A review of Strobopagurus Lemaitre , 1989 ( Crustacea : Decapoda : Paguroidea : Parapaguridae ) , with description of a new species *

The genus Strobopagurus Lemaitre, 1989, was established by Lemaitre (1989) for a small group of distinctive parapagurids characterized primarily by their short, broad shields with oblique rows of long setae dorsally, stout ocular peduncles with strongly dilated corneas, slender chelipeds, straight dactyls on the ambulatory legs, and in males, the strongly twisted distal segments of the second pleopods. Lemaitre (1989) included three taxa in this genus: S. gracilipes (A. Milne-Edwards, 1891), at the time known from the eastern Atlantic and Hawaii; S. sibogae (de Saint Laurent, 1972), from the western Pacific; and S. kilburni (Kensley, 1973), from off eastern Africa. New specimens of S. gracilipes and SCI. MAR., 68 (3): 355-372 SCIENTIA MARINA 2004

S. sibogae have rarely been reported since their original descriptions, whereas S. kilburni has remained exclusively known from the type material.
While continuing the study of the remarkably rich parapagurid collections obtained during the French campaigns of the last three decades to the western Indian Ocean, New Caledonia and other Pacific regions, numerous specimens assignable to S. gracilipes, the type species of the genus, and S. sibogae, were found.Also, abundant specimens of an undescribed species were discovered.The evaluation of this and all other materials of Strobopagurus taxa found in various museums, has provided the opportunity to update the diagnosis of the genus, as well as the morphology and distribution of its species.Furthermore, a comparison of the type materials of S. kilburni and S. sibogae showed that the former is a junior synonym of the latter.
In this study, the genus Strobopagurus is rediagnosed, the newly discovered species is fully described, and the other two species herein recognized as valid are reviewed and diagnosed, including comparative illustrations of diagnostic characters, and color information where available.A key to aid in the identification of species is also presented.

MATERIALS AND METHODS
The morphological terminology employed, and measurements, follows those defined by Lemaitre (1989Lemaitre ( , 1999Lemaitre ( , 2004)).However, on the fourth pereopod, the length of the propodus is measured in a straight line from the proximal end of the ventral margin to the tip of the distalmost scale of the rasp; the height of the propodus is measured perpendicularly to the dorsal margin, from its midpoint, to the ventral margin.The numbers or range in millimeters (mm) included in the Material examined and figure legends, are measurements for shield length (sl), measured from the midpoint of the rostral lobe to the midpoint of the posterior margin of the shield.
The specimens from the French campaigns remain deposited in the Muséum national d'Histoire naturelle, Paris (MNHN), except for some representatives sent to the National Museum of Natural History, Smithsonian Institution, Washington D.C. (USNM).Other specimens used have been returned to the following museums: Bernice P. Bishop Museum, Honolulu, Hawaii, U.S.A. (BPBM); Fisheries Milne-Edwards, 1891: 132.Gender: masculine.Other species: Strobopagurus breviacus sp.nov., and S. sibogae (de Saint Laurent, 1972).
Diagnosis: Eleven pairs of biserial or quadriserial gills weakly divided distally.Shield slightly to distinctly broader than long, evenly calcified; with oblique rows of long setae.Ocular peduncles stout.Corneas strongly dilated.Posterior carapace densely setose, membranous to weakly calcified.Antennal peduncle with or without small dorsodistal spine on fourth segment.Epistomial spine absent.Right cheliped elongate, often more slender in males than in females; palm with rounded mesial face, and weakly to well delimited dorsolateral margin.Left cheliped evenly or sometimes weakly calcified on merus, carpus, and proximal portion of palm.Ambulatory legs with dactyls straight or nearly so.Fourth pereopod with propodal rasp consisting of 1 row of corneous scales at least distally.Fifth pereopod with small, subterminal corneous tooth on prehensile margin of dactyl laterally (Fig. 6).Second abdominal somite with left pleuron terminating ventrally in small subtriangular lobe.Males with well developed paired first and second gonopods; first gonopods each with short, broad subtriangular distal lobe; second gonopods each with strongly twisted distal segment, with rudimentary exopod on both left and right gonopods, or only on left or right.
Distribution: Eastern Atlantic; western Indian Ocean; and western and central Pacific.Depth: 40-1200 m.
