Oncopagurus elongatus, 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: 244-252
treatment provided by
Oncopagurus n. sp. 3 – McLaughlin et al., 2010: 39.
Type material. Holotype, Vanuatu, MUSORSTOM 8, sta CP 1080, 15°57.30'S, 167°27.73'E, 799–850 m, 5 October 1994: F 4.0 mm (MNHN-IU-2013-5497). GoogleMaps
Paratypes, Fiji: MUSORSTOM 10, sta CP 1361, 18°00.00'S, 178°53.71'E, 1058–1091 m, 13 August 1998: 1 M 3.0 mm (MNHN-IU-2013-5510, ex MNHN Pg. 6722). — BORDAU 1, sta CP 1490, 18°50.60'S, 178°32.13'W, 785–820 m, 11 March 1999: 1 M 3.6 mm ( USNM 1207994 View Materials , ex MNHN Pg. 6720) GoogleMaps . Vanuatu: MUSORSTOM 8, sta CP 1080, 15°57.30'S, 167°27.73'E, 799–850 m, 5 October 1994: 2 F 3.7, 3.9 mm (MNHN-IU-5498) GoogleMaps . Tonga Islands : BORDAU 2, sta CP 1565, 20°58'S, 175°16'W, 869–880 m, 9 June 2000: 2 M 3.0, 3.4 mm, 2 F 2.6, 2.8 mm, 4 ov F 3.1–3.3 mm (MNHN- IU-2013-5509, ex MNHN Pg. 6721) GoogleMaps . French Polynesia, Austral Islands : BENTHAUS: sta DW 1933, Thiers Bank, 24°40.72'S, 146°01.31'W, 500–850 m, 14 November 2002:1 M 2.8 mm ( USNM 1207995 View Materials , ex MNHN Pg. 6723); sta DW 2020, Rimatara, 22°36.96'S, 152°49.13'W, 920–930 m, 25 November 2002: 1 M 3.0 mm, 2 F 2.3, 2.9 mm (MNHN- IU-2013-5508, ex MNHN Pg. 6724) GoogleMaps .
Description. Gills biserial to weakly quadriserial. Shield ( Fig. 20A View Fig ) about as broad as long; dorsal surface weakly calcified medially and sometimes also near anterior margin, with scattered short setae; rostrum broadly rounded, weakly produced, with short mid-dorsal ridge; anterior margins weakly concave; lateral projections bluntly subtriangular; anterolateral margins sloping; posterior margin broadly rounded; ventrolateral margins of shield usually without spine. Anterodistal margin of branchiostegite rounded, unarmed, setose.
Ocular peduncles ( Fig. 20A, B View Fig ) about half length of shield, diminishing in width distally, somewhat inflated and weakly calcified ventroproximally; with longitudinal row of long setae dorsally extending to edge of cornea and forming “eye-brow”; ventroproximal surface weakly calcified. Cornea reduced, not dilated, about as wide as distal width of peduncle. Ocular acicles subtriangular, each terminating in strong spine; separated basally by about half basal width of 1 acicle.
Antennular peduncle ( Fig. 20A, C View Fig ) long, slender, exceeding distal margin of cornea by 0.7 length of penultimate 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 unarmed or with small spine and setae, and strong spine proximally. Ventral flagellum with 5 or 6 articles.
Antennal peduncle ( Fig. 20A, C View Fig ) exceeding distal margin of cornea by about 0.3–0.5 length of fifth segment. Fifth segment unarmed except for scattered setae and distolateral tufts of setae. Fourth segment with dorsodistal spine. Third segment with strong ventromesial distal spine. Second segment with dorsolateral distal angle produced, terminating in simple spine; mesial margin with spine on dorsodistal angle. First segment with lateral face unarmed or with small spine; ventromesial angle produced, with 2 or 3 small blunt spines laterally. Acicle nearly straight (in dorsal view), exceeding distal margin of cornea by about 0.1–0.2 length of acicle, terminating in strong spine; mesial margin armed with 8–13 spines, setose. Flagellum long, slightly exceeding extended right cheliped, articles with long setae 3 or 4 flagellar articles in length every 3 or 4 articles, and scattered short seate <1 article in length.
