Catapaguroides tenuiclavus, Komai & Rahayu, 2013

Komai, Tomoyuki & Rahayu, Dwi Listyo, 2013, The Hermit Crab Genus Catapaguroides A. Milne-Edwards & Bouvier, 1892 (Crustacea: Decapoda: Anomura: Paguridae) From The Bohol Sea, Philippines, With Descriptions Of Eight New Species, Raffles Bulletin of Zoology 61 (1), pp. 143-188 : 178-182

Catapaguroides tenuiclavus , new species

( Figs. 23 , 24 )

Material examined. –– Holotype: male (sl 0.89 mm), PANGLAO 2004, stn T23 , Cortes, Bohol Island , 09°42.2'N, 123°50.6'N, 35–45 m, 12 Jun.2004, NMCR 39067.

Paratype: 1 male (sl 0.89 mm), same data as holotype, ZRC 2012.1096 .

Description. –– Eight pairs of biserial phyllobranchiate gills; no arthrobranchs on third maxilliped; 2 arthrobranchs on cheliped each reduced to minute, non-lamellate buds; other arthrobranchs well developed, distinctly lamellate; no pleurobranchs on wall of seventh thoracic somite.

Shield ( Fig. 23A ) 1.1 times longer than wide; anterior margins between rostrum and lateral projections concave; anterolateral margins sloping; posterior margin roundly truncate; dorsal surface almost glabrous, with few tufts of short setae laterally. Rostrum broadly triangular, with blunt tip. Lateral projections triangular, not reaching level of rostrum, with submarginal spinule.

Ocular peduncle ( Fig. 23A ) long, subequal in length to shield, moderately stout, slightly constricted at midlength; dorsal surface mesially with 3 or 4 tufts of or individual setae arranged in longitudinal row; cornea normally developed, rounded, not dilated, approximately as long as wide, corneal width approximately 0.3 of peduncular length. Ocular acicle small, triangular, without submarginal or subterminal spinule, separated to each other basally by basal width of more than 1 acicle. Interocular lobe with nearly flat anterior surface.

Antennular peduncle ( Fig. 23A ) elongate, when fully extended, overreaching distal corneal margin by full length of ultimate segment and 0.1 length of penultimate segment. Basal segment with spinule proximolaterally. Ultimate segment 0.9 length of shield, slightly broadened distally in lateral view, with 2 long plumose setae at dorsolateral distal portion. Dorsal flagellum subequal in length to ultimate peduncular segment, with distal portion about twice length of proximal aesthetasc-bearing portion.

Antennal peduncle ( Fig. 23A ) falling short of distal corneal margin. Fifth and fourth segments with few short setae. Third segment with 1 prominent spine at ventromesial distal margin. Second segment with dorsolateral distal angle produced in simple spine far falling short of midlength of fourth segment; dorsomesial distal angle with minute spine. First segment unarmed. Antennal acicle slender, slightly arcuate, only reaching corneal base, terminating in slender spine, with row of short setae along entire length. Antennal flagellum exceeding 4.0 length of shield; articles each with some short to long setae on distal margin (long setae present every 2 or 3 articles).

Third maxilliped moderately stout, with crista dentata on ischium consisting of 2 teeth ( Fig. 23B ). Carpus without dorsodistal spine.

Chelipeds ( Figs. 23C–F , 24A–C ) distinctly unequal and dissimilar. Right cheliped ( Fig. 24A–C ) moderately long; propodal-carpal articulation rotated clockwise about 20° from perpendicular. Chela about 2.2 times longer than wide, elongate subovate, widest slightly proximal to base of dactylus. Dactylus articulating slightly obliquely with palm, about 0.7 length of palm, slightly curved ventrally; dorsal surface convex, dorsomesial margin not delimited; mesial surface unarmed; cutting edge with 3 prominent calcareous teeth (proximalmost teeth tubercle-like, distal 2 teeth triangular), terminating in tiny corneous claw; scattered tufts of short to long setae on surfaces. Palm 0.9 times as long as carpus, with parallel lateral and mesial margins; dorsal surface convex, spineless, but with prominent proximal protuberance slightly mesial to midline, and with numerous long setae arranged in irregular longitudinal rows; dorsolateral and dorsomesial margins not delimited; lateral, mesial and ventral surfaces also with long setae; ventral surface slightly convex. Fixed finger with 2 blunt triangular calcareous teeth on cutting edge, terminating in minute corneous claw. Carpus subcylindrical, about 1.2 length of merus, not broadened distally, about 2.0 times longer than distal width; dorsal surface with dorsolateral row of 5 small spines (including 1 spine on dorsodistal lateral angle), no mesial spines; mesial surface with numerous scattered long setae; ventrolateral distal angle with 1 small spine; lateral and ventral surfaces with some long setae. Merus with few moderately short setae on dorsal margin; dorsodistal margin without spine; lateral surface almost glabrous, ventrolateral margin generally convex, with 2 strong spines distally; mesial surface mostly glabrous, ventromesial margin with 2 small spines at distal angle; ventral surface slightly concave, with several long setae. Ischium unarmed, with moderately long setae on surfaces.

