Pagurixus festinus McLaughlin & Haig, 1984

Komai, Tomoyuki & Osawa, Masayuki, 2006, A review of the Pagurixus boninensis species group, with descriptions of six new species (Crustacea: Decapoda: Anomura: Paguridae), Zootaxa 1214 (1), pp. 1-107 : 58-64

Pagurixus festinus McLaughlin & Haig, 1984

( Figs. 23–25 , 48 )

Pagurixus festinus McLaughlin & Haig, 1984: 130 , fig. 3 [type locality: Kahe Point, Oahu, Hawaii].

Type material

(Not examined). HOLOTYPE: Bernice P. Bishop Museum ( BPBM) S10334 , male (SL 1.7 mm), Kahe Point, Oahu, Hawaii , 22°22’N, 158°08’E, 5 m, coll. S. L. Coles, 13 July 1977 . PARATYPES: BPBM S4713 , S 3483 , 3 males (SL 1.2–1.4 mm), Oahu, coll. C. H. Edmondson ; BPBM S4716 , Hanauma Bay, Oahu , coll. C. H. Edmondson, December 1929 ; Allan Hancock Foundation ( AHF) 776, BPBM, Florida International University ( FIU), Nationaal Natuurhistorisch Museum, Leiden ( RMNH), National Museum of Natural History , Smithsonian Institution ( USNM), 17 males, 23 females, 11 ovigerous females, Kahe Point, Oahu, 2.5–8 m, coll. S. L. Coles, 6 April 1976 to 5 August 1977; BPBM S4714 , S 4715 , S3200 , 9 males, 1 female (SL 1.3–1.8 mm), Kahala, Oahu, coll. C. H. Edmondson, January 1930 to May 1931; no registration number, 1 male (SL 1.3 mm), Kaneohe Bay, Oahu, coll. S. Berry, 20 November 1964 ; AHF 6141 , 1 male (SL 1.3 mm), north end of Kaneohe Bay, Oahu, coll. E. S. Reese, 19 March 1961 .

Other material. P. A. McLaughlin’s reference collection, 3 males (SL 1.5–1.7 mm), 2 females (SL 1.0, 1.1 mm), Kahe Point, Oahu, Hawaii, 22°22’N, 158°08’W, 2.5–8 m, collector S.L. Cole, 6 April 1976 – 5August 1977.

Description

Shield ( Fig. 23A ) 1.1–1.2 times as long as broad; anterior margin between rostrum and lateral projections slightly concave or almost straight; anterolateral margins sloping; dorsal surface with few tufts of short setae laterally. Rostrum triangular, reaching level of midlength of ocular acicles. Lateral projections obsolete, unarmed or armed with submarginal spinule.

Ocular peduncle ( Fig. 23A ) comparatively long and stout, 0.7–0.8 length of shield, each with row of short stiff setae on dorsal surface mesially; corneas slightly dilated, corneal width 0.3–0.4 of peduncular length; basal part not inflated. Ocular acicles subtriangular or subovate, with small submarginal spine.

Antennular peduncle ( Fig. 23A, B ) overreaching distal margin of cornea by 0.3–0.5 length of ultimate segment. Ultimate segment with tuft of long setae at dorsolateral distal angle; 2 longitudinal setal rows on ventral surface each consisting of short, obliquely

transverse rows of short setae ( Fig. 23C, D ). Basal segment with small lateral spine on statocyst lobe. Ventral flagellum with numerous long setae on lateral and mesial margins.

Antennal peduncle ( Fig. 23A ) reaching distal margin of cornea. Second segment with very small spine at dorsomesial distal angle; laterodistal projection very short, falling far short of 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 comparatively short, arcuate, overreaching base of cornea, but not reaching distal margin of cornea; mesial margin with row of long stiff setae. Flagellum moderately long, exceeding 3.0 length of shield.

Right cheliped of males ( Fig. 24A–C ) large, but not particularly elongate. Chela roundly triangular in dorsal view, 1.6–1.8 times longer than broad. Dactylus 0.6–0.7 length of palm; dorsomesial margin not delimited; surfaces with coarse granules; 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 claw. Palm not particularly elongate, at most slightly longer than carpus; convex dorsal surface granular, particularly on lateral and mesial parts, dorsolateral margin faintly delimited, but dorsomesial margin not delimited; lateral, mesial and ventral surfaces also coarsely granular, occasionally with few tufts of short setae on ventral surface. Cutting edge of fixed finger with row of unequal, blunt calcareous teeth (middle one largest), terminating in calcareous claw. Carpus subequal in length to merus; dorsal surface lacking conspicuous spines or tubercles, dorsolateral and dorsomesial margins not delimited; dorsodistal margin unarmed; all surfaces granular, lateral surface perpendicular, lacking median longitudinal ridge; ventral surface moderately convex. Meral­carpal articulation lacking any pronounced clockwise rotation; dorsal surface of merus almost smooth, dorsodistal margin with row of short bristles, but without spines; lateral face microscopically granular, ventrolateral margin unarmed or armed with 1 small subdistal spine; mesial face smooth, with few stiff setae, ventromesial margin with row of low tubercles; ventral surface with low tubercles and several long setae. Ischium with smooth ventromesial margin; surfaces unarmed.

