Plesionika ensis (A. Milne Edwards 1881) A. Milne Edwards 1881
- Dataset
- Report on some Plesionika Bate, 1888 and first record of Stylopandalus Coutiére, 1905 (Caridea, Pandalidae) from Brazilian waters
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Malacostraca
- order
- Decapoda
- family
- Pandalidae
- genus
- Plesionika
- species
- Plesionika ensis
description
Description: Rostrum long, curved downwards in proximal region, and upwards beyond antennular peduncle; far overreaching scaphocerite, 2.3 – 2.6 (avg. 2.4, n = 6) times as long as carapace; ventral margin with 40 – 51 (avg. 43, n = 6) teeth closely disposed, dorsal margin with one to three (avg. 2, n = 11) large teeth well spaced, reaching antennular peduncle end, one distal tooth and two to three post-rostral teeth the proximal one variably movable; eye large, spherical, with ocellus; strong antennal and small pterygostomian spines present; carapace smooth (Fig. 3 A). Stylocerite straight at base and tapering only near the triangular apex, not overreaching the distal margin of first antennular peduncle article (Fig. 3 B). Scaphocerite 0.94 – 1.05 (avg. 0.99, n = 12) as long as carapace, with blunt apex, distal tooth strongly overreaching blade (Fig. 3 C). Maxilliped III with epipod, penultimate segment 0.76 – 0.93 (avg. 0.84, n = 13) times longer than terminal segment. Pereopods 1 – 4 with epipod, pereopod 5 without epipod. Pereopod 2 chelate, equal in size (Fig. 3 D, E), carpus with 15 – 28 (avg. 17, n = 12) articles. Pereopod 3 overreaching scaphocerite with propod distal third; propod 0.45 – 0.55 (avg. 0.48, n = 10) times as long as carapace; 4.3 – 7.6 (avg. 5.8, n = 11) times longer than dactyl (Fig. 4 A), dactyl with two stout setae (Fig. 4 B). Dorsal surface of abdominal somite 3 with a straight spine; pleura of somite 3 rounded, pleura of somite 4 triangular but not acute, pleura of somite 5 triangular and acute (Fig. 4 C). Telson 0.72 – 0.92 (avg. 0.77, n = 13) 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. 4 D).
discussion
Remarks: Working with material from Brazilian waters (9 o 05
N / 34 o 50
W, Alagoas), collected by the Challenger Expedition, Bate (1888) described Plesionika uniproducta based on two specimens, one male and one female. According to Crosnier & Forest (1973), the female is actually P. e n s i s and the male is actually Plesionika martia (A. Milne Edwards, 1883). In this way, Bate (1988) was the first to record P. e n s i s and P. martia to Brazilian waters, both identified as P. uniproducta. According to Chan & Crosnier (1997) Plesionika ensis is in a group together with Plesionika reflexa Chace, 1985. These species are very similar as pointed by Chace (1985), Crosnier (1986), Chan & Crosnier (1997) and Fransen (2006). Chace (1985) compares the type series of P. reflexa with specimens identified as P. e n s i s from various parts of the world and gives several characters that might prove to be of specific significance. The proportional length of dactyl and propod of pereopod 3 being 0.17 – 0.25 in the 14 specimens of P. e n s i s from western Atlantic and 0.30 – 0.46 in P. reflexa from South China Sea and Philippines; in the Brazilian material this proportion is 0.13 – 0.23, with the average of 0.18 (n = 11) fitting with the range of western Atlantic P. e n s i s. Populations of P. e n s i s from East Atlantic, however, have a similar ratio (0.26 – 0.40), as P. re f l e x a material cited above (Chace, 1985; Fransen, 2006). In Hawaiian material of P. e n s i s there are two forms, one with a very short dactyl (0.12 – 0.16) and other with a range intermediate (0.21 – 0.30) between that of the western and Eastern Atlantic populations (Chace, 1985). Other feature cited by Chace (1985) as useful to distinguish both species is the dorsal spine on abdominal somite 3 with a tendency to recurve upwards in P. reflexa, whereas no such inclination has been noticed in typical form of P. e n s i s. Chan & Crosnier (1997) mentioned that the absence of any specimen with a recurved dorsal spine in the Atlantic is sufficient reason to not synonymize P. reflexa with P. e n s i s. In the 13 Brazilian specimens examined herein the dorsal spine on abdominal somite 3 is straight (Fig. 4 C). The scaphocerite distal tooth also may be of taxonomic importance, in P. reflexa it slightly overreaches blade, while in P. e n s i s it strongly overreaches blade (Chace, 1985; Fransen, 2006), as was observed in Brazilian material (Fig. 3 C). Chan & Crosnier also pointed that the western Atlantic population of P. e n s i s presents a rostrum 2.2 – 2.8 (avg. 2.5) times carapace length, with 35 – 48 ventral teeth (avg. 42, n = 6). The material herein examined fits in this range, with rostrum 2.3 – 2.6 (avg. 2.4, n = 6) times as long as carapace and ventral margin with 40 – 51 teeth (avg. 43, n = 6). Chan & Crosnier (1997) comment that many more species may be also present in the material now identified as P. e n s i s and P. reflexa (as occur with the great diversity of species contained in the “ P. m a r t i a (A. Milne Edwards, 1883) ” (Chace, 1985) and “ P. narval (Fabricius, 1787) ” (Chan & Crosnier, 1991) groups). Or the problem of these two species may be similar to the case of P. e d w a rd s i i and P. crosnieri, in which both species are distributed in the Indo-Pacific but only one occurs in the Atlantic (Chan & Yu, 1991; Chan & Crosnier, 1997).distribution
Distribution: Western Atlantic: Florida, Gulf of Mexico, Antilles, Brazil (Maranhão, Paraíba, Alagoas, Bahia, Rio de Janeiro). Eastern Atlantic: Senegal, Gabon, Congo, Angola. Indian and Pacific: Andaman Sea, Arabian Sea, Hawaii, Fiji. Adults in Atlantic founded in depths from 230 to 732 m, in Indo-West-Pacific in depths from 101 to 1251 m, the shallowest record is in Hawaiian waters at 55 m (modified from De Man, 1920; Crosnier & Forest, 1973; Cabral et al., 2000).
materials_examined
Material examined: REVIZEE: E- 0 500, 13 o 22 ’ S, 38 o 40 ’ W, 394 m, 1 male (12 mm), 1 ovigerous female (14 mm), MNRJ 14668; E- 0513, 15 o 53´S, 38 o 02´W, 489 m, 4 males (13 – 15 mm), 1 female (13 mm), 3 ovigerous females (13 – 14.5 mm), MNRJ 14658; E- 0518, 13 o 21 ’ S, 38 o 38 ’ W, 518 m, 1 male (21 mm), 1 female (17 mm), MNRJ 14660; D- 0 464, 21 o 48´S, 40 o 01´W, 618 m, 1 male (13.5 mm); MNRJ 13735.