Oplophorus gracilirostris, A.Milne-Edwards, 1881

Cardoso, Irene & Contents, Paulo Young Table Of, 2005, Deep-sea Oplophoridae (Crustacea Caridea) from the southwestern Brazil, Zootaxa 1031 (1), pp. 1-76 : 52-58

Oplophorus gracilirostris A. Milne Edwards, 1881

( Figs 39–43 )

Oplophorus gracilirostris A. Milne Edwards, 1881: 6; De Man, 1920: 48; Chace, 1947: 44, figs 4–7; 1986: 59, fig. 32a–e.

Oplophorus longirostris Bate, 1888: 765 , pl. 127, fig. 2.

Hoplophorus smithii Wood­Mason & Alcock, 1891: 194 .

Material examined: Revizee Program: E­0511, 15°42’S, 38°37’W, 251m, 1 female (16mm), MNRJ 14878 .

Diagnosis: Carapace with rostrum overreaching scaphocerite, ventral margin with six teeth; antennal spine present; branchiostegal spine present, without distinct carina; with sharp tooth near posterior end of ventral margin; with posterior extensions of upper lateralk, rostral carina subparallel in dorsal aspect. Scaphocerite with 14 teeth on outer margin, without barb near apex of inner margin. Abdomen not dorsally carinate on somite 6; pleura of somite 1 with small tooth on ventral margin; somites 3 to 5 with posteromesial tooth, the one of somite 3 distinctly strong. Female pleopod 1 with endopod leaf­shaped, numerous plumose setae on lateral margin; female pleopod 2 with appendix interna rounded, plumose setae on lateral margins, hook setae on apex.

Description: Eyestalk with ocellus on medio­distal portion ( Fig. 39B ). Carapace with rostrum longer than carapace, overreaching scaphocerite, ventral margin convex, with six teeth, dorsal margin with 11 teeth ( Fig. 39A ); dorsal margin sharply carinate throughout entire length; posterior extensions of upper lateral rostral carina subparallel in dorsal aspect; antennal spine present; branchiostegal spine present, without distinct carina; supraorbital and pterygostomian spine absent; cervical groove and suprabranchial carina absent; with sharp tooth near posterior end of ventral margin ( Fig. 39A ). Stylocerite short, with slightly rounded apex, reaching 1/3 of first antennular peduncle article; first antennular peduncle article with distal margin serrate and a broad tooth on distal outer margin that reaches 1/2 of second antennular peduncle article ( Fig. 39C ). Scaphocerite ending in acute apex, with 14 teeth on outer margin, without barb near apex of inner margin ( Fig. 39D ). Mandible with palp three­articulated, incisor process with about 14 teeth, molar process with grooves, three acute teeth and a basal tubercle ( Fig. 40A, B ). Maxilla 1 with two endites; distal endite with numerous stout, pectinate setae on inner margin; basal endite with pectinate setae on anterior and inner margins and papposepectinate setae on posterior margin; palp with rounded apex, two stout setae ( Fig. 40C ). Maxilla 2 with two endites; distal endite elongate, pectinate setae on inner and outer margins; basal endite rounded, densely plumose setae on inner margin; endopod as long as distal endite, pectinate setae on apex; scaphognathite with densely plumose setae on all margins ( Fig. 40D ). Maxilliped 1 endite with pectinate setae on outer and inner margins; endopod three­articulated, as long as endites, several pappose setae on apex and inner margin; exopodal lobe with densely plumose setae in all margins ( Fig. 40E ). Maxilliped 2 endopod with elongate ischium and merus, pappose setae on inner margins; carpus short; propod rounded with long, stout, pectinate setae on inner margin; dactyl with long, stout, pectinate setae on inner margin; broad, elongate exopod, densely plumose articulated setae on all margins ( Fig. 40F ). Maxilliped 3 slender, elongate, with simple setae on all segments; propod­dactyl with stout setae on distal portion; exopod densely plumose setae on all margins ( Fig. 40G ). Pereopods 1 and 2 chelate. Pereopod 3 ischium unarmed; merus with three stout setae on inner margin. Pereopod 4 ischium with three and merus with ten stout setae on inner margin. Pereopod 5 ischium and merus with 2 stout setae on ventral margin; dactyl rounded, with numerous long, stout, pectinate setae ( Fig. 39A ). Epipods with mesial teeth present on pereopods 1 to 3; epipods well developed on pereopod 4, except for vertical component ( Fig. 41A, B ). Abdomen dorsally carinate on somites 2 to 4; somites 3 to 6 with posteromesial tooth; the one of somite 3 distinctly strong; somite 6 shorter than somite 5 ( Fig. 39A ). Female pleopod 1 leaf­shaped, plumose setae on lateral margins ( Fig. 41C ). Female pleopod 2 appendix interna rounded, scattered plumose setae on lateral margins, hook setae on apex ( Fig. 41D ). Exopod of uropod with uncomplete diaresis, without distal spine on outer margin ( Fig. 42 ). Telson not sulcate in dorsal midline, with two pairs of dorsolateral stout setae, posterior stronger, without distal setae ( Fig. 42 ).