Remarks: Lemaitre (1993) and Zhadan (1997) summarized the morphological similarities and differences between Strobopagurus and Bivalvopagurus Lemaitre, 1993, and suggested the existence of a close phylogenetic relationship between the two.Species of these two genera have broad, short shields typically with dense setae, strongly dilated corneas, short basal antennular segments, densely setose posterior carapaces, slender chelipeds and ambulatory legs, the latter with straight dactyls, and second pleopods with twisted distal segments.Strobopagurus does differ from Bivalvopagurus in the degree of calcification of the shield and posterior carapace (weak in the former, strong in the latter), and first and second abdominal somites (membranous in the former, calcified in the latter); the rostrum and lateral projections of the shield are weakly produced in the former whereas they are well produced and often spinose in the latter; in both sexes the third to fifth pleopods are unpaired in the former, and paired albeit asymmetrical (reduced on the right side) in the latter; the telson and uropods are asymmetrical in the former, whereas they are symmetrical or nearly so in the latter.
A small, subterminal corneous tooth laterally on the prehensile margin of the dactyl of the fifth pereopod (Fig. 6) has been found to be present on all Strobopagurus species.Its function is unknown.The presence or absence of this tooth has not been reported in other parapagurids, although during this study it was found to occur at least in the monotypic genus Bivalvopagurus, and at least one species of Paragiopagurus, P. fasciatus Lemaitre and Poupin, 2003.
Description: Shield (Fig. 1A) weakly convex in lateral view; dorsal surface moderately calcified; with rows of long setae on each side, usually as follows: 1 oblique row from level of rostrum to level of lateral projection, 1 oblique row from midpoint between base of antennal peduncle and posterior midline of shield, and 1 longitudinal row parallel to lateral margin of shield.Rostrum broadly rounded, with short longitudinal dorsal ridge; in juveniles (sl <3.0 mm) occasion-ally with small terminal spine (Fig. 1C).Anterior margins weakly concave; lateral projections broadly subtriangular, unarmed; anterolateral margins sloping; posterior margin broadly rounded.Anterodistal margin of branchiostegite rounded, setose.
Ocular peduncles slightly more than 0.5 length of shield, constricted at about midpoint; with short row of setae dorsally.Ocular acicles subtriangular, each terminating in prominent simple spine (rarely bifid), separated by about basal width of 1 acicle.segment unarmed or with minute dorsodistal spine, with scattered setae.Third segment with small, blunt or sharp ventromesial distal spine.Second segment with dorsolateral distal angle produced, terminating in strong spine; mesial margin rounded distally, with or without small spine.First segment with unarmed lateral face.Flagellum long, nearly twice as long as ambulatory legs, naked or at most with scattered short setae less than 1 flagellar article in length.Acicle (Fig. 1A,B) not reaching or slightly exceeding distal margin of cornea, sparsely setose, frequently strongly curved outward, and terminating in strong spine; with 4-9 small spines on mesial margin.Mandible (Fig. 2A) as figured.Maxillule (Fig. 2B, C) with external lobe of endopod weakly developed, internal lobe with long seta distally.Maxilla (Fig. 2D) with endopod exceeding distal margin of scaphognathite.First maxilliped (Fig. 2E) with endopod exceeding exopod in distal extension.Second maxilliped (Fig. 2F) without distinguishing characters.Third maxilliped (Fig. 2G,H) with crista dentata consisting of about 14 small corneoustipped teeth; basis with 1 small tooth mesially.Sternite of third maxillipeds with spine on each side of midline.
Left cheliped (Fig. 3B) with dense setae on dorsal surfaces of chela and carpus, and ventral surfaces of carpus and merus; frequently iridescent (preserved) on dorsal surface of palm and carpus.Fingers straight, tips curving inwards and terminating in corneous claws; cutting edge of dactyl with comb-like row of small corneous spinules, cutting edge of fixed finger with small blunt to sharp calcareous teeth.Palm unarmed but with setae.Carpus with small dorsodistal spine.Merus unarmed except for dorsal row of short tufts of setae.Ischium and coxa each with ventromesial margin setose.
Ambulatory legs (Fig. 4A-F) similar from right to left except for slightly shorter meri on left.Dactyl about 1.9-2.2times as long as propodus, terminating in sharp corneous claw; with dorsodistal row of bris-tle-like setae; mesial face with median longitudinal row of about 9 minute corneous spinules.Propodus with dorsal row of short setae.Carpus with small dorsodistal spine, and dorsal row of short setae.Merus about 2.4 times (first leg) or 1.9 (second leg) as long as high; with dorsal row of short setae; ventrodistal margin armed with irregular rows of small spines (first leg), or unarmed (second leg).Ischium unarmed.Coxa with ventromesial row of setae.Anterior lobe of sixth thoracic sternite (Fig. 4G), with or without small subterminal spine.
