Plesionika revizeei, Cardoso, Irene A., 2011

Cardoso, Irene A., 2011, New species of Plesionika Bate, 1888 (Crustacea, Decapoda, Pandalidae) from Southwestern Atlantic, Zootaxa 3089, pp. 51-59 : 52-58

Plesionika revizeei n. sp.

( Figs. 1–3 )

Material examined. E-0541, 21o13’S / 40o14’W, 573 m, holotype: ovigerous female (16), MNRJ 14663; E-0541, 21o13’S / 40o14’W, 573 m, paratypes: 7 males (14.4–19), 2 ovigerous females (16.6–17.6), MNRJ 21509. E-0543, 21o23’S / 40o11’W, 666 m, paratypes: 15 males (15.2–18.9), 6 ovigerous females (16–18), MNRJ 14669; E-0541, 21o13’S / 40o14’W, 573 m, paratype: 1 ovigerous female (16.8), MNHN 16975; E-0543, 21o23’S / 40o11’W, 666 m, paratypes: 3 ovigerous females (15.8–17.2), 5 males (16.6–20.5), MZUSP 18891; R01, st.28, 33o35’S / 50o43’W, 533 m, 1 female (16.6), FURG 3247; R07, st.14, 34o15’S / 51o37’W, 408 m, 5 males (13.2–15.1), 15 females (12.6– 13.8), FURG 3248; R01, st.27, 33o33’S / 50o43’W, 330 m, 2 females (13.3, 14.2), FURG 3249; R07, st.19, 33o35’S / 50o45’W, 440 m, 7 males (11.4–15.4), 1 ovigerous female (17.7), 35 females (10.2–17.4), FURG 3250; DPA II, lance 12, 26o11’S / 45o49’W, 501 m, 9 males (14.1–17.3), 3 females (14.1–15.3), FURG 3651.

Comparative material of Plesionika willisi ( Pequegnat, 1970) : Alaminos, 29o27,6´N /0,86o46,5´W, 384 m, allotype: 1 male (14.5), USNM 128803; Alaminos, 29o27,6´N /0,86o46,5´W, 384 m, paratypes: 2 males (10.6–10.7), 2 ovigerous females (12.5–13.6), USNM 128804; Gulf of Mexico, 29º11,30´N /0,88º12,36´W, 311 m, 2 males (8.2– 10.1), USNM 282665; Gulf of Mexico, 29º29,54´N /0,86º53,42´W, 378 m 2 males (9.3–9.2), 4 females (8.7–9.6), USNM 282664; Gulf of Mexico, 26º17´N /0,96º18´W, 274 m, 1 female (11), USNM 282666.

Diagnosis. Rostrum relatively long 1.48–2.29 (mean 1.87, n=12) times as long as carapace, far overreaching antennal scale, slightly curved dorsally; armed dorsally throughout length with 9–13 widely spaced teeth; one postrostral tooth at proximal sixth of carapace; ventral margin, with 17–30 teeth, basal third unarmed, second third with closely spaced teeth and distal third with widely spaced teeth; carapace without postrostral ridge; antennal spine small; orbital margin slightly concave; lower part of branchiostegite not membranous. Well developed epipods on maxilliped 3 to pereopod 1, pereopods 2–4 each with reduced epipods. Second pereopods subequal, each carpus divided in 19–27 articles. Tergite of abdominal somite 3 rounded, posterodorsal margin unarmed; fourth pleura rounded and fifth pointed at posteroventral angle. Telson 0.79–1.26 (mean 0.92, n=12) times as long as abdominal somite 6, with three pairs of dorsolateral, and three pairs of distal spines. Pereopod 3 overreaching antennal scale by length of distal three segments; dactyl long and slender with a tuft of simple setae on apex.

Description. Rostrum relatively long 1.48–2.29 (mean 1.87, n=12) times as long as carapace; overreaching distal margin of antennal scale by one fourth to one third of its length, slightly curved dorsally; dorsal margin with 9–13 widely spaced teeth distributed on all rostrum length; one postrostral tooth; ventral margin with 17–30 teeth, basal third unarmed, second third with closely spaced teeth and distal third with widely spaced teeth. Carapace without postrostral ridge; small antennal and pterygostomian spines; no lateral carinae; orbital margin slightly concave ( Fig. 1 A).

Abdomen with dorsal surface and posterodorsal margin of somite 3 rounded ( Fig. 2 A); pleura of somite 3 and 4 rounded, of somite 5 pointed ( Fig. 2 B). Telson 0.79–1.26 (mean 0.92, n=12) times as long as abdominal somite 6, shallowly sulcate in dorsal midline, with three pairs of dorsolateral spines, and three pairs of distal spines ( Fig. 3 A).

