Paguristes acanthomerus Ortmann, 1892

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 : 378-387

Paguristes acanthomerus Ortmann, 1892

(®gures 11±14)

Paguristes acanthomerus Ortmann, 1892: 279 , pl. 12, ®gure 6; Doēin, 1902: 645; Alcock, 1905: 155; Balss, 1913: 39; Terao, 1913: 373; Yokoya, 1933: 74; Gordan, 1956: 321; Okada et al., 1966: 138; Miyake, 1978: 32, ®gure 11; Miyake and Imafuku, 1980a: 3; Takeda, 1982: 58, ®gure 172; Kim, 1985: 71, ®gure 2B; Baba, 1986: 191, 298, ®gure 138; Yu and Foo, 1990: 50, unnumbered ®gure.

Paguristes kagoshimensis: Miyake, 1978: 32 (part).

Material examined. LECTOTYPE (herein designated). Tokyo Bay; 1880±1881; coll. L. DoÈderlein; ovigerous female (SL 11.0 mm); MZS 393 (spirit).

PARALECTOTYPES. Sagami Bay , 126±144 m ; 1881; coll. L. DoÈderlein; three females (SL 5.0± 7.4 mm); MZS 394 (spirit) .

Other material. OOE Kochi, Tosa Bay, Shikoku, 190 m; 10 August 1991; RV Toyohata-maru, beam trawl; coll. K. Sasaki; ®ve males (SL 9.4±13.2 mm); CBM-ZC 179. OOE Takeoka, Uchibo coast of Boso Peninsula, 50±60 m; 21 May 1994; gill net; coll. T. Komai; one female (SL 9.2 mm); CBM-ZC 459. Same locality, 30±40 m; 29 August 1994; gill net; coll. T. Komai; one male (SL 21.3 mm), two ovigerous females (SL 13.5, 14.7 mm); CBM-ZC 616. OOE Minabe, Kii Peninsula, 80±100 m; 24 March 1995; gill net; coll. T. Komai; one female (SL 6.0 mm), one ovigerous female (SL 7.7 mm); CBM-ZC 1164. SE of Katsuyama Ukishima Islet, 140±220 m; 10 May 1995; gill net; coll. T. Komai and M. Miya; two females (SL 7.3, 8.0 mm); CBM-ZC 1665. OOE Kominato, Sotobo coast of Boso Peninsula, 100±150 m; 27 February 1997; gill net; coll. T. Komai; one male (SL 9.2 mm); CBM-ZC 3524. OOE Kochi, Tosa Bay, 33ss16.02¾N, 133ss40.02¾E, 189±190 m; 9 April 1993; RV Toyohata-maru, beam trawl; one male (SL 6.9 mm); CBM-ZC 3832. Sagami Bay, 110 m; 1904±1905; coll. F. Doēin; (SL 7.7±12.9 mm), three females (SL 8.7±8.8 mm); reported by Balss (1913), No. 2463; ZSM 228/1. Enoura, Suruga Bay, 200 m; 1904±1905; coll. F. Doēin; one female (SL 8.1 mm); No. 2461; ZSM 228/2. Near Misaki, Sagami Bay, 300 m; 24 October 1904; coll. F. Doēin; four males (SL 7.6±13.3 mm), three females (SL 6.1±8.5 mm); reported by Balss (1913), No. 2455; ZSM 228/3. Higashi-ohne, Sagami Bay, 140 m; 9 February 1955; one male (SL 6.3 mm); reported by Miyake (1978), det no. 110; NSMT-CrR 941. Goronba, Sagami Bay, 110±200 m; 21 January 1958; one male (not measured); reported by Miyake (1978), det no. 197; NSMT- CrR 1412. Similar locality, 110±140 m; 24 July 1963; one female (SL 4.7 mm); reported by Miyake (1978) as Paguristes kagoshimensis , det no. 525; NSMT-CrR 2161. 5 km oOE westnorth-by-west of Jogashima Islet, Sagami Bay, 110±175 m; one female (SL 9.2 mm); reported by Miyake (1978), det no. 535; NSMT-CrR 2191. Same data; one male (SL 11.7 mm); reported by Miyake (1978), det. no. 536; NSMT-CrR 2192. Ta-Shi, depth unknown; November 1996; commercial trawler; coll. T.-Y. Chan; one male (SL 17.9 mm); NTOU.

Description. Thirteen pairs of biserial phyllobranchiae.

