Pagurixus laevimanus ( Ortmann, 1892 )

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 : 10-16

publication ID	https://doi.org/ 10.11646/zootaxa.1214.1.1
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treatment provided by	Felipe
scientific name	Pagurixus laevimanus ( Ortmann, 1892 )
status

Treatment

Pagurixus laevimanus ( Ortmann, 1892) View in CoL

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 , 47 View FIGURE 47 )

Eupagurus laevimanus Ortmann, 1892: 302 View in CoL , pl. 12, fig. 13 [type locality: Tahiti].—Alcock, 1905: 176; Forest, 1954: 74; 1956: 52.

Pagurus laevimanus .— Holthuis, 1953: 49.— Gordan, 1956: 331.— Komai & Myorin, 2005: 2 (in part).

? Pagurus laevimanus .— Minei, 1973: 45.

Not Pagurixus laevimanus View in CoL .— McLaughlin & Haig, 1984: 142, fig. 7 (see Remarks).— Asakura, 1995: 365, fig. 21–279 [= Pagurixus anceps ( Forest, 1954) View in CoL ].— Komai & Asakura, 1995: 353 [= Pagurixus anceps ( Forest, 1954) View in CoL ].

Type material

HOLOTYPE: MZS 464 View Materials (spirit), male (SL 3.7 mm), Tahiti, French Polynesia, coll. Museum Godeffroy, 1888.

Redescription

Shield ( Fig. 1A View FIGURE 1 ) approximately as long as broad; anterior margin between rostrum and lateral projections concave; anterolateral margins slightly terraced; posterior margin truncate; dorsal surface with few tufts of short setae laterally. Rostrum triangular, distinctly overreaching lateral projections, terminating acutely. Lateral projections triangular, somewhat produced, each with large submarginal spine.

Ocular peduncle ( Fig. 1A View FIGURE 1 ) relatively short and stout, about half length of shield, each with short transverse row of short setae near base of cornea and 2 tufts of short setae on dorsal surface; corneas slightly dilated, corneal width about 0.4 of peduncular length; basal part weakly inflated, as broad as corneal width. Ocular acicles subovate, each with small submarginal spine.

Antennular peduncle ( Fig. 1A View FIGURE 1 ) overreaching distal margin of cornea by 0.3 length of ultimate segments. Ultimate segment ( Fig. 1A, B, C View FIGURE 1 ) with tufts of long setae at dorsolateral and dorsomesial angles; 2 setal rows on ventral surface each consisting of numerous short transverse rows of very short setae. Basal segment unarmed. Ventral flagellum with numerous long setae on lateral and mesial margins.

Antennal peduncle ( Fig. 1A View FIGURE 1 ) overreaching distal margin of cornea by half length of fifth segment. Fifth and fourth segments with some tufts of short setae. Third segment with spinule at ventromesial distal angle. Second segment with long spine at dorsomesial distal angle; laterodistal projection reaching midlength of fourth segment, terminating in simple spine. First segment with small laterodistal spine; ventromesial distal margin with spinule lateral to antennal gland opening. Antennal acicle moderately long, overreaching base, but not to distal margin of cornea.

Right cheliped ( Fig. 2A–C View FIGURE 2 ) elongate. Chela subovate in dorsal view, 2.1 times longer than broad. Dactylus 0.7 length of palm; dorsal surface smooth, with short, faint median ridge proximally; dorsomesial margin with granular ridge; cutting edge with 1 prominent calcareous tooth at midlength and row of long corneous teeth in distal 0.2, terminating in small corneous claw. Palm slightly longer than carpus; convex dorsal surface granular, dorsolateral margin delimited by granular ridge, dorsomesial margin not delimited; mesial face covered with larger granules; ventral surface also granular. Carpus subequal to merus in length; dorsolateral and dorsomesial margins delimited by row of moderately large spines (spines of mesial row larger than those of lateral row); all surfaces granular; lateral surface divided into oblique dorsal and perpendicular ventral sections by distinct, tuberculate longitudinal ridge. Meralcarpal articulation lacking any pronounced clockwise rotation; dorsal surface of merus with numerous transverse ridges and tufts of short setae, dorsodistal margin with 3 large spines; lateral and ventral faces with small tubercles or granules ventrally; ventrolateral margin with row of moderately large spines; ventromesial margin with row of small spines; ventral surface concave, with few tiny spinulose tubercles and scattered long setae. Ischium with row of minute denticles on ventromesial margin; posterolateral angle with few spinules.

Left cheliped ( Fig. 2D–F View FIGURE 2 ) elongate, slender. Chela 2.5 times longer than broad. Dactylus subequal in length to palm, with some tufts of short setae on lateral face; dorsal surface with few, low tubercles proximolaterally; cutting edge with fine row of long corneous teeth, terminating in small corneous claw. Palm about half length of carpus; dorsal surface elevated in midline and armed with row of small tubercles extending onto fixed finger, sloping mesial part with some small tubercles, dorsomesial margin not delimited; lateral part of dorsal surface also sloping, dorsolateral margin delimited by row of small tubercles; lateral, mesial, ventral surfaces each with scattered low protuberances and tufts of short setae. Carpus elongate, subcylindrical, about 1.2 length of chela and subequal in length to merus; length about 2.7 of distal width and 3.6 of greatest height; dorsolateral and dorsomesial margins each with row of moderately large spines and tufts of long setae; lateral surface divided into two sections by tuberculate or spinulose ridge on midline, dorsal section oblique and slightly concave, ventral section perpendicular; mesial surface with several tufts of long setae; ventral surface smooth, with scattered long setae. Merus with row of short transverse ridges on dorsal surface, dorsodistal margin with 1 slender spine; lateral surface with several tiny tubercles or spinules adjacent to ventrolateral margin, otherwise smooth, ventrolateral margin with row of moderately small spines; mesial face with tiny tubercles and short, multidenticulate protuberances adjacent to ventromesial margin, otherwise nearly smooth, ventromesial margin with row of spinules or small tubercles. Ischium with row of minute denticles on ventromesial margin, otherwise unarmed.

