Rediscovery and range extension of Ciliopagurus liui

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Sep 17, 2013 - recognition, but omitted several diagnostic details and no detailed ..... gently convex, with scattered small, low tubercles or protuberances,.

Zootaxa 3710 (5): 467–484 www.mapress.com /zootaxa / Copyright © 2013 Magnolia Press

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ISSN 1175-5326 (print edition)

ZOOTAXA

ISSN 1175-5334 (online edition)

http://dx.doi.org/10.11646/zootaxa.3710.5.5 http://zoobank.org/urn:lsid:zoobank.org:pub:364284D2-63E4-4EC6-8363-31E9A46252F0

Rediscovery and range extension of Ciliopagurus liui Forest, 1995 and description of a new species of Pagurus Fabricius, 1775 (Crustacea: Decapoda: Anomura: Paguroidea) from the Kerala State, southwestern India TOMOYUKI KOMAI1, REMA RESHMI2 & APPUKUTTAN NAIR BIJU KUMAR2 1 2

Natural History Museum and Institute, Chiba, 955-2 Aoba-cho, Chuo-ku, Chiba, 260-8682 Japan. E-mail: [email protected] Department of Aquatic Biology & Fisheries, University of Kerala, Thiruvananthapuram 695581, Kerala, India.

Abstract Two species of paguroid hermit crabs, Ciliopagurus liui Forest, 1995 (Diogenidae) and Pagurus spinossior n. sp. (Paguridae), are reported from the Kerala State, southwestern India. Ciliopagurus liui, is first recorded from the Indian Ocean. This species was originally described on the basis of a single male specimen from the Tonkin Gulf in the South China Sea, though its geographical range also included Japan, based on literature. Supplemental description and illustrations are provided for better understanding of the diagnostic features of this little known species. Pagurus spinossior n. sp., described on the basis of a single male specimen, appears closest to P. spinulentus (Henderson, 1888), known only by the holotype from the Philippines, but the lack of spinules on the dorsal margins of the dactyli of the second pereopods, the different shape of the anterior lobe of the thoracic sternite 6, and the more numerous spines on the terminal to posterior margins of the telson distinguish the new species from P. spinulentus. Key words: Supplemental description, Pagurus spinossior n. sp.

Introduction Alcock’s (1905) monograph on hermit crabs (Anomura: Paguroidea) in the collections of the Indian Museum, Calcutta, is the landmark for our knowledge on the Indian fauna of this group of Decapoda. Subsequently, several taxonomic works pertaining to the local fauna have been published (e.g., Kamalaveni 1950; Sankolli 1961; Tirmizi & Siddiqui 1982; Forest 1984, 1987, 1989, 1995; Khan & Natarajan 1984; Nayak & Neelakantan 1985, 1989; Thomas 1989; Lemaitre 1999, 2004; McLaughlin & Dworschak 2001; McLaughlin & Holthuis 2001; McLaughlin 2004, 2005; Reshmi & Bijukumar 2010, 2011; Komai et al. 2012, 2013). At present, approximately 90 species belonging to five families, viz. Coenobitidae, Diogenidae, Paguridae, Parapaguridae and Pylochelidae, are known from the area. Nevertheless, discovery of new species is still continuing (e.g., Komai et al. 2012, 2013), clearly indicating that the inventory of the local fauna is far from complete. During investigations of the crustacean fauna in waters around the Kerala State, southwestern India, conducted by the second and third authors, six specimens of a colorful diogenid hermit crab species and one specimen of a pagurid species were collected from by-catch made by local commercial trawlers, and submitted for identification to the first author. Detailed examination revealed that the diogenid specimens are C. liui, representing the first record of the species from the Indian Ocean, and that the pagurid represents an undescribed species of Pagurus Fabricius, 1775. Forest’s (1995) original description of C. liui, written in French, is detailed enough for species recognition, but omitted several diagnostic details and no detailed illustrations were given for some complex structures such as stridulating apparatus of the chelipeds and annulations on the chelipeds and ambulatory legs. Furthermore, the present specimens provide information on intraspecific variation in morphology and coloration in life of the species. Consequently, we provide a detailed description and illustrations based on our specimens for better understanding of the diagnostic features of the species. Pagurus spinossior n. sp. appears closest to P. spinulentus (Henderson, 1888), known only by the holotype from the Philippines. Differentiating characters between the new species and P. spinulentus are discussed. Accepted by S. Ahyong: 3 Sept. 2013; published: 17 Sept. 2013

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The examined material is deposited in the Natural History Museum and Institute, Chiba (CBM) and the museum collections of the Department of Aquatic Biology and Fisheries, University of Kerala, India (UOK/AQB/ AR/AN). General terminology follows McLaughlin et al. (2007), except for numbering of thoracic sternites; specific terminology for the ornamentation of chelipeds and ambulatory legs for Ciliopagurus liui follows McLaughlin & Bailey-Brock (1975). Shield length (sl), measured from the tip of the rostrum to the midpoint of the posterior margin of the shield, indicates specimen size.