Shield (®gure 11A) longer than broad (1.2±1.4 times longer than broad); anterolateral margins sloping; anterior margin between rostrum and lateral projections concave; posterior margin truncate; dorsal surface corrugated with rounded protuberances on gastric and posterolateral regions, laterally with numerous small spines or spinules and tufts of short to long setae. Rostrum long, narrowly triangular, weakly to somewhat curved ventrally, distinctly exceeding lateral projections; terminating in acute spine; dorsal surface obtusely carinate proximally; lateral margins not denticulate. Lateral projections triangular, usually with small marginal spine. Branchiostegites (®gure 11C) calci®ed anteriorly and dorsally, with row of small spines on anterodorsal and distal margins.

Ocular peduncles (®gure 11A) long, slender (7±8 times longer than width of cornea), 0.9±1.0 times as long as shield, cylindrical, somewhat ināted basally, corneas not dilated; dorsal or dorsomesial surfaces with longitudinal row of tufts of long setae. Ocular acicles subtriangular with elongate, acute spine directed anteromesially; separated by 0.3±0.4 basal width of one acicle.

Antennular peduncles (®gure 11A, B) moderately long, not reaching distal margins of corneas. Ultimate segment slender, 1.1±1.2 times longer than penultimate segment, unarmed, with few short setae on dorsal surface. Penultimate segment without ventral spine. Basal segment without spine on dorsolateral margin of statocyst lobe and laterodistal margin, ventrodistal margin deeply notched, ventromesial distal angle produced, bearing small acute spine.

Antennal peduncles (®gure 11A, C) moderately short, usually reaching midlength of ocular peduncle; with supernumerary segmentation. Fifth and fourth segments unarmed. Third segment with strong ventromesial distal spine, mesial and lateral faces with tufts of setae. Second segment with dorsolateral distal angle slightly produced, terminating in simple or bi®d spine, lateral margin with one or two small spines and tufts of long setae; dorsomesial distal angle usually with small spine, dorsomesial margin weakly elevated. First segment with one or two spines on lateral face, ventral margin produced, armed with one spine on either side of antennal gland opening. Antennal acicles moderately long, reaching or over-reaching distal margin of ®fth segment, terminating in strong simple or bi®d spine; mesial margin with row of three to ®ve large spines, predominantly on proximal 0.6 and obscured by long setae, lateral margin with one to three smaller spines. Antennal ¯agella moderately long, 1.6±1.9 times longer than shield, over-reaching tips of chelipeds, composed of more than 40 articles; articles each with short to moderately long setae or bristles on distal margin and all surfaces, articles in distal 0.7 with long setae every four or ®ve articles.

Endopod of maxillule (®gure 11E) moderately slender, without bristle on mesial margin; internal lobe strongly produced, with seven or eight bristles on rounded distal margin; external lobe very well developed, elongate, strongl y recurved, distolateral corner with four short setae. Third maxilliped (®gure 11F) with basis and ischium partially fused; coxa with ventromesial portion noticeably produced; basis with three or four small denticles on dorsomesial margin, partially obscured by setae; ischium (®gure 11G) with well developed crista dentata composed of row of relatively stout corneous teeth, ventrodistal margin with one prominent spine, dorsolateral corner unarmed; merus with three to ®ve prominent spines on ventral margin, dorsodistal margin unarmed; carpus unarmed on dorsodistal margin; dactyl moderately long.

Chelipeds (®gure 12A±D) moderately short, subequal or slightly unequal with left slightly larger; armature generally similar. Chela subtriangular in dorsal view, about 1.7 times longer than wide. Dactyl 1.5±1.7 times longer than palm; cutting edge with row of small calcareous teeth, terminating in strong corneous claw; overlapped by ®xed ®nger; dorsomesial margin with row of strong spines and tufts of stiOE setae, dorsal surface with double row of strong spines near dorsomesial margin, becoming single row distally, and tufts of stiOE setae; mesial surface with scattered moderately small spines and one distinct row of moderately small, occasionally corneous-tipped spines ventrally; ventral surfaces unarmed, but with tufts of stiOE setae. Palm shorter than carpus; dorsomesial margin with four or ®ve strong spines, dorsal surfaces with several irregular rows of prominent, occasionally corneous-tipped spines, decreasing in size on ®xed ®nger, and numerous tufts of long setae; dorsolateral margin with row of strong, occasionally corneous-tipped spines, decreasing in size on ®xed ®nger; mesial surface with few moderately small spines dorsally and low protuberances accompanied by setae, mesiodistal margin smooth; lateral and ventrolateral surfaces somewhat concave, with irregular rows of moderately strong spines and tufts of long setae; ventral surface with longitudinal row of moderately small spines and tufts of setae on midline, extending onto ®xed ®nger, and one prominent spine proximal to base of dactyl. Fixed ®nger nearly straight or slightly curved ventrally; cutting edges with row of small calcareous teeth in proximal 0.6 and row of small corneous teeth in distal 0.4, terminating in strong corneous claw; leaving narrow hiatus in right, no hiatus in left. Carpus about 0.6±0.7 times as long as merus; dorsomesial margin with row of ®ve to seven strong, conical spines, increasing in size distally; dorsal surface sloping to lateral surface without delineation of dorsolateral margin, with ®ve or six irregular rows of moderately large to small spines and tufts of long stiOE setae (midline unarmed), dorsodistal margin with row of submarginal spines; mesial surface with few moderately strong spines or multidenticulate tubercles accompanied by tufts of long setae, mesiodistal margin unarmed; lateral surface with scattered moderately strong to small spines and few tufts of setae, laterodistal margin with row of small spines; ventral faces unarmed, with few setae. Merus extremely deep; dorsal surface strongly convex in lateral view, with spinulose transverse ridges accompanied by long setae, distalmost ridge with row of strong spines, extending to lateral face, dorsodistal margin with row of strong spines extending onto laterodistal margin; mesial surfaces nearly smooth, with few tufts of short setae dorsally, ventromesial margin with row of small spines and tufts of stiOE setae distally and one moderately to extremely large, conical spine proximally; lateral surface spinulose dorsally and ventrally, with tufts of short setae dorsally, ventrolateral margin strongly convex, with row of moderately strong spines and numerous tufts of long setae, distoventral corner with one prominent spine; ventral face unarmed, but with tufts of long setae. Ischium with row of small blunt spines on ventromesial margin, ventrolateral distal angle unarmed on left, with few spinules on right. Coxa with few spinules on ventrolateral margin.

