Oncopagurus tuamotu ( Lemaitre, 1994 )

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 : 293-295

Oncopagurus tuamotu ( Lemaitre, 1994)

Figs. 50 , 51 , 53G

Sympagurus tuamotu Lemaitre, 1994: 407 , figs 24–26, 28i (type locality:Tuamotu, Tureia, French Polynesia, SMCB sta 336, 20° 46,2'S, 138° 34,6'W); Lemaitre, 1996: 194; Poupin, 1996: 20, pl. 9f; Zhadan, 1997: 63 (table); McLaughlin et al., 2010: 39.

Type material. Holotype, French Polynesia, Tuamotu , Tureia, SMCB sta 336, 20°46.2'S, 138°34.6'W, trapped, 760 m, 29 October 1990: F 3.7 mm ( MNHN Pg. 5153).

Paratypes, French Polynesia, Austral Islands , Raivavae, sta D 66, 23°50.54'S, 147°42.73'W, trapped, 400 m, 3 December 1990: 1 M 3.4 mm ( MNHN Pg. 5154); 1 F 2.1 mm ( USNM 265396 ) .

Additional material. French Polynesia, Society Islands, Moorea Island: sta DW 3463, 17.5667°N, 149.9°S, 460–505 m, 20 October 2009: 1 F 3.4 mm ( UF 23839 ) ; sta DW 3478, 17.5667°N, 149.75°S, 678–810 m, 22 October 2009: 1 M 3.9 mm ( UF 24544 ) ; sta DW 3478, 17.5667°N, 149.75°S, 678–810 m, 22 October 2009: 1 ov F 3.6 mm ( UF 24546 ) .

Diagnosis. Shield ( Fig. 50A ) about as broad as long; rostrum broadly rounded, weakly produced, with short mid–dorsal ridge; lateral projections subtriangular, terminating bluntly or in small spine. Ocular peduncles more than half length of shield, with dorsal row of setae, cornea weakly dilated; ocular acicles subtriangular, each terminating in strong spine. Antennular peduncle ( Fig. 50A ) exceeding distal margin of cornea by entire length of ultimate segment. Antennal peduncle ( Fig. 50A ) reaching or slightly exceeding distal margin of cornea; fourth segment with strong spine on dorsolateral distal angle; second segment with dorsolateral distal angle terminating in strong, simple or trifid spine occasionally with 1–3 small spines dorsally, mesial margin with spine on dorsolateral distal angle; first segment with 1 or 2 small spines on lateral face; acicle slightly curved outward (in dorsal view), at most slightly exceeding distal margin of cornea, terminating in strong spine, mesial margin armed with 11 or 12 spines or 6–8 spines in small specimens (sl <2.1 mm); flagellum with numerous setae <1 or 2 flagellar articles in length. Maxillule with external lobe of endopod weakly developed, internal lobe broad and with 3 long setae. Third maxilliped crista dentata with 7 teeth, proximal 2 or 3 teeth distinctly larger than distal teeth. Right cheliped ( Fig. 50B, C ) with chela operculate, having dense, plumose setae on distal half of chela; dactyl set at strongly oblique angle to longitudinal axis of palm; palm broader than long, dorsolateral, dorsomesial and ventromesial margins well delimited by row of blunt to sharp spines, mesial face strongly concave, expanded distally, dorsal surface smooth except for few small tubercles proximally, ventral surface smooth except for few small tubercles distolaterally; carpus with lateral margin well delimited by row of spines, dorsal face with irregular rows of small spines, dorsodistal margin with row of strong spines, ventromesial distal margin mesially expanded, with row of spines. Left cheliped usually well calcified; palm dorsal surface unarmed or with small, setose tubercle on dorsomesial angle, and scattered setae; carpus with strong dorsodistal spine, and often small spine on mid-dorsal margin. Ambulatory legs with dactyls ( Fig. 50D ) each having ventromesial row of about 10 small corneous spinules; carpus with small dorsodistal spine. Anterior lobe of sternite XII (between second ambulatory legs) setose, armed with simple or bifid spine. Fourth pereopod propodal rasp ( Fig. 50E ) with 1 row of ovate scales at least distally. Fifth pereopod propodal rasp extending to mid–length of segment. Uropods and telson markedly asymmetrical; telson ( Fig. 50F ) lacking transverse suture, posterior lobes separated by shallow cleft, terminal margin of lobes armed with long, corneous and often curved spines. Male lacking first gonopods; second pair of gonopods ( Fig. 50G, H ) weakly developed, usually asymmetrical (right slightly larger and more setose than left), 2-segmented, distal segment flat or spatulate, setose distally. Female with vestigial second right pleopod.

