SL 4.9 mm); CBM-ZC 3022. OOE Shionomisaki, Kii Peninsula, 33ss26.13¾N, 135ss40.64¾E, 160 m; 16 April 1997; dredge; coll. S. Nagai; one male (SL 6.2 mm), one female (SL 4.1 mm); CBM-ZC 3574. Same data as holotype; one male (SL 4.9 mm), one female (SL 3.1 mm); CBM-ZC 3831. Okinayama Bank, Sagami-nada, 34ss58.47¾N, 139ss34.13¾E, 121±129 m; TRV Shin’yo-maru cruise to Izu Islands , stn 19; 23 October 1996; dredge; coll. T. Komai; two males (SL 2.4, 3.8 mm); CBM-ZC 4777. Tanabe Bay , Kii Peninsula, 33ss39.061¾N, 135ss06.826¾E, 180±187 m; RV Tansei-maru, KT 96-6, stn TB-3; ORE dredge; coll. E. Tsuchida; two males (SL 2.3, 7.5 mm), one female (SL 6.0 mm); CBM-ZC 4933. East of Kakeroma Island , Amami Islands , 28ss04.71¾N, 129ss27.38¾E, 310 m; TRV Toyoshio-maru cruise to Amami Islands , stn 8; November 1994; sledge net; coll. E. Tsuchida; three males (SL 1.8±5.0 mm), one female (SL 2.3 mm); CBM-ZC 4962. 4 km oOE westsouth-by-west of Jogashima Islet, Sagami Bay , 120±260 m; 15 February 1966; one male (SL 6.3 mm), one female (SL 4.6 mm); reported by Miyake (1978) as Paguristes palythophilus , det no. 609; NSMT-CrR 2393 .

Description. Thirteen pairs of quadriserial phyllobranchiae (®gure 2A).

Shield (®gure 7A) 1.2±1.3 times longer than broad; anterolateral margins sloping; anterior margin between rostrum and lateral projections concave; posterior margin truncate; dorsal surface with paired low elevations, small spines or spinules and scattered tufts of setae laterally. Rostrum triangular, somewhat curved ventrally, distinctly over-reaching lateral projections; terminating in small acute spine; dorsal surface not carinate. Lateral projections subtriangular, usually with small marginal spine. Branchiostegites (®gure 7C) calci®ed anteriorly and dorsally, with row of small spines on anterodorsal and distal margins.

Ocular peduncles (®gure 7A) moderately slender (3.5±4.0 times longer than width of cornea), about 0.7 times as long as shield, cylindrical, not ināted basally, corneas slightly dilated; dorsal or dorsomesial surfaces with longitudinal row of tufts of setae. Ocular acicles subtriangular, terminating in small acute spine; separated by 0.7±0.8 of basal width of one acicle.

Antennular peduncles (®gure 7A, B) moderately short, reaching or slightly overreaching ocular peduncles. Ultimate segment slender, 1.1±1.2 times longer than penultimate segment, with row of long setae on dorsal surface. Penultimate segment without ventral spine. Basal segment unarmed on dorsolateral margin of statocyst lobe and laterodistal margin; ventromesial distal angle produced, terminating in spinule.

Antennal peduncles (®gure 7A, C) moderately long, reaching base of corneas; with supernumerary segmentation. Fifth segment unarmed. Fourth segment with small spine at dorsodistal margin. Third segment with ventromesial distal angle strongly produced, terminating in strong spine. Second segment with dorsolateral distal angle weakly produced, terminating in simple or bi®d spine, mesial and lateral margins unarmed; dorsomesial distal angle with prominent spine, mesial margin elevated, with few setae. First segment unarmed on laterodistal margin, ventromesial margin strongly produced, with one small spine distolateral to antennal gland opening. Antennal acicles relatively long, reaching to distal 0.3 of ocular peduncles, terminating in simple or bi®d spine, with long setae; mesial margin with four to six moderately strong spines in proximal 0.7; lateral margin with two or three spines. Antennal ¯agella (®gure 7D) long, 2.1±2.2 times longer than shield, exceeding tips of chelipeds, composed of about 40 articles; articles in proximal 0.3 each with several short to moderately long setae or bristles on all surfaces or margins, those in distal 0.7 with long setae every two or three articles in addition to moderately long setae and bristles.