Second pereopods (®gure 13A, B) moderately long and slender. Dactyls long, 1.4±1.7 times longer than propodi; weakly curved in lateral view, nearly straight or slightly twisted in dorsal view; terminating in strong corneous claws; dorsal surfaces slightly protuberant, with one or two small corneous-tipped spines proximally and tufts of long stiOE setae; mesial surfaces lacking row of corneous spinules, but with row of tufts of long stiOE setae near dorsal and ventral margins; lateral surfaces with double row of long stiOE setae on midline, becoming single row in distal half, and single row of tufts of long setae near ventral margin; ventral margins each with 24±29 slender corneous spinules, slightly increasing in size distally. Propodi distinctly longer than carpus; dorsal surfaces with row of strong spines mesially, partially obscured by tufts of long setae, dorsodistal margins unarmed; mesial faces each with row of low protuberances accompanied by tufts of setae dorsal to midline, and row of tufts of short setae near ventral margin; lateral surfaces each with row of low protuberances near dorsal margin, accompanied by long setae, and three rows of tufts of setae; ventral surfaces each with row small acute spines and tufts of long setae, ventrodistal margins with one or two calcareous spinules. Carpi moderately long; dorsal surfaces each with single or double row of strong spines mesially and tufts of long setae; mesial surfaces with few short setae, mesiodistal margins unarmed; lateral faces strongly convex, each with distinct sulcus lined with tufts of stiOE setae, and median row of low, occasionally spinulose, protuberance s accompanied by tufts of stiOE setae; ventral surfaces each with few tufts of moderately short setae, ventrodistal margins with row of longer setae. Meri strongly compressed laterally; dorsal surface protuberant, each with three to ®ve spinules proximally and row of tufts of long setae; mesial surfaces with row of tufts of short setae dorsally; ventral surfaces each with double row of spinules and numerous long setae, ventromesial margins unarmed distally, ventrolateral margins each with small spine slightly proximal to ventrolateral corner. Ischia each with row of small tubercles on dorsal surface laterally, obscured by dense setae; ventral surfaces with few small tubercles mesially, obscured by dense setae. Coxae each with row of small tubercles on laterodistal margin.

Third pereopods (®gure 13C, D) generally similar to second in setation. Dactyls with one or two proximal spinules on dorsal surfaces; mesial surfaces unarmed; ventral margins each with row of 20±25 small corneous spines. Propodi with protuberant dorsal surfaces; mesial surfaces unarmed, with two rows of tufts of short setae; lateral surfaces each with submarginal spinule near laterodistal margin. Carpi each with single row of small spines on dorsal surface. Meri each with protuberant dorsal surface bearing one small subdistal spine and few proximal spinules; ventral surfaces unarmed, ventrolateral margins each with small subdistal spine. Coxae each with row of tubercles on laterodistal margins; females with paired gonopores.

Fourth pereopods (®gure 13H) thickly setose on dorsal and ventral faces. Dactyl stout, slightly curved, terminating in strong corneous claw; dorsal surface unarmed; ventral surface with row of ®ve to eight small rounded corneous teeth laterally and one small tube-like preungual process arising from base of claw. Propodus moderately stout, each with nearly straight ventral margin; propodal rasp composed of four or ®ve rows of small corneous scales, becoming fewer proximally, extending to 0.7 length of ventral surface. Carpus without dorsodistal spine.

