Pagurina bifida, Lemaitre & Felder & Poupin, 2017

Lemaitre, Rafael, Felder, Darryl L. & Poupin, Joseph, 2017, Discovery of a new micro-pagurid fauna (Crustacea: Decapoda: Paguridae) in the Lesser Antilles, Caribbean Sea, Zoosystema 39 (2), pp. 151-195 : 170-175

Pagurina bifida n. sp.

( Figs 13-15 ; Table 1)

TYPE MATERIAL. — Holotype. ♂ 0.8 mm, Guadeloupe, sta GB 34, Petite-Terre , 16°10.45’N, 61°8.16’W, 10 m, 27.V.2012, MNHN- IU-2013-5643.

ETYMOLOGY. — The specific name is derived from the Latin, using the prefix bi-, meaning two or double, and the suffix - fid, divided, in reference to bifid condition of the ocular acicles of the holotype of this new species.

DISTRIBUTION. — Known so far only from Guadeloupe, Lesser Antilles, Caribbean. Depth: 10 m.

HABITAT. — Gastropod shells.

DESCRIPTION OF HOLOTYPE

Shield ( Fig. 13A )

Glabrous, about as long as broad; anterior margin between rostrum and lateral projections weakly concave; anterolateral margins sloping; posterior margin roundly truncate. Rostrum broadly and bluntly subtriangular, reaching distally to about same level of lateral projections. Lateral projections subtriangular, terminating in small sharp spine.

Ocular peduncles

Relatively short and stout, about 0.7 length of shield; dorsal surfaces naked; corneas weakly dilated. Ocular acicles subtriangular, terminating in bifid spine.

Antennular peduncles exceeding distal margins of cornea when fully extended by about 0.2 length of ultimate segment. Ultimate segment naked except for three or four long dorsodistal setae. Penultimate and basal segments naked; basal segment with blunt ventromesial angle, and small spine on lateral face.

Antennal peduncles Reaching to about distal margins of corneas when fully extended. Fifth and fourth segments unarmed except for scattered short setae. Third segment with blunt ventrodistal angle. Second segment with dorsolateral distal angle produced into spine- like process; dorsomesial distal angle with small spine. First segment unarmed. Antennal acicle relatively short, reaching to about proximal margin of cornea, broadly curving outward, terminating in strong spine with setae, mesial margin with few short setae. Flagella missing in holotype.

Mouthparts ( Fig. 13B )

Mouthparts not dissected. Third maxilliped ischium with weakly dentate (serrate) crista dentata, lacking accessory tooth.

Right cheliped ( Fig. 14 A-C)

Chelipeds slightly unequal, right somewhat stronger than left, sparsely setose. Right cheliped moderately elongated. Chela about 2.3 times as long as broad, dactyl and fixed finger each terminating in small corneous claw slightly overlapping when closed. Dactyl about 0.7 times as long as palm, unarmed except for two small tubercles on dorsal surface and sparse setae on mesial margin; cutting edge with two large calcareous teeth proximally, and uneven row of small fused and sharp calcareous teeth distally. Fixed finger with scattered setae and row of small, slender spines proximally on dorsolateral margin; cutting edge similar to that of dactyl. Palm approximately as long as carpus, dorsally convex; dorsal surface with median row of low tubercles or small spines; dorsolateral margin with distal row of small, slender, sharp spines obscured by setae; ventral surface convex, glabrous. Carpus with dorsal surface convex, with scattered setae; dorsodistal margin with two small blunt spines; lateral face rounded; dorsomesial margin with row of two sharp spines distally; mesial face flat, nearly vertical; ventral surface convex, glabrous. Merus subtriangular, dorsal margin with few short setae; ventrolateral and ventromesial margins with one or two small, slender spines respectively. Ischium unarmed. Coxa with row of setae on ventromesial distal angle.

