Lithopagurus tribulomanus, Mclaughlin & Lemaitre, 2004

Mclaughlin, Patsy A. & Lemaitre, Rafael, 2004, The discovery of two new species of Lithopagurus Provenzano, 1968 (Crustacea, Decapoda, Anomura, Paguroidea, Paguridae) and the first records of the genus in the western Pacific, Zoosystema 26 (3), pp. 483-494 : 490-493

Lithopagurus tribulomanus n. sp.

( Fig. 3 )

TYPE MATERIAL. — Indonesia. Kai Islands, KARUBAR, stn DW 18, 05°18’S, 133°10’E, 205-212 m, 24.X.1991, holotype 2.0 mm (MNHN-Pg 7080).

ETYMOLOGY. — The specific epithet is from the Latin tribulosus meaning thorny, and manus meaning hand, forming a compound name used as an adjective and reflecting the spiny or thorny armature of the right chela of this species.

TYPE LOCALITY. — Kai Islands, Indonesia, 05°18’S, 133°10’E, 205- 212 m.

DISTRIBUTION. — Known only from the type locality.

DESCRIPTION

Shield ( Fig. 3A ) somewhat vaulted; considerably longer than broad; anterior margin between rostrum and lateral projections weakly concave; unarmed anterolateral margins sloping; posterior margin truncate; dorsal surface well calcified, glabrous. Rostrum triangular, produced to nearly midlength of ocular acicles and well beyond level of lateral projections, terminating in prominent spine. Lateral projections weakly developed, subacute, each with tiny marginal spinule.

Ocular peduncles long, 0.8 shield length, slightly swollen basally; corneal diameter approximately 0.2 of peduncular length. Ocular acicles acutely triangular, reaching beyond proximomesial margins of ocular peduncles, each with prominent terminal spine; left with one and right with two accessory spinules on lateral margin; separated basally by more than basal width of one acicle.

Antennular peduncles when fully extended overreaching ocular peduncles by approximately 0.3 length of ultimate segments. All segments unarmed, glabrous.

Antennal peduncles reaching beyond proximal halves of ocular peduncles, but not reaching to basal margins of corneas. Fifth and fourth segments each with few scattered setae. Third segment with sparse tuft of setae and tiny spinule at ventrodistal margin. Second segment with dorsolateral distal angle produced, terminating in bifid spine, lateral margin with subdistal spinule, dorsomesial distal angle with well developed spine. First segment unarmed. Antennal acicles approximately reaching proximal 0.3 ocular peduncles; terminating in bifid spine, and with lateral and mesial subdistal spinules, smallest on left. Antennal flagella short, only slightly longer than carapace; each article with irregularly set, short to moderately long (2-4 article-length) setae.

Right cheliped ( Fig. 3B ) very much larger than left, operculate. Dactyl broad, slightly shorter than palm; articulation with chela somewhat oblique; cutting edge with row of moderately small, calcareous teeth, terminating in calcareous claw; dorsal surface flat, with scattered short setae and numerous small, acute or rounded tubercles, dorsomesial margin with abundance of long setae not concealing irregular double row of small spines in proximal half becoming rounded tubercles and decreasing in size distally; rounded ventromesial surface with low tubercles or granules becoming obsolete toward cutting edge. Palm approximately twice length of carpus; circumscribed marginally by double row of small, slender spines accompanied by long, simple setae, flat dorsal surface with covering of short to moderately long, simple setae and rounded, sometimes spinulose tubercles and small spines; rounded mesial and lateral surfaces tuberculate, with closely-spaced tubercles becoming obsolete on ventral surface; cutting edge of fixed finger with row of fused calcareous teeth, terminating in large, upturned, calcareous claw. Carpus approximately equal to length of merus, broadly subtriangular in dorsal view; dorsodistal margin unarmed but with row of moderately short setae, dorsomesial margin with row of prominent, acute spines and few long setae, dorsal surface with scattered short setae, dorsolateral margin not delimited; lateral surface with short row of three small spines dorsodistally (not readily visible in dorsal view), remainder of surface unarmed; mesial and ventral surfaces unarmed. Merus roundly subtriangular; dorsodistal margin with small spine, dorsal surface with widely-spaced, very sparse tufts of setae; ventromesial margin with one prominent, forwarddirected spine distally; ventrolateral margin with row of small, acute spines; ventral surface unarmed. Ischium with one prominent, proximallydirected spine on ventromesial margin. Coxa with row of five small spines on ventrodistal margin. Left cheliped ( Fig. 3C, D ) short, slender. Combined length of dactyl and palm approximately equal to individual lengths of carpus and merus. Dactyl, palm and fixed finger all unarmed, but with irregular rows of sparse tufts of long setae. Carpus with row of spines on dorsomesial margin in proximal half, dorsolateral margin with row of spines in distal 0.6. Merus with pair of small spines at dorsodistal margin, dorsal surface with widely-spaced sparse tufts of setae; two prominent, slender, posteriorly-directed spines on ventromesial margin. Ischium with one prominent, posteriorly-directed spine on ventromesial margin. Coxa unarmed.