Eye kidney-shaped, without ocellus. Antennular peduncle not reaching mid-length of antennal scale; stylocerite not reaching distal margin of first antennular peduncle article, outer margin concave, inner margin convex ( Fig. 1 B). Antennal scale 0.74–1.33 (mean 1.07, n=15) as long as carapace, distolateral tooth overreaching the distal margin of antennal scale.

Well developed epipods on maxilliped 1 to 3. Epipod on maxilliped 3 elongated to posterior region, more robust, but similar in shape to that of pereopods ( Fig. 1 D). Maxilliped 3 penultimate segment 1.38–1.73 (mean 1.56, n=13) times terminal segment; exopod reduced, 0.12 times as long as ischium-merus length.

Pereopod 1 not overreaching antennal scale, with well developed epipod, elongated to the posterior region, bearing a terminal hook ( Fig. 2 D). Pereopods 2–4 with epipods reduced, decreasing in size, but with similar shape to that of pereopod 1, without terminal hook ( Fig. 1 D). Pereopod 2, reaching distal eight of carpus of pereopod 1, subequal in length ( Fig. 2 C, D), carpus with 19–27 (mean 22.2, n=16) articles; merus without annulations. Pereopod 3 overreaching antennal scale by length of distal three segments; propod 1.61–2.05 (mean 1.83, n=4) times as long as carapace; 10.4 (n=1) times longer than dactyl ( Fig. 2 E), dactyl long and slender with a tuft of simple setae on apex ( Fig. 2 F).

Male pleopod 1, endopod posterior margin with short simple setae, anterior margin with short stout setae, distal margin with a cluster of hook setae, distal lobe not well developed ( Fig. 3 B). Male pleopod 2 with appendix interna as long as appendix masculina, with hook setae; appendix masculina with strong and long acute simple setae on distal and anterior margins ( Fig. 3 C). Female pleopod 1 with endopod leaf like bearing plumose setae in all margins ( Fig. 3 D). Female pleopod 2 appendix interna with blunt apex bearing a cluster of hook setae ( Fig. 3 E). Uropod exopod much longer than endopod, with a complete diaresis and a stout seta on its distal seventh ( Fig. 3 A).

Color in life. Body somewhat transparent to light pink (especially on carapace) with tip of rostrum, base of pereopods and telson reddish. Abdomen with red markings on inter-segmental area.

Type locality. 21o13’S / 40o14’W, 573m, Brazil, off Rio de Janeiro state.

Distribution. Southwestern Atlantic: Brazil (Rio Grande do Sul, Rio de Janeiro and Espírito Santo states) in depths from 533 to 666 m.

Remarks. The closest related species to Plesionika revizeei n. sp. is P. willisi , described as Parapandalus by Pequegnat (1970) to the Gulf of Mexico. A careful analysis of the type series deposited at NMNH showed that these two species are really distinct. The main feature that distinguish them is the epipods on pereopods 1–4.

In P. revizeei n. sp. the pereopod 1 presents a well developed epipod and pereopods 2–4 present a reduced epipod (clearly defined, but small). In all examined material (13 specimens) of P. willisi the epipods were absent. Pequegnat (1970) didn´t mention about epipods in its original description, but in the key presented to genera of Pandalidae the feature leading to Parapandalus is the absence of epipods on pereopods. After the original description of P. willisi ( Pequegnat,1970) few works reported this species, being the most important that of Cruz and Fransen (2004) which mention some features missing in the original description, as the absence of epipods on pereopods.

A comparison between some diagnostic features of these two species is shown at Table 1 . The rostrum length and the rostral formula are overlapping in some aspects but P. revizeei n. sp. generally presents fewer dorsal teeth than P. willisi ( Fig. 4 A). The rostral teeth distribution is similar in the two species (with the basal third unarmed, second third with closely spaced teeth and distal third with widely spaced teeth) ( Figs. 1 A, 4A). In P. willisi there is a postrostral ridge that continues to the middle of the carapace ( Pequegnat 1970) this feature was also observed in the material examined at NMNH ( Fig. 4 A), while in P. revizeei n. sp. none postrostral ridge was observed.

The abdominal somite 3 posterodorsal surface and the pleura of abdominal somites 3 and 4 are similar in both species ( Figs. 2 A, 4D). The pleura of somite 5 however, is pointed in P. re v i z e e i n. sp. and rounded in the material of P. willisi examined at NMNH ( Figs. 2 B, 4E). Pequegnat (1970) didn´t observe this feature, but Cruz and Fransen (2004) observed a pointed pleura in Colombian material.

The relative size of telson and abdominal somite 6 is slightly distinct between the two species ( Table 1 ) the telson of both species has three pairs of dorsolateral spines, and three pairs of distal spines ( Figs. 3 A, 4F). The antennular peduncle and the antennal scale are similar in both species ( Figs. 1 B, 4B and 1C, 4C).

According Pequegnat (1970) and Cruz and Fransen (2004) the carpus of pereopod 2 from P. willisi shows a tendency to present a lower number of articles (17–19) than P. revizeei n. sp. (19–27) with a slight overlapping. Considering the examined material of P. willisi ( NMNH) the range of articles in this species becomes wider (16– 20) but this tendency remains.

