Oncopagurus spiniartus, 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 : 283-293

publication ID	https://doi.org/ 10.5281/zenodo.5458372
publication LSID	lsid:zoobank.org:pub:08BE1873-6F6F-4255-9520-9A89F48E4F16
persistent identifier	https://treatment.plazi.org/id/8C6A8943-FFB2-7824-FF1D-FA04FC02FEA6
treatment provided by	Tatiana
scientific name	Oncopagurus spiniartus
status	sp. nov.

Treatment

Oncopagurus spiniartus , new species

Figs. 42–45 View Fig View Fig View Fig View Fig , 51 View Fig

Type material. Holotype, Southern Indian Ocean , Île Amsterdam and Île St. -Paul, CENTOB, MD 50, DC 82, sta 19, 38°428'S, 77°283'E, 165 m, 17 July 1986: M 2.3 mm [dismembered] (MNHN- IU-5494, ex MNHN Pg. 7610).

Paratypes, Southern Indian Ocean , Île Amsterdam and Île St. -Paul: CENTOB, MD 50, DC 114, sta 24, 39°000'S, 77°464'E, 160 m, 19 July 1986: 2 M 2.8, 2.9 mm, 1 F 2.1 mm (MNHN-IU-5495, ex MNHN Pg. 7609) .

Description. Gills biserial. Shield ( Fig. 42A View Fig ) 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 subtriangular, terminating in small blunt or sharp 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. 42A View Fig ) more than half length of shield; with longitudinal row of long 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. 42A View Fig ) exceeding distal margin of cornea by 0.7 to nearly full length or ultimate segment. Ultimate segment slightly less than twice as long as penultimate segment, naked or with scattered setae dorsally. Basal segment with strong ventromesial spine; lateral face with distal subrectangular lobe armed with small spine, and strong spine proximally. Ventral flagellum with 5 or 6 articles.

Antennal peduncle ( Fig. 42A, B View Fig ) not exceeding distal margin of cornea, reaching at most to about midportion 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 often with smaller dorsal subterminal spine; mesial margin with spine on dorsodistal angle. First segment with lateral face usually armed with small spine; ventromesial angle produced, with 2 or 3 small spines laterally. Acicle relatively short, reaching to about proximal margin of cornea, nearly straight (in dorsal view), terminating in strong spine; mesial margin armed with 6–10 spines, sparsely setose. Flagellum slightly exceeding extended right cheliped, articles with setae 1 or 2 flagellar articles in length.

Mandible ( Fig. 43A View Fig ) with 3-segmented palp; cutting edge calcified, with small tooth medially; molar process with small tooth medially. Maxillule ( Fig. 43B View Fig ) with external lobe of endopod slender, moderately developed, not recurved, internal lobe with long, terminal seta. Maxilla ( Fig. 43C View Fig ) with endopod not exceeding distal margin of scaphognathite. First maxilliped ( Fig. 43D View Fig ) with endopod not exceeding exopod in distal extension. Second maxilliped ( Fig. 43E View Fig ) without distinguishing characters. Third maxilliped ( Fig. 43F View Fig ) with merus to dactyl each distinctly longer than broad, ischium about twice as long as broad; crista dentata with about 7 sharp teeth diminishing in strength distally, proximal tooth distinctly larger than others; basis with 1 small mesial spine; coxa lacking spine. Sternite of third maxillipeds unarmed or with small spine on each side of midline.

Chelipeds markedly dissimilar. Right cheliped ( Fig. 44A, B View Fig ) massive, chela operculate; carpus and chela with sparse to moderately dense setae on dorsal surfaces, setae more dense on dorsal surfaces of fingers and mesial face of carpus. Fingers curved ventromesially, each terminating in small, usually blunt corneous claw; cutting edges with 1 or 2 large calcareous teeth and several irregularly sized smaller calcareous teeth, with short row closely set minute corneous teeth distally. Dactyl about 1.3 times as long as mesial margin of palm, set at strongly oblique angle to longitudinal axis of palm; mesial margin broadly curved, well delimited by row of spines diminishing in size distally; dorsal face with moderately dense small spines or tubercles decreasing in density distally; ventromesial face concave. Fixed finger broad at base, dorsal face with scattered small spines or tubercles, lateral margin well delimited by row of spines; ventrolateral face concave. Palm about 1.5–1.7 times as broad as long; dorsal surface with numerous small spines or tubercles; dorsolateral margin broadly rounded, well delimited by row of spines, dorsomesial margin delimited by row of spines or tubercles; dorsomesial face rounded, with small spines or tubercles and usually well delimited, blunt ventromesial margin; ventral surface smooth, at most with scattered short setae. Carpus longer than broad; dorsolateral margin usually well delimited by row of spines; dorsodistal margin with row of small spines; dorsal face with numerous small spines or tubercles; ventral face nearly flat, with scattered small tubercles or spines. Merus with scattered setae dorsally, and moderately dense setae ventrodistally; with scattered small tubercles on dorsal face and small dorsodistal spine; 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 ventromesial row of setae.

