Plesionika edwardsii Brandt 1851

Plesionika edwardsii (Brandt, 1851)

(Figs. 1, 2)

Pandalus narval – H. Milne Edwards, 1837: 385 (not Astacus narval Fabricius, 1787).

Pandalus (Pontophilus) edwardsii Brandt, 1851: 122.

Pandalus (Parapandalus) longirostris Borradaile, 1899: 413, pl.37, fig.10.

Plesionika edwardsii – Holthuis, 1947: 316; Pequenat, 1970: 93; Omori, 1971: 241; Crosnier & Forest, 1973: 202, fig. 63b, 64b; Chace, 1985:62, fig. 26; Crosnier, 1986: 362; Kensley et al., 1987: 314; Chan & Yu, 1991: 550, figs. 2, 3b; Chan & Crosnier, 1997: 193, fig. 23; Cabral et al., 2000: 246; Cruz & Fransen, 2004: 141; Viana et al., 2007: 36.

Material examined: REVIZEE: E- 0 511, 15o42’S, 38o37’W, 251 m, 8 males (13–22 mm), 10 females (20.5–26 mm), MNRJ 14655; D-0538, 13o08’S, 38o24’W, 623 m, 1 female (15 mm), MNRJ 21425. FURG: R 0 1, st. 24, 33o27’S / 50o 15’W, 108m, 21 males (12.3–17.2mm), 18 ovigerous females (16.4–20.6mm), 0 4 females (14.2–17.2mm), FURG 3252.

Description: Rostrum long, curved downwards in proximal region, and upwards beyond antennular peduncle; far overreaching scaphocerite, 1.7–2.3 (avg. 1.97, n=12) times as long as carapace; ventral margin, with 30–49 (avg. 42, n=12) teeth closely disposed, dorsal margin with 19–33 (avg. 28, n=12) teeth, the anterior larger and well spaced, posterior closely spaced; two or three post-rostral teeth, the proximal one small and variably movable; eye subspherical, pear like, with ocellus; strong antennal and pterygostomian spines present; carapace smooth, without carinae (Fig. 1 A). Stylocerite acute, outer margin slightly concave, inner margin convex, overreaching the distal margin of first antennular peduncle article (Fig. 1 B). Scaphocerite 0.7–1.0 (avg. 0.9, n=14) as long as carapace, distal tooth not overreaching blade (Fig. 1 C). Maxilliped 3 with epipod, penultimate segment 0.96–1.1 (avg. 1.0, n=14) times longer than terminal segment. Pereopods 1 and 2 without epipod, pereopods 3 and 4 with reduced epipod, pereopod 5 without epipod. Pereopod 2 chelate, equal in size (Fig. 1 D, E), carpus with 18–28 (avg. 22, n=12) articles. Pereopod 3 overreaching scaphocerite with carpus distal fourth; propod 0.57–0.75 (avg. 0.7, n=6) times as long as carapace; 12.7–15.6 (avg. 13.7, n=6) times longer than dactyl (Fig. 2 A), dactyl with four stout setae (Fig. 2 B). Abdomen with dorsal surface of somite 3 rounded; pleura of somite 3 rounded, of somite 4 triangular but not acute, somite 5 triangular and acute (Fig. 2 C). Telson 0.87–1.19 (avg. 1.01, n=14) times as long as abdominal somite 6; not sulcate in dorsal midline, with three pairs of dorsolateral stout setae, and three pairs of stout distal setae (Fig. 2 D).

Distribution: Western Atlantic: Virginia (U.S.A.), Mexico (Gulf of Mexico), Bahamas, Brazil (Pernambuco, Sergipe, Rio de Janeiro). Eastern Atlantic: Spain, Canary Islands, Madeira Islands; Morocco; Senegal, Angola. Mediterranean. Indian and Pacific: La Reunion, Indonesia, Philippines, Taiwan, New Britain, New Caledonia, Vanuatu, Fiji, French Polynesia, Tubuai, Society Islands, Eastern Australia. Adults living in depths from 50 to 680 m, most commonly 200 to 400 m (modified from Chace 1940; Crosnier & Forest, 1973; Chan & Yu, 1991; Chan & Crosnier, 1997; Cabral et al., 2000).

Remarks: Chan & Crosnier (1997) organized the Plesionika species that occur in French Polynesia in groups to make comparisons and discussions clearer. According to them, Plesionika edwardsii is placed alone in her own group.

The material examined herein presents rostrum with less ventral and dorsal teeth (30–49; 19–33) than observed by Chace (1985) (33–50; 28–34) in Philippines material and Chan & Yu (1991) (37–51; 28–36) in material from various localities, but the range of Brazilian material includes that observed by Kensley et al. (1987) (36–44; 21–28) in Eastern Australian material. Besides that, the average of ventral (42) and dorsal (28) teeth observed in Brazilian material fits on the range observed by these authors for Plesionika edwardsii, and the teeth disposition in both margins also agrees with their descriptions. The number of post-rostral teeth observed in Brazilian material (two or three) is also in the range observed by Chace (1985) (one to three) and by Chan & Yu (1991) (two to four). The rostrum and telson size observed herein (1.7–2.3 as long as carapace and 0.87–1.19 as long as abdominal somite 6) agrees with that observed by Kensley et al. (1987) (1.8–2.3 and 0.9–1.0). Kensley et al. (1987) and Chan & Yu (1991) observed epipods on pereopods 1–4 reduced, but Chan & Yu (1991) observed that sometimes they are inconspicuous on pereopods 1 and 2. In the Brazilian material, the epipods in pereopods 3 and 4 are also reduced and the epipods in pereopods 1 and 2 are always inconspicuous.

The closest species to P. e d w a rd s i i is Plesionika crosnieri Chan & Yu, 1991 described from Taiwan. As cited by the authors, the main differences between these species are the number of post-rostral teeth (two to four versus only one), the number of ventral and dorsal teeth (37–52, 27–36 versus 30–43, 16–19) and the distal tooth of scaphocerite overreaching blade or not. The Brazilian material presents all the features cited above to P. e d w a rd s i i, only the average of rostrum ventral teeth (42) fits in the range of both species.