Left cheliped ( Fig. 14 D-F)

Moderately elongated; dactyl and fixed finger unarmed dorsally except for scattered setae, terminating in sharp corneous claws slightly overlapping when closed, cutting edges consisting of fused row of small calcareous teeth interspersed with fused corneous teeth. Dactyl about as long as palm; dorsal and ventral surfaces rounded. Palm dorsal surface with median row of small tubercles; dorsolateral and dorsomesial margins with row of slender, sharp spines obscured by setae; ventral surface glabrous. Carpus about 1.3 times as long as merus; dorsodistal margin with two small spines, dorsal margin with row of few small spines or tubercles; dorsolateral surface with two sharp spines distally; ventral surface glabrous. Merus unarmed dorsally, nearly naked; ventrolateral and ventromesial margins each with distal row of three or four sharp spines or small tubercles, respectively. Ischium unarmed. Coxa with row of setae on ventromesial distal angle.

Ambulatory legs ( Fig. 15 A-E)

With sparse long setae on dorsal margins of segments. Dactyl about 1.4 times as long as propodus, broadly curved, terminating in slender needle-like claw, ventromesial margin with row of three short corneous spinules. Propodus straight, about 1.5 times as long as carpus, lacking spines. Carpus with two small dorsodistal spines. Merus and ischium lacking spines. Anterior lobe of thoracic sternite XI (between pereopods 3; Fig. 13C ) subrectangular, with fringe of short setae on distal margin.

Fourth pereopods ( Fig. 15F )

Semichelate. Dactyl triangular, terminating in strong, sharp corneous claw, lacking preungual process; propodus longer than high, rasp with single row of six rounded corneous scales. Carpus unarmed except for few long setae dorsally. Merus unarmed except for dorsal setae.

Fifth pereopods

Chelate. Propodal rasp dorsally extending for about half surface of propodus.

Uropods and telson ( Fig. 13D )

Uropods markedly asymmetrical, left largest. Telson nearly symmetrical, longer than broad, with distinct lateral indentations. Anterior and posterior lobes subequal in length. Posterior lobes separated by narrow, median U-shaped cleft; terminal margins weakly oblique, each armed with row of small spines that includes a distinctly larger and ventrally curved spine on lateral angle, followed on lateral side by smaller spine.

Sexual tubes ( Fig. 13C ) and pleopods

Males with paired gonopores; with very short, papilla-like sexual tube protruding from coxa of left gonopore, right coxa lacking sexual tube; with unpaired left pleopods 3-5. Females unknown.

Genetic data

See Table 1.

Colour

Unknown.

REMARKS

In addition to the generic characters, Pagurina bifida n. gen., n. sp. stands out by the relatively stout ocular peduncles, the relatively strong left cheliped, scant armature on the ventromesial margins of the dactyls of the pereopods 2 and 3 dactyls, and the poorly developed row of scales on the propodal rasp of the pereopod 4. The bifid condition of the ocular acicles is a characteristic of this new species, even though a similar condition occurs in various other species and genera across the Paguridae , including another micro-pagurid described herein as Pagurellus jenniferae n. gen., n. sp.

Figures

FIG. 13. — Pagurina bifida n. gen., n. sp., holotype ♂ 0.8 mm, Guadeloupe, sta GB 34, MNHN-IU-2013-5643: A, shield and cephalic appendages, dorsal view; B, basis-ischium of left and right third maxillipeds, outer view; C, sternites IX-XIII, coxae of chelipeds and pereopods 2-5, and left sexual tube, ventral view; D, telson, dorsal view. Scale bars: A, C, D, 0.5 mm; B, 0.2 mm.

FIG. 14. — Pagurina bifida n. gen., n. sp., holotype ♂ 0.8 mm, Guadeloupe, sta GB 34, MNHN-IU-2013-5643: A-C, right cheliped,dorsal view (A), lateral view (B), mesial view (C); D-F, left cheliped, dorsal view (D); lateral view (E); mesial view (F). Scale bar: 0.5 mm.

FIG. 15. — Pagurina bifida n. gen., n. sp., holotype ♂ 0.8 mm, Guadeloupe, sta GB 34, MNHN-IU-2013-5643: A, left pereopod 2, lateral view; B, dactyl of same, mesial view; C, left pereopod 3, lateral view; D, dactyl of same, mesial view; E, carpus of same, mesial view; F, propodus and dactyl of right pereopod 4, lateral view. Scale bar: 0.5 mm.