Pliopagurus curvimanus, Komai, 2013

Komai, Tomoyuki, 2013, A New Genus and New Species of Paguridae (Crustacea: Decapoda: Anomura) from the Bohol Sea, the Philippines, Species Diversity 18 (1), pp. 23-32 : 25-31

Pliopagurus curvimanus sp. nov.

Figs 1–5

Material examined. Holotype: PANGLAO 2004, stn L42, Balicasag Island, Bohol Sea , 09°31.2′N, 123°40.7′E, 80–90 m, 2 July 2004, male (sl 2.5 mm), NMCR 39083.

Paratypes: same data as holotype, 1 ovigerous female (sl 1.3 mm), ZRC 2013.0578 ; same data as holotype, 1 ovigerous female (sl 1.5 mm), CBM-ZC 11571 .

Description. Shield ( Fig. 1A ) about 1.1 times as long as wide; anterior margin between rostrum and lateral projections concave; dorsal surface with some tufts of short setae laterally, paragastric grooves delimited only on posterior parts; anterolateral margins sloping. Rostrum broadly triangular, subacutely pointed, extending beyond lateral projections. Lateral projections broadly rounded, moderately separated from rostrum, each with 1 submarginal spinule.

Ocular peduncles ( Fig. 1A ) about 0.8 times as long as shield, moderately slender, faintly constricted at mid-length, each with longitudinal row of tufts of short setae on dorsal surface; cornea slightly dilated; basal width of peduncle subequal to corneal width. Ocular acicles narrowly triangular, separated basally by about basal width of 1 acicle, each with acutely or subacutely pointed tip, without submarginal spine distally; distal part of ocular acicle nearly flat on dorsal surface. Interocular lobe clearly visible.

Antennular peduncles ( Fig. 1A ) slightly overreaching distal corneal margins. Ultimate segment with single short seta near dorsolateral distal angle, dorsal surface with few additional short setae. Basal segment with moderately inflated statocyst lobe bearing small lateral spine; ventrodistal angle slightly produced.

Antennal peduncles ( Fig. 1A ) slightly overreaching distal corneal margins. Fifth segment with row of short, stiff setae on mesial margin. Fourth segment with some short, stiff setae. Third segment with tiny spine at ventromesial distal angle, although this spine not visible in dorsal view. Second segment with dorsolateral distal angle produced into strong spine not reaching midlength of fourth segment, mesial margin without additional spinules; dorsomesial distal angle with tiny spine. First segment unarmed on lateral surface; ventrodistal margin strongly produced, with minute terminal spine. Antennal acicle slightly arcuate, reaching distal corneal margin, terminating in tiny spine, with row of short setae dorsomesially (right antennal acicle of holotype abnormally short, only reaching corneal base). Antennal flagellum about 5 times as long as shield, overreaching extended right cheliped; each article with 1–3 short setae, with 1 additional mesial long setae every 2 articles.

Mandible without distinguishing characters. Maxillule ( Fig. 2A ) with proximal endite subquadrate; distal endite slightly widened distally, mesial margin truncate; endopod with obsolete inner lobe bearing 2 bristle-like setae and slender, non-recurved outer lobe. Maxilla ( Fig. 2B ) with anterior lobe of scaphognathite not reaching level of distal margin of distal endite. First maxilliped ( Fig. 2C ) with exopod moderately expanded proximolaterally. Second maxilliped ( Fig. 2D ) with endopod relatively short; exopod long.

Third maxilliped ( Fig. 1B ) moderately stout. Ischium ( Fig. 1C ) bearing well-developed crista dentata consisting of row of small corneous teeth increasing in size proximally and 1 accessory tooth. Merus and carpus unarmed. Exopod overreaching distal margin of ischium.