Distribution: Western Atlantic: Bahamas, Gulf of Mexico, Caribbean Sea, Brazil (Bahia). Indian and Pacific Oceans: southeastern Africa, Indonesia, Philippines, southern Japan, Fiji Islands, Hawaii. Adults probably are mesopelagic ( Chace 1986; Kensley 1987).

Remarks: Oplophorus gracilirostris occurs in the Indian, Pacific and Atlantic Oceans. In the Western Atlantic this species was previously recorded only from Central America. This is the first record of this genus and species from Atlantic South America ( Fig. 43 ).

The genus Oplophorus comprises four species, two of them, O. gracilirostris and O. spinosus (Brullé, 1839) occur in the Northwestern Atlantic. Oplophorus gracilirostris has the carapace with a posteroventral tooth and the scaphocerite without a barb on the distal inner margin, while O. spinosus has the carapace without a posteroventral tooth and the scaphocerite with a barb on the distal inner margin.

The material examined agrees with the description and figures of Chace (1947, 1986) by the rostrum overreaching the scaphocerite, the scaphocerite without a barb on the distal inner margin, in the carapace with a posterior ventral tooth, and in the pleura of abdominal somite 1 with a ventral tooth.

Figures

FIGURE 39 — Oplophorus gracilirostris A. Milne Edwards, 1881, female, MNRJ 14878 (carapace length 16mm); A, lateral view; B, ocular peduncle and cornea, lateral view; C, right antennule, dorsal view; D, right scaphocerite, dorsal view (as, antennal spine; brs, branchiostegal spine; hg, hepatic groove; lrc, lateral rostral carina; st, stylocerite; sto, sharp tooth).

FIGURE 40 — Oplophorus gracilirostris A. Milne Edwards, 1881, female, MNRJ 14878; A, left mandible, dorsal view; B, right mandible, dorsal view; C, left maxilla 1, dorsal view; D, left maxilla 2, dorsal view; E, left maxilliped 1, dorsal view; F, left maxilliped 2, dorsal view; G, left maxilliped 3, dorsal view.

FIGURE 41 — Oplophorus gracilirostris A. Milne Edwards, 1881, female, MNRJ 14878; A, epipod of right second pereopod, lateral view; B, epipod of left second pereopod, lateral view; C, endopod of right first pleopod, lateral view; B, appendix interna of right second pleopod, lateral view (ai, appendix interna).

FIGURE 42 — Oplophorus gracilirostris A. Milne Edwards, 1881, female, MNRJ 14878; telson and uropods, dorsal view.

FIGURE 43 — Geographic distribution of Oplophorus gracilirostris A. Milne Edwards, 1881.