Oncopagurus brevis, Lemaitre, 2014

Lemaitre, Rafael, 2014, A worldwide taxonomic and distributional synthesis of the genus Oncopagurus Lemaitre, 1996 (Crustacea: Decapoda: Anomura: Parapaguridae), with descriptions of nine new species, Raffles Bulletin of Zoology 62, pp. 210-301 : 224-229

Oncopagurus brevis , new species

Figs. 6–9 , 51

Type material. Holotype, Hawaiian Islands , R / V Townsend Cromwell, sta TC 33–38, 20°41.3'N, 156°41.3'W, 289–296 m, 9 November 1967: M 3.2 mm ( BPBM S10992 ).

Paratypes, Central Pacific , Hawaiian Islands: R/V Townsend Cromwell: sta 33–18, 21°03.7'N, 156°43.7'W, 245 m, 1 November 1967: 2 M 2.9, 3.2 mm, ( BPBM S10957 ) ; sta TC 33–38, 20°41.3'N, 156°41.3'W, 289–296 m, 9 November 1967 (4 lots): 3 M 2.4–3.0 mm, 2 ov F 2.4, 2.8 mm ( BPBM S10992 ) , 2 M 3.2, 3.7 mm ( USNM 1224577 , ex BPBM S10992 ), 1 F 2.7 mm ( BPBM S10954 ) , 1 M 3.2 mm, 1 F 2.4 mm ( USNM 1224574 , ex BPBM S10961 ) ; sta TC 40–76, 21°06.8'N, 156°31.9'W, 439 m, 22 November 1968: 1 ov F 2.5 mm ( BPBM S10947 ) ; sta TC 40–91, 21°03.8'N, 156°32.8'W, 274 m, 25 November 1968: 1 M 2.7 mm ( BPBM S10946 ) . West Lanai , sta Mac 3, 20°48'N, 157°01'W, 256–274 m, 11 October 1967: 1 M 1.9 mm ( USNM 1224573 ex BPBM). — BURCH: Mamala Bay, Oahu, sta 77050, 21°16.8'N, 157°53.5'W, 174 m, 28 May 1977: 1 F 1.4 mm ( BPBM S10980 ) ; sta 79036, 21°16.6'N, 157°54.2'W, 265 m, 28 May 1979: 1 M 1.8 mm, 1 ov F 1.6 mm ( BPBM S10988 ) ; sta 79077, 21°16.3'N, 157°51.7'W, 238–256 m, 1 December 1979 (2 lots): 6 M 1.0– 1.8 mm, 3 ov F 1.3–1.9 mm ( USNM 1224578 , ex BPBM S10978 ), 2 ov F 1.6, 1.7 mm ( USNM 1224576 , ex BPBM S10967 ) ; sta 80051, 21°16.9'N, 157°55.0'W, 183 m, 30 August 1980 (2 lots): 2 M 2.3, 2.4 mm ( USNM 1224575 , ex BPBM S10990 ), 1 M 2.3 mm, 1 F 1.3 mm ( BPBM S10975 ) ; sta 82034, 21°17.0'N, 158°01.3'W, 183– 146 m, 11 June 1982 (3 lots): 1 ov F 1.4 mm ( BPBM S10966 ) , 2 ov F 1.3, 1.4 mm ( BPBM S10976 ) . — South west Oahu : Makua, [no lat. or long.], 12–107 m, [no date]: 1 M 1.4 mm ( BPBM S5560 )

Description. Gills biserial. Shield ( Fig. 6A ) about as long as broad; dorsal surface weakly calcified medially (weak calcification often reaching to anterior margin), with scattered short setae; rostrum broadly rounded, weakly produced, with short mid-dorsal ridge; anterior margins weakly concave; lateral projections bluntly subtriangular, sometimes with minute terminal spine; anterolateral margins sloping; posterior margin broadly rounded; ventrolateral margins of shield usually with slender spine on one or both sides. Anterodistal margin of branchiostegite rounded, unarmed, setose.

Ocular peduncles ( Fig. 6A ) more than half length of shield, each with longitudinal row of short setae dorsally; lateral and ventral faces usually weakly calcified. Cornea weakly dilated. Ocular acicles subtriangular, each terminating in strong spine; separated basally by about basal width of 1 acicle.

Antennular peduncle ( Fig. 6A ) exceeding distal margin of cornea by about full length of ultimate segment. Ultimate segment about twice as long as penultimate segment, with scattered setae dorsally. Basal segment with strong ventromesial spine; lateral face with distal subrectangular lobe armed with small spine distally, and strong spine proximally. Ventral flagellum with 6 articles.

