Catapagurus latus, Komai & Rahayu, 2021

Komai, Tomoyuki & Rahayu, Dwi Listyo, 2021, Three new species of the pagurid hermit crab genus Catapagurus A. Milne-Edwards, 1880 (Decapoda: Anomura: Paguroidea) from the Bohol Sea, the Philippines, Raffles Bulletin of Zoology 69, pp. 156-174 : 167-172

Catapagurus latus , new species

( Figs. 9–12 )

Material examined. Holotype: ovigerous female (sl 2.0 mm), NMCR 50803, PANGLAO 2004, stn T33 , Bohol Sea, Bohol Island, Baclayon , 9°36.0′N, 123°53.7′E, 67–74 m, sand with sponges, trawl, 3 July 2004.

Description. Shield ( Fig. 9A ) 1.1 times as broad as long; anterior margin between rostral lobe and lateral projections concave; anterolateral margins sloping, rounded; posterior margin roundly truncate; dorsal surface with longitudinal rows of tufts of short setae on either side of midline and posterior to lateral projections; carapace lateral lobes narrow, well calcified. Rostral lobe broadly rounded, produced as far as lateral projections. Lateral projections broadly triangular, each with terminal, submarginal spine. Posterior carapace 0.8 length of shield; posterolateral plates moderately wide anteriorly, drawn out into relatively thin bands reaching to posterior margins, posterior median plate short, weakly calcified.

Ocular peduncles ( Fig. 9A ) moderately short (0.7 times as long as shield), moderately stout, widened distally; corneal width approximately 0.5 peduncular length. Ocular acicles narrow, short, only reaching 0.1 length of ocular peduncles, terminating acutely; widely separated basally.

Antennular peduncle ( Fig. 9A, B ) overreaching distal corneal margin by half-length of penultimate article. Ultimate article 0.6 times as long as shield, 5.1 times as long as distal height, with tuft of 3 long setae at dorsodistal lateral margin. Penultimate article glabrous. Basal article with gently inflated statocyst lobe proximal to midlength and weakly produced, subacute ventrodistal margin.

Antennal peduncle ( Fig. 9A ) overreaching distal corneal margin by half-length of article 5. Articles 5 and 4 with few short setae. Article 3 unarmed at ventromesial distal angle. Article 2 with produced, dorsolateral distal angle reaching midlength of article 4 and terminating in bifid spine; dorsomesial distal angle with small spine. Article 1 with small spine at dorsolateral distal angle. Antennal acicle reaching base of article 5 and overreaching corneal base, terminating in spine. Flagella long, about 10 times as long as shield, almost glabrous.

Maxilliped 3 ( Fig. 9C ) endopod moderately stout; merus without dorsodistal spine; ischium with crista dentata consisting only of 3 small teeth; accessory tooth small, subdistal in position.

Right cheliped ( Fig. 10A–D ) short, relatively slender. Chela ( Fig. 10A ) elongate subovate, 2.3 times as long as wide. Dactylus 0.9 length of palm; all surfaces with scattered setae; dorsal surface weakly convex; dorsomesial margin not delimited, rounded; occlusal margin with 1 low, triangular calcareous tooth at proximal one-third, and with row of minute corneous teeth in distal half. Palm 0.7 length of carpus, 3.9 times as long as distal width; dorsomesial and dorsolateral margins not delimited, convex dorsal surface with sparse granules and short to moderately long setae; ventral surface gently convex, almost smooth, with scattered tufts of short to long setae; fixed finger with longitudinal rows of short setae, occlusal margin with low, obtuse calcareous tooth at midlength, unarmed in distal half. Carpus ( Fig. 10D ) subequal in length to merus, slightly widened distally, 3.9 times as long as distal width; dorsal surface with sparse granules, dorsomesial margin delimited with row of granules, dorsolateral margin delimited with row of spinules becoming obsolete proximally; sparse setae on both margins; lateral surface with scattered granules in dorsal half, smooth in ventral half; mesial surface with scattered short setae on distal half, ventromesial distal angle unarmed; ventral surface gently convex, smooth, with few setae. Merus subtriangular in cross section; dorsodistal margin with small spine; dorsal surface with widely spaced long setae; lateral face smooth, gently sinuous ventrolateral margin with small distal spine; mesial face also smooth, weakly sinuous ventromesial margin with small distal spine; ventral surface smooth. Ischium armed with small spine on ventrolateral distal margin. Coxa unarmed.