Right cheliped of female ( Fig. 25A–C ) moderately stout for genus. Chela subovate or roundly triangular in dorsal view, 1.8–2.0 times longer than broad. Dactylus subequal to or slightly shorter than palm; dorsal surface with row of small tubercles on midline; mesial face also with row of small tubercles on midline; 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 shorter than carpus; dorsal surface with sparse, low tubercles, forming irregular longitudinal rows on weakly elevated midline; dorsolateral margin delimited by tuberculate ridge, dorsomesial margins not delimited; lateral and ventral surface with scattered, low tubercles, mesial faces with small, low tubercles arranged in oblique rows. Cutting edge of fixed finger with row of small calcareous teeth over entire length, terminating in small corneous claw. Carpus noticeably widened distally, shorter than merus; dorsolateral margin not delimited, dorsomesial margins faintly delimited by row of very small tubercles and few long bristles; lateral face nearly perpendicular, devoid of median longitudinal ridge. Merus with smooth dorsal surface; lateral face smooth, ventrolateral margin unarmed or with few low protuberances; mesial face smooth, ventromesial margin unarmed. Ischium unarmed.

Left cheliped ( Fig. 24D–F ) moderately slender, similar between male and female. Chela 2.5–2.7 times longer than broad. Dactylus longer than palm, with sparse setae on surfaces (setae on ventral surface longest); surfaces unarmed; cutting edge with row of small corneous teeth in distal half, terminating in small corneous claw. Palm 0.5–0.6 length of carpus; dorsal surface somewhat elevated in mid­line and bearing scattered tiny tubercles or granules, dorsolateral and dorsomesial margins not delimited; lateral and ventral surfaces nearly smooth, mesial face with some very low protuberances and short setae; scattered tufts of long setae present on ventral surface. Cutting edge of fixed finger with row of small calcareous teeth interspersed by corneous teeth in distal half. Carpus somewhat compressed laterally, 0.8–0.9 length of chela and subequal in length to merus; length 2.5–2.7 of distal width and about twice of greatest height; dorsolateral and dorsomesial margins faintly delimited, without conspicuous spines or tubercles, but dorsomesial margin with few long bristles; surfaces nearly smooth, lateral face nearly perpendicular, devoid of median longitudinal ridge; sparse long setae present on mesial and ventral surfaces. Merus nearly smooth on dorsal surface, dorsodistal margin with row of stiff setae; lateral and mesial faces nearly smooth; ventrolateral margin with 1 small subdistal spine followed by low protuberances or tubercles; ventromesial margin nearly smooth; ventral surface with scattered long stiff setae. Ischium with smooth ventromesial margin, surfaces unarmed.

Ambulatory legs ( Fig. 25D, E, H ) moderately long and slender, generally similar from right to left. Dactyli ( Fig. 18F, G ) 0.8–0.9 (second) or 0.9–1.1 (third) of propodal length, 5.0–6.0 times longer than high (4.3–4.5 in left third of female), terminating in large corneous claws; dorsal surfaces each with sparse short setae; lateral faces microscopically granular at least in part; mesial faces unarmed; ventral margins each with 5–7 long corneous spines notably increasing in size distally. Propodi not tapering distally, 3.9–4.5 times longer than high (2.9–3.3 in left third of female); dorsal surfaces nearly smooth, with sparse short setae; lateral faces nearly smooth; ventral margins each with 3–6 corneous spinules, ventrodistal margin with paired small corneous spines. Carpi usually with small dorsodistal spine; dorsal surfaces smooth, with row of sparse short setae; lateral faces nearly smooth. Meri nearly smooth on dorsal surface, with row of tufts of short to moderately long setae; lateral surfaces nearly smooth; ventrolateral distal margins unarmed or armed with very small subdistal spine (second) or always unarmed (third), ventral surfaces faintly tuberculate (second) or smooth (third).

Fourth pereopods ( Fig. 23E, F ) similar from right to left in both males and females. Dactyli moderately broad, terminating in small corneous claws; dorsal margins each with row of moderately long setae. Propodi with few long setae on nearly flat mesial faces. E ach carpus lacking prominent tuft of setae on mesial face near ventrodistal angle.