Chelipeds appreciably unequal and dissimilar. Right cheliped ( Fig. 3 A–D) thick, suboperculiform; angle of articulation of chela and carpus about 30°. Dactylus distinctly shorter than palm, strongly curved ventrally; dorsal surface with distinct median ridge accompanied by shallow sulcus mesially, otherwise almost smooth; dorsomesial margin carinate, with row of small blunt denticles decreasing in size distally; mesial surface with broad, shallow sulcus medially, flanked by rows of short setae; cutting edge with row of rounded calcareous teeth, terminating in small corneous claw. Palm slightly widened distally, slightly longer than carpus; dorsal surface gently convex, unarmed, with sparse single setae or tufts of short setae; dorsolateral margin with tuberculate carina extending to midlength of fixed finger but not to proximal margin of palm; dorsomesial margin slightly elevated, with single row of small spines or tubercles proximally decreasing in size and acuteness and with row of moderately long stiff setae, dorsomesial distal angle slightly produced; lateral surface almost glabrous, slightly rugose with scattered short, oblique ridges; mesial surface nearly flat, with scattered granules and sparse setae, and with low, oblique ridge proximoventrally; ventral surface almost glabrous, with shallow concavity at base of fixed finger. Fixed finger with large, subtriangular tooth on median part of cutting edge, terminating in small corneous claw. Carpus subequal in length to merus, distinctly widened distally; dorsomesial margin with row of long setae and small spines at least in distal half; dorsal midline slightly elevated, with 4–6 tiny to moderately small spines and 2 irregular rows of long setae; dorsolateral surface sloping, almost glabrous; mesial surface shallowly depressed distally, with long setae dorsally and ventrally; ventral surface strongly convex, with scattered short to long setae. Merus unarmed on dorsodistal margin; dorsal surface also unarmed, with moderately long setae in distal half; lateral surface glabrous, distal half of ventrolateral margin slightly concave and with row of some tiny spines; mesial surface also almost glabrous, distal half of ventromesial margin with row of small spines; ventral surface convex in proximal half, with numerous long setae, distal half forming concavity accommodating proximal part of carpus when entire cheliped flexed. Ischium unarmed, with short setae dorsally and ventrally.

Left cheliped ( Fig. 4 A–D) with chela curving laterally and ventrally, like a bird beak in general shape, subequal in length to carpus and merus combined; angle of articulation of chela and carpus about 45°. Dactylus about twice as long as palm, surfaces unarmed, bearing scattered long setae; dorsal surface with shallow median sulcus extending beyond midlength; cutting edge with row of closely-set corneous teeth (several teeth partially fused), terminating in small corneous claw. Palm short, about half length of carpus; dorsomesial margin with row of 4 or 5 small spines; dorsal surface sloping to lateral surface, with row of long setae on midline; lateral and mesial faces with sparse short setae; ventral surface slightly convex, with few short setae; fixed finger with scattered tufts of long setae, cutting edge with row of small corneous teeth, terminating in small corneous claw. Carpus subequal in length to merus; dorsolateral margin with row of 3 or 4 spines (dorsodistal spine strong, other 2 spines small) in distal half, dorsomesial margin with row of 4 or 5 spines decreasing in size proximally, each margin also bearing row of long, stiff setae; dorsodistal margin with 1 additional minute spine laterally; lateral surface with short to long setae dorsally, otherwise glabrous, ventrolateral distal angle with minute spine; mesial surface smooth, with long setae dorsally and ventrally; ventral surface convex, with several long setae. Merus unarmed on dorsodistal margin; dorsal surface with row of short setae; lateral surface nearly glabrous, generally convex ventrolateral margin with row of prominent spines in distal half; mesial surface also smooth, with few setae dorsally and ventrally, ventromesial margin with row of tiny spines or tubercles in distal two-thirds; ventral surface with numerous setae. Ischium unarmed, with short setae dorsally and ventrally.

Ambulatory legs ( Fig. 5A, D ) generally similar on right and left. Dactyli slightly curved ventrally in lateral view, nearly straight in dorsal view, 1.5–1.6 times as long as propodi; dorsal margins each with row of sparse tufts of moderately long setae decreasing in length distally; lateral and mesial surfaces without sulcus or groove, mesial surfaces each with 2 min corneous spinules adjacent to dorsal margin in distal half (second; Fig. 5B ) or double row of 6 or 7 min corneous spinules adjacent to dorsal margin (third; Fig. 5D ); ventral margins each with row of 8–11 slender corneous spines. Propodi with numerous tufts of long setae on dorsal margins and fewer tufts of long setae on ventral margins; lateral and mesial faces with few tufts of short setae ventrally; ventrodistal margins each with 1 slender corneous spine. Carpi each with tiny dorsodistal spine; dorsal surfaces each with row of long setae; ventral surfaces with few short and long setae (second) or almost glabrous (third). Meri with tufts of moderately long setae on dorsal margins; lateral and mesial faces smooth, bearing row of short or very short setae ventrally; ventral margins each with tufts of long setae (second) or few short to long setae (third), ventrolateral distal margin slightly concave and armed with tiny subterminal spine (second) or straight and unarmed (third). Ischia about half length of meri (second) or subequal in length to it (third). Female with paired gonopores on coxae of third pereopods.