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

First and second pleopods in males paired, modi®ed. First pleopod (®gure 14A±C) with double or triple row of long setae on mesial face of basal segment. Inferior lamella strongly twisted, with blunt longitudinal ridge on ventral surface, continuous with proximolateral margin; distal margin broadly rounded, with corneous plate composed of fused spines; mesial margin with numerous bristles. External lobe well developed, rounded, distinctly exceeding inferior lamella in distal extension. Internal lobe relatively broad, rounded, separated from external lobe by V-shaped notch; mesial margin with thick, long setae.

Second pleopod (®gure 14D, E) with basal segment ¯attened, bearing few short setae proximally. Endopodite somewhat ¯attened, twisted, margins bluntly edged, with tufts of long stiOE setae on lateral margin; mesial surface with one tuft of setae proximally and row of long setae distally. Appendix masculina moderately broad, twisted, not noticeably elongate distally; articulation suture clearly discernible on every face; distal margin rounded; exterior (lateral) surface concave, with numerous bristles dorsally and distally; ventral margin slightly produced somewhat distal to midlength, with tuft of stiOE setae; interior (mesial) face faintly sulcate, with numerous bristles dorsally.

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

Females with ®rst pleopods (®gure 14F) paired; articulation between basal and distal segments obsolete; basal segment slightly broadened basally; distal segment slightly narrower and shorter 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 exopod well developed, not articulated, endopod vestigial.

Brood pouch (®gure 14G) extremely large, embracing ventrolateral, lateral and dorsal surfaces of second to fourth abdominal somites, margins indented, with thick, short to long plumose setae. Second and third abdominal tergites contiguous, well calci®ed, with moderately short, but not dense setae on left margin, fourth abdominal tergite poorly developed, without dense setae.

Uropods strongly asymmetrical; protopods with rasp on posterior surface, posteroventral margin with three or four small spines.

Telson (®gure 11J) with posterior lobes strongly asymmetrical, left lobe larger than right; each lobe subtriangular with rounded apex, separated by moderately deep median cleft, terminal and lateral margins unarmed but with long setae; lateral indentations distinct; anterior lobes unarmed on convex lateral margins.

Coloration. In life: carapace, chelipeds and ambulatory pereopods generally reddish brown to orange ±red. Ocular peduncles generally red, with two white stripes (dorsolaterally and mesially), not reaching to bases of corneas.

In preservative: faded to light reddish brown or light brown; markings of ocular peduncles preserved for long time.

Variation. Paguristes acanthomerus shows a slight variation in the development of the ventral spine of the merus of the cheliped. The spine is usually very prominent, as ®gured. However, in the male specimen from Taiwan ( NTOU, SL 17.9 mm), the spine is much smaller than in other specimens.

Size. One of the largest species of the genus. Largest male: SL 21.3 mm; largest female: SL 14.7 mm; smallest ovigerous female: SL 7.7 mm.

Habitat. Gastropod shells.

Distribution. Paci®c coast of Japan, from Boso Peninsula to Kyushu; East China Sea; Korea; north-east of Taiwan; 50± 250 m.

Remarks. Although Ortmann (1892) included four specimens from two Japanese localities (one female from Tokyo Bay and three females from Sagami Bay) in his original description of Paguristes acanthomerus , he did not designate a holotype. All four specimens are still extant in the collection of the MuseÂe Zoologique, Strasbourg. Here, the specimen from Tokyo Bay is selected as the lectotype of P. acanthomerus , and thus the other three are paralectotypes of the species.

The absence of spines on the terminal margins of the telson provides evidence that Paguristes acanthomerus should be placed in group B of the genus (cf. McLaughlin and Provenzano, 1974b). This species is readily recognized by the presence of a strong ventral spine on the merus of the cheliped. I have con®rmed that P. acanthomerus also has a distinct ventral row of small spines on the mesial face of the dactyl of the cheliped, like P. versus . Therefore, limited observation may lead to misidenti®cation between P. acanthomerus and P. versus . However, the biserial nature of the gills and the presence of the prominent ventral spine on the merus of the cheliped immediately separate P. acanthomerus from P. versus . In addition to the armament of the merus of the cheliped, P. acanthomerus has many distinctive features, such as the elongate, narrowly separated ocular peduncles, very strong distal spine on the ocular acicles, subtriangular chelae lacking a row of corneous teeth on the cutting edge of the dactyls, extremely deep merus of the cheliped, and enlarged brood pouch with indented margins.

During a re-examination of Miyake’s (1978) material, I have found that the female specimen (NSMT-CrR 2161) referred to P. kagoshimensis by Miyake (1978; det. no. 525) actually represents P. acanthomerus .