Anterior lobe of sixth thoracic sternite ( Fig. 23G ) subrectangular or subsemicircular, with anterolateral angles rounded, anterior margin with row of short setae. Eighth thoracic sternite ( Fig. 23H ) composed of two very unequal (right larger than left), closely set, rounded lobes.

Males with coxae of fifth pereopods unequal ( Fig. 23H ). Right coxa with very short ventromesial protrusion clearly demarcated basally, bearing tuft of stiff setae directed toward left and reaching to left coxa; no papilla­like sexual tube or protrusion of vas deferens apparent. Left coxa with gonopore partially masked by short setae directed ventrally, without papilla­like sexual tube or protrusion of vas deferens. Females with single left gonopore.

Telson ( Fig. 23I ) with terminal margins horizontal or slightly oblique, bearing 4 or 5 very small spinules.

Colour in life. Unknown.

Distribution Known only from Hawaii ( Fig. 48 ); 2.5– 8 m.

Remarks

As pointed out by McLaughlin & Haig (1984), P. festinus superficially resembles species of the P. anceps group, but the possession of two ventral series of setae on the ultimate segment of the antennular peduncle suggests its close relationship to the P. boninensis group. Pagurixus festinus appears similar to P. boninensis , P. paulayi n. sp., and P. ruber n. sp. These four species are characterized by the lack of a lateral ridge on either carpus of the chelipeds and the relatively slender second and right third pereopods with moderately long, slender dactyli (0.8–1.1 of the propodi length and usually 5.0 or more times longer than high). Morphological differences among the four species are summarized in Table 3. Pagurixus festinus is distinguished from P. boninensis and P. ruber b by the structure of the setal series on the ventral surface of the ultimate peduncular segment of antennule. Each setal series of P. festinus consists of short obliquely transverse rows of short setae, but that of the latter two species is composed of clearly separated tufts of short setae. Pagurixus boninensis further differs from P. festinus in the presence of a dorsomesial row of spines on the carpus of the right cheliped and the possession of a prominent ventromesial protrusion on the coxa of the right fifth pereopod in males. P. ruber n. sp. differs from P. festinus by the lack of a distinct left gonopores in males, which is present in P. festinus . Pagurixus festinus can be distinguished from P. paulayi n. sp. by the granular, but not spinulose right cheliped and the presence of left male gonopore.

Figures

FIGURE 18. Pagurixus concolor n. sp. Holotype male (SL 2.5 mm) from Vadoo, Maldives (CBM­ ZC 7860). A, right second pereopod, lateral view; B, left third pereopod, lateral view; C, right second pereopod, dactylus and distal part of propodus, mesial view; D, left third pereopod, dactylus and distal part of propodus, mesial view. Scale bars: 1 mm for A, B; 0.5 mm for C, D.

FIGURE 23. Pagurixus festinus McLaughlin & Haig, 1984. Male (SL 1.6 mm) from Kahe Point, Oahu, Hawaii (P. A. McLaughlin’s reference collection). A, shield and cephalic appendages, dorsal view; B, left antennule, lateral view; C, ultimate segment of left antennular peduncle, ventrolateral view; D, same, ventromesial view; E, dactylus and propodus of left fourth pereopod, lateral view; F, same, mesial view; G, sixth thoracic sternite, ventral view; H, coxae of fifth pereopods and eighth thoracic sternite, ventral view; I, telson, dorsal view. Scale bars: 0.5 mm.

FIGURE 24. Pagurixus festinus McLaughlin & Haig, 1984. Male (SL 1.6 mm) from Kahe Point, Oahu, Hawaii (P. A. McLaughlin’s reference collection). A, right cheliped, chela and carpus, dorsal view (carpus damaged); B, entire right cheliped, mesial view; C, same, lateral view (carpus damaged); D, left cheliped, chela and carpus, dorsal view; E, entire left cheliped, mesial view; F, same, lateral view. Scale bar: 0.5 mm.

FIGURE 25. Pagurixus festinus McLaughlin & Haig, 1984. A–C, female (SL 1.1 mm) from Kahe Point, Oahu, Hawaii (P. A. McLaughlin’s reference collection); D, F, male (SL 1.6 mm) from same lot; E, G, H, male (SL 1.7 mm) from same lot. A, right cheliped, chela and carpus; B, entire right 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; H, dactylus and propodus of right third pereopod, lateral view. Scale bars: 0.5 mm.

FIGURE 48. Geographic distribution of Pagurixus boninensis (), P. festinus (), P. brachydactylus n. sp. (), P. carinimanus n. sp. (), P. paulayi n. sp. (Π), P. pseliophorus n. sp ()., and P. ruber n. sp. ().