Fourth pereopods ( Fig. 1D ) semichelate. Dactyli each with row of minute corneous teeth on ventral margins; no preungual process. Propodi with rasp consisting of single row of corneous scales.

Coxae of fifth pereopods in male ( Fig. 1E ) symmetrical, bearing tufts of moderately short setae at anterolateral and anteromesial angles, each with very short, abruptly tapering sexual tube directed anteroventrally. Coxae of female fifth pereopods ( Fig. 1F ) unequal with left larger, right with tufts of setae at anterolateral and anteromesial angles, left with numerous longer setae extending from anterior margin to posterolateral angle.

Third thoracic sternite unarmed on anterior margin. Sixth thoracic sternite ( Fig. 1G ) with anterior lobe subtrapezoidal; anterior margin rounded, with several long setae. Eighth thoracic sternite ( Fig. 1E ) slightly bilobed, with few short setae.

Pleon dextrally twisted. Male with 3 (third to fifth) unpaired left pleopods, decreasing in size posteriorly, third unequally biramous, fourth and fifth uniramous. Female with paired first pleopods modified as gonopods, each indistinctly bi-articulated ( Fig. 1F ); unpaired, left second to fifth pleopods present, second and third subequally biramous, fourth slightly unequally biramous, and fifth strongly unequally biramous. Uropods strongly asymmetrical.

Telson ( Fig. 1H ) with faint (holotype) or shallow (paratypes) lateral indentations; posterior lobes slightly asymmetrical, subtriangular, each with few short setae proximally on lateral margin; terminal margins strongly oblique, each with some spinules.

Coloration in preservative. No distinct markings seen on shield, antennae, chelipeds, or ambulatory legs. Ocular peduncle with orange and white stripes, white stripes on dorsal and ventral midline and on lateral and mesial faces, white stripe on dorsal mid-line much narrower than orange stripes.

Distribution. Known only from the type locality, Balicasag Island, Bohol Sea, the Philippines, 80–90 m deep.

Habitat. Gastropod shells.

Etymology. From the combination of the Latin, curvatis (=curved) and manus (=hand), in reference to the noticeably curved left chela. Used as a noun in apposition.

Key to genera of the “ Pylopagurus-Tomopagurus ” group [emended from Lemaitre and McLaughlin (2003a)]

1. Pleon reduced; males without unpaired pleopods; females with unpaired second to fourth pleopods......................................... Protoniopagurus

– Pleon not reduced; males with some unpaired pleopods; females with unpaired second to fifth pleopods.. ............................................... 2

2. Protopods of uropods prominently produced posteriorly; dorsal surface of right chela commonly with characteristic covering of mushroom-shaped tubercles........................................ Agaricochirus

– Protopods of uropods not prominently produced posteriorly; dorsal surface of right chela usually without characteristic covering of mushroom-shaped tubercles ............................................... 3

3. Spines on dorsal surfaces of chelae with basal rosettes..................................... Rhodochirus

– Spines on dorsal surfaces of chelae without basal rosettes.......................................... 4

4. Propodal rasps of fourth pereopods each with more than one row of corneous scales................... 5

– Propodal rasps of fourth pereopods each with only one row of corneous scales........................... 7

5. Left chela triangular or subtriangular in cross-section, dactylus and fixed finger not dorsoventrally flattened.. ............................................... 6

– Left chela not triangular or subtriangular in cross-section, dactylus and fixed finger dorsoventrally flattened................................... Manucomplanus

6. Telson with lateral indentations suggesting division into anterior and posterior portions..... Anisopagurus

– Telson without lateral indentations suggesting division into anterior and posterior portions.. Enallopaguropsis