Endopod of maxillule (®gure 7E) moderately slender, without bristle on mesial margin; internal lobe strongly produced, with four bristles on rounded distal margin; external lobe very well developed, elongate, strongly recurved, distolateral margin with four setae. Third maxilliped (®gure 7F) with basis and ischium partially fused; basis with few small spines on dorsomesial margin; ischium (®gure 7G) with well developed crista dentata composed of slender corneous teeth, ventral margin with one moderately small distal spine; merus with four or ®ve acute spines on ventral margin and one small spine on dorsodistal margin; carpus without dorsodistal spine; dactyl moderately short.

Chelipeds (®gure 8A±D) moderately short, equal or slightly subequal with left slightly larger. Chela subovate in dorsal view, 1.8±2.0 times longer than broad. Dactyl 1.3±1.4 times longer than palm, weakly curved ventrally near base; cutting edge with three or four moderately strong calcareous teeth (distal-most tooth sometimes denticulate) in proximal half and row of small corneous teeth in distal half, terminating in small corneous claw; overlapped by ®xed ®nger; dorsomesial margin with row of moderately large to small, corneous-tipped spines decreasing in size distally, and tufts of stiOE setae; dorsal surface with single or double row of moderately small spines near dorsomesial margin and few small tubercles proximally; mesial surface with scattered small, corneous-tipped spines (ventral spines forming single row along margin) and tufts of stiOE setae; ventral surface unarmed, but with few tufts of stiOE setae. Palm slightly shorter than carpus; dorsomesial margin with ®ve or six strong, occasionally corneous-tipped spines and tufts of long stiOE setae; dorsal surface sloping to lateral surface without delineation of dorsolateral margin, with several irregular rows of small to moderately large spines or tubercles, extending onto ®xed ®nger; mesial surface with scattered protuberances accompanied by tufts of setae and sometimes with vertical row of spines near mesiodistal margin; lateral surface with scattered small to moderately small spines or spinulose tubercles and tufts of setae; ventral surface with row of low protuberances accompanied by tufts of long setae on midline, extending onto ®xed ®nger and few small tubercles or protuberances mesially. Fixed ®nger weakly curved ventrally, not noticeably depressed near base of ventral face; cutting edge concave proximally, with row of small calcareous teeth, terminating in small corneous claw; with small hiatus proximally when closed. Carpus about 0.6 times as long as merus; dorsomesial margin with row of four or ®ve strong spines; dorsal surface with tufts of stiOE setae and small spines or spinulose tubercles mesial to sinuous sulcus, dorsodistal margin produced, with row of small spines lateral to articular knob; dorsolateral margin indicated by row of small spines or tubercles; mesial surface with few large low protuberances, accompanied by tufts of stiOE setae; lateral surface with scattered small to moderately large spines or spinulose tubercles and tufts of stiOE setae, laterodistal margin smooth; ventral surface unarmed, ventrodistal margin produced, sometimes with small spine. Merus moderately deep; dorsal surface with row of short transverse multispinose ridges or spinulose tubercles, becoming smaller and more obtuse proximally and accompanied by row of long setae, distalmost ridge extending to lateral and mesial faces; dorsodistal margin with row of small spines; mesial surface with few small protuberances dorsally, accompanied by tufts of short setae and deep groove along subdistal ridge, ventromesial margin with row of small spinulose tubercles (proximalmost tubercle sometimes enlarged); lateral surface with numerous short vertical, often denticulate ridges, ventrolateral margin with row of small spines in distal half; ventral face with small tubercles proximolaterally and scattered tufts of long setae. Ischium with row of spinules on ventromesial margin; ventrolateral distal margin with several tiny spinules. Coxa unarmed.