Mandible ( Fig. 21A View Fig ) with 3-segmented palp; cutting edge calcified, with small corneous tooth medially; molar process with small corneous tooth medially. Maxillule ( Fig. 21B View Fig ) with external lobe of endopod obsolete, internal lobe with long, terminal seta. Maxilla ( Fig. 21C View Fig ) with endopod exceeding distal margin of scaphognathite. First maxilliped ( Fig. 21D View Fig ) with endopod exceeding exopod in distal extension. Second maxilliped ( Fig. 21E View Fig ) without distinguishing characters. Third maxilliped ( Fig. 21F, G View Fig ) with merus to dactyl each distinctly longer than broad, ischium less than twice as long as broad; crista dentata with about 13–15 often corneous-tipped teeth diminishing in size distally; basis with mesial spine; coxa lacking spine. Sternite of third maxillipeds with small spine on each side of midline.
Chelipeds markedly dissimilar. Right cheliped ( Fig. 22A–D View Fig ) with chela operculate, having moderately dense setae on dorsal surfaces of carpus and chela. Fingers curved ventromesially, terminating in small, usually blunt corneous claw; cutting edges each with 3 (dactyl) or 2 (fixed finger) large calcareous teeth. Dactyl about as long as mesial margin of palm, set at oblique angle to longitudinal axis of palm; mesial margin broadly curved, well defined by row of blunt or sharp spines diminishing in size distally; dorsal face with scattered small tubercles and small spines proximally; ventromesial face moderately concave, smooth. Fixed finger broad at base, dorsal and ventral faces smooth. Palm broader than long, dorsal surface with scattered small spines or tubercles medially; dorsolateral margin sharply delimited by row of spines, dorsomesial margin with row of spines; mesial face rounded ( Fig. 22B View Fig ), or in females often concave and expanded distomesially and with well delimited ventromesial margin ( Fig. 22D View Fig ), with scattered small tubercles; ventral surface nearly smooth or at most with scattered small tubercles. Carpus distinctly longer than broad; dorsal surface with numerous small spines or tubercles; dorsolateral and dorsomesial margins rounded; ventromesial margin well defined by row of spines; ventral face with scattered small tubercles. Merus with numerous small spines on dorsal surface; ventromesial margin with row of spines. Ischium with dorsal row of setae. Coxa unarmed, but with ventromesial row of setae.
Left cheliped ( Fig. 22E View Fig ) usually weakly calcified on dorsolateral face of carpus and lateral face of merus. Fingers 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 slightly shorter or subequal in length to mesial margin of palm. Palm unarmed except for dorsomedian row of 2 or 3 small spines or tubercles, and sparse setae; ventral face smooth. Carpus with small dorsodistal spine; dorsal margin with long setae; ventral face smooth. Merus with long setae on dorsal margin; ventral face smooth. Ischium and coxa unarmed, but with ventromesial row of setae.
Ambulatory legs ( Fig. 23A–D View Fig ) similar right from left except for longer meri on right; exceeding extended right cheliped by about 0.2 length of dactyls. Dactyl broadly curved, about 1.6 times as long as propodus, and terminating in sharp corneous claw; with dorsal and dorsomesial distal rows of long setae, and ventromesial row of about 4–7 slender, corneous spinules. Propodus with row of setae on dorsal margin, and naked or with scattered setae elsewhere. Carpus with long setae dorsally, small dorsodistal spine, and often 1 or 2 small well-spaced spines on dorsal margin. Merus with long setae dorsally, often with row of 3 or 4 small, wellspaced spines on dorsal margin. Ischium unarmed except for setae on dorsal and ventral margins. Coxa with ventromesial row of setae. Anterior lobe of sternite XII (between second ambulatory legs, Fig. 20D View Fig ) subsemicircular, setose, with distinct spine.
Fourth pereopod ( Fig. 23E, F View Fig ) semichelate. Dactyl slender, 2.0–2.5 times as long as dorsal margin of propodus, distinctly longer and slenderer in females than in males, broadly curved and 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, Fig. 20E View Fig ) with dense row of long setae.
Fifth pereopod ( Fig. 23G View Fig ) semichelate. Propodal rasp extending to mid-length of segment. Coxa with dense row of long setae on anteroventral and distoventral margins. Anterior lobe of sternite XIV (fifth pereopods, Fig. 20E View Fig ) with dense row of long setae.