Uropods and telson asymmetrical.Telson (Fig. 5B, C) with weak lateral indentations; dorsal surface frequently with scattered, low blister-like tubercles; terminal half divided into 2 distinctly asymmetrical posterior lobes separated by shallow, unarmed Ushaped cleft; terminal margins of posterior lobes armed with row of corneous spines stronger, and curved, on left side; females frequently with several submarginal rows of spines on terminal margin of left posterior lobe (Fig. 5C).
Males first and second gonopods (Fig. 5D, E) as diagnosed for genus; second gonopods sometimes missing rudimentary exopod on left or right gonopod (Fig. 5E).
Coloration in life: Unknown.Distribution: Western Pacific: New Caledonia region; Fiji; Tonga; Vanuatu; and Solomon Islands.Depth: 150 to 756 m.
Similarities: This new species is most similar to S. sibogae.The two can be separated by differences in shape and armature of the right cheliped (chela and carpus), and relative length of the antennal acicles.The mesial and lateral margins of the right chela in S. breviacus are nearly straight in outline (viewed dorsally), whereas they are arched in all but the largest sized specimens (sl > 8.0 mm) of S. sibogae.The dorsomesial and dorsolateral margins of the chela, and the dorsal surface of the carpus are unarmed or have small blunt spines in S. breviacus, whereas the margins of the chela are strongly spinose, and the carpus has many spines on the dorsal surface in S. sibogae.The antennal acicles at most reach to about the distal margins of the corneas in S. breviacus, whereas the acicles exceed the corneas by 0.2 or more the length of each acicle in S. sibogae.Unfortunately the coloration of S. breviacus is not known, and thus cannot be compared to the distinct color pattern of S. sibogae.
Terminal half of telson divided into 2 nearly symmetrical, rounded posterior lobes separated by wide U-shaped cleft, and armed with often curved corneous spines.
Coloration in life (Fig. 8A-D): Somewhat variable.Shield and cephalic appendages white or light orange, antennular and antennal peduncles sometimes light red.Chelipeds white or light orange becoming darker distally on carpi and near base of fingers on palm.Ambulatory legs white, most frequently with lateral faces of meri, carpi, and propodi partially light orange or with light orange stripe; dactyls light orange proximally near propodi, white distally.
Distribution: Eastern Atlantic: from Portugal to Morocco, including the Azores, Canary and Cape Verde Islands. Western, central, and South Pacific: New Caledonia region; Vanuatu; Solomon Islands; Taiwan; Hawaiian Islands; and French Polynesia.Depth: 75 to 1200 m.
Variations: As stated in the diagnosis, the right cheliped in large males of this species can be quite long, and slender.One male examined (Taiwan 2003, stn CP 214, sl 6.0 mm, NTOU A00001) has what appears to be an abnormal right cheliped, similar in size to the left cheliped (Fig. 8B).Small specimens (sl < 2.0 mm), and immature individuals usually have paired, asymmetrical pleopods.
Similarities: This species can be distinguished from the other two congeners, S. sibogae and S. breviacus sp.nov., primarily by the shape of the propodus and dactyl of the fourth pereopod, the more slender segments (the meri in particular) of the ambulatory legs, and shape of telson.On the fourth pereopod, the propodus is short and subcircular (in lateral view) in S. gracilipes, whereas it is long and ovate in the other two species; the dactyl is stout and short, about as long as the dorsal margin of the propodus in S. gracilipes, whereas the dactyl is elongate, and longer than the dorsal margin of the propodus in the other two congeners.The length/height ratio of the meri of the ambulatory legs varies from 2.7 to 3.6 in S. gracilipes; from 1.9 to 2.4 in S. breviacus sp.nov.; and from 2.0 to 2.5 in S. sibogae.The terminal half of the telson is divided into nearly symmetrical posterior lobes in S. gracilipes, whereas the lobes are distinctly asymmetrical in the other two congeners.Also, the two species differ in coloration (Fig. 8) of chelipeds and ambulatory legs.