Left cheliped ( Fig. 44C, D View Fig ) usually weakly calcified on dorsolateral face of carpus. Fingers each terminating in small corneous claw; dorsal and ventral surfaces unarmed except for 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 longer than length of mesial margin of palm. Palm unarmed except for dorsomesial row of small sharp or blunt spines and scattered tufts of setae; ventral face smooth. Carpus with irregular dorsal row of about 9 small spines in addition to 1 dorsodistal and 1 dorsolateral spine on distal margin; dorsal surface with long setae; ventral face smooth. Merus with long 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. 45A–D View Fig ) similar right from left except for longer segments and stronger spination on right, extending to about tip of dactyls of right cheliped or slightly exceeding them. Dactyls broadly curved, about 1.5 times as long as propodi, and terminating in sharp corneous claws; each with dorsal and dorsomesial distal rows of long setae, and 10–13 small spinules on ventromesial margin. Propodi each with row of about 8 small spines (reduced or obscure on right side) and sparse setae on dorsal margin; ventral margin with few setae. Carpi each with row of 9 or 10 small spines and few setae on dorsal margin, and small dorsodistal spine. Meri each with row of 9 or 10 small spines and long setae on dorsal margin. Ischia with setae dorsally and ventrally. Coxae with ventromesial row of setae. Anterior lobe of sternite XII (between third pereopods, Fig. 42C View Fig ), setose, with subdistal spine.

Fourth pereopod ( Fig. 45E View Fig ) 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 (between fourth pereopods) with row of setae.

Fifth pereopod ( Fig. 45F View Fig ) semichelate. Propodal rasp not reaching mid–length of segment. Coxa with row of long setae on anteroventral and ventrodistal margins. Anterior lobe of sternite XIII (between fifth pereopods) with row of setae.

Uropods markedly asymmetrical; left exopod ( Fig. 42D View Fig ) slender, slightly more than 3 times as long as broad, rasp narrow, consisting of 1–4 rows of small scales. Telson ( Fig. 42E View Fig ) moderately asymmetrical, 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, often curved corneous spines, terminal margin of right lobe armed with 4 or 5 small spines.

Male with paired first and second gonopods ( Fig. 42F, G View Fig ) occasionally with first pair missing and poorly developed second pair; first gonopod with distal portion subovate, with setae distally; second gonopod with distal segment flat and with long setae distally, proximal segment with long setae distomesially. Females with vestigial second right pleopod.

Variations. With only four known specimens, variations cannot be properly ascertained. However, it appears that in males, gonopods can vary in development irrespective of whether the individuals are mature or not. One of the males (holotype), despite being an adult, lacks first gonopods, and the second gonopods are incompletely and asymmetrically developed.

Colouration. Unknown.

Habitat. Presumably gastropod shells.

Distribution. So far known only from Île Amsterdam and Île St.-Paul, in the southern Indian Ocean. Depth: 165 m.

Remarks. This new species is characterised by the spinose condition of the left cheliped and ambulatory legs. The carpus of the left cheliped has a row of nine small spines on the dorsal margin; the meri, carpi and propodi of the ambulatory legs (both sides), each have a row of nine small spines on the dorsal margin. Also, the ambulatory legs are not as slender as in other Oncopagurus species ; this is particularly visible in the meri and carpi.

Not many samples of parapagurids are known from the isolated islands at higher latitudes of the southern Indian Ocean. The discovery of this new species in the only known samples from Île Amsterdam and Île St.-Paul, suggests that additional sampling could yield even more species form this region.

Etymology. The specific name is derived from the Latin, spina, spine, and artus, limb, and is in reference to the

spinose condition of the carpi and meri of the ambulatory legs in this new species.

Oncopagurus stockmani Zhadan, 1997 Figs. 46–49 View Fig View Fig View Fig View Fig , 51 View Fig

Parapagurus dimorphus View in CoL – Zarenkov, 1990: 238.

Sympagurus africanus subsp. nov. – Parin et al., 1997: 163

Oncopagurus stockmani Zhadan, 1997: 65 View in CoL , figs 6–8 (type locality: Nazca and Sala-y-Gómez ridges, southeastern Pacific, R/V Professor Stockman, sta 1873, 22°07'S, 81°18'W); McLaughlin et al., 2010: 39; Retamal & Moyano, 2010: 313.

