Petalosarsia jonesi, Akiyama, Tadashi & Gerken, Sarah, 2012

Akiyama, Tadashi & Gerken, Sarah, 2012, The Cumacean (Crustacea: Peracarida) Genus Petalosarsia (Pseudocumatidae) from the Pacific Ocean, Zootaxa 3320, pp. 1-35 : 19-22

Petalosarsia jonesi sp. nov.

( Figs. 13–15 )

Material examined. Holotype, ovigerous female, 2.99 mm (NSMT-Cr 22083), western region of the Sulu Sea, 08°06.41ˏN, 118°29.18ˏE – 08°07.32ˏN, 118°28.44ˏE, 796–804 m (KH-02-4, St. 8A), 23–24 November 2002. Paratype ovigerous female, 2.68 mm (NSMT-Cr 22084), paratype young male, posterior portion of pleon lost, 0.79 mm in carapace length (NSMT-Cr 22085), western region of the Sulu Sea, 08°06.41ˏN, 118°26.49ˏE – 08°07.04ˏN, 118°26.06ˏE, 688–693 m, (KH-02-4, St. 7B), 23 November 2002.

Description. Ovigerous female ( Figs. 13 , 14 ). Integument weakly calcified and smooth. Carapace laterally compressed, length 1.9 times width, length 1.4 times depth, length 0.29 times total body length; dorsal surface arched, without dorsolateral carina and transverse ridge; ventral margin smooth; anterolateral angle and antennal notch hardly discernible, but defined by 2–3 teeth ( Fig. 13 C, D); width of anterior portion of pseudorostral lobes (between teeth of left and right antennal notch), 0.48 times width of carapace; pseudorostrum slightly dorsally directed, 0.26 times length of carapace. Width of triangular eye lobe 0.13 times width of carapace; pseudorostrum long and slightly dorsally directed, 0.26 times carapace length. Pereon 0.62–0.65 times length of carapace; pereonite 4 with a prominent tooth projecting forward on dorso-posterior margin. Pleon very slender, 0.52 times length of carapace.

Antenna 1 ( Fig. 13 E) 1st article of peduncle 1.2 times combined length of 2nd and 3rd articles; 2nd and 3rd peduncular articles equal in length; distal end of 2nd article not fringed with thin collar; main flagellum of 3 articles, 0.7 times 1st peduncular article; 1st article of main flagellum 2.0 times combined length of 2nd and 3rd; accessory flagellum minute, with 2 apical setae. Antenna 2 ( Fig. 13 F) bi-articulate, with a plumose seta on each article. Maxilliped 1 ( Fig. 13 J) with 1 branchial lobule; basal article subequal in length to remaining distal articles. Maxilliped 2 ( Fig. 13 K) basis, 1.0 times combined length of ischium, merus, carpus and propodus, with a short seta near proximal end. Maxilliped 3 ( Fig. 13 L) basis 1.0 times distal articles together, with 2 plumose setae on inner margin; carpus with 5 plumose setae on inner margin.

Pereopod 1 ( Fig. 14 A) basis 1.0 times combined length of ischium and carpus, with 3 plumose setae on inner margin; length of carpus 2.4 times width and 3.2 times dactylus length, 0.85 times basis length. Pereopod 2 ( Fig. 14 B) basis 0.75 times distal articles together, with 2 plumose setae on inner margin; dactylus much longer than carpus. Pereopod 3 ( Fig. 14 C) basis 2.2 times length of remaining distal articles, with 2 plumose setae; exopod absent. Pereopod 4 ( Fig. 14 D) basis 1.6 times length of remaining distal articles, with plumose seta; exopod absent. Pereopod 5 ( Fig. 14 E) basis 0.9 times length of remaining distal articles.

Uropod ( Fig. 14 F) peduncle slender, 1.31 times pleonite 6 length, 0.59 times exopod, 0.50 times endopod length, with minute setae on inner margin; near inner distal corner not serrated; exopod 0.85 times endopod length, with 2 setae on outer margin and brush of setae on inner margin; terminal seta long; endopod with 4 spiniform setae on inner margin; terminal setae small. Telson somewhat flattened at posterior margin, 0.25–0.36 times pleonite 6 length.

Paratype young male, posterior half of abdomen and uropods lost. Overall appearance similar to ovigerous females. Pleon with no pleopods ( Fig. 15 A). Carpus of pereopod 1 shorter than female ( Fig. 15 B). Pereopod 4 with developed exopod ( Fig. 15 C).

Etymology. The species name is dedicated to Dr. Norman S. Jones, who made great contribution to cumacean taxonomy and described Petalosarsia longirostris .

Distribution. Sulu Sea, 688–804 m depth.

Remarks. The present new species is closely allied to Petalosarsia longirostris Jones, 1973 from the tropical deep Atlantic, 1624–1796 m, with a combination of characters which differ from the other Japanese species: (1) carapace without dorsolateral carina, dorsal surface arched, (2) antenna 1 slender, 2nd article of peduncle equal in length to the 3rd, (3) inner distal corner of carpus in pereopod 1 not near rectangular, but forming obtuse angle, (4) pereopod 2 with some stiff, naked setae on inner margin of distal three articles, arranged like a comb, (5) uropod peduncle slender, shallowly concaved on proximal inner margin, not completely covering opening of anus when left and right uropods closed. Petalosarsia jonesi can be distinguished from P. longirostris by (1) inferior margin of carapace not serrated, (2) dorsal crest of pereonite 4 with a marked spine projecting forward, (3) exopod on pereopod 3 absent, (4) uropod peduncle a little longer than pleonite 6, and (5) uropod exopod with a brush of simple setae on inner margin. Another noteworthy character is that the basis of maxilliped 2 lacks round plate or other ornaments on the ventral surface or inner margin.

Figures

FIGURE 13. Petalosarsia jonesi sp. nov., ovigerous female. A, lateral view; B, anterior portion of body, from above; C, D, anterolateral angle of carapace; E, antenna 1; F, antenna 2 and labrum; G, mandibles; H, maxilla 1; I, maxilla 2; J – L, maxillipeds 1 – 3.

FIGURE 14. Petalosarsia jonesi sp. nov., ovigerous female. A – E, pereopods 1 – 5; E, uropod with pleonite 6.

FIGURE 15. Petalosarsia jonesi sp. nov., young male. A, anterior portion of body, lateral view; B, distal three articles of pereopod 1; C, pereopod 4.