Taxonomy Family Diogenidae Genus Ciliopagurus Forest, 1995 Ciliopagurus liui Forest, 1995 (Figs 1–5) Ciliopagurus krempfi.—Miyake 1982: 104 (in part), pl. 35, fig. 2 left. Ciliopagurus liui Forest, 1995: 75, figs. 12j, 15d, 17a, 33c.—McLaughlin et al. 2010: (list).

Material examined. Kerala State, India, 08°11’N, 75°44’E to 08°15’N, 76°11’E, 25–30 m, 25 May 2011, 2 males (sl 7.3, 7.6 mm), 2 females (sl 6.4, 7.3 mm), CBM-ZC 11806; same data, 2 females (sl 8.8, 9.0 mm), UOK/AQB/ AR/AN12–13. Description of Indian specimens. Cephalothorax (Fig. 1) strongly depressed dorsoventrally. Shield (Fig. 2A) approximately as long as broad; anterior margin nearly transverse, with faint concavity either side of obsolete rostrum; anterolateral angle blunt, but distinctly delineated; lateral margins convex, with row of moderately long setae in anterior one-third; posterior margin narrow, roundly truncate; dorsal surface flat, with scattered shallow pits and few tufts of short setae laterally; Y-shaped groove present posteriorly, integument around the groove decalcified. Posterior carapace substantially widened. Ocular peduncles (Fig. 2A) equal in length, long and slender, about 0.8 times as long as shield and 5.5–6.0 times longer than corneal width, cylindrical, slightly inflated basally (slightly wider than cornea); cornea not dilated; dorsal surfaces with scattered very short setae. Ocular acicles narrowly triangular, mesial margins nearly straight, lateral margins sloping, terminating in simple or bifid spine; narrowly separated basally (distance between acicles less than half width of 1 acicle). Antennular peduncles (Fig. 2A) not reaching corneal bases. Ultimate segment about 0.4 times as long as shield and about 1.5 length of penultimate segment, dorsal surface glabrous. Penultimate segment with tuft of moderately short setae slightly proximal to midlength. Basal segment short; ventrodistal margin terminating in tiny spine; laterodistal margin with 3 or 4 spinules; lateral surface armed with 1 minute spine. Antennal peduncles (Fig. 2A) reaching distal one-third of ocular peduncles. Fifth segment slightly flattened dorsoventrally, with tuft of short setae at dorsolateral distal angle; lateral surface non-calcified. Fourth segment with simple or bifid spine on dorsodistal margin. Third segment with prominent spine at ventrodistal angle and few tufts of short setae. Second segment with dorsolateral distal angle produced, terminating in bifid spine, lateral margin with 1 or 2 small tubercles; dorsomesial distal angle with minute spinule, mesial margin with short stiff setae. First segment with ventrodistal margin with few minute spinules or tubercles lateral to antennal gland opening. Antennal acicle reaching midlength of fifth segment, terminating in acute, simple or bifid spine; mesial margin with 4 or 5 small spines, lateral margin with 2–4 small spines. Flagellum slightly shorter than carapace; each article with some minute setae (< 0.2 length of one article) on distal margin. Maxillule with endopod bearing 2 bristles on moderately well developed internal lobe, external lobe well developed, slender, recurved (Fig. 2B). Third maxilliped with basis and ischium incompletely fused; basis with 1 or 2 minute corneous-tipped denticles (Fig. 2C); ischium with crista dentata well-developed, consisting of row of blunt or distally truncate corneous teeth, without accessory tooth (Fig. 2C); merus and carpus unarmed on dorsodistal margins; exopod broad (broadest at proximal two-fifths), uncalcified in lateral half, mesial surface with shallow concavity in distal half, accommodating proximal part of exopodal flagellum.

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FIGURE 1. Ciliopagurus liui Forest, 1995, male (sl 7.3 mm), CBM-ZC 11806, entire animal in dorsal view, showing coloration in life.

Chelipeds short, fairly flattened dorsoventrally, subequal or slightly unequal, when unequal, left larger (Fig. 1). Left cheliped (Figs. 3A–D, 4A–D) with dactylus subequal in length to palm; cutting edge with 2 obsolete calcareous teeth in proximal 0.6, distal 0.4 bordered by darkly pigmented corneous plate leading to tip; dorsomesial margin not delimited, dorsal and mesial surfaces with 7 shallow transverse furrows proximally bounded by low, setose ridges (3 furrows and striae in proximal half complete (extending to ventromesial margin of dactylus), others not complete); dorsal parts of ridges bearing minute corneous spinules; mesial surface (Fig. 4B) with transverse rows of corneous rods forming stridulating apparatus, these rods becoming shorter and fewer distally, distal ones corneous spine-like; ventral surface with a few tufts of stiff setae. Palm longer than carpus; dorsolateral or lateral margin not delimited, dorsomesial margin bluntly angular, surfaces each marked by shallow transverse furrows, each furrow bounded proximally by setose, microscopically denticulate to almost smooth ridges (main ridges 7 in number on dorsal surface, shorter additional striae interspersed by main ridges); 4 furrows on mesial surface, each