Second and third pereopods ( Fig. 3E, F ) generally similar. Dactyls only slightly longer than propodi; dorsal surfaces each with row of sparse tufts of moderately long setae; ventral margins each with row of five or six corneous spines. Propodi each with tufts of long setae dorsally, ventrodistal margins each with one or two corneous spinules and additional one or two similar spinules in distal halves. Carpi each with spine at dorsodistal angle and one small spine in proximal half. Meri with scattered setae on dorsal margins; ventral margins each with row of small spines (second) or unarmed (third). Ischia each with two or three, anteriorly or posteriorly-directed, spines on ventromesial margins (second) or unarmed (third). Coxae each with one posteriorly-directed spine on ventromesial distal margin (second) or unarmed (third). Fourth pereopods with propodal rasp consisting of three or four rows of sharp corneous scales; dactyl with small terminal claw. Anterior lobe of sternite of third pereopods subquadrate, with three small marginal spines.

Pleon short, bulbous. Distal segments of apparently three-segmented male paired second pleopods ( Fig. 3G ) each with terminal tuft of long setae. Tergite of sixth pleomere divided unequally by incomplete, transverse suture; both portions well calcified with moderately dense covering of short setae. Uropods symmetrical. Telson ( Fig. 3H ) longer than broad, subtrapezoidal, unarmed, terminal margin with row of setae.

AFFINITIES

In addition to generic characters, Lithopagurus tribulomanus n. sp. shares with L. yucatanicus the short bulbous pleon, but little else. Lithopagurus tribulomanus n. sp. is set apart from both L. yucatanicus and L. boucheti n. sp. by several characters. These include the longer rostrum and ocular peduncles, more operculate right chela, the dorsal surface of which is circumscribed by a double row of acute spines, very prominent and posteriorlydirected spines on the ventromesial margin of the merus of the left cheliped, and the apparently three-segmented paired second pleopods.

REMARKS

The operculate right cheliped and reduced pleon characteristic of all three species of Lithopagurus suggests more specialized habitats than the typical gastropod shells. The habitats of L. boucheti n. sp. and L. tribulomanus n. sp. are unknown, but Provenzano (1968) reported that one of the paratypes of L. yucatanicus was occupying a fragment of lithistid sponge at the time of capture.

Figures

FIG. 3. — Lithopagurus tribulomanus n. sp., holotype (MNHN-Pg 7080),Indonesia, KARUBAR, stn DW 18, 05°18’S, 133°10’E, 205- 212 m, 24.X.1991; A, shield and cephalic appendages (aesthetascs omitted); B, chela and carpus of right cheliped, dorsal view; C, chela and carpus of left cheliped, dorsal view; D, merus and ischium of left cheliped, lateral view; E, left second pereopod, lateral view; F, left third pereopod, lateral view; G, right second pleopod; H, telson. Scale bar: A-F, 1.0 mm; G, H, 0.5 mm.