Catapaguroides pusillus, 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 : 175-178

Catapaguroides pusillus , new species

( Figs. 21 , 22 )

Material examined. –– Holotype: ovigerous female (sl 0.9 mm), PANGLAO 2004, stn T1 , Bolod , Panglao Island, 09°32.4'N, 123°47.3'E, 83–102 m, mud with many sponges, 30 May 2004, NMCR 39066.

Description. –– Nine pairs of biserial phyllobranchiate gills; only single rudimentary bud of arthrobranch above base of third maxilliped; 2 arthrobranchs on cheliped very small, weakly lamellate; other arthrobranchs distinctly lamellate; no pleurobranchs on wall of seventh thoracic somite.

Shield ( Fig. 21A ) about 1.2 times longer than wide; anterior margins between rostral lobe and lateral projections concave; anterolateral margins sloping; posterior margin rounded; dorsal surface almost glabrous, with few tufts of short setae laterally. Rostrum broadly triangular, blunt terminally. Lateral projections triangular, exceeding to level of rostrum, acutely pointed.

Ocular peduncle ( Fig. 21A ) about 0.7 length of shield, moderately slender, slightly widened basally; dorsal surface mesially with 2 or 3 tufts of short to long setae in distal half, additional tuft of setae on lateral surface near corneal base; cornea slightly narrowed distally, but not coneshaped, rounded, as long as wide, corneal width about 0.3 of peduncular length. Ocular acicle somewhat elongate, narrowly triangular, without submarginal or subterminal spinule, separated to each other basally by basal width of 1 acicle. Interocular lobe with slightly convex anterior surface.

Antennular peduncle ( Fig. 21A ), when fully extended, overreaching distal corneal margin by 0.7 length of ultimate segment. Basal segment with spinule proximolaterally. Ultimate segment 0.6 length of shield, slightly broadened distally in lateral view, with 2 long plumose setae at dorsolateral distal portion. Dorsal flagellum with distal portion distinctly longer than proximal aesthetasc-bearing portion.

Antennal peduncle ( Fig. 21A ) reaching 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 bifid spine reaching midlength of fourth segment; dorsomesial distal angle with small spine. First segment unarmed. Antennal acicle slender, slightly sinuous, slightly falling short of distal corneal margin, terminating in slender spine, with prominent tuft of long setae distally and few shorter setae in distal half. Antennal flagellum about 3.0 of shield length; articles each with some short to long setae on distal margin.

Third maxilliped moderately stout; crista dentata on ischium consisting of 2 small teeth. Carpus without dorsodistal spine.

Chelipeds ( Fig. 22 ) distinctly unequal and dissimilar. Right cheliped ( Fig. 22A–C ) moderately large, not particularly elongate; propodal-carpal articulation rotated clockwise about 30° from perpendicular. Chela subovate in dorsal view, about 2.1 times longer than wide, widest at base of dactylus. Dactylus articulating obliquely with palm, about 0.9 length of palm, slightly curved ventrally; dorsal surface convex, dorsomesial margin not delimited; mesial surface

armed with 1 small spine proximally; cutting edge with

3 roundly triangular calcareous teeth, terminating in tiny corneous claw; tufts of short setae on surfaces arranged in irregular longitudinal rows. Palm about 0.8 length of carpus; dorsal surface convex, entirely unarmed, with scattered moderately long setae; lateral, mesial and ventral surfaces with few short to long setae, ventral surface slightly convex. Fixed finger with 3 large calcareous teeth on cutting edge, terminating in minute corneous claw. Carpus 1.1 length of merus, noticeably widened distally, about 1.3 times longer than distal width; dorsal surface with 2 small spines on dorsolateral margin and 1 moderately small spine on dorsomesial margin proximal to midlength; dorsodistal margin with 1 small spine at lateral angle and 1 moderately strong spine at mesial angle; lateral and mesial surfaces almost glabrous, ventrolateral distal angle with 1 small spine; ventral surface slightly convex. Merus with few short setae on dorsal surface; dorsodistal margin with 1 small spine mesially; lateral surface glabrous, ventrolateral margin with 2 moderately strong subdistal spines; mesial surface also glabrous, ventromesial margin strongly elevated, with 2 moderately small spines (proximal spine far separated from and smaller than distal spine); ventral surface concave, with few moderately long setae. Ischium unarmed, with few short setae on dorsal and ventral margins.