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continuous with dorsal furrows, each bounded proximally by low ridges bearing rows of corneous rods forming stridulating apparatus (for details, see below); ventral surface almost flat, laterally with 4 or 5 setose transverse ridges bordered by row of minute corneous spines and moderately long, stiff setae. Fixed finger with 4 furrows extending from dorsal to ventral surface, each proximally bounded by low ridges; on ventral surface, ridges bearing row of minute corneous spines; cutting edge with 2 low, blunt calcareous teeth in proximal three-fifths, distal twofifths bordered by darkly pigmented corneous plate extending to tip. Carpus about half length of merus, subtrapezoidal in dorsal view; dorsal, lateral and mesial surfaces each with shallow transverse furrows, and each furrow bounded proximally by low, smooth or minutely denticulate ridges (3 main ridges and 2 interspersing striae limited to dorsal surface); dorsodistal margin almost smooth, fringed with dense row of short setae becoming longer laterally, ventrodistal margin with less dense, longer stiff setae; dorsomesial distal angle with 1 small spine; ventral surface almost flat, mesially with 1 transverse ridge extending from mesial surface. Merus subrectangular in cross section, subtriangular in dorsal view; dorsal, lateral and to lesser extent mesial surfaces with 4 shallow transverse furrows, bounded proximally by low, smooth ridges, each ridge with dense short setae marginally; dorsal surface with additional setose striae interspersed by main ridges, dorsodistal margin unarmed, fringed with row of dense short stiff setae extending laterally and mesially; mesial surface nearly smooth except for transverse ridges or striae, ventromesial margin unarmed; ventrolateral distal margin with 1 or 2 tiny spines; ventral surface laterally with some transverse ridges extending from lateral surface and a few additional short striae, ventrodistal margin with row of stiff setae becoming longer laterally. Ischium with ventromesial margin smooth, terminating distally in blunt prominent tubercle; lateral surface with 1 transverse ridge. Right cheliped similar to left cheliped in armature and ornamentation. Stridulating apparatus on palm (Fig. 4C) consisting of 4 distal ridges bearing corneous rods and 2 proximal ridges with minute corneous teeth. First (distalmost) ridge broad, bearing about 10 long corneous rods equally spaced (rods nearly horizontal to oblique, each terminating in minute spine distally). Second ridge very short, limited to dorsal side, bearing 4 or 5 corneous rods. Third ridge as wide as second, but narrower than first ridge, with about 10 rods aligned with those on first ridge and extending over width of ridge, each rod terminating in minute spine distally. Fourth ridge slightly wider than third ridge, bearing about 10 corneous rods, these rods much shorter than those on distal ridges, ventral ones more strongly oblique. In total, about 40 corneous rods present. Ambulatory legs (Figs. 1, 5A–F) moderately stout, second slightly overreaching tips of chelipeds; generally similar in armature and ornamentation, but dactyli of third distinctly longer than those of second. Dactyli about 1.4 (second) or 1.6 (third) times as long as propodi, terminating in strong terminal claws, in lateral view gently curved ventrally, in dorsal view nearly straight, bearing 8–10 transverse, occasionally squamiform ridges continuous on dorsal and ventral margins, 1 or 2 distalmost ridges interrupted on lateral or mesial surfaces; these ridges bearing dense stiff setae, becoming longer ventrally (ventral setae forming prominent tufts); ventral surfaces with row of 5– 12 slender corneous spines increasing in size distally (3 or 4 distalmost spines darkly pigmented). Propodi each with series of prominent ridges and rows of short stiff setae circumscribing segment (6 main ridges and a few interspersing, short striae limited to lateral or mesial faces); setae on transverse ridges becoming noticeably longer ventrally, forming prominent tufts. Carpi subtriangular in cross section with broad dorsal surface, each with 1 or 2 dorsodistal spines mesially; dorsal surfaces each with 5 transverse ridges bearing rows of short dense setae, of them 1 or 2 ridges extending onto ventral surfaces though sometimes interrupted medially. Meri trapezoidal in cross section with dorsal surfaces broader than ventral surfaces; dorsal surfaces each with 9 or 10 transverse ridges bearing row of dense setae, of them 7–9 extending onto lateral surfaces and 5 or 6 to mesial surfaces, all ridges interrupted on ventral surfaces; mesial faces slightly concave; ventral surfaces each with row of tufts of long stiff setae mesially. Ischium with 1 or 2 short transverse striae on dorsal surfaces, without conspicuous spines. Fourth pereopods (Fig. 2D) semichelate. Dactylus about twice as long as palm, slightly curved, overreaching tip of fixed finger by about 0.3 length, terminating in minute corneous claw, lateral surface with row of small corneous spines ventrally; preungual process absent; ventral (opposable) surface broad, nearly flat. Propodal rasp very well developed, encompassing half to two-thirds of lateral surface, consisting of numerous small corneous scales increasing in size distally. Carpus with dorsodistal spine. Merus with some short setose striae or tufts of setae on lateral surface. Tufts of long stiff setae present on dorsal surfaces of dactylus to merus and distal part of ventral surface of merus. Fifth pereopods chelate.

