Eudorella bathyhwanghaensis, Akiyama, Tadashi & Gamô, Sigeo, 2012

Akiyama, Tadashi & Gamô, Sigeo, 2012, The cumacean Genus Eudorella (Crustacea: Peracarida) from Japanese Waters, Northwest Pacific, and E. suluensis sp. nov. from the Sulu Sea, Indo-West Pacific, Zootaxa 3319, pp. 1-56 : 15-19

Eudorella bathyhwanghaensis sp. nov.

( Figs. 10–12 )

Material examined. Holotype preparatory female, 7.5 mm (NSMT-Cr 22111), allotype adult male, 6.5 mm (NSMT-Cr 22112), Tosa Bay, 32°48.0ˏN, 133°46.6ˏE – 32°47.6ˏN, 133°45.4ˏE, 1053–1056 m, 27 June, 2000 (KT- 00-8, St. BT-4), 27 June 2000. Paratypes; 2 preparatory females, 6.6–6.8 mm, 1 subadult male (NSMT-Cr 22113), 32°57.6ˏN, 133°44.7ˏE – 32°57.6ˏE, 133°42.0ˏE, 994–1001 m, 25 June, 2000 (KT-00-8, St. BT-3) 25 June 2000; 2 preparatory females, 4 subadult males (NSMT-Cr 22114), Tosa Bay, 33°11.1ˏN, 133°40.1ˏE – 33°11.9ˏN, 133°41.0ˏE, 518–522 m (KT-00-8, St. BT-1), 25 June 2000; 1 ovigerous and 4 preparatory females, 5.8–6.8 mm, 1 subadult male, 6.3 mm, 4 juveniles, 1 manca (NSMT-Cr 22115), Enshu Nada, 34°07.58ˏN, 137°57.91ˏN – 34°06.73ˏN, 137°56.89ˏE, 890–1024 m (KT-02-5, St. EN-1), 26 May, 2002; 3 preparatory females, 5.7–6.4 mm (NSMT-Cr 22116), Okinawa Trough, 28°32.22ˏN, 127°01.84ˏE – 28°31.05ˏN, 127°01.49ˏE, 576–594 m, (KH-05- 1, St. OT-6) 13 May 2005; 1 ovigerous female, 6.9 mm (NSMT-Cr 22117), Shima Spur, 34°00.62ˏN, 136°52.76ˏE – 33°59.40ˏN, 136°52.75ˏE, 780.6–818.4 m, 24 November, 2005 (KT-05-30, St. KB-1-2) 24 November 2005; 1 ovigerous female, 7.6 mm (NSMT-Cr 22118), 32°06.14ˏN, 129°28.96ˏE, 603 m (N275, St. K2), 3 December, 2007; 5 juveniles (NSMT-Cr 22119), off Kushimoto, 33°25.97ˏN, 135°59.29ˏE – 33°25.24ˏN, 135°58.58ˏE, 1021–1031 m (KT-05-30, St. KM-1-1), 24 November, 2005

Description. Preparatory females and ovigerous females ( Figs. 10 , 11 ). Body moderately calcified. Carapace length 0.18–0.20 times total body length, 1.1–1.4 times greatest width and 1.2–1.3 times depth; frontal margin markedly serrated ( Fig. 10 C); antennal notch narrow, with 1–2 teeth on lower end; anterolateral corner round; anterior half of inferior margin with 11–14 teeth. Pereon 1.2–1.4 times carapace length. Pleon 0.55–0.58 times total body length; dorso-posterior end of 5th pleonite with no long seta.

