Plesionika miles (A. Milne Edwards, 1883 )

Cardoso, Irene, 2009, Report on some Plesionika Bate, 1888 and first record of Stylopandalus Coutiére, 1905 (Caridea, Pandalidae) from Brazilian waters, Zootaxa 2120, pp. 53-68 : 61-62

Plesionika miles (A. Milne Edwards, 1883)

( Figs. 5 , 6 )

Material examined: REVIZEE – Fishery: E-0533, 19o42’S, 39o26’W, 239m, 4 ovigerous females (8–9mm), 2 males (7, 9mm), MNRJ 14661; E-0542, 21o25'S, 40o 13'W, 259m, 2 ovigerous females (11, 12mm), 2 females (8.5, 9.5mm), 2 males (10.5, 10.5mm), MNRJ 14670; E-0504, 14o28'S, 38o54'W, 278m, 1 male (9mm), MNRJ 14672. UFPE: Akaroa, 5B, 0 9o 05`S, 36o51W, 46m, 1 male (5.3 mm), UFPE 9564.

Description: Rostrum long, curved downwards in proximal region, and slightly upwards beyond antennular peduncle; far overreaching scaphocerite, 2.1–2.7 (avg. 2.5, n=5) times as long as carapace; ventral margin with 28–35 (avg. 31, n=5) teeth, anterior teeth closely disposed, distal teeth well spaced; dorsal margin with 13–16 (avg. 14, n=5) teeth, anterior teeth well spaced, distal teeth closely disposed, two to three postrostral teeth the proximal one variably movable; eye very large, subspherical, pear like, with ocellus; small antennal and strong pterygostomian spines present; carapace smooth ( Fig. 5 A). Stylocerite outer margin straight, inner margin convex, apex triangular, almost reaching the distal margin of first antennular peduncle article ( Fig. 5 B). Scaphocerite 0.78–1.11 (avg. 0.99, n=12) as long as carapace, with blunt apex, distal tooth strongly overreaching blade ( Fig. 5 C). Maxilliped III with epipod, penultimate segment 0.90–1.34 (avg. 1.02, n=9) times longer than terminal segment. Pereopods 1–3 with epipod, pereopod 4 with reduced epipod, pereopod 5 without epipod. Pereopod 2 chelate, equal in size ( Fig. 5 D, E), carpus with 15–19 (avg. 17, n=11) articles. Pereopod 3 overreaching scaphocerite with carpus distal 1/8–1/10; propod 0.52–0.68 (avg. 0.6, n=5) times as long as carapace; 2.69–3.55 (avg. 3, n=5) times longer than dactyl ( Fig. 6 A), dactyl long, slender, with one distal stout setae ( Fig. 6 B). Dorsal surface of abdominal somite 3 rounded and pronounced; pleura of somites 3 and 4 rounded, pleura of somite 5 triangular and acute, margin inferior strongly concave ( Fig. 6 C). Telson 0.72–0.90 (avg. 0.8, n=9) times as long as abdominal somite 6; sulcate on dorsal midline, with three pairs of dorsolateral stout setae, and two pairs of stout distal setae ( Fig. 6 D).

Distribution: Western Atlantic: Martinique, Dominique, Brazil (Alagoas, Bahia, Espírito Santo and Rio de Janeiro). Adults living in depths from 54 to 700 m (modified from Crosnier & Forest, 1968; 1973).

Remarks: Based on a material from Western Atlantic collected by “Blake” expedition, A. Milne Edwards (1883) figured Plesionika miles (as Pandalus miles ) from Martinique Island for the first time. According to the new edition ( Forest & Holthuis, 1997) of the study done by A. Milne Edwards in 1883, the Museum of Comparative Zoology no longer has any of the specimens of P. miles figured originally. There are two lots, however, in the Muséum National d´Historie Naturelle (MNHN), Paris (Na 2024, Na 2025) collected by “Blake”, they are from Dominica and one has the indication “ Type ”. Forest & Holthuis (1997) also considered the possibility that the indications in legend of the original figure may be incorrect, or that the Paris Museum material are possible syntypes of P miles . Crosnier & Forest (1968; 1973) examined and figured the P. m i l e s material from MNHN, in order to compare it with one species that they described ( Plesionika brevipes Crosnier & Forest, 1968 ).

Plesionika brevipes was found in the Eastern Atlantic and according to Crosnier & Forest (1968; 1973) it is very closely related with P. m i l e s, mainly in carapace and rostrum morphology. The features cited by Crosnier & Forest (1968; 1973) to distinguish P. brevipes from P. m i l e s and the comparison with Brazilian material features are presented in Table 1. The Brazilian material fits in all the main features cited by them as distinctive to P. m i l e s.

Other species close related with P. m i l e s is Plesionika willisi described by Pequegnat (1970) with material from the Gulf of Mexico. The author ( Pequegnat, 1970) pointed as the main differences between these species, the number of rostrum ventral teeth, 18–22 in P. willisi and 34–35 in P. m i l e s (avg. 31 in Brazilian P. miles ), and the pereopods that are considerably longer in P. willisi . Cruz & Fransen (2004) pointed that P.

willisi presents the telson about 0.7 length of abdominal somite 6 (avg. 0.8 in Brazilian P. miles ), carpus of pereopod 2 with 17–19 articles (15–19 in Brazilian P. m i l e s) and the pereopod 3 overreaching sacphocerite by distal part of merus (overreaching by carpus distal 1/8–1/ 10 in Brazilian P. miles ).

A striking question about P. m i l e s is regarding the presence of epipods on pereopods. De Man (1920) commented that the presence of epipods on pereopods of four Parapandalus species (P. m i l e s, P. escatilis , P. longicauda and P. stylopus ) was unknown. Crosnier & Forest (1968) affirms that the epipods are absent in the pereopods of P. brevipes but no comments were done about the epipods in P. miles . Cruz & Fransen (2004) included P. m i l e s in the key to Atlantic species of Plesionika in a group that lacks epipods on pereopods, but no comments were done. The Brazilian material of P. miles presents epipods in pereopods 1–4 and probably the syntype series of this species also has these structures which have been overlooked for all these years.

Figures

FIGURE 5. Plesionika miles (A. Milne Edwards, 1883), male, MNRJ 14661 (carapace length 9 mm); A, lateral view; B, right antennule, dorsal view; C, right scaphocerite, dorsal view (as, antennal spine; ps, pterygostomian spine; st, stylocerite); D, right pereopod 2, lateral view; E, left pereopod 2, lateral view.

FIGURE 6. Plesionika miles (A. Mine Edwards, 1883), ovigerous female, MNRJ 14661 (carapace length 11.4 mm); A, propod and dactyl of pereopod 3, lateral view; B, dactyl of pereopod 3, lateral view. P. m i l e s (A. Mine Edwards, 1883), ovigerous female, MNRJ 14661 (carapace length 9 mm); C, pleura of abdominal somites 3 – 5, lateral view (AS, abdominal somite). P. miles (A. Mine Edwards, 1883), male, MNRJ 14661 (carapace length 9 mm); D, telson and uropods, dorsal view.