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FIGURE 2. Ciliopagurus liui Forest, 1995, male (sl 7.6 mm), CBM-ZC 11806. A, shield and cephalic appendages, dorsal view; B, endopod of maxillule, internal view; C, ischium of left third maxilliped, ventral view (setae omitted); D, left fourth pereopod (ischium broken); E, third to sevenths thoracic sternites, ventral view; F, sixth pleonite, dorsal view; G, telson, dorsal view. Scale bars: 2 mm for A, F, G; 1 mm for B–D, E.

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FIGURE 3. Ciliopagurus liui Forest, 1995, male (sl 7.6 mm), CBM-ZC 11806. A, left chela, dorsal view (setae omitted); B, carpus of left cheliped, dorsal view (setae omitted); C, left chela, ventral view; D, carpus of left cheliped, ventral view. Scale bar: 2 mm.

Thoracic sternum (Fig. 2E) extremely broad, flattened plate-like. Sternite 3 fully visible, with anterior margin produced medially, divided by distinct median notch. Sternite 4 subtriangular, anteriorly with setose, submarginal transverse stria. Anterior and posterior lobes of sternite 6 (of third pereopods) rod-like, former slightly narrower than latter, with transverse submarginal row of setae; posterior lobe without median groove. Membranous part between calcified plates of sternites 7 and 8 broad, with prominent, subtriangular process on each lateral margin, each process bearing many long setae. Sternite 8 (of fifth pereopods) also very narrow, rod-like, slightly widened laterally, without conspicuous median groove. Males with 4 unpaired left pleopods (second to fifth pleopods; length: third = fourth > fifth > second); each exopod well developed, whereas endopods reduced, about half length of exopods, both rami multi-articulated. Female with 4 biramous unpaired pleopods (length: third = fourth = fifth > second), with both rami multiarticulated and well developed. Uropods asymmetrical. Pleonite 6 (Fig. 2F) divided into two parts by distinct transverse groove across at about posterior two-thirds; lateral indentations shallow; anterior margin oblique; posterior part with deep median longitudinal groove, posterolateral margins with few faint tubercles and tufts of setae. Telson (Fig. 2G) with distinct lateral indentations; anterior lobe slightly wider than posterior lobe; posterior lobes broadly and roundly subtriangular, slightly unequal (left slightly larger than right), with narrow, deep median cleft; terminal margins unarmed, but with row of moderately long stiff setae.

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FIGURE 4. Ciliopagurus liui Forest, 1995, male (sl 7.6 mm), CBM-ZC 11806. A, left cheliped, lateral view; B, same, dactylus, mesial view (setae omitted); C, same, palm, mesial view; D, same, carpus to ischium, mesial view (setae omitted). Scale bars: 2 mm.

Coloration in life (Fig. 1). Shield pale red, lateral parts yellowish. Posterior carapace translucent generally; posteromedian plate with red tinge medially. Ocular peduncle red, without conspicuous markings; cornea black. Antennular and antennal peduncles red, antennal flagellum uniformly light red. Palms of chelipeds generally orange-red, transverse ridges lined by red, transverse sulci whitish. Dactyli of ambulatory legs generally orangered, becoming slightly paler distally; propodi with distal parts cream or light yellow with tinge of red, followed by 7 or 8 alternate rings of red and white (white ring corresponding to furrows), proximally part whitish; carpi similarly annulated with 4 or 5 white and red rings, proximal part yellow or cream; meri also annulated with 7 or 8 alternated white and red rings (red rings broader than white rings, sometimes bicolored with red and orange), proximal parts yellow or cream; ischia generally red or orange, with few white rings or short striae. Pleon with numerous, short to long, red and white transverse or obliquely transverse stripes. Biocoenoses. The cone shell, Conus inscriptus Reeve (Gastropoda: Conidae). Distribution. Tonkin Gulf in the South China Sea (type locality), Japan, and now southern India. Remarks. Ciliopagurus liui was originally described on the basis of a single male specimen collected in the Tonkin Gulf, southern China, at a depth of 53 m (Forest 1995). In addition, Forest (1995) referred a specimen from Japan, identified as C. krempfi (Forest, 1952) by Miyake (1982: 104, pl. 55, fig. 2, left), to C. liui, though Forest did not personally examine the Japanese specimen. We tried to locate the Japanese specimen, but whereabouts of the specimen remains unknown. Since the original description, there have been no additional records of this species. The present specimens agree well with the type description of C. liui by Forest (1995) in every diagnostic aspect, including the terminally simple or at most bifid ocular acicles, the relatively long antennal acicle reaching to the

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FIGURE 5. Ciliopagurus liui Forest, 1995, male (sl 7.6 mm), CBM-ZC 11806. A, right second pereopod, lateral view (setae omitted); B, same, mesial view; C, left third pereopod, lateral view; D, same, mesial view; E, same, dactylus, lateral view (perpendicular), showing setation; F, same, propodus, lateral view (perpendicular), showing setation). Scale bars: 2 mm.