The material of P. willisi examined by Cruz and Fransen (2004) and examined at NMNH present the orbital margin strongly convex in ventral part and almost straight in dorsal half, distinct from P. revizeei n. sp. that presents an uniform, slightly concave orbital margin.

Plesionika willisi Plesionika willisi Plesionika revizeei n. sp. literature material examined

Regarding the remaining Plesionika Atlantic species P. revizeei n. sp. is related with a group of species presenting epipods on at least pereopods 1–2, second pereopods equal, rostrum dorsal margin armed in all length and rostrum more than 1.5 (mean) times as long as carapace ( Cruz & Fransen 2004 and present key) that includes only P. e d w a rd s i i and P. longipes . The rostral formula easily distinguish these two species from P. revizeei n.sp.. The presence of well developed epipods on pereopods 3–4 in P. longipes is also a distinctive feature that can helps identification. Besides that, regarding rostrum morphology (rostrum dorsal margin armed in all length with widely spaced teeth) P. revizeei n. sp. is closely related also with Plesionika miles A. Milne Edwards, 1883 . Distinctive features between P. revizeei sp. nov. and P. m i l e s are the post rostral teeth (five in P. miles versus one in P. revizeei n. sp.) and the epipods on pereopods 2–4 (well developed in P. m i l e s versus reduced in P. revizeei n. sp.).

Etymology. In honor of the Brazilian oceanographic Program named REVIZEE. This Program intended to make a fauna survey of the Brazilian continental shelf and slope, sampling a scientific valuable material and contributing to the South Atlantic deep sea knowledge.

Figures

FIGURE 1. Plesionika revizeei n. sp., ovigerous female (16 mm), MNRJ 14663. A. lateral view (as - antennal spine; ps-pterygostomian spine); B. right antennular peduncle, ventral view (st-stylocerite); C. right antennal scale, ventral view; D. left basis and epipods of maxilliped 3 and pereopods 1 – 5, lateral view (Mxp-maxilliped; P-pereopod).

FIGURE 2. Plesionika revizeei n. sp., male (14.4 mm), MNRJ 21509. A. abdominal somites 3 – 5, dorsal view; B. abdominal somites 3 – 5, lateral view. Ovigerous female (16 mm), MNRJ 14663. C. left pereopod 2, dorsal view; D. right pereopod 2, dorsal view. Male (14.4 mm), MNRJ 21509. E. left pereopod 3, propod and dactyl; F. left pereopod 3, dactyl.

FIGURE 3. Plesionika revizeei n. sp., ovigerous female (16 mm), MNRJ 14663. A. telson and uropods, dorsal view. Male (14.4 mm), MNRJ 21509. B. right endopod of first pleopod, lateral view; C. right appendix masculina and interna of second pleopod, lateral view. Ovigerous female (16 mm), MNRJ 14663. D. right endopod of first pleopod, lateral view; E. appendix interna of second pleopod, lateral view.

FIGURE 4. Plesionika willisi (Pequegnat, 1970), allotype, male (14.5 mm), USNM 128803. A. Carapace, lateral view (asantennal spine; ps-pterygostomian spine). Female (10.9 mm), USNM 282666. B. right antennular peduncle, ventral view (ststylocerite); C. right antennal scale, ventral view. Allotype, male (14.5 mm), USNM 128803. D. abdominal somites 3 – 5, dorsal view. E. abdominal somites 2 – 6, lateral view. Paratype, male (10.6 mm), USNM 128804. F. telson and uropods, dorsal view.

Tables

TABLE 1. Comparison between P. willisi (literature and material examined) and P. revizeei n. sp. (AS – abdominal somite).

Rostrum length	twice to more than twice as long 1.73–2.17 as long as cara- as carapace pace (mean 1.99, n=12)	1.48–2.29 as long as carapace (mean 1.87, n=12)
Rostral formula	12–15 +1 dorsal 12–15 +1 dorsal 18–22 ventral 17–23 ventral	9–13 + 1 dorsal 17–30 ventral
AS 3 posterodorsal margin	rounded rounded	rounded
AS 3, 4 pleura	rounded rounded	rounded
AS 5 pleura	pointed rounded	pointed
Telson	0.7 as long as AS 6 0.70–0.77 as long as AS 6 (mean 0.73, n=9)	0.79–1.26 as long as AS 6 (mean 0.92, n=12)
Antennal scale	4–5 times as long as wide 0.74–1.33 as long as cara- pace (mean 1.07, n=15)	1.03–1.14 as long as carapace (mean 1.08, n=5)
Pereopod 2 carpus	17–19 16–20 (mean 17.61, n=13)	19–27 (mean 22.2, n=16)
Epipods	absent in all pereopods absent in all pereopods	present in pereopods 1–4