Colouration ( Fig. 53G ). Shield whitish to cream overall, with light orange portion medially on each side; anterior portion light pink. Ocular peduncles whitish or light pink. Antennules solid red. Antennal peduncles whitish or light orange. Right cheliped with white chela; carpus and merus orange on proximal half, white distally. Left cheliped with chela orange proximally, white distally; carpus and merus orange on proximal half. Ambulatory legs with orange band on proximal third to one-half of ischia, meri, carpi, propodi and dactyls, and white distally.

Habitat. Gastropod shells, usually with anthozoan polyps growing on shell.

Distribution. So far has been found only in French Polynesia. Depth: 400– 810 m.

Remarks. (See also Oncopagurus cidaris ). The shape of the right cheliped of this species resembles that in females of O. indicus . In males and females of O. tuamotu , and females of O. indicus , the dorsomesial and ventromesial margins of the right palm are each well delimited by a row of blunt to sharp spines, and the mesial face is strongly concave and expanded distally. In other characters, the two species differ, such as in the longer and denser setation of the antennal flagella in O. tuamotu than in O. indicus (with numerous setae one to two flagellar articles in the former vs. few setae less than one flagellar article in length in the latter); the stouter and more strongly armed right cheliped (the carpus in particular) in O. tuamotu than in O. indicus (compare Figs. 26B, D and 50B ); and in males, the absence of first gonopods and presence of asymmetrical second gonopods in of O. tuamotu , whereas there are paired, symmetrical first and second gonopods in males of O. indicus .

The colour pattern of this species differs only slightly from that of O. indicus . The main difference is in the colour of the dactyls of the ambulatory legs (compare Fig. 53A, G ), which is orange or reddish basally in O. tuamotu , whereas it is entirely white in O. indicus .

Figures

Fig. 50. Oncopagurus tuamotu (Lemaitre, 1994), French Polynesia: A–F, holotype female 3.7 mm, Tuamotu, Tureia (MNHN Pg 5153); G, H, paratype male 3.4 mm, Austral Islands (MNHN Pg 5154). A, shield and cephalic appendages, dorsal; B, right cheliped, dorsal; C, chela of same, ventral; D, dactyl of left second ambulatory leg, mesial; E, propodus and dactyl of left fourth pereopod, lateral; F, telson, dorsal; G, male left second gonopod, anterior; H, male right second gonopod, anterior. Scale bars = 3 mm (A–D); 1 mm (E–H). [Adapted from Lemaitre (1994)].

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

Fig. 53. Colouration in species of Oncopagurus (in life or fresh, except where noted). A, O. indicus (Alcock, 1905): Taiwan, TAIWAN 2003, sta CP 214: female 4.6 mm (NTOU). B, C, O. monstrosus (Alcock, 1894): B, [not sexed or measured], Taiwan (NTOU); C, male 3.6 mm, TAIWAN 2004, sta CP 269 (NTOU). D, O. orientalis (de Saint Laurent, 1972): male 3.6 mm, Taiwan, TAIWAN 2004 (MNHN Pg). E, F, O. rossanae, new species, French Polynesia, BENTHAUS: E, paratype male 2.5 mm, sta DW 1905 (MNHN Pg 6692); F, holotype M 2.9 mm, sta DW 1973 (MNHN-IU-2013-6869). G, O. tuamotu (Lemaitre, 1994): [not sexed or measured], French Polynesia, Moorea (UF). (Photographs by: Tin-Y. Chan [A–D]; Joseph Poupin [E, F]; Gustav Paulay [G]).

Fig. 26. Oncopagurus indicus (Alcock, 1905): A–C, H–M, male 4.0 mm, Queensland, Australia (QM W16600); D–G, female 3.3 mm Queensland (QM W16599). A, shield and cephalic appendages, dorsal; B, carpus and chela of male right cheliped, dorsal; C, chela of same, mesial; D, carpus and chela of female right cheliped, dorsal; E, F, G, chela of same, ventral (E), mesial (F), lateral (G); H, dactyl of right first ambulatory leg, mesial; I, merus of right second ambulatory leg, lateral; L, left first gonopod, mesial; M, left second gonopod, anterior. Scale bars = 1 mm (A, C–H, L, M); 0.5 mm (I–K). [Adapted from Lemaitre (1996)].