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midlength of the fifth segment of the antennal peduncle, the smooth transverse ridges on the chelae and the pattern of annulation on the ambulatory legs. The characteristic coloration in life also agrees well with that of the specimen reported from Japan (Miyake 1982: pl. 55, fig. 2; as C. krempfi), particularly in the uniformly reddish ocular and antennal peduncles, chelipeds and ambulatory legs with alternated white and red bands, and the pleon with irregular pattern of short to long red and white transverse stripes. As Forest (1995) discussed, Ciliopagurus liui appears closest to C. macrolepis Forest, 1995 described on the basis of a single male specimen from the Banda Sea, Indonesia. He cited armature and shape of the antennal acicle, proportion of the dactyli of the ambulatory legs, and development of annulation of the ambulatory legs to differentiate the two species. We confirm that the armature of the antennal acicle and the development of transverse furrows of the ambulatory legs are reliable, but other characters might overlap between the two species. Mesial spines on the antennal acicle are less numerous in C. liui than in C. macrolepis (up to six versus eight or nine). As Forest (1995) noted, transverse furrows on the propodi and meri of the ambulatory legs are deeper in C. macrolepis than in C. liui. Ciliopagurus is currently represented by 19 extant and two fossil species (Forest 1995; Bakel et al. 2003; Poupin 2001; Poupin & Malay 2009; McLaughlin et al. 2010; Komai et al. 2012). All but C. caparti (Forest, 1952) occur in the Indo-West Pacific to Central Pacific. Ciliopagurus caparti is distributed in the tropical eastern Atlantic. From the Indian Ocean, the following seven species of the genus have been recorded: C. grandis Komai, Reshmi & Biju Kumar, 2012, C. haigae Forest, 1995, C. krempfi (Forest, 1952), C. shebae (Lewinsohn, 1969), C. strigatus (Herbst, 1804), C. tenebrarum (Alcock, 1905), and C. tricolor Forest, 1995. Of them, C. grandis, C. strigatus and C. tenebrarum are known from India. The present study documents the occurrence of C. liui in the Indian Ocean.

Family Paguridae Genus Pagurus Fabricius, 1775 Pagurus spinossior n. sp. (Figs 6–10) Material examined. Holotype: off Neendakara, Kerala State, India, 08°44’N, 75°59’E, 50 m, 24 May 2011, male (sl 8.7 mm), CBM-ZC 11807. Description. Eleven pairs of biserial gills. Shield (Fig. 7A) slightly wider than long; anterior margin between rostrum and lateral projections slightly concave; anterolateral margins sloping; posterior margin truncate; dorsal surface slightly convex transversely, with tufts of short setae on either side of midline; paragastric grooves faint. Rostrum broadly rounded, reaching level of lateral projections. Lateral projections roundly triangular, with conspicuous marginal spine directed outward. Posterior carapace (Fig. 6) approximately as long as shield; posteromedian plate narrow, well calcified. Ocular peduncles (including cornea) (Fig. 7A) stout, increasing in width distally, about 0.6 times as long as shield; not inflated basally; cornea dilated, its width about 0.6 of peduncular length; dorsal surface with longitudinal row of tufts of stiff setae. Ocular acicles roundly subtriangular, separated basally by width of one acicle, with small submarginal spine distally; dorsal surface nearly flat. Interocular lobe clearly visible, medially concave. Antennular peduncles (Fig. 7A), when fully extended, overreaching distal corneal margins by 0.7 of ultimate segment. Ultimate segment about 1.6 times as long as penultimate segment, slightly widened distally in lateral view, with row of few long setae on dorsal surface. Basal segment with distolateral margin distinctly produced as short, setose process; statocyst lobe weakly inflated, with prominent spine distolaterally; ventromesial distal angle slightly produced, bluntly pointed. Antennal peduncles (Fig. 7A) slightly overreaching distal corneal margins, with supernumerary segmentation. Fifth and fourth segments with few setae distally. Third segment with small spine at ventromesial distal angle. Second segment with dorsolateral distal angle strongly produced, reaching distal margin of fourth segment, terminating in bifid, acute spine; dorsomesial distal angle with tiny spine; mesial and lateral faces with several

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short setae. First segment with spinule on lateral face; ventrodistal margin with 1 prominent spine lateral to excretory pore. Antennal acicle slightly overreaching distal corneal margin, slightly sinuous, terminating in small spine; dorsomesial margin with sparse tufts of long setae. Antennal flagellum about 4 times as long as shield; each article with 3 long setae (about 8 articles length) every 12–15 articles.