Left cheliped ( Fig. 22D–G ) moderately slender, reaching beyond base of dactylus of right cheliped; propodal-carpal articulation without rotation. Chela not arched, 3.2 times longer than wide; no hiatus between fingers. Dactylus about 1.3 length of palm, unarmed, with tufts of short to long setae arranged in irregular longitudinal rows; dorsomesial margin not delimited; cutting edge with row minute corneous teeth, terminating in minute corneous claw. Palm about 0.6 length of carpus; dorsal surface slightly convex, unarmed; surfaces with short to long setae. Fixed finger with sparse corneous teeth on cutting edge, terminating in minute corneous claw. Carpus slightly widened distally, 2.3 times longer than distal width; dorsal surface laterally with 1 small spine slightly proximal to midlength, mesially with 1 similar spine at proximal 0.3, and with short and long setae laterally and mesially; dorsodistal margin armed with 1 small spine at each lateral and medial angle; lateral and mesial faces with few long setae, ventrolateral distal angle with 1 small spine; ventral surface slightly convex, with some long setae. Merus almost glabrous, with 1 subdistal spine on dorsal surface; dorsodistal margin unarmed; ventrolateral margin with 2 strong spines subdistally; ventromesial margin also with 2 strong spines (proximal spine far separated from distal spine); ventral surface slightly convex, with several long setae. Ischium spineless, with few short setae on mesial surface.

Only left third pereopod preserved. Left third pereopod ( Fig. 21B ) long and slender. Dactylus unusually short and unarmed (also no marginal setae, no corneous claw), perhaps in process of regeneration. Propodus with sparse long setae on dorsal and ventral margins; ventrodistal margin with pair of small, slender corneous spines. Carpus without dorsodistal spine; dorsal margin with sparse setae. Merus armed with 1 tiny spine at proximal 0.3 of dorsal margin; ventrolateral margin with 2 widely spaced spines on distal 0.3; few long setae on dorsal and ventral margins. Ischium also with few setae on ventral margin. Female with unpaired left gonopore.

Fourth pereopod ( Fig. 21C ) semichelate; dactylus with several minute corneous teeth on ventral margin; propodal rasp consisting of 6 corneous scales arranged in single row. Fifth pereopods semichelate.

Anterior lobe of sixth thoracic sternite ( Fig. 21D ) subsemicircular, slightly skewed to left, with long setae on anterior margin.

Telson missing.

Eggs about 0.3 x 0.4 mm.

Male unknown.

Colouration. –– Not known.

Distribution. –– Known only from the type locality, 83– 102 m.

Remarks. –– The holotype is an ovigerous female and incomplete with both the right and left second pereopods and the posterior part of the abdomen missing. Nevertheless, the present new species is assignable to Catapaguroides by the lack of pleurobranch, the poorly developed crista dentata of the third maxilliped, and the semichelate fourth pereopod. Catapaguroides pusillus , new species, is readily distinguished from other congeneric species by the following unique features: ocular acicles elongate; merus of left cheliped with dorsal subdistal spine; and merus of second pereopod with proximal spine on dorsal margin and subdistal spine on ventral margin.

Etymology. –– From the Latin “ pusillus ” [= small], referring to the small size of this new species.

Figures

Fig. 21. Catapaguroides pusillus, new species, holotype, female (sl 0.9 mm), PANGLAO 2004, stn T1, NMCR 39066. A, shield and cephalic appendages, dorsal view; B, left second pereopod, lateral view (dactylus possibly in process of regeneration); C, left fourth pereopod, lateral view; D, sixth thoracic sternite, ventral view. Scale bars: 0.5 mm (A); 0.25 mm (B–D).

Fig. 22. Catapaguroides pusillus, new species, holotype, female (sl 0.9 mm), PANGLAO 2004, stn T1, NMCR 39066. A, right cheliped, mesial view; B, same, lateral view (setae omitted); C, same, chela and carpus, dorsal view; D, left cheliped, mesial view; E, same, lateral view (setae omitted); F, same, chela, dorsal view; G, same, carpus, dorsal view. Scale bar = 0.5 mm.