Left cheliped ( Fig. 11A–C ) slender, subequal in length to right cheliped; dactylus and fixed finger almost straight. Chela narrowly subovate, 4.4 times as long as wide. Dactylus 1.1 times as long as palm, terminating in small, curved corneous claw; surfaces almost smooth, with sparse tufts of setae; dorsomesial margin not delimited; occlusal margin with row of moderately spaced, minute corneous teeth almost over entire length. Palm 0.7 length of carpus, 2.0 times as long as wide; dorsomesial and dorsolateral margins not delimited, transversely convex dorsal surface with sparse granules and scattered short setae; ventral surface slightly convex, smooth, with few setae; fixed finger smooth on surfaces, with sparse tufts of short setae; occlusal margin with row of minute corneous teeth, terminating in small, curved corneous claw. Carpus subequal in length to merus; dorsal surface with sparse granules, dorsomesial margin delimited with row of granules, dorsolateral margin delimited with spinules becoming obsolete proximally; dorsal surface with sparse granules; lateral surface with sparse granules on dorsal half, almost smooth on ventral half, ventrolateral distal margin unarmed; mesial surface smooth, ventromesial distal margin unarmed. Merus dorsodistal margin with small spine; dorsal surface with several widely spaced setae; lateral surface smooth, gently sinuous ventral margin with small distal spines; mesial surface almost smooth, slightly sinuous ventromesial margin with small distal spine; ventral surface smooth, with few setae. Ischium unarmed. Coxa unarmed.

Right pereopod 2 ( Fig. 12A–C ) moderately stout, far overreaching tips of outstretched chelipeds, strongly twisted at articulation between carpus and propodus. Dactylus broadly blade-shaped (greatest width at midlength), 1.2 times as long as propodi, 6.0 times as long as wide; in dorsal view, straight; in lateral view, nearly straight; dorsal margin broadly convex, with row of numerous minute setae in proximal 0.3 and row of about 20 short to moderately long stiff setae in distal 0.7; mesial face shallowly excavate, each with row of about 60 minute stiff setae close to straight ventral margin (those setae not visible in lateral view); lateral surfaces and ventral margins unarmed. Propodus slender, 1.9 length of carpus; dorsal margin with widely spaced setae; lateral surface slightly granulate dorsodistally, otherwise nearly smooth; ventral margin with cluster of short setae in distal one-fourth, no spiniform setae on ventrodistal margin. Carpus short, about half-length of merus; dorsal surfaces granulate, with row of sparse short setae; lateral surfaces sparsely granulate, mesial and ventral surfaces almost smooth. Merus unarmed on dorsodistal margin; dorsal surface with subdistal transverse ridge, small spine located at distal 0.25 and row of sparse moderately short setae; lateral and mesial faces smooth except for granulate ventral part; ventral margin gently convex, granulate, ventrolateral distal angle with small spine. Ischium unarmed. Left pereopod 2 broken off, not preserved.

Pereopods 3 ( Fig. 12D–F ) generally similar to, but slightly longer than pereopods 2. Dactyli blade-shaped (greatest width at distal 0.3), 7.5 times as long as wide, 1.3 times as long as propodi; dorsal margins broadly convex, each with row of numerous minute setae in proximal half and row of about 20 short to moderately long stiff setae over entire length (more widely spaced proximally); mesial faces shallowly excavate, each with row of about 70 minute stiff setae close to straight ventral margin; lateral surfaces and ventral margins unarmed. Propodi each with cluster of short setae in distal 0.2 of ventral margin. Meri unarmed on dorsodistal margin; dorsal surface with subdistal transverse ridge, small spine located at distal 0.2 and row of sparse setae; lateral surface with scattered short setae; mesial surface glabrous; ventral margins slightly sinuous, smooth, ventrolateral distal angle with small spine. Ischia short, similar to that of pereopods 2.

Pereopods 4 semichelate ( Fig. 9E ); dactyli each with well developed preungual process far extending beyond tip of corneous claw; propodal rasp consisting of single row of corneous scales on distal 0.8 of ventral margin. Pereopods 5 chelate.

Thoracic sternite 6 (pereopods 3) ( Fig. 9F ) with wide, subrectangular anterior lobe, much shorter than large posterior lobe; posterior lobe distinctly longer than anterior lobe. Sternite 8 consisting of two small rounded lobes moderately separated.

Pleon dextrally twisted, with unequally biramous pleopods 2–5. Uropodal protopods not protruding posteriorly.

Telson ( Fig. 9G ) with lateral indentations suggesting separation of anterior and posterior portions; triangular posterior lobes separated by large U-shaped median cleft, each terminating in acute corneous tip; strongly oblique terminal margins unarmed, but with some minute setae subdistally on either side.