Uropods and telson strongly asymmetrical ( Fig. 20F, G View Fig ). Telson lacking transverse suture; dorsal surface with scattered setae, lateral margins with long setae; posterior lobes separated by shallow U-shaped cleft; terminal margins of lobes armed with slender, long corneous spines (about 18 on left lobe, 10 on right lobe) weakly curved ventrally, spines on terminal margin of left lobe often extending nearly to midportion of lateral margin. Male with paired first and second gonopods; first gonopod ( Fig. 20H, I View Fig ) with distal portion subovate, with setae distally; second gonopod with distal segment setose distally and on lateral margin medially. Female with or without vestigial second right pleopod.
Habitat. Gastropod shells with or without zoanthids incompletely covering the shells.
Distribution. Western and Central Pacific, from Vanuatu, Fiji and the Tonga Islands, and the Austral Islands, French Polynesia. Depth: 500–1091 m.
Remarks. This new species is the fourth in Oncopagurus to have reduced or subconical corneas, the others being O. conicus , O. minutus , and O. petilus , new species. However, O. elongatus , new species, is unusual in several other respects. In the shape and relative length of the ocular peduncles, O. elongatus , new species, superficially resembles species of Parapagurus . In O. elongatus , new species, the ocular peduncles are at most about half the length of the shield, decreasing in width distally, whereas the peduncles in all other species of Oncopagurus are more than half the lenght of the shield and are more or less equal in width throughout (except for O. conicus ). The ocular peduncles in O. elongatus , new species have a row of long and often dense setae dorsally that extends to the proximal margin of the corneas, forming a sort of “eyebrow”. The gills in O. elongatus , new species, are atypical for a species of Oncopagurus as they vary in this new species from biserial to weakly quadriserial, instead of strictly biserial as in other congeners. The anterior lobes of sternites XIII and XIV, and the coxae of the fourth and fifth pereopods, have longer, denser setae ( Fig. 20E View Fig ) than in other congeners.
In Oncopagurus elongatus , new species, there is a distinct sexual dimorphism on the right cheliped and fourth pereopod. The right palm in females (especially larger ones) have the mesial face expanded distomesially, and a distinctly delimited ventromesial margin ( Fig. 22D View Fig ). The dactyl of the fourth pereopod in females is distinctly longer and more strongly curved than in males. A similar dimorphism of this dactyl is present in O. cidaris , although the length of the dactyl in O. elongatus , new species is even strikingly longer relative to the dactyl of the male.
Etymology. The specific name is from the Latin, elongatus , in reference to the strikingly long dactyl of the fourth pereopod usually seen in females of this new species.
Paratypes, Indonesia, Tanimbar Island: R/ V Baruna Jaya 1, sta DW 49, 08°00'S, 132°59'E, 210– 206 m, 29 October 1991: 15 M 1.4–2.6 mm, 2 ov F (2.2, 2.3 mm), 1 juv 1.2 mm ( MNHN Pg. 5344) GoogleMaps ; sta DW 80, 09°37'S, 131°02'E, 199–201 m, 4 November 1991: 5 M 1.2–2.7 mm, 2 F 1.2, 1.5 mm, 1 ov F 1.8 mm ( USNM 276035 View Materials ) GoogleMaps ; sta CP 86, 09°26'S, 131°13'E, 225–223, 4 November 1991: 2 M 1.3, 1.7 mm ( MNHN Pg. 5343),1 M 2.3 mm, 2 F 1.3, 2.7 mm, 1 ov F 2.5 mm ( USNM 276036 View Materials ) GoogleMaps .
