Pteropagurus spina, Mclaughlin, Patsy A. & Rahayu, Dwi Listyo, 2006

Mclaughlin, Patsy A. & Rahayu, Dwi Listyo, 2006, A new genus with two new species of hermit crabs (Crustacea, Decapoda, Paguroidea, Paguridae) from an unique habitat, Zootaxa 1116, pp. 55-68 : 64-65

Pteropagurus spina n. sp. ( Fig. 5 )

Type material. New Caledonia. Holotype, ovigerous female (sl = 1.2 mm), MUSORSTOM 5, stn 274, 24°44.8'S, 159°41.0'E, 285 m, 0 9.10.1986 ( MNHN Pg 7637).

Description. Shield ( Fig. 5 a) slightly broader than long, weakly calcified; anterior margin between rostrum and lateral projections somewhat concave; anterolateral margins terraced; posterior margin roundly truncate. Triangular rostrum produced nearly to midlength of ocular acicles; lateral projections each with acute marginal spine. Carapace lateral projections reaching 0.5 of shield. Posterior carapace with moderately narrow median plate; cardiac sulci reaching to posterior margin. Branchiostegites membranous, unarmed.

Ocular peduncles moderately stout, approximately 0.7 length of shield; corneal diameter approximately 0.4 of total peduncular length (including cornea). Ocular acicles narrowly triangular, reaching to or beyond proximal margin of ultimate peduncular segment, each with small submarginal spine; separated basally by more than basal length of rostrum.

Antennular peduncles when fully extended overreaching distal margins of corneas by nearly full length of ultimate peduncular segment; ultimate segment with 1 long, stiff seta on distal margin; penultimate segment with few scattered setae; basal segment with acute spine on dorsolateral margin, ventral margin not produced distally.

Antennal peduncles overreaching distal corneal margins by approximately 0.3 length of ultimate segment. Fifth and fourth segments with very few scattered setae; third segment with small spine at ventrodistal angle; second segment with dorsolateral distal angle produced, terminating in small spine, dorsomesial angle with prominent spine; first segment with hook­like spine at dorsolateral distal margin on left only, ventrolateral margin unarmed. Antennal acicle reaching slightly beyond distal margin of fourth peduncular segment, slender, terminating in simple spine. Antennal flagellum with 1 or 2 very short to moderately long setae every article.

Chelipeds subequal in length, but right slightly stouter; dactyl and fixed finger of right without small hiatus proximally. Dactyl of right cheliped ( Fig. 5 b) approximately 0.8 length of palm; dorsomesial margin minutely serrate, dorsal surface somewhat convex, unarmed, but with few scattered, short setae mesially and ventrally; cutting edge with 2 low, broad, calcareous teeth, terminating in tiny corneous claw, slightly overlapped by fixed finger. Palm slightly longer than carpus, dorsomesial margin delimited by 3 acute spines and sparse tufts of setae in distal half, dorsal surface weakly convex, unarmed; dorsal surface of fixed finger similarly unarmed, but dorsolateral margin microscopically serrate and with few scattered short setae; cutting edge with two broad, low calcareous teeth, terminating in tiny corneous claw. Carpus approximately equal to length of merus; dorsomesial distal angle with acute spine and 1 additional small spine on dorsomesial margin distally, dorsal surface with 2 small spines in midline in distal 0.3, dorsomesial and dorsolateral margins not distinctly delimited; remaining surfaces unarmed. Merus laterally compressed; all surfaces unarmed; ventromesial and ventrolateral margins each with small spinule at ventrodistal angle. Ischium unarmed.

Left cheliped ( Fig. 5 c) slightly longer than right, much slenderer; Dactyl longer than palm; without hiatus between fixed finger and dactyl; surfaces rounded and unarmed, but with sparsely scattered, moderately long setae ventrally; cutting edge with row of minute corneous teeth, terminating in tiny corneous claw; palm with convex dorsal surface unarmed but with few scattered setae; dorsomesial margin with 3 small spines, dorsolateral margins not delimited; fixed finger rounded and unarmed but with several moderately long setae laterally; cutting edge with row of minute corneous teeth, terminating in tiny corneous claw. Carpus longer than palm but slightly shorter than merus; dorsomesial margin delimited by acute spine at distal angle and small spine at midlength, dorsolateral margin not delimited; remaining surfaces unarmed but few scattered setae and small spine at ventromesial distal angle. Merus with surfaces unarmed but with few scattered short setae, ventromesial and ventrolateral distal angles each with small spine and 1 additional small spine on ventrodistal margin. Ischium unarmed.

Second and third pereopods ( Figs 5 d, e) similar in armature but unequal in length, second appreciably shorter. Dactyls approximately straight in dorsal and lateral views, approximately (second) to slightly longer than propodi (third); dorsal surfaces each with few scattered setae; dorsal surfaces each with row of stiff bristles; ventral surfaces each with 4–7 corneous spines and few scattered setae. Propodi 1.1–1.2 length of carpi; surfaces all unarmed but with sparse setae dorsally and ventrally. Carpi with dorsal margins with or without 1 or 2 minute spinules, other surfaces unarmed but all with spare setae. Meri unarmed, but each with few widely­spaced setae dorsally. Ischia unarmed. Fourth pereopods ( Fig. 5 f) semichelate; propodal rasp with 2 rows of scales.

Males unknown. Female with paired gonopores; without paired first pleopods; unpaired left pleopods 2–5; non­eyed eggs approximately 0.8 mm diameter, numbering 10.

Uropods with 2 rows of scales. Telson ( Fig. 5 g) with terminal margins obliquely rounded, separated by moderately deep median cleft, terminal margins each with row of tiny spinules.

Etymology. From the Latin spina , a noun in apposition, and referring to the spines on the chelipeds of this species that are in marked contrast to the unarmed chelipeds of the type species.

Color. Not known.

Habitat. Pteropod shells.

Distribution. Presently known only from the type locality.

Figures

FIGURE 5. Pteropagurus spina n. sp. holotype ovig. female (sl = 1.2 mm) (MNHN Pg 7637). a, shield and cephalic appendages (aesthetascs omitted); b, carpus and chela of right cheliped (dorsal view); c, carpus and chela of left cheliped (dorsolateral view); d, left second pereopod (lateral view); e, left third pereopod (lateral view); f, fourth pereopod (lateral view); g, sternites of second and third pereopods (thoracic sternites XI & XII) (ventral view); h, telson. Scales equal 0.5 mm.