Catapaguroides brevidactylus, 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 : 145-149

Catapaguroides brevidactylus , new species

( Figs. 1 , 2 )

Material examined. –– Holotype: male (sl 1.1 mm), PANGLAO 2004, stn B10, Momo Beach , Panglao Island, 09°36.5'N, 123°45.6'E, 3–14 m, reef wall with small caves, 10 Jun.2004, NMCR 39061.

Description. –– Ten pairs of biserial phyllobranchiate gills; 2 arthrobranchs on third maxilliped each reduced to minute bud; other arthrobranchs distinctly lamellate; no pleurobranchs on wall of seventh thoracic somite.

Shield ( Fig. 1A ) approximately as long as wide; anterior margins between rostral lobe and lateral projections concave; anterolateral margins terraced, posterior margin truncate; dorsal surface almost glabrous, with few tufts of short setae laterally. Rostral lobe rounded, without setae. Lateral projections triangular, produced to level of rostral lobe.

Ocular peduncle ( Fig. 1A ) about 0.7 length of shield, slightly widened basally, with row of tufts of short to long setae on dorsal surface and 1 tuft of short setae on lateral face slightly proximal to corneal base; cornea normally developed, rounded, not dilated, slightly wider than long, corneal width about 0.3 of peduncular length. Ocular acicles narrowly triangular, terminating in acute marginal spine, separated basally by basal width of 1 acicle. Interocular lobe visible in dorsal view.

Antennular peduncle ( Fig. 1A ), when fully extended, overreaching distal corneal margin by full length of ultimate segment. Basal segment with spinule proximolaterally. Ultimate segment slightly broadened distally in lateral view, with 2 long plumose setae on dorsolateral distal portion. Dorsal flagellum with distal portion distinctly longer than proximal aesthetasc-bearing portion.

Antennal peduncle ( Fig. 1A ) overreaching distal corneal margin by 0.2 length of fifth segment. Fifth and fourth segments with few short setae. Third segment with 1 prominent spine at ventromesial distal angle. Second segment with dorsolateral distal angle produced in sharp spine nearly reaching midlength of fourth segment; dorsomesial distal angle with spinule. First segment unarmed. Antennal acicle slender, arcuate, nearly reaching to distal corneal margin, terminating in slender spine and with row of relatively short setae distally. Antennal flagellum long, about 4.0 times longer than shield; articles each with some short to long setae.

Third maxilliped moderately stout; crista dentata on ischium consisting of 2 teeth ( Fig. 1B ). Carpus without dorsodistal spine.

Chelipeds ( Fig. 2 ) subequal in length but distinctly dissimilar. Right cheliped ( Fig. 2A–C ) moderately large, not particularly elongate; right chela subovate, about 2.1 times longer than broad; palm-carpal articulation rotated clockwise about 20° from perpendicular. Dactylus 0.9 times as long as palm, slightly curved ventrally; dorsal surface rounded, dorsomesial margin not delimited; mesial surface armed with 1 small spine located at proximal 0.2; cutting edge with 2 obtuse calcareous teeth, terminating in small corneous claw; tufts of short to moderately long setae arranged in irregular longitudinal rows on surfaces. Palm 1.2 times longer than carpus; dorsal surface convex, unarmed, but with 3 irregularly longitudinal rows of tufts of short to long setae; dorsolateral and dorsomesial margins not delimited; lateral and mesial faces also with tufts of short to long setae; ventral surface slightly convex, with tufts of short to long setae extending onto fixed finger. Fixed finger with 1 obtuse calcareous tooth on cutting edge, terminating in minute corneous claw. Carpus subequal in length to merus, widened distally, 1.3 times longer than distal width; dorsal surface with tufts of moderately long setae, and 1 small mesial spine proximal to midlength and 3 spines on dorsolateral margin, dorsomesial distal angle with 1 larger spine; dorsomesial margin not delimited; lateral surface with few short setae dorsally, with 1 small spine at ventrodistal angle; mesial face with tufts of long stiff setae dorsally; ventral surface convex, with some long setae. Merus with few moderately long setae on dorsal surface distally; dorsodistal margin with 1 spine mesially; lateral surface glabrous, ventrolateral margin slightly concave in distal half, with 2 small spines; mesial surface also glabrous, ventromesial margin with 1 small spine at distal angle; ventral surface with few setae. Ischium unarmed.

Left cheliped ( Fig. 2D–F ) slender. Chela 3.0 times longer than wide, not arched; palm-carpal articulation rotated counterclockwise about 30° from perpendicular. Dactylus and fixed finger only slightly curved ventrally, without hiatus; dactylus 1.3 times longer than palm, unarmed but with scattered tufts of short to long setae; dorsomesial margin not delimited; cutting edge with row of minute corneous teeth, terminating in small corneous claw. Palm about half length of carpus; dorsal surface slightly convex, unarmed; surfaces with tufts of short to long setae arranged in irregular longitudinal rows. Carpus slightly widened distally, 2.8 times longer than distal width; dorsal surface laterally with 1 small spine proximal to midlength and tufts of long setae medially and on dorsomesial margin; dorsodistal margin with 2 small spines at lateral and mesial angles; lateral and mesial surfaces almost glabrous, ventral surface with few long setae. Merus with some tufts of short setae on dorsal margin; ventrolateral margin with 2 small spines distally; ventromesial margin with 1 spine distally; ventral surface with scattered long setae. Ischium unarmed.