Antennal peduncle ( Fig. 6A, B ) at most slightly exceeding distal margin of cornea. Fifth segment unarmed except for scattered setae and laterodistal tuft of setae. Fourth segment armed with strong dorsodistal spine. Third segment with strong ventromesial distal spine. Second segment with dorsolateral distal angle produced, terminating in strong simple spine; mesial margin with spine on dorsodistal angle. First segment with small blunt or sharp spine on one or both sides; ventromesial angle produced, with 2 or 3 small spines laterally. Acicle short, reaching only to about proximal margin of cornea, nearly straight (in dorsal view), terminating in strong, often bifid spine; mesial margin armed with 5–8 spines, sparsely setose. Flagellum slightly reaching or slightly exceeding extended right cheliped, articles with few setae less than 1 to 2 flagellar articles in length.

Mandible ( Fig. 7A ) with 3-segmented palp; cutting edge calcified, with small tooth medially; molar process with small tooth medially. Maxillule ( Fig. 7B ) with external lobe of endopod slender, moderately developed, not recurved, internal lobe with long, terminal seta. Maxilla ( Fig. 7C ) with endopod slightly exceeding distal margin of scaphognathite. First maxilliped ( Fig. 7D ) with endopod slightly exceeding exopod in distal extension. Second maxilliped ( Fig. 7E ) without distinguishing characters. Third maxilliped ( Fig.7F ) with merus to dactyl each distinctly longer than broad, ischium about twice as long as broad; crista dentata with about 8 blunt or sharp teeth diminishing in strength distally, proximal 2 or 3 teeth distinctly larger than others; basis with 1 small mesial spine; coxa with spine. Sternite of third maxillipeds with small spine on each side of midline.

Chelipeds markedly dissimilar. Right cheliped ( Fig. 8A–E ) massive, chela operculate; carpus and chela with sparse setae on dorsal surfaces, setae more numerous on dorsodistal surfaces of fingers and mesial face of carpus. Fingers curved ventromesially, each terminating in small, usually blunt corneous claw; cutting edges with 2 or 3 large calcareous, mostly serrated teeth and, short row of closely set minute corneous teeth distally on dactyl. Dactyl about as long or slightly longer than mesial margin of palm, set at strongly oblique angle to longitudinal axis of palm; mesial margin broadly curved proximally, strongly curved disatlly, delimited by row of small spines diminishing in size distally; dorsal face with scattered setae and small spines or tubercles proxiamlly; ventromesial face concave, elevated longitudinally on midline. Fixed finger broad at base, dorsal face smooth except for setae, lateral margin delimited by row of spines; ventral face moderately concave mesially, elevated longitudinally on midline. Palm about as broad as long; dorsal surface with scattered small spines or turbercles; dorsolateral margin nearly straight or broadly rounded, well delimited by irregular row of calcareous spines, dorsomesial margin delimited by row of small spines or tubercles; dorsomesial face nearly flat, sloping mesially, covered with small, well-spaced tubercles; ventral surface smooth except for scattered short setae. Carpus longer than broad, dorsal surface covered with numerous small spines or turbercles; dorsodistal margin with row of small spines; dorsolateral margin well defined by row of small spines on distal 0.3, rounded proximally; mesial face sloping, weakly expanded distomesially and with row of ventromesial spines distally; ventral face nearly flat to concave, at most with scatttered small tubercles. Merus with irregular row of thick, bristle-like setae on dorsal margin ( Fig. 8E ), and 1 or less frequently 2, strong blunt or sharp dorsodistal spines; dorsolateral surface with scattered small tubercles and setae; mesial face with long setae; ventromesial margin with row of blunt to sharp spines; ventrolateral margin with row of small tubercles. Ischium with ventromesial row of small, blunt spines. Coxa with row of small spines on ventrodistal margin, and ventromesial row of setae.

Left cheliped ( Fig. 8F ) usually weakly calcified on nearly entire dorsolateral face of carpus, and often also dorsodistal part of merus. Fingers each terminating in small corneous claw; dorsal and ventral surfaces with scattered tufts of setae; cutting edge of dactyl with row of minute, fused corneous teeth; cutting edge of fixed finger with row of well-spaced small calcareous teeth. Dactyl about as long as length of mesial margin of palm; with small proximal spine or tubercle on dorsal face. Fixed finger lacking spines on dorsal face. Palm with scattered setae on dorsal surface; with dorsomesial row of small spines or tubercles; ventral face smooth except for scattered setae. Carpus with irregular row of small spines distally on dorsal margin in addition to small dorsodistal and dorsolateral spine on distal margin; dorsal margin with long setae; ventral face smooth except for scattered setae. Merus with setae on dorsal margin; with ventrolateral row of small spines; ventral face smooth. Ischium and coxa unarmed, but with ventromesial row of setae.