Remarks: Lemaitre (1994) tentatively reported a female specimen from French Polynesia as S. cf.gracilipes.This same specimen had been reported by Poupin (1993) as Strobopagurus cf.sibogae.Reexamination of the specimen has removed any doubts on its identity, and represents S. gracilipes.So far, S. sibogae is not known to occur in French Polynesia. Zhadan (1997) reported a number of specimens from the ridges of Sala y Gómez, in the southeastern Pacific, as Strobopagurus aff.gracilipes.He found the specimens to be intermediate between S. gracilipes and Bivalvopagurus sinensis.To explain their morphology Zhadan invoked a process of "progressive carcinization" similar to that presumed by Blackstone (1989) for southern and northern populations of Pagurus hirsutiusculus (Dana, 1851) in the eastern Pacific.Zhadan chose to assign his specimens tentatively to S. gracilipes based on the presence of unpaired left third to fifth pleopods.However, the degree of development of right third to fifth pleopods in B. sinensis can vary substantially (pers.obs.), and they can often be small or obscured by tufts of setae.The description and characters depicted by Zhadan (1997) suggest instead that his specimens represent either B. sinensis or perhaps an undescribed species of that currently monotypic genus.It should be pointed out that the concept of carcinization, as traditionally applied to the Paguridae, and Blackstone's (1989) assumption, have both been shown to be erroneous (Crain and McLaughlin, 1993;McLaughlin and Lemaitre, 1997;McLaughlin et al., 2004).
Strobopagurus gracilipes has a broad, disjunct distribution that includes the eastern Atlantic, and western, central and South Pacific.At least two other parapagurids, Paragiopagurus ruticheles (A.Milne-Edwards, 1891) and Sympagurus acinops Lemaitre, 1989, have similar, disjunct distributions (Lemaitre, 1990, unpub. obs.).It is conceivable that such distributions may reflect the existence of cryptic species.However, so far no adult morphological characters have been found that allow separation of Atlantic and Pacific populations of any of these three species.
Two megalopas inhabiting gastropod shells, believed to be of S. gracilipes, were found at BIO-CAL station DW 33 (MNHN Pg 7119) along with adults of this species.These megalopas differ from other parapagurid megalopas previously reported (see de Saint Laurent-Dechancé, 1964;Lemaitre and McLaughlin, 1992;Lemaitre, 1997) by the short, broadly subtriangular rostrum (Fig. 7A) with a shallow, median indentation, and the straight dactyls (Fig. 7D, E) of the first and second ambulatory legs, which lack ventromesial spines.In other parapagurid megalopas, the dactyls of the pereopods have a row of ventromesial spines, and are evenly curved; the rostrum is obtusely subtriangular, rounded, more produced anteriorly than in S. gracilipes, and lacks a median indentation.The chelipeds (Fig. 7B, C) of the megalopas of S. gracilipes are smooth, unarmed, similar to those of the megalopa of Sympagurus dimorphus (see Lemaitre and McLaughlin, 1992).In other characters so far studied, all parapagurid megalopas are nearly identical.(de Saint Laurent, 1972) (Figs.1F; 3E-H; 4J, K; 5H, I, 8E)
Material examined (see also Lemaitre, 1996Lemaitre, , 1997)) Diagnosis: Shield (Fig. 1F) convex in lateral view.Rostrum broadly rounded, with short longitudinal dorsal ridge.Ocular peduncles more than half length of shield.Ocular acicles each terminating in strong spine (occasionally bifid).Antennular peduncles exceeding distal margin of corneas by slightly more than length of ultimate segments.Antennal peduncles exceeding distal margin of corneas by about 0.3 or less length of fifth segments; fourth segment with small dorsodistal spine; second segment with dorsolateral distal angle produced, terminating in strong spine (occasionally bifid), mesial margin with small spine at dorsodistal angle; first segment with row of short spines on ventrodistal margin.Antennal acicles exceeding distal margin of corneas by as much as 0.3 length of acicles; mesial margin armed with 5-7 spines on proximal half.Sternite of third maxillipeds with small spine on each side of midline.Right cheliped (Fig. 3E, G) with chela usually ovate, or oblong in large specimens (sl > 8.0 mm); dactyl with row of spines on mesial margin; palm with dorsal surface covered with short, fine setae not hiding surface beneath, dorsal surface lacking spines or tubercles, and with dorsomesial and dorsolateral margins well delimited by row of often strong spines (usually double row on mesial margin); carpus armed with often numerous small spines on dorsal surface.Left cheliped densely setose; carpus with dorsolateral, and often also dorsomesial rows of spines.Ambulatory legs with meri shorter on left side than on right; merus about 2.5 (first leg) or 2.0 (second leg) times as long as dorsoventral height.Fourth pereopod (Fig. 5H) semichelate; dactyl elongate, as long or longer than dorsal margin of propodus; propodus ovate (lateral view), about 1.8 times as long as greatest height; propodal rasp with 1 row of ovate scales.Anterior lobe of sixth thoracic sternite (second ambulatory legs) usually unarmed, setose.Uropods and telson (Fig. 5I) strongly asymmetrical; terminal half of telson divided into 2 rounded, distinctly asymmetrical posterior lobes by broad, U-shaped cleft, and armed with strong, often curved corneous spines.