Additional material. Philippines: MUSORSTOM 3: sta CP 27, 14°00'S, 120°19'E, 188–192 m, 22 March 1976: 1 M 2.3 mm ( MNHN Pg.) GoogleMaps . Vanuatu: MUSORSTOM 8: sta DW 978, 19°22.62'S, 169°27.11'E, 413– 408 m, 22 September 1994: 1 M 1.4 mm ( MNHN Pg.); sta DW 1014, 17°54.53'S, 168°19.08'E, 495–498 m, 27 September 1994: 1 M 2.5 mm ( MNHN Pg.) — BOA 1: sta DW 2459, 16°10.16'S, 167°19.57'E, 336–353 m, 12 September 2005: 1 M 2.2 mm ( MNHN Pg.) GoogleMaps . Tonga Islands : BORDAU 2: sta DW 1537, 21°41'S, 175°19'W, 391–421 m, 4 June 2000: 1 ov F 2.2 mm ( MNHN Pg.); sta DW 1567, 21°02'S, 175°19'W, 351–356 m, 10 June 2000: 1 M 2.3 mm, 1 F 1.4 mm, 5 ov F 1.2–2.6 mm ( MNHN Pg.) GoogleMaps . New Caledonia: MUSORSTOM 4: sta CC 174, 19°00.30'S, 163°18.50'E, 385 m, 17 September 1985: 1 M 1.7 mm GoogleMaps
(MNHN-IU-2013-5541); sta DW 181, 18°57.20'S, 163°22.40'E, 355 m, 18 September 1985: 1 M 2.0 mm (MNHN-IU-2013-5542) — MUSORSTOM 5: sta CP 309, 22°10.20'S, 159°22.80'E, 340 m, 12 October 1986: 1 M 1.9 mm (MNHN-IU-2013-5539) — SMIB 3: sta DW 1, 24°55.70'S, 168°21.80'E, 520 m, 20 May 1987: 1 M 3.5 mm, 1 ov F 3.1 mm ( USNM 1211196 View Materials ) — MUSORSTOM 6: sta DW 391, 20°47.35'S, 167°05.70'E, 390 m, 13 February 1989: 1 M 1.8 mm (MNHN-IU-2013-5544); sta DW 417, 20°41.80'S, 167°03.65'E, 283 m, 16 February 1989: 2 M 1.6, 1.7 mm, 2 F 1.7, 2.1 mm ( USNM 1211197 View Materials ); sta DW 418, 20°41.75'S, 167°03.35'E, 283 m, 16 February 1989: 1 M 2.4 mm ( USNM 1211200 View Materials ); sta DW 428, 20°23.54'S, 166°12.57'E, 420 m, 17 February 1989: 1 M 2.1 mm (MNHN-IU-2013-5538); sta DW 451, 20°59.00'S, 167°24.50'E, 330 m, 20 February 1989: 1 M 2.1 mm (MNHN- IU-2013-5543); sta DW 452, 21°00.30'S, 167°25.50'E, 300 m, 20 February 1989: 2 M 1.8, 2.1 mm (MNHN-IU-2013-5540); sta DW 453, 21°00.50'S, 167°26.90'E, 250 m, 20 February 1989: 1 F 1.3 mm ( USNM 1211201 View Materials ); sta DW 456, 21°00.71'S, 167°26.35'E, 240 m, 20 February 1989: 1 M 1.5 mm, 1 F 1.7 mm ( USNM 1211198 View Materials ); sta CB 481, 21°21.85'S, 167°50.30'E, 300 m, 23 February 1989 (2 lots): 1 F 1.8 mm (MNHN-IU-2013-5537), 1 F 1.7 mm ( USNM 1211199 View Materials ) — BATHUS 2: sta DW 730, 23°02.56'S, 166°58.30'E, 350–400 m, 12 May1993: 1 M 2.3 mm, 3 F 1.8–1.9 mm ( MNHN Pg.); sta DW 749, 22°33.39'S, 166°26.02'E, 369– 258 m, 13 May 93: 1 F 1.7 mm ( MNHN Pg.) — Passe Boulari, 12°33.62'S, 166° 25.97'E, [no depth], 12 September 1994, coll. B. Richer de Forges : 4 M 1.3–2.6 mm, 1 F 1.7 mm ( ZMMU) — EBISCO: sta DW 2538, 22°20'S, 159°25'E, 318–323 m, 10 October 2005: 1 M 2.6 mm ( MNHN Pg.) GoogleMaps .