FIGURE 6. Pagurus spinossior n. sp., holotype, male (sl 8.7 mm), CBM-ZC 11807, entire animal in dorsal view, showing coloration in formalin preservative.

Mouthparts not dissected. Third maxilliped (Fig. 7B) moderately slender; carpus unarmed on dorsodistal margin; merus with 1 tiny spine on dorsodistal margin, unarmed on ventral margin; ischium with crista dentata consisting of clearly spaced corneous teeth increasing in size proximally, and with 1 strong accessory tooth (Fig. 7C); basis-ischium fusion incomplete; basis with 1 spinule on mesial margin; exopod reaching midlength of carpus. Chelipeds distinctly unequal and dissimilar (Fig. 6). Right cheliped (Figs. 8A, B; 9A–C) moderately stout, not particularly elongate. Chela subovate in dorsal view, about 2.0 times as long as wide; no hiatus between fingers; spines on dorsal surface subconical, usually corneous-tipped. Dactylus subequal in length to palm, nearly straight, overlapped by fixed finger distally; dorsal surface with longitudinal row of small spines on midline, dorsomesial margin delimited by double row of small to moderately large spines; all surfaces with scattered tufts of short to

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moderately long setae, mesial surface with row of small spines becoming double row proximally; cutting edge with row of low, rounded calcareous teeth in proximal 0.8, and with row of minute corneous teeth in distal 0.2, terminating in small corneous claw. Palm about 0.8 times as long as carpus; dorsal surface gently convex, armed with numerous small to large spines arranged in about 10 irregular longitudinal rows and tufts of long stiff setae each arising at just anterior to base of spine; dorsomesial margin delimited by double row of small to large spines, dorsolateral margin not clearly delimited; lateral surface with numerous scattered small spines or tubercles and tufts of short to long stiff setae; mesial face flat, perpendicular, with numerous, closely spaced small spiniform tubercles and sparse stiff setae; ventral surface gently convex, with scattered small, low tubercles or protuberances, each bearing tufts of stiff setae. Fixed finger nearly straight, somewhat depressed dorsoventrally, dorsal surface and dorsolateral margin with longitudinal rows of large spines continued from palm, ventral surface unarmed, with tufts of long stiff setae arranged in some longitudinal rows; cutting edge with low, blunt calcareous teeth in proximal half, faintly crenulate in distal half, terminating in minute corneous claw. Carpus moderately widened distally, subequal in length to merus; dorsal surface covered with scattered numerous small spines or spiniform tubercles and tufts of long stiff setae, dorsodistal margin with row of tiny spines, dorsolateral margin not delimited; dorsomesial margin with double row of large spines; lateral surface armed with numerous small spines or spiniform tubercles and tufts of stiff setae continuing from dorsal surface; mesial surface also with scattered numerous small tubercles or spines and tufts of long stiff setae; ventral surface convex, with numerous long setae mesially, devoid of even trace of shallow depression or foramen (Fig. 9C). Merus with irregular rows of short transverse ridges (sometimes marginally multidenticulate) becoming weak proximally, each ridge bearing tuft of short to long stiff setae; dorsodistal margin with 4 prominent spines decreasing in size laterally; lateral surface with short, multidenticulate ridges in dorsal half (becoming weak proximally), nearly smooth in ventral half, ventrolateral margin with row of large spines becoming smaller proximally; mesial surface generally with scattered minute, low tubercles and tufts of short setae, and ventrally with several multidenticulate tubercles, ventromesial margin with row of small tubercles; ventral surface armed with numerous small spines and tubercles, and tufts of moderately long stiff setae. Ischium with row of small spiniform tubercles on ventromesial margin; ventrolateral distal angle with 2 small spines, lateral surface with some small tubercles. Coxa unarmed. Left cheliped (Fig. 9D–F) moderately slender. Chela about 2.4 times as long as wide (greatest width at base of dactylus), with numerous tufts of short to long setae on surfaces; no hiatus between fingers. Dactylus approximately twice longer than palm; dorsal surface with partially double row of large slender spines decreasing in size on midline; mesial surface with row of small spines or tubercles, becoming double row proximally, on midline; ventral surface unarmed; cutting edge with row of small, slender corneous teeth, terminating in moderately large corneous claw. Palm about half length of carpus; dorsal surface slightly convex transversely, armed with large slender spines arranged in 5 irregular longitudinal rows; dorsomesial margin with partially double row of large spines; dorsolateral or lateral margin not clearly delimited, but with row of large spines extending onto fixed finger; mesial surface armed with numerous, closely spaced small spines or tubercles; ventral surface with scattered low protuberances and lateral spiniform tubercles; cutting edge of fixed finger with row of small, rounded calcareous teeth interspersed by sets of 2–5 partially fused small corneous teeth, terminating in moderately small corneous claw. Carpus slightly shorter than merus, with tufts of short to long stiff setae each arising from armature on every surface; dorsal surface very narrow, dorsolateral margin with row of large spines, dorsomesial margin with row of small spines or tubercles becoming smaller and lower proximally; lateral surface with numerous small spines or tubercles, ventrolateral distal angle with moderately large spine; mesial surface with low protuberances of various size, becoming spiniform tubercles or small spines distally; ventral surface slightly convex, with scattered small tubercles, devoid of even trace of depression or foramen. Merus with short, sometimes multidenticulate transverse ridges on dorsal surface, dorsodistal margin with 1 prominent spine; lateral surface with small, multidenticulate ridges or tubercles, particularly conspicuous on ventral side, and tufts of short to moderately long setae, ventrolateral distal margin with 4 spines; mesial surface with low protuberances dorsally and multidenticulate tubercles ventrally, and with few tufts of stiff setae, ventromesial distal margin with row of tiny tubercles; ventral surface slightly convex, with numerous small spines or tubercles and tufts of moderately long stiff setae. Ischium with row of tiny spines or tubercles on ventromesial margin; ventrolateral angle with cluster of 4 small spines, lateral surface also with cluster of tiny tubercles. Coxa unarmed.