Type material. Holotype (not seen), southeastern Pacific , Nazca and Sala-y-Gómez Ridges, R / V Professor Stockman, 18 th cruise, sta 1873, 22°07'S, 81°18'W, 235 m, 22 April 1987, coll. A. N. Mironov: M 6.1 mm ( ZMUM Ma–4758). GoogleMaps

Paratypes: 2 M 4.5, 6.4 mm, same station data as holotype (MNHN- IU-2013-6871).

Additional material. Eastern Pacific: SEPBOP, R/ V Anton Bruun, cruise 12: sta 65–MV–IV–54, off Más a Tierra Island , Juan Fernández Islands , [approx. 33°38'29"S 78°50'28"W], 150 m, 13 December 1965: ov F 7.0 mm ( USNM 1211233 View Materials ); CIMAR 6, stan 38, Robinsoe Crusoe Island, Juan Fernández Islands, 146 m, 23 October 2000: 1 F 4.9 mm, 1 ov F 4.0 mm ( USNM 1211234 View Materials ) GoogleMaps .

Re-description. Gills biserial. Shield ( Fig. 46A View Fig ) about as long as broad; dorsal surface weakly calcified medially, with scattered short setae; rostrum broadly rounded, weakly produced, with short mid-dorsal ridge; anterior margins weakly concave; lateral projections subtriangular, terminating in small blunt or sharp 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. 46A View Fig ) about half length of shield, 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. 46A View Fig ) exceeding distal margin of cornea by about full length or slightly more, of ultimate segment. Ultimate segment about twice as long as penultimate segment, naked or 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 8 articles.

Antennal peduncle ( Fig. 46A View Fig ) 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 (often with small spine dorsally); mesial margin with spine on dorsodistal angle. First segment with lateral face unarmed or with small blunt spine; ventromesial angle produced, with 2 or 3 small spines laterally. Acicle reaching or slightly exceeding distal margin of cornea, weakly curved outward (in dorsal view), terminating in strong spine; mesial margin armed with 6–9 spines, sparsely setose. Flagellum slightly exceeding extended right cheliped, articles with few setae less than 1 to 2 flagellar articles in length.

Mandible ( Fig. 47A View Fig ) with 3-segmented palp; cutting edge calcified, with small tooth medially; molar process with small tooth medially. Maxillule ( Fig. 47B View Fig ) with external lobe of endopod slender, moderately developed, not recurved, internal lobe with long, terminal seta. Maxilla ( Fig. 47C View Fig ) with endopod not exceeding distal margin of scaphognathite. First maxilliped ( Fig. 47D View Fig ) with endopod slightly exceeding exopod in distal extension. Second maxilliped ( Fig. 47E View Fig ) without distinguishing characters. Third maxilliped ( Fig. 47F View Fig ) with merus to dactyl each distinctly longer than broad, ischium about twice as long as broad; crista dentata with about 12–18 blunt or sharp teeth gradually diminishing in strength distally, proximal tooth 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. 48A–D View Fig ) massive, chela operculate; carpus and chela with sparse to moderately dense setae on dorsal surfaces, setae more dense on dorsaldistal surfaces of fingers and mesial face of carpus. Fingers curved ventromesially, each terminating in small, usually blunt corneous claw; cutting edges with 1 or 2 large calcareous, mostly serrated teeth and, with short row of closely set minute corneous teeth distally on dactyl. Dactyl about as long as mesial margin of palm, set at strongly oblique angle to longitudinal axis of palm; mesial margin broadly curved, delimited by row of spines diminishing in size distally; dorsal face with numerous small spines or tubercles; ventromesial face concave and elevated longitudinally on midline. Fixed finger broad at base, dorsal face covered with numerous small spines or tubercles, lateral margin delimited by row of spines; ventral face concave mesially, elevated longitudinally on midline. Palm about 1.3 times broader than long; dorsal surface covered with numerous well-spaced small spines or turbercles; dorsolateral margin broadly rounded, or well delimited by irregular row of calcareous spines, dorsomesial margin delimited by row of small spines or tubercles; dorsomesial face nearly flat, sloping mesially, with many small tubercles; ventral surface with numerous small spines or tubercles, and scattered short setae. Carpus longer than broad, dorsal surface covered with numerous small spines or turbercles; dorsodistal margin with row of small spines; dorsolateral face rounded; mesial face strongly sloping, expanded distomesially and with row of strong ventromesial spines distally; ventral face nearly flat, with well spaced small tubercles. Merus with scattered setae dorsally, and moderately dense setae ventrodistally; dorsal surface with scattered small tubercles and transverse, distal row of setae near dorsodistal margin; 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 row of small spines on ventrodistal margin, and ventromesial row of setae.