Eggs 0.5 × 0.6 mm in non-eyed stage.

Colouration in life. Not known.

Distribution. Presently known only from the Bohol Sea, central Philippines, at depth of 67– 74 m.

Remarks. The ovigerous female holotype is the only representative for this new species at present. In spite of the lack of male specimens, this new species is assigned to Catapagurus based on the gill formula consisting of 11 pairs of biserial gills, the somewhat reduced crista dentata on the maxilliped 3 ischium, the presence of a prominent preungual process on the pereopods 4 dactyli, and the lack of paired pleopods 1 ( McLaughlin, 2003, 2004). The broadly bladeshaped dactyli of the ambulatory legs suggest relationship to certain species of the Catapagurus ensifer species group of Asakura (2001), including C. albatrossae ( Asakura, 2001), C. alcocki, C. ensifer Henderson, 1888 , C. haigae ( Asakura, 2001), C. insolitus Komai & Osawa, 2009 , and C. kosugei ( Asakura, 2001) ( Asakura, 2001; Komai & Osawa, 2009).

Among the above-mentioned species, Catapagurus latus , new species, appears closest to C. haigae, known from the Arafura Sea and the Philippines, in having a ventral row of numerous (>50) minute setae on each ventromesial margin of the pereopod 2 and 3 dactyli ( Asakura, 2001). This new species is readily distinguished from C. haigae by many characters, as outlined below: (1) the ultimate article of the antennular peduncle is more elongate in C. latus , new species, than in C. haigae (5.1 length of the distal height versus 3.6 length; Fig. 9B and Asakura, 2001: fig. 19C); (2) the crista dentata of the maxilliped 3 is less developed (consisting only of three teeth) in C. latus , new species ( Fig. 9D ), than in C. haigae with five to nine teeth (cf. Asakura, 2001: fig. 22C); (3) the merus of the left cheliped is armed with a dorsodistal spine in C. latus , new species ( Fig. 11A ), while unarmed in C. haigae (cf. Asakura, 2001: fig 31K); (4) the dorsal margin of each dactylus of the pereopods 2 and 3 is furnished with a row of closely spaced minute setae in the proximal part in C. latus , new species ( Fig. 12A, D ), but such minute setae are not seen in C. haigae (cf. Asakura, 2001: fig. 36C); (5) the ambulatory propodi are each provided with a short row of setae on the distal part of the ventral margin in C. latus , new species ( Fig. 12A, D ), whereas such setae are not seen on any pereopod in C. haigae (cf. Asakura, 2001: fig. 38C); (6) the meri of the pereopods 2 and 3 are devoid of dorsodistal spines in C. latus , new species ( Fig. 12B, E ), rather than armed each with a dorsodistal spine in C. haigae (cf. Asakura, 2001: fig. 40I); (7) the thoracic sternite 6 is simply subrectangular in C. latus , new species ( Fig. 9F ), whereas it is bilobed in C. haigae (cf. Asakura, 2001: fig. 8E). Of the above characters, the possession of the setal row on the ambulatory propodi might be unique within Catapagurus to C. latus , new species.

Etymology. The Latin latus (= broad) refers to the broadly blade-shaped dactyli of the ambulatory legs of the new species.

Figures

Fig. 9. Catapagurus latus, new species, holotype, ovigerous female (sl 2.0 mm), NMCR 50803. A, shield, carapace lateral lobes and cephalic appendages, dorsal view; B, left antennule, ultimate article of peduncle and flagella, lateral view; C, left maxilliped 3, lateral view; D, ischium and basis, ventral view; E, left pereopod 4, dactylus and propodus, lateral view; F, thoracic sternite 6, ventral view; G, telson, dorsal view.

Fig. 10. Catapagurus latus, new species, holotype, ovigerous female (sl 2.0 mm), NMCR 50803. A, chela of right cheliped, dorsal view; B, right cheliped, mesial view; C, same, lateral view; D, carpus of right cheliped.

Fig. 11. Catapagurus latus, new species, holotype, ovigerous female (sl 2.0 mm), NMCR 50803. A, chela and carpus of left cheliped, dorsal view; B, left cheliped, mesial view; C, same, lateral view; D, carpus of left cheliped.

Fig. 12. Catapagurus latus, new species, holotype, ovigerous female (sl 2.0 mm), NMCR 50803. A, right pereopod 2, dactylus and propodus, lateral view; B, same, carpus, merus, and ischium, lateral view; C, same, dactylus, mesial view; D, left pereopod 3, dactylus and propodus, lateral view; E, same, carpus, merus, and ischium, lateral view; F, same, dactylus, mesial view.