Second pereopods (®gure 9A, B) moderately long and slender. Dactyls long, 1.5±1.7 times longer than propodi; weakly curved ventrally in lateral view, nearly straight in dorsal view; terminating in strong, curved, corneous claw; dorsal surfaces protuberant, with numerous tufts of long setae and few small corneous-tipped spines proximally; mesial surfaces unarmed, but with three rows of tufts of long setae (middle row conūent with dorsal row in distal half); lateral surfaces with three rows of tufts of setae; ventral margins each with row of 15±20 slender corneous spines. Propodi distinctly longer than carpus; dorsal surfaces each with row of moderately strong spines mesially, becoming smaller distally, and tufts of long setae; mesial surfaces unarmed, but with two rows of tufts of long setae; lateral surfaces each with three rows of low protuberances, accompanied by tufts of setae; ventral surfaces each with row of low, setose protuberances, sometimes bearing one or two small corneous spinules, ventrodistal margins unarmed. Carpi moderately long; dorsal surfaces each with single or double row of moderately strong spines mesially and tufts of long setae; mesial faces with few tufts of short setae; lateral faces each with tufts of stiOE setae on midline and faint longitudinal sulcus lined by row of setae; ventral surfaces with few tufts of long setae, ventrodistal margins with long setae. Meri strongly compressed laterally; dorsal surfaces weakly protuberant, with numerous tufts of moderately long to long setae and few proximal spinules; mesial surfaces with few tufts of short setae dorsally; lateral surfaces with scattered short vertical rows of short setae; ventral surfaces each with row of spinules mesially and numerous tufts of long setae, both ventromesial distal and ventrolateral distal margins unarmed. Ischia each with spinule on distal margin; ventral surface with row of spinules mesially. Coxae unarmed.

Third pereopods (®gure 9C, D) generally similar to second in setation. Dactyls more strongly curved than in second, somewhat ¯attened dorsoventrally in distal halves; dorsal surfaces more strongly protuberant in distal halves than in second, accompanied by tufts of dense stiOE setae; mesial surfaces each with row of tufts of moderately short setae on midline and row of tufts of long setae near ventral margin; lateral surfaces with three rows of tufts of setae (dorsal and middle rows conūent in distal half); ventral margins each with 15±20 slender corneous spinules. Propodi slightly protuberant on dorsal surfaces; mesial surfaces unarmed, but with three or four rows of tufts of short to moderately long setae. Carpi each with dorsodistal spine and occasionally with one or two small proximal spines. Meri slightly protuberant on dorsal surfaces; ventral surfaces with few spinules mesially, both dorsomesial and dorsolateral distal margins unarmed. Ischia without spine on dorsal and ventral surfaces. Coxae unarmed; females with paired gonopores.

Fourth pereopods (®gure 7H) thickly setose on dorsal and ventral surfaces. Dactyl (®gure 7I) slightly curved, terminating in strong corneous claw; dorsal surface unarmed; ventral surface with row of small corneous teeth laterally and tube-like preungual process arising from proximal to base of terminal claw. Propodus moderately stout, with almost straight ventral margin; dorsal surface unarmed; propodal rasp composed of double or triple row of corneous scales, becoming fewer proximally, extending to half length of ventral margin. Carpus without dorsodistal spine.

Fifth pereopods chelate, setose. Coxae in males each with gonopore.

First and second pleopods in males paired, modi®ed as gonopods. First pleopod (®gure 10A±C) with double or triple row of long setae on mesial face of basal segment. Inferior lamella strongly twisted, with distinct longitudinal ridge on ventral surface, continuous with proximolateral margin; distal margin broadly rounded, with single row of moderately strong, closely-set, hooked corneous spines; mesial margin with several rows of bristles, extending onto ventral surface proximally; lateral margin strongly sinuous. External lobe well developed, rounded, reaching distal margin of inferior lamella. Internal lobe moderately large, rounded, separated from basal lobe by deep U-shaped notch; mesial margin with dense, long setae.

Second pleopod (®gure 10D, E) with basal segment somewhat ¯attened, without short setae basally. Endopodite slightly twisted, margins bluntly edged, with row of sparse bristles on ventrolateral margin and tuft of long setae at ventrodistal margin; lateral face deeply sulcate. Appendix masculina elongate in distal part, strongly twisted; articulation suture discernible only on interior (mesial) face; distal margin rounded; dorsal margin with dense bristles; ventral margin slightly produced at level of mid-length, with tuft of long setae; exterior (lateral) face with several irregular rows of dense bristles along dorsal margin; interior (mesial) face with few long setae.