Ambulatory legs ( Fig. 9A–D ) similar right from left except for longer segments, extending to about tip of dactyls of right cheliped or slightly exceeding them. Dactyls broadly curved, about 1.5 times as long as propodi, terminating in sharp corneous claws; each with dorsal and dorsomesial distal rows of long setae, and 4–10 small spinules on ventromesial margin. Propodi each with short setae on dorsal margin; ventral margin naked or with few setae. Carpi each with setae on dorsal margin, and small dorsodistal spine. Meri each with setae on dorsal margin, unarmed ventrally or at most with scattered setae. Ischia with setae on dorsal and ventroproximal margin. Coxae with ventromesial row of setae. Anterior lobe of sternite XII (between second ambulatory legs, Fig. 6C ), setose, with subdistal spine.

Fourth pereopod ( Fig. 9E ) semichelate. Dactyl terminating in sharp corneous claw; with ventrolateral row of small corneous spinules. Propodus longer than broad, rasp with 1 row of rounded scales at least distally. Carpus with long setae on dorsal margin. Merus with rows of long setae on dorsal and ventral margins. Coxa with anteroventral row of setae. Anterior lobe of sternite XIII with row of setae.

Fifth pereopod ( Fig. 9F ) semichelate. Propodal rasp reaching mid-length of segment. Coxa with row of long setae on anteroventral and ventrodistal margins. Anterior lobe of sternite XIII with row of setae.

Uropods and telson ( Fig. 6D, E ) markedly asymmetrical; left exopod about 2.4 times as long as broad, rasp consisting of 2–4 rows of small scales. Telson lacking transverse suture; dorsal surface with scattered setae; lateral margins with long setae medially; posterior lobes separated by shallow, unarmed U-shaped cleft; terminal margin of left lobe armed with about 10 corneous, often curved spines, right lobes armed with about 4 or 5 small, corneous spines.

Male lacking first gonopods; with poorly developed, asymmetrical second gonopods ( Fig. 6F, G ), left consisting of 2 flat, elongated segments with a few setae, right obsolete, consisting of minute stub. Females lacking second right pleopod.

Colouration. Unknown.

Habitat. Gastropod or scaphopod shells.

Distribution. So far known only from the Hawaiian Islands, in the Central North Pacific. Depth: 146– 439 m.

Remarks. This new species is, so far, known only and perhaps endemic to the Hawaiian Islands. The new species is distinguished by having: short antennal acicles; thick bristle-like, and often corneous or yellow-coloured setae on the dorsal margin of the merus of the right cheliped; and the males lacking first gonopods and with poorly developed, asymmetrical second gonopods.

Etymology. The specific epithet is from the Latin, brevis , meaning short, and makes reference to the short acicles of this new species.

Figures

Fig. 6. Oncopagurus brevis, new species, A–F, holotype, male 3.2 mm, Hawaiian Islands (BPBM S10992); G, paratype, male 3.0 mm, same station as holotype (BPBM S10992). A, shield and cephalic appendages, dorsal; B, right antennal peduncle, lateral; C, anterior and posterior lobes of thoracic sternite XII (between second ambulatory legs), ventral; D, exopod of left uropod, dorsal; E, telson, dorsal; F, left second gonopod, anteromesial; G, right second gonopod, lateral. Scale bars = 1 mm (A); 0.5 mm (B–G).

Fig. 7. Oncopagurus brevis, new species, paratype, male 3.0 mm, Hawaiian Islands (BPBM S10992). Left mouthparts, internal: A, distal half of mandible; B, maxillule; C, maxilla; D, first maxilliped; E, second maxilliped; F, third maxilliped. Scale bars = 0.25 mm (A–D); 0.5 mm (E, F).

Fig. 8. Oncopagurus brevis, new species, holotype, male 3.2 mm, Hawaiian Islands (BPBM S10992). A, right cheliped, dorsal; B–D, chela of same, ventral (B), lateral (C), mesial (D); E, merus of right cheliped, mesial; F, left cheliped, dorsal. Scale bar = 1mm.

Fig. 9. Oncopagurus brevis, new species, holotype, male 3.2 mm, Hawaiian Islands (BPBM S10992). A, right first ambulatory leg, lateral; B, dactyl of same, mesial; C, right second ambulatory leg, lateral; D, dactyl of same, mesial; E, propodus and dactyl of left fourth pereopod, lateral; F, propodus and dactyl of left fifth pereopod, lateral. Scale bar = 1 mm (A–D); 0.25 mm (E, F).

Fig. 51. Bathymetric distribution of Oncopagurus species from the world, with maximum and minimum depths (meters) indicated for each.