7. Ocular acicles multispinose; coxae of male fifth pereopods asymmetrical................. Pylopaguridium

– Ocular acicles simple; coxae of male fifth pereopods symmetrical.................................... 8

8. Telson with lateral indentations suggesting division into anterior and posterior portions................ 9

– Telson without lateral indentations suggesting division into anterior and posterior portions..... Enallopagurus

9. Chela of right cheliped subovate to subcircular, margins unarmed, weakly tuberculate or minutely crenulate and/or serrate, but never armed with prominent, blunt or acute spines............................ 10

– Chela of right cheliped variable, margins armed with prominent, blunt or acute spines or tubercles....... 11

10. Fourth pereopods with large, very prominent preungual process at base of claw............. Phimochirus

– Fourth pereopods without prominent preungual process at base of claw..................... Pylopagurus

11. Dactylus and fixed finger of left chela excavated ventrally and presenting spoon-shaped appearance........................................... Tomopagurus

– Dactylus and fixed finger of left chela not excavated ventrally and not presenting spoon-shaped appearance .............................................. 12

12. Left chela with midline elevated into prominent keel or crest and/or with lateral margin expanded and distinctly carinate; male without sexual tubes or papilla-like protrusions of vasa deferentia.................... 13

– Left chela with midline not elevated into prominent keel and lateral margin not delimited; male with very short but prominent sexual tubes................................................. Pliopagurus gen. nov.

13. Right chela circumscribed by row of dorsomesial, dorsoproximal and dorsolateral marginal spines.............................. Lophopagurus (Australeremus)

– Right chela not circumscribed by row of dorsomesial, dorsoproximal and dorsolateral spines............. 14

14. Left chela with midline elevated into prominent keel or crest, lateral margin at most granulate or minutely tuberculate............. Lophopagurus (Lophopagurus)

– Left chela with midline slightly elevated, but not into prominent keel or crest, lateral margin strongly spinose................................... Haigiopagurus

Figures

Fig. 1. Pliopagurus curvimanus gen. nov., sp. nov. A–C, E, G, H, holotype, male (sl 2.5mm), PANGLAO 2004, stn L42, NMCR 39083; D, paratype, ovigerous female (sl 1.3mm), same station, ZRC 39083; F, paratype, ovigerous female (sl 1.5mm), same station, CBM-ZC 11571. A, shield and cephalic appendages, dorsal view; B, left third maxilliped, lateral view; C, same, ischium and basis, ventral view; D, left fourth pereopod, lateral view; E, coxae of fifth pereopods and eighth thoracic sternite, ventral view; F, coxae of fifth pereopods and first pleopods, ventral view; G, sixth thoracic sternite, ventral view; H, telson, dorsal view. Scale bars: 1mm for A; 0.5mm for B–H.

Fig. 2. Pliopagurus curvimanus gen. nov., sp. nov., holotype, male (sl 2.5mm), PANGLAO 2004, stn L42, NMCR 39083, left mouthparts. A, maxillule, ventral view; inset, endopod, lateral view; B, maxilla, ventral view; C, first maxilliped, ventral view; D, second maxilliped, ventral view.Scale bar: 0.5mm.

Fig. 3. Pliopagurus curvimanus gen. nov., sp. nov., holotype, male (sl 2.5mm), PANGLAO 2004, stn L42, NMCR 39083. A, right cheliped, mesial view; B, same, lateral view; C, same, chela, dorsal view; D, same, carpus, dorsal view.Scale bar: 1mm.

Fig. 4. Pliopagurus curvimanus gen. nov., sp. nov., holotype, male (sl 2.5mm), PANGLAO 2004, stn L42, NMCR 39083. A, left cheliped, mesial view; B, same, lateral view; C, same, chela, dorsal view; D, same, carpus, dorsal view.Scale bar: 1mm.

Fig. 5. Pliopagurus curvimanus gen. nov., sp. nov., holotype, male (sl 2.5mm), PANGLAO 2004, stn L42, NMCR 39083. A, left second pereopod, lateral view; D, same, dactylus, mesial view (only mesial setae shown); C, left third pereopod, lateral view; D, same, dactylus, mesial view (only mesial setae shown). Scale bars: 1mm for A, C; 0.5mm for B, D.