Only left second pereopod preserved. Left second pereopod ( Fig. 1C ) long and slender, overreaching right cheliped by about 0.7 length of dactylus. Dactylus 1.2 times longer than propodus, 8.3 times longer than wide, straight in dorsal view, slightly curved ventrally in lateral view, terminating in long, slender corneous claw; dorsal margin with sparse long setae; mesial surface without spines or bristle-like thick setae ( Fig. 1D ); ventral margin with 6 slender corneous spines. Propodus with pair of small corneous spines on ventrodistal margin; dorsal and ventral margins with sparse, short to long setae. Carpus with dorsodistal spinule and few short setae on dorsal surface. Merus unarmed, with sparse short to long setae on dorsal and ventral margins. Ischium with few moderately short setae on ventral margin. Distinct notch on ventral margin at articulation between merus and ischium.

Fourth pereopod ( Fig. 1E ) semichelate; dactylus with several minute corneous denticles on ventral margin; propodal rasp consisting of 5 corneous scales. Fifth pereopods semichelate.

Anterior lobe of sixth thoracic sternite ( Fig. 1F ) subsemicircular, skewed to left, with moderately short setae on anterior margin.

Male with short sexual tube emanating from coxa of right fifth pereopod ( Fig. 1G ), directed from right to left, tapering distally, reaching mesial margin of coxa of left fifth pereopod. Coxa of left with short, papilla-like sexual tube directed anteromesially, not obscured by tufts of setae on eighth thoracic sternite. Eighth thoracic sternite ( Fig. 1G ) with single broad lobe bearing row of numerous setae on anterior margin.

Telson ( Fig. 1H ) semicircular, wider than long; no lateral indentations; posterior lobes slightly asymmetrical, separated by narrow median cleft; terminal margins slightly oblique, left with 4 minute spines, right apparently unarmed, outer angles not spinose.

Female unknown.

Colouration. –– Not known.

Distribution. –– Known only from Panglao Island, 3– 14 m.

Remarks. –– Catapaguroides brevidactylus , new species, is most similar to C. mortenseni de Saint Laurent, 1968 . Shared characters are: cornea normally developed, rounded; antennular peduncle overreaching distal corneal margin by full length of ultimate segment; antennal peduncle distinctly overreaching distal corneal margin; chela of right cheliped subovate in dorsal view, with lateral margin of palm and mesial margin of dactylus rounded, not crested; palm of right cheliped unarmed; and carpus of right cheliped bearing spines (de Saint Laurent, 1968). It is readily distinguished from the latter species by the shape of the ocular peduncle. In C. brevidactylus , the ocular peduncle is slightly widened proximally with a non-dilated cornea, whereas in C. mortenseni , it is widened distally with a dilated cornea. Furthermore, the dactylus of the right cheliped is armed with a proximal spine in C. brevidactylus , rather than unarmed in C. mortenseni ; the palm of the right cheliped lacks a dorsomesial distal spine in C. brevidactylus unlike in C. mortenseni ; the carpus of the right cheliped bears two spines on the dorsodistal margin in C. brevidactylus , whereas the margin lacks spines in C. mortenseni . In addition, it is suggested that the bathymetric range is different between the two species: C. brevidactylus inhabits shallow coral reefs at depths of 3–14 m, whereas C. mortenseni was recorded from upper bathyal zone at depths of 472–550 m (de Saint Laurent, 1968).

Etymology. –– From the combination of the Latin “ brevis ” [= short] and “ dactylus ” [= claw], in reference to the relatively short dactylus of the ambulatory leg for the genus. Used as a noun in apposition.

Figures

Fig. 1. Catapaguroides brevidactylus, new species, holotype, male (sl 1.1 mm), PANGLAO 2004, stn 10, NMCR 39061. A, shield and cephalic appendages, dorsal view; B, ischium-basis of left third maxilliped, ventral view; C, left second pereopod, lateral view; D, same, dactylus, mesial view (dorsal setae omitted); E, left fourth pereopod, lateral view; F, sixth thoracic sternite, ventral view; G, coxae of fifth pereopods and eighth thoracic sternite, ventral view; H, telson, dorsal view. Scale bars = 0.5 mm (A, C–E); 0.25 mm (B, F–H).

Fig. 2. Catapaguroides brevidactylus, new species, holotype, male (sl 1.1 mm), PANGLAO 2004, stn B10, NMCR 39061.A, right cheliped, mesial view; B, same, lateral view; C, same, chela and carpus, dorsal view; D, left cheliped, mesial view; E, same, lateral view; F, same, chela and carpus, dorsal view. Scale bar = 0.5 mm.