Left cheliped ( Fig. 48E, F View Fig ) usually weakly calcified on nearly entire dorsolateral face of carpus. 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 on dorsal face. Fixed finger with 1 or 2 small spines or tubercles proximally on dorsal face. Palm with scattered setae on dorsal surface; with dorsomesial row of small spines or tubercles and scattered small tubercles or spines on rest of dorsal face; ventral face smooth except for scattered setae. Carpus with dorsal irregular row of small spines in addition to 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. 49A–D View Fig ) similar right from left except for longer segments and stronger spination on right, extending to about tip of dactyls of right cheliped or slightly exceeding them. Dactyls ( Fig. 49B, D View Fig ) 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 15–35 small spinules on ventromesial margin (in large specimens such as holotype, sl 7.0 mm, spinules arranged irregularly on proximal 0.6 of ventromesial margin and in regular row distally). Propodi with setae on dorsal margin; ventral margin with few setae. Carpi each with setae on dorsal margin, and small dorsodistal spine; carpi of right with row of small spines on dorsal margins. Meri each with setae on dorsal margin, and 2 or 3 small spines distally on ventrolateral margin. Ischia with setae on dorsal and ventroproximal margins. Coxae with ventromesial row of setae. Anterior lobe of sternite XII (between second ambulatory legs, Fig. 46B View Fig ), setose, with subdistal spine.

Fourth pereopod ( Fig. 49E View Fig ) semichelate. Dactyl terminating in sharp corneous claw; with ventrolateral row of small corneous spinules. Propodus longer than broad, rasp with 2 or 3 rows of ovate 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 (between fourth pereopods) with row of setae.

Fifth pereopod ( Fig. 49F View Fig ) semichelate. Propodal rasp reaching to or slightly exceeding mid-length of segment. Coxa with row of long setae on anteroventral and ventrodistal margins. Anterior lobe of sternite XIII (between fifth pereopods) with row of setae.

Uropods markedly asymmetrical; left exopod ( Fig. 46C View Fig ) about 2.7 times as long as broad, rasp consisting of 2–5 rows of small scales. Telson ( Fig. 46D View Fig ) moderately asymmetrical, lacking transverse suture; dorsal surface with scattered setae; lateral margins with long setae medially; posterior lobes separated by shallow, armed, U-shaped cleft; terminal margin of left and right lobes armed with about 2 or 3 irregular rows of often weakly curved corneous, unequal spines.

Male with paired first and second gonopods well developed; first gonopod ( Fig. 46E View Fig ) with ovate or subtriagular distal lobe; second gonopods ( Fig 46F View Fig ) with spatulate distal segment, densely setose distally. Female with vestigial second right pleopod.

Colouration. Unknown.

Habitat. Gastropod shells with or without zoanthid or Hydractinia colonies.

Distribution. So far known only from the type locality, Nazca and Sala-y-Gómez Ridges, in the southeastern Pacific. Depth: 146– 330 m.

Remarks. Oncopagurus stockmani is unique among species of Oncopagurus in having two rows of scales throughout the propodal rasp of the fourth pereopods. Individuals of this species are among the largest known in species of Oncopagurus , reaching up to 8.0 mm (a paratype reported by Zhadan, 1997: 65) in shield length.

As noted by Zhadan (1997), the presence of several rows of scales on the propodal rasp of the fourth pereopod, misled Zarenkov (1990) to report earlier specimens of Oncopagurus stockmani collected at R/V Professor Stockman, sta 1873, as Parapagurus dimorphus [= Sympagurus dimorphus ( Studer, 1883) ], a species which has two or more rows of scales on the propodal rasp. The ressemblance of these two species is only superficial as they differ in fundamental generic characters such as type and number of gills, and presence or shape of the epistomial spine. Zhadan (1997) compared his Oncopagurus stockmani with other congenerics, and stated that two other species, O. africanus and O. haigae , also had more than one row of scales on the propodal rasp of the fourth pereopod. However, in actuality the propodal rasp in O. africanus and O. haigae may have more than one row of scales only on the proximal portion of the segment where the scales can often be arranged in a small cluster. Except for O. stockmani , all species of Oncopagurus invariably have only one row of scales on the propodal rasp, at least distally.

Previous to this study, Oncopagurus stockmani was known exclusively based on the type material from the Nazca and Sala-y-Gómez ridges, in the southeastern Pacific. The range of this species is herein extended about 2000 km to the southeast, where it has been found in the Juan Fernández Islands, Chile .