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FIGURE 7. Pagurus spinossior n. sp., holotype, male (sl 8.7 mm), CBM-ZC 11807. A, shield and cephalic appendages, dorsal view; B, left third maxilliped, lateral view; C, same, ischium, ventral view, showing crista dentata and accessory tooth; D, dactylus to carpus of left fourth pereopod, lateral view; E, sixth thoracic sternite, ventral view; F, coxae of fifth pereopods and eighth thoracic sternite, ventral view. Scale bars: 5 mm for A; 2 mm for B, D–F; 1 mm for C.

Ambulatory legs (Figs. 6, 10A, B, E) moderately long and slender, right second pereopod overreaching tip of extended right cheliped by half length of dactylus. Dactyli 1.7–1.8 times as long as propodi, 11.0–12.0 times longer than broad, in dorsal view slightly twisted, in lateral view gently curving ventrally; dorsal margins each with row of numerous bristle-like setae, but without conspicuous spines or spinules; lateral faces each with shallow median sulcus and single or double row of long stiff setae decreasing in length distally; mesial faces also shallowly sulcate medially, with row of tufts of long bristle-like setae (dorsal) and row of bristle-like setae (ventral) flanking median

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sulcus (second) or only with row of bristle-like setae ventral to median sulcus (Fig. 10C, F); ventral margins each with row of 25–30 minute slender corneous spinules (Fig. 10D). Propodi distinctly longer than carpi, somewhat narrowing distally; dorsal surfaces each with double row of small spines and tufts of moderately short setae, dorsodistal margin with 1 spine (second) or unarmed (third); lateral surfaces with sparse tufts of short setae; mesial surfaces almost glabrous; ventral surfaces each with 2 rows of tufts or single setae, without corneous spinules. Carpi each with row of moderately large spines decreasing in size proximally; lateral faces with some scattered tufts of short setae. Dorsal surfaces of meri each with multidenticulate transverse ridges and minute tubercles, and tufts of setae arising from these ornamentations (second) or with very low protuberances bearing tufts of setae (third); lateral and mesial faces almost glabrous except for few tufts of short setae; ventrolateral distal margins each with 1 or 2 tiny spines (second) or unarmed (third), ventral surfaces each with 2 or 3 irregular rows of small spines or tubercles (second, armature more numerous in right than in left), single row of small tubercles (right third), or unarmed (left third), all with tufts of long stiff setae. Ischia unarmed, each with moderately short setae on dorsal and ventral margins. Fourth pereopods (Fig. 7D) semichelate, stiff long setae on dorsal margins of dactyli to meri and ventral margin of meri. Dactyli gently curved, terminating in prominent corneous claw, each with row of minute, closely spaced corneous teeth on ventral margin; no preungual process. Propodal rasp consisting of 3 or 4 rows of corneous scales. Fifth pereopods chelate. Coxae (Fig. 7F) each with gonopore partially masked by tuft of setae. Thoracic sternite 3 with anterior margin nearly straight, with pair of spinule on either side of midpoint; ventral surface with prominent tuft of setae medially. Anterior lobe of thoracic sternite 6 (Fig. 7E) triangular, approximately as long as wide, distinctly skewed to left, terminating anteriorly in 2 small spines and with 2 additional small spines on either side of apex and with some stiff setae subdistally. Thoracic sternite 8 (Fig. 7F) divided in two similar lobes by shallow median groove, each anterolateral angle slightly produced. Pleon dextrally twisted (Fig. 6). Male with 3 unpaired, very unequally biramous left pleopods (third to fifth pleopods). Uropods markedly asymmetrical; protopods unarmed. Telson (Fig. 7G) with distinct lateral indentations; posterior lobes rounded, slightly unequal, median cleft Vshaped, each terminal margin with row of small corneous spines extending onto lateral margin (15 on left, 13 on right). Coloration in formalin (Fig. 6). Shield, antennae, chelipeds and ambulatory legs generally light tan. Ocular peduncles with purple tint distally. Ambulatory legs with tinge of pale brown on distal and proximal parts of propodi and meri and ventral parts of carpi. Distribution. Known only from the type locality, off Neendakara, Kerala State, at a depth of 50 m. Biocoenoses. At the time of capture, the specimen was naked. Remarks. Pagurus spinossior n. sp. appears closest to P. spinulentus, the latter is so far represented only by the holotype from the Philippines (McLaughlin & Forest 1999). The two species share many diagnostic characters, including the rounded rostrum, dilated corneas, long antennal peduncle and acicle reaching beyond the distal corneal margin, the strongly produced dorsolateral distal angle of the second segment of the antennal peduncle, the generally strongly spinose chelipeds, the clearly defined, strongly spinose mesial surface of the palm of the right cheliped, and the dorsally spinose or spinulose propodi and carpi of the ambulatory legs. Nevertheless, the new species can be easily distinguished from P. spinulentus by the following characters (cf. Henderson 1888; McLaughlin & Forest 1999): (1) the carpus of the right cheliped is devoid of a ventral foramen in P. spinossior n. sp., but in P. spinulentus, it bears a moderately large median foramen, though an actual opening is not present; (2) the ventrodistal margins of the meri of the chelipeds do not have any prominent setation in P. spinossior n. sp., whereas they each carry a dense fringe of pinnate setae in P. spinulentus; (3) the dactyli of the second pereopods are smooth on the dorsal surface in P. spinossior n. sp., rather than spinulose in P. spinulentus; (4) setae on the chelipeds and ambulatory legs consist only of simple setae in P. spinossior n. sp., but they are a mixture of simple and pinnate setae in P. spinulentus; (5) the anterior lobe of thoracic sternite 6 is approximately as long as wide in the new species, rather than distinctly wider than long in P. spinulentus; (6) spines on the posterior lobes of the telson are more numerous in P. spinossior n. sp. than in P. spinulentus (15 on left and 13 on right versus nine on both sides). Pagurus cavicarpus (Paul’son, 1875), a species known also from Indian waters (Alcock 1905, as Eupagurus carpoforaminatus var. nephromma Alcock, 1905; McLaughlin & Forest 1999), is also substantially similar to the