Antenna 1 ( Fig. 10 D) 1st article of peduncle short, with no setae on lower margin, 2–3 setae on inner margin; 3rd articles of peduncle shorter than 2nd, with 4–5 plumose setae and 1 simple seta on outer margin, 4–6 plumose setae on inner margin, 1–2 plumose or simple setae on frontal margin; main flagellum 1st article with 2–4 plumose setae on outer margin; accessory flagellum much shorter than 1st article of main flagellum. Antenna 2 ( Fig. 10 E) with with 2–3 plumose setae on lower margin in addition to 3 plumose setae on outer margin. Maxilliped 1 ( Fig. 10 I) with 6–8 branchial lobules. Maxilliped 2 ( Fig. 10 J) basis length shorter than combined lengths of succeeding 3 articles, with a group of short setae on inner margin and one simple seta on ventral surface. Maxilliped 3 ( Fig. 11 A) basis length 1.1 times distal articles combined, with 13–17 and 10–12 plumose setae on inner margin and ventral surface, respectively; ischium without spine on inner margin; carpus with 9–12 plumose setae on inner margin.

Pereopod 1 ( Fig. 11 B, distal 5 articles lost in the illustrated specimen) basis length 0.6–0.7 times length of distal articles combined, with 2–3 very robust spiniform setae on ventral surface in addition to plumose setae on inner and outer margin; propodus length 1.3–1.5 times carpus and 1.9–2.2 times dactylus. Pereopod 2 ( Fig. 11 C) basis length 0.6–0.7 times distal articles combined; carpus 1.2–1.3 times merus; distal margin of propodus with deep notch for nearly entire length of article; dactylus slightly swollen, with 16–17 stiff setae on lateral margin and apical end. Pereopod 3 ( Fig. 11 D) basis length 1.6–2.4 times as long as distal articles combined. Pereopod 4 ( Fig. 11 E) basis 1.7–2.2 times the distal articles combined. Pereopod 5 ( Fig. 11 F) basis 1.2–1.5 times distal articles combined.

Uropod ( Fig. 11 G). Peduncle length 1.37–1.54 times pleonite 6 length, 0.94–1.06 times exopod, and 0.87–0.96 times 1st article of endopod, with 4–6 setae on inner margin. Exopod length 0.85–0.95 times 1st article of endopod and with 12–15 plumose setae on inner margin and apical end, and with 4–5 simple setae on dorsal surface. Endopod 1st article length 4.1–5.7 times that of 2nd article and with 15–19 spiniform setae on inner margin and 5–8 setae on outer margin; 2nd article with 3–5 spiniform setae on inner margin; terminal robust setae defined at base.

Allotype adult male ( Fig. 12 ). Carapace length 0.22 times total body length, 1.4 times greatest width, latter being subequal in length to depth; upper front corner round, with some short setae; frontal margin serrated with 7 teeth; antennal notch absent; anterolateral corner with 3 teeth ( Fig. 12C ). Pereon length 1.1 times carapace length. Pleon 0.54 times total body length; dorso-posterior end of 5th pleonite with no long setae; pleonite 6 slightly elongate posteriorly, reaching opening of anus.

Antenna 1 ( Fig. 12D ) 3rd article of peduncle shorter than 2nd, with 3 plumose setae and 1 simple seta on outer, 4 plumose setae on inner, and 1 plumose seta on frontal margin. 4-articulate main flagellum longer than 2nd joint of peduncle. Accessory flagellum length 1.2 times 1st article of main flagellum and 0.6 times combined length of 1st and 2nd articles of main flagellum. Antenna 2 ( Fig. 12E ) with 6 plumose setae on basal articles; distal portion of flagellum lost during collection. Maxilliped 3 ( Fig. 12F ) basis 1.5 times distal articles combined, with 12 and 9 plumose setae on inner margin and ventral surface, respectively.

Pereopod 1 ( Fig. 12G ) basis length 0.9 times distal articles combined, with 2 robust spiniform setae on ventral surface; propodus 1.3 times carpus and 1.9 times dactylus. Pereopod 2 ( Fig. 12H ) basis length 1.1 times distal articles combined; carpus 1.4 times merus; dactylus with 16 stiff setae projecting radially. Pereopod 3 ( Fig. 12I ) basis 3.0 times distal articles combined; carpus with 1 robust, curved seta distally, and 4 straight setae on lateral margin; propodus with 1 robust, curved seta on lateral margin; terminal seta on dactylus slightly curved. Pereopod 4 and 5 ( Fig. 12J, K ) bases 2.7 and 1.7 times distal articles combined respectively. Pleopod 1 normal ( Fig. 12L ).