Left cheliped ( Fig. 23C–F ) slender, reaching midlength of right chela; propodal-carpal articulation rotated counterclockwise about 20° from perpendicular. Chela not arched, 2.8 times longer than wide; fingers without hiatus. Dactylus subequal in length to palm, unarmed, with numerous tufts of long setae; dorsomesial margin not delimited; cutting edge with row of minute corneous teeth in distal half, terminating in small corneous claw. Palm about 0.6 length of carpus; dorsal surface moderately convex, spineless; surfaces with numerous tufts of long setae or individual short to long setae arranged in irregular longitudinal rows. Fixed finger with row of minute corneous teeth in distal half of cutting edge, terminating in small corneous claw. Carpus slightly widened distally, 2.3 times longer than distal width; dorsal surface with 1 small mesial spine distal to midlength and with several tufts of long setae; dorsodistal margin unarmed; lateral and mesial surfaces also with tufts of long setae dorsally and distally, ventrolateral distal angle with 1 small spine; ventral surface slightly convex, with some long setae. Merus with few short setae on dorsal margin distally; dorsodistal margin unarmed; lateral surface with tufts of long setae ventrally, ventrolateral margin with 1 small subdistal spine; mesial surface with several long setae adjacent to ventral margin, ventromesial margin raised, with 1 small distal spine; ventral surface concave transversely, with some long setae. Ischium unarmed.

Ambulatory legs ( Fig. 24D, F ) long and slender. Dactyli ( Fig. 24E, G ) 1.4–1.5 times longer than propodi, about 14.0 times longer than wide, straight in dorsal view, gently curved ventrally in lateral view, terminating in very long, slender corneous claws; dorsal margins each with row of stiff setae increasing in length distally, distal 5 or 6 setae thickened, bristle-like; mesial faces each with row of short stiff setae on midline (second) or almost glabrous (third); ventral margins unarmed, each bearing sparse, short or long setae. Propodi each with single elongate corneous spine flanked by 2 or 3 much shorter spines (second) or only with pair of small corneous spines (third) on ventrodistal margin; dorsal and ventral margins with sparse short stiff setae. Carpi without dorsodistal spine; few setae on dorsal margins. Meri unarmed; dorsal margins each with few tufts of short setae; ventral margins glabrous. Ischia with few short setae on dorsal and ventral margins. Second pereopods with shallow notch on ventral margin at articulation between merus and ischium.

Fourth pereopod ( Fig. 23G ) semichelate; dactylus with several minute corneous teeth on ventral margin; propodal rasp consisting of 8 corneous scales arranged in single row. Fifth pereopods semichelate.

Anterior lobe of sixth thoracic sternite ( Fig. 23H ) subtrapezoidal, slightly skewed to left, bearing some submarginal short setae anteriorly; anterior margin faintly tuberculate.

Male with moderately long sexual tube emanating from coxa of right fifth pereopod ( Fig. 23I ), directed from right to left, distinctly overreaching lateral margin of coxa of left fifth pereopod. Coxa of left without trace of papilla-like sexual tube, but gonopore well marked. Eighth thoracic sternite ( Fig. 23I ) with single broad lobe bearing numerous setae.

Telson ( Fig. 23J ) almost as long as wide, not narrowed posteriorly; no lateral indentations; posterior lobes somewhat asymmetrical, separated by deep U-shaped median cleft; terminal margins oblique, left with 4 small spines, right with 3 small spines.

Female unknown.

Colouration. –– Not known.

Distribution. –– Known only from the type locality, 33– 45 m.

Remarks. –– Catapaguroides tenuiclavus , new species, somewhat resembles C. iejimensis , C. levigatus , new species, and C. umbra in sharing the following features: cornea normally developed, rounded; antennal peduncle not overreaching distal corneal margin; right chela subovate, non-operculiform; left cheliped with spineless palm and carpus bearing one or more dorsal spines. Catapaguroides tenuiclavus is, however, readily distinguished from the latter three species by the long antennular peduncle overreaching the distal corneal margin by the full length of the ultimate segment, the possession of a prominent hump-like proximal protuberance on the palm of the right cheliped, and the elongate claws of dactyli of the ambulatory legs. In the latter three species, the antennular peduncle overreaches the distal corneal margin by at most half length of the ultimate segment; the palm of the right cheliped has a sharp proximal spine in C. iejimensis and C. umbra , whereas such a spine or protuberance is absent in C. levigatus ; claws of the ambulatory dactyli are not particularly elongate. Furthermore, in C. tenuiclavus , there are no arthrobranch gills above the base of the third maxilliped, whereas the latter three species have two arthrobranchs above the base of the third maxilliped.

Etymology. –– From the combination of the Latin, “ tenuis ” [= narrow] and “ clavus ” [= nail], alluding to the elongate corneous claws on the dactyli of the ambulatory legs. Used as a noun in apposition.

Figures

Fig. 23. Catapaguroides tenuiclavus, new species, holotype, male (sl 0.89 mm), PANGLAO 2004, stn T23, NMCR 39067. A, shield and cephalic appendages, dorsal view; B, ischium-basis of left third maxilliped, ventral view; C, left cheliped, mesial view; D, same, lateral view (setae omitted); E, same, chela, dorsal view; F, same, carpus, dorsal view; G, distal three segments of left fourth pereopod, lateral view; H, sixth thoracic sternite, ventral view; I, coxae of fifth pereopods and eighth thoracic sternite, ventral view; J, telson, dorsal view. Scale bars = 0.5 mm (A, C–F); 0.25 mm (B, G–J).

Fig. 24. Catapaguroides tenuiclavus, new species, holotype, male (sl 0.89 mm), PANGLAO 2004, stn T23, NMCR 39067.A, right cheliped, mesial view; B, same, lateral view (setae omitted); C, same, chela and carpus, dorsal view; D, left second pereopod, lateral view; E, same, dactylus, mesial view; F, left third pereopod, lateral view; G, same, dactylus, mesial view. Scale bar = 0.5 mm.