Third to ®fth pleopods of males unpaired, similar in size, exopods very well developed, endopods rudimentary.

Females with ®rst pleopods (®gure 10F) paired; articulation between basal and distal segments obscure; basal segment somewhat ināted basally; distal segment much more slender than basal segment. Second to ®fth pleopods unpaired; second to fourth pleopods with both rami well developed, exopods much longer than endopods, multiarticulated, endopod incompletely biarticulated; ®fth pleopod much shorter than preceding pleopods, with exopods well developed, not articulated, endopod vestigial.

Brood pouch (®gure 10G) relatively small, subtriangular, margins with thick, very long plumose setae. Second to fourth abdominal tergites somewhat calci®ed on left, each with moderately dense, long setae on left margins obscuring pleopods, ®fth tergite not concealed by brood pouch.

Telson (®gure 7J) with posterior lobes slightly asymmetrical, left lobe slightly larger; each lobe subtriangular with rounded apex, separated by shallow median cleft, terminal and lateral margins unarmed but with long setae; lateral indentations distinct; anterior lobes unarmed on convex lateral margins.

Coloration. In life: shield generally red with scattered small white spots, gastric region paler or colourless. Ocular peduncles white on dorsal surfaces, occasionally with short to long red median stripe; remaining faces uniformly red. Antennular peduncles white. Antennal peduncles and ¯agella red. Chelipeds and ambulatory pereopods red or orange ±red, with scattered small spots of white.

Size. Largest male: SL 7.5 mm; largest female: SL 6.0 mm.

Habitat. Gastropod shells.

Distribution. Known with certainty from the Paci®c coast of Japanese main islands, from Sagami-nada to Amami Islands, and north-east of Taiwan; at depths of 120± 260 m.

Etymology. The speci®c name is from the Latin albus, meaning white, and maculatus, meaning spotted, in reference to the scattered white spots on the red or orange±red chelipeds and ambulatory pereopods.

Remarks. This new species is similar to Paguristes palythophilus , and Miyake (1978, 1982) and Takeda (1982) confounde d the two species. The diOEerences between the two species are discussed in Remarks under the latter species. The new species also bears close similarity to P. versus sp. nov. described below. The absence of a distinct ventral row of small spines on the mesial face of the dactyl of the cheliped is useful to separate P. albimaculatus from P. versus . In addition, the spines or spinules on the mesial face of the dactyl of the cheliped are much more numerous in P. albimaculatus than in P. versus . The corneas are weakly dilated in P. albimaculatus , but they are not dilated in P. versus . Furthermore, the colour of the ocular peduncles of P. albimaculatus is distinctive. In P. albimaculatus , the dorsal surfaces of the ocular peduncles are white, occasionally with a median stripe of red. In P. versus , the dorsal surfaces of the ocular peduncle are reddish brown with a longitudinal row of pale spots and with a longitudinal stripe of white mesially and laterally.

As previously noted, re-examination of Miyake’s (1978) material identi®ed as P. palythophilus has revealed that the two specimens (one male and one female; NSMT-CrR 2393; Miyake det. no. 609) actually represent P. albimaculatus and that his text-®gure 10 agrees well with the male specimen. The photograph of P. palythophilus in his subsequent report ( Miyake, 1982: pl. 32, ®gure 4) clearly depicts P. albimaculatus . The illustration of P. palythophilus of Takeda (1982, ®gure 174) is not very accurate, but it almost certainly depicts P. albimaculatus , because in his illustration the dorsally white ocular peduncles and the white-spotted chelipeds and ambulatory pereopods are clearly shown. The photograph of P. kagoshimensis published by Baba (1986) clearly depicts the white ocular peduncles each with a narrow, incomplete median stripe of red, and therefore it should be referred to P. albimaculatus . The colour photograph published by Yu and Foo (1990) as P. kagoshimensis seems to be reproduced from Baba’s (1986) photograph of P. kagoshimensis .