Ambulatory legs ( Fig. 3A, B View FIGURE 3 ) relatively long and slender, similar from right to left. Dactyli ( Fig. 3C, D View FIGURE 3 ) 0.7–0.8 length of propodi, 5.1–5.8 times longer than high, terminating in large corneous claws; dorsal surfaces each with row of short setae; lateral and mesial faces each with few tufts of short setae, unarmed (second) or armed with row of corneous spinules adjacent to dorsal margin (third); ventral margins each with 7 or 8 long corneous spines notably increasing in size distally. Propodi tapering distally, 4.5–4.9 times longer than high; dorsal surfaces with row of low protuberances and moderately short stiff setae; ventral margins each with row of 4 corneous spinules, ventrodistal margins with paired corneous spines. Carpi distinctly shorter than propodi; dorsal surfaces each with dorsodistal spine, row of low protuberances and numerous short setae; lateral faces each with short setae dorsally. Meri with row of low protuberances and moderately short setae on dorsal surfaces (second), or with spinulose transverse ridges or protuberances and tufts of short setae (third); lateral surfaces with few tufts of moderately short setae (second) or with several tufts of short setae dorsally (third); ventrolateral distal margins each with small subdistal spine, ventral surfaces with row of small spines (second) or smooth (third).

Fourth pereopods ( Fig. 1D View FIGURE 1 ) similar from right to left, not showing marked modification. Dactyli moderately broad, terminating in small corneous claws, each with row of short setae on dorsal margin. Propodi with few short setae on nearly flat mesial faces.

Anterior lobe of sixth thoracic sternite ( Fig. 1G View FIGURE 1 ) transversely oblong, anterolateral angles slightly produced, rounded, anterior margin with row of moderately short setae. E ighth thoracic sternite ( Fig. 1F View FIGURE 1 ) composed of two subequal, closely set, rounded lobes.

Coxae of fifth pereopods ( Fig. 1F View FIGURE 1 ) subequal; right with tuft of short stiff setae directed toward left (many setae broken off), posteromesial protrusion absent, no development of sexual tube or papillae apparent; left coxa with gonopore partially masked by short setae.

Telson ( Fig. 1G View FIGURE 1 ) with terminal margins slightly oblique, with 8 (left) or 7 (right) small, slender spines.

Colour in life. Unknown.

Distribution So far known only from the type locality, Tahiti, French Polynesia ( Fig. 47 View FIGURE 47 ).

Remarks

Morphological differences among the species of the subgroup A are summarized in Table 1. Pagurixus laevimanus is most similar to P. tweediei in characters of the antennular peduncle, left cheliped, ambulatory legs, thoracic lobes and telson. Nevertheless, the holotype of P. laevimanus differs from all the specimens here identified with P.tweediei in having a row of large spines on the dorsolateral margin of the carpus of the right cheliped and a row of spines on the entire ventrolateral margin of the meri of the chelipeds. Furthermore, the dorsolateral margin of the left palm is more clearly ridged in the holotype of P. laevimanus than in the available male specimens of P. tweediei ; the dorsodistal margin of the merus of the left cheliped is armed with one large spine in P. laevimanus , rather than unarmed in P. tweediei . Unfortunately, no information on the coloration in life is available for the holotype of P. laevimanus . For the time being, we regard P. laevimanus and P. tweediei as distinct species, but future study of more specimens may eventually reveal that the two nominal species are conspecific.

Ortmann’s (1892: 302, pl. 12, fig. 13) description of Pagurus laevimanus (as Eupagurus ) was brief and insufficient for species recognition. Ball & Haig (1972) suggested that Pagurus laevimanus belonged to the subgenus Pagurixus , but they did not give further information. Minei (1973) recorded Pagurus laevimanus from Okinawa Island, but no morphological information was given. During this study, the occurrence of Pagurixus laevimanus s. s. in the Ryukyu Islands was not confirmed. His record is only questionably included in the synonymy. McLaughlin & Haig (1984) redescribed what they believed to be Pagurixus laevimanus from the Mariana Islands and New Guinea. Reexamination of the holotype of Pagurixus laevimanus has revealed that the specimens that McLaughlin & Haig (1984) interpreted as Pagurixus laevimanus are quite different from P. laevimanus s. s. Although McLaughlin & Haig’s specimens were not reexamined, there is little doubt that they represent an undescribed species. This undescribed species will be treated in a separate paper Komai & Osawa (in press). Following McLaughlin & Haig (1984), Komai & Asakura (1995) identified a specimen from the Kerama Islands, Ryukyu Islands, as P. laevimanus . Reexamination of that specimen has shown that the specimen is actually P. anceps .

Kingdom	Animalia
Phylum	Arthropoda
Class	Malacostraca
Order	Decapoda
Family	Paguridae
Genus	Pagurixus