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present new species, but the former differs from the latter in the short dorsolateral distal angle of the second segment of the antennal peduncle, the presence of a deep ventral foramen on each carpus of chelipeds, distinctly weaker spines on the palms of the chelipeds, spinulose dorsal margins of the second pereopods, and fewer marginal spines on the posterior lobes of the telson (McLaughlin & Forest 1999). From waters around India, the following seven species of Pagurus have been recorded (Alcock 1905; Sankolli 1961): Pagurus carpoforaminatus (Alcock, 1905), P. cavicarpus (Paul’son, 1875), P. hirtimanus (Miers, 1880), P. investigatoris (Alcock, 1905), P. kulkarnii Sankolli, 1961, P. macardlei (Alcock, 1905), and P. pergranulatus (Henderson, 1896). The present new species is the eighth of the genus known from India.

FIGURE 8. Pagurus spinossior n. sp., holotype, male (sl 8.7 mm), CBM-ZC 11807. A, right cheliped, mesial view (setae omitted); B, same, lateral view. Scale bar: 2 mm.

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FIGURE 9. Pagurus spinossior n. sp., holotype, male (sl 8.7 mm), CBM-ZC 11807. A, right chela, dorsal view (setae omitted); B, carpus of right cheliped, dorsal view; C, same, ventral view; D, chela and carpus of left cheliped, dorsal view; E, left cheliped, mesial view; F, same, lateral view. Scale bar: 2 mm.

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FIGURE 10. Pagurus spinossior n. sp., holotype, male (sl 8.7 mm), CBM-ZC 11807. A, right second pereopod, lateral view; B, same, mesial view (setae omitted except for mesial setae on dactylus); C, same, dactylus, mesial view, only mesial setae shown; D, same, distal part, mesial view; E, left third pereopod, lateral view; F, same, dactylus, mesial view, only mesial setae shown. Scale bars: 5 mm for A–C, E, F; 1 mm for D.

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Etymology. The specific epithet “spinossior” (= most spinose) refers to the strong armature on the chelipeds of this new species.

Acknowledgements We thank Dr. Michitaka Shimomura of the Kitakyushu Museum of Natural History and Human History for providing us with information on the material studied by Prof. Sadayoshi Miyake, and two anonymous referees for reviewing the manuscript and offering comments and suggestions for improvements. We also thank the Kerala State Council for Science, Technology and Environment, India, for financial support to the second and third authors for the project on the taxonomy of hermit crabs of the Kerala coast.

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