Coloration in life (Fig. 8E): Shield and cephalic appendages mostly white except for light orange antennules.Chelipeds mostly light orange, with white fingertips, dark orange ventrolateral margins of carpi, and dark orange band near dorsodistal margin of meri; chelae sometimes mostly white with light orange dorsomesial face.Ambulatory legs white; dactyl light orange proximally; carpi and propodi with dorsolateral and dorsoventral stripes; meri with dark orange band near dorsodistal margin, and light orange proximally fading to white distally.
Distribution: Western Indian Ocean: Mozambique Channel; Madagascar.Western Pacific: Indonesia; Philippines; New Caledonia region; Solomon Islands; Taiwan; China Sea; and Japan.Depth: 40 to 980 m.
Variations: Variations in shape of the right cheliped of S. sibogae are related to size, particularly in males.Most specimens of both sexes have the lateral margins of palm and fixed finger, and the mesial margin of the palm, distinctly arched (Fig. 3E), with chela and carpus each about 1.4 times as long as broad.In contrast, large males (sl > 8.0 mm) have the lateral margins of palm and fixed finger, and mesial margin of palm, nearly straight, with chela and carpus each about 2.1 times longer than broad (Fig. 3G).
Similarities: (See S. breviacus).Remarks: In the original description of this species by de Saint Laurent (1972: 116) the paratypes were not listed in detail, although it was mentioned that they came from "Indonesia ("Siboga", and coll.Mortensen), China Sea (F.R.S. Hong Kong), and Japan (coll.K. Sakai)".Thus, it is unclear which were to be considered paratypes.Of the specimens used and labeled by de Saint Laurent, only those listed above under "presumed paratypes" have been located and examined.Kensley (1973), in his description of Parapagurus kilburni, contrasted his species with Parapagurus gra-cilipes (A.Milne-Edwards, 1891) (= Strobopagurus gracilipes), and Parapagurus macrocerus Forest, 1955 (= Paragiopagurus macrocerus).Kensley justified his new species on the basis of differences in the antennal acicles, cheliped armature, and telson.It appears that Kensley was unaware of de Saint Laurent's (1972) description of Parapagurus sibogae (= Strobopagurus sibogae) as he did not mention her taxon or 1972 publication.A comparison of Kensley's (1973)  McLaughlin, Shannon Point Marine Center, Western Washington University, and anonymous review-ers, provided useful criticism to the manuscript.Sarah Trunnell, American University, enthusiastically assisted in producing the SEM micrograph (Fig. 6).Rose A. Gulledge helped in putting together computer images of the plates, and processing specimens for the USNM.
description and type material of Parapagurus kilburni with Strobopagurus sibogae, has shown that the two are indistinguishable morphologically, and therefore the former must be considered a junior synonym of the latter.ACKNOWLEDGEMENTS Completion of this study was possible, in part, by a one-month research grant from the MNHN.The cruises TAIWAN 2000-2003, were supported in Taiwan (R.O.C.) by Taiwan Fisheries Research Institute, National Science Council; National Museum of Marine Science & Technology, Keelung; and National Museum of Marine Biology & Aquarium, Pingtung; and in France by MNHN, and Institut de Recherche pour le Développement.Much thanks are due to Bertrand Richer de Forges, Philippe Bouchet, and other colleagues working on board and in landbased laboratories in Noumea and Paris, and Tin-Yam Chan in Keelung, Taiwan, for their continuing leadership in making these campaigns a success.As usual, Alain Crosnier has nurtured my parapagurid studies in many ways.His advice, generous hospitality, and sense of humor during working visits to his Paris museum laboratory, have been instrumental and are gratefully acknowledged.At the Paris museum, I am grateful also to Danièle Guinot and Nguyen Ngoc-ho, for placing type and comparative specimens at my disposal, and processing specimens; and Régis Cleva, for assisting in collectionsrelated tasks.Thanks are extended to other colleagues and curators who have provided specimens, arranged loans, or provided information; these include: Tin-Yam Chan, NTOU; Dirk Platvoet, ZMA; Joseph Poupin, Institut de Recherche de l'École Navale, Brest Naval, France; Michelle van der Merwe, SAM; Beatrice Burch, BPBM; and Torben Wolff, ZMK.The color photographs were kindly provided by T.-Y.Chan, and J. Poupin.Patsy A.