Uropod ( Fig. 12M ) peduncle length 1.67 times as long as pleonite 6 and 0.83 times exopod, 0.60 times endopod, with 10 setae on inner margin. Exopod length 0.84 times 1st article of endopod, with 15 weakly ciliated setae on inner margin and apical end, 4 short simple setae on dorsal surface. Endopod 1st article 6.3 times 2nd article, with 34 small spiniform setae and 2 simple setae on inner margin, 12 short simple setae on outer margin; 2nd article with 4 spiniform setae on inner and 3 short simple setae on outer margin; terminal spiniform setae minute, defined at base.

Etymology. The species name refers to the close relationship of the present new species with Eudorella hwanghaensis , and its deeper, bathyal habitat.

Remarks. The present new species is very similar to Eudorella hwanghaensis Hong & Park, 1999 , from the Yellow Sea. Female specimens of the present new species can be discriminated from E. hwanghaensis by (1) basal article of antenna 1 main flagellum with 2–4 ˏplumoseˏ setae (3–5 ˏsimpleˏ setae) on outer margin, (2) uropod peduncle slightly shorter than endopod basal article (equal or longer than endopod basal article in E. hwanghaensis ). The following characters show incomplete distinctions: (1) Antenna 2 with 2–3 plumose setae on lower margin (3–5 in E. hwanghaensis ), and (2) basis of pereopod 1 with 2–3 robust spiniform setae on ventral surface (1–2 in E. hwanghaensis ).

The adult male of E. bathyhwanghaensis is discriminated from that of E. hwanghaensis as follows. (1) The secondary sexual character of pereopod 3 is different; only one seta out of 5 at distal corner on carpus is unusually stiff and curved; and 4 remaining simple setae on the article are normal in the genus (all 5 setae of carpus in E. hwanghaensis are unusual: two distal setae curved and stiff, remaining 3 unusually long). (2) The uropod is elongate, the combined length of peduncle and endopod four times that of pleonite 6 (versus nearly three times in E. hwanghaensis ), and the setae on the rami are short or minute (normal for the genus in E. hwanghaensis ).

E. bathyhwanghaensis also resembles E. ryukyuensis Akiyama & Gamô, 2005 . Females of the former species are discriminated from the latter as follows. (1) Antenna 1 main flagellum basal segment with 2–3 plumose setae (9 plumose setae in E. ryukyuensis ). (2) Robust spiniform setae on ventral surface of basis of pereopod 1 arranged linearly (in triangular form in E. ryukyuensis ). (3) Combined length of propodus and dactylus longer than carpus in pereopod 2 (subequal in length in E. ryukyuensis ). The secondary sexual character of pereopod 3 in the adult male specimen of E. bathyhwanghaensis is different from the adult male of E. ryukyuensis , where pereopod 3 does not show any secondary sexual characters ( Akiyama & Gamô 2005).

Distribution. Pacific coast of southern coast of Honshu, off Kyusyu and Nansei Islands, the East China Sea, 576–1056 m.

Figures

FIGURE 10. Eudorella bathyhwanghaensis sp. nov., preparatory female. A, body, lateral view; B: anterior portion of body, from above C, anterior portion of carapace; D, antenna 1; E, antenna 2; F, mandibles; G, maxilla 1; H, maxilla 2; I, J, maxillipeds 1, 2.

FIGURE 11. Eudorella bathyhwanghaensis sp. nov., preparatory female. A, maxilliped 3; B: basis of pereopod 1; C – F, pereopods 2 – 5; G, uropod with pleonite 6.

FIGURE 12. A – M, Eudorella bathyhwanghaensis sp. nov., adult male. A, body, lateral view; B: anterior portion of body, from above C, anterior portion of carapace; D, antenna 1; E, antenna 2; F, maxilliped 3; G – K, pereopods 1 – 5; L, pleopod 1; M, uropod with pleonite 6. N, subadult male, distal three articles of pereopod 3.