Diagnosis. Shield ( Fig. 24A View Fig ) as broad as long; rostrum broadly rounded, weakly produced, with short mid-dorsal ridge; lateral projections subtriangular, terminating in small spine. Ocular peduncle more than half length of shield, with dorsal row of long setae; cornea moderately dilated. Ocular acicles ( Fig. 24A, B View Fig ) subtriangular, terminating bluntly or subacutely, with strong, distinctly or rarely indistinctly submarginal spine. Antennular peduncle ( Fig. 24A View Fig ) exceeding distal margin of cornea by entire length of ultimate segment. Antennal peduncle ( Fig. 24A View Fig ) reaching distal margin of cornea; fourth segment with strong dorsodistal spine; second segment with dorsolateral distal angle terminating in strong, simple spine, mesial margin with spine on dorsodistal angle; first segment with small spine on lateral face; antennal acicle slightly curved outward (in dorsal view), short, not reaching distal margin of cornea, terminating in strong spine (rarely bifid), mesial margin armed with row of 8–11 spines; flagellum exceeding extended right cheliped, with serial arrangement of short (<1 article in length) and long (3–5 articles in length) setae every 2–4 articles. Third maxilliped with crista dentata consisting of about 8 calcareous or corneous-tipped teeth, proximal 2 or 3 teeth distinctly larger than distal teeth. Right cheliped ( Fig. 24C–E View Fig ) massive, chela operculate; dorsal surfaces of merus, carpus and chela each with moderately dense setae; chela with dense fringe of long setae on lateral and mesial margins; dactyl set at strongly oblique angle to longitudinal axis of palm, mesial margin well delimited by row of strong spines, dorsal face with scattered small tubercles; palm longer than broad, dorsolateral margin well delimited by row of strong spines, dorsomesial margin delimited by row of spines, mesial face rounded and with scattered tubercles, dorsal surface with irregular rows of spines medially, ventral face with irregularly arranged tubercles or blunt spines, and raised frequently very prominent cluster of tubercles medially ( Fig. 24D, E View Fig ); carpus with dorsolateral margin usually well delimited by row of spines distally, dorsal face with numerous small spines. Left cheliped usually weakly calcified on dorsolateral face of carpus and lateral face of merus, palm unarmed except for scattered setae and proximomedial row of blunt spines on dorsal face. Ambulatory legs ( Fig. 24F, G View Fig ) with dactyls each with row of 1–5 minute spinules on ventromesial margin, carpi each with small dorsodistal spine. Anterior lobe of sternite XII (between second ambulatory legs) rounded, setose, unarmed or with small subdistal spine. Fourth pereopod propodal rasp ( Fig. 24H View Fig ) with 1 row of rounded scales at least distally. Fifth pereopod propodal rasp extending to mid–length of segment. Uropods and telson markedly asymmetrical; telson ( Fig. 24I View Fig ) lacking transverse suture, posterior lobes separated by shallow unarmed cleft, terminal margin of lobes armed with long, often strongly curved corneous spines. Male with paired first and second gonopods; first gonopod in juveniles (sl <1.5 mm) not present or not fully developed, in adults with nearly flat distal lobe and long marginal setae ( Fig. 24J View Fig ); second gonopod ( Fig. 24K View Fig ) with distal segment flat, with long setae marginally and on anterior face. Female with vestigial second right pleopod.
Variations. The terminal spine on the ocular is clearly submarginal ( Fig. 24B View Fig ), although in some small specimens it appears that the acicle is not fully developed and the terminal spine can be interpreted as indistinctly submarginal. (See also Oncopagurus elevatus , new species).
Habitat. Gastropod shells.
Distribution. Previously known only from the original description ( Lemaitre, 1997) based on specimens from Tanimbar Island, Indonesia, this species has been found during this study in a wide area of the Western Pacific, including the Philippines, Vanuatu, Tonga Islands, and New Caledonia. Depth: 188– 520 m.
Remarks. (See also Oncopagurus elevatus , new species). When this species was described ( Lemaitre, 1997), the peculiar armature of the ventral surface of the right palm was considered unique among species of Oncopagurus . During this study, however, three of the new species discovered ( O. elevatus , new species, O. crusoei , new species, and O. rossanae , new species) were found to also have a distinct armature on the ventral face of the palm and fingers of the right chela, although the armature differs in development in each of the species (see Remarks under those new species for comparisons). In O. glebosus the ventral surface of the right palm has numerous irregularly arranged tubercles which typically form a prominent, raised cluster medially ( Fig. 24D, E View Fig ). In small individuals (sl <1.5 mm) the cluster is not as prominent, with smaller and more separated tubercles than in large individuals.
Oncopagurus glebosus is also distinguished from other congeners and even all other parapagurids, by the unique condition of the ocular acicles. This is the only species in the family known to have ocular acicles terminating in a submarginal (or rarely indistinctly submarginal) spine ( Fig. 24B View Fig ), whereas the ocular acicles in all other parapagurids terminate in a simple to multifid marginal spine.
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