Lebbeus armatus ( Owen, 1839 )

Komai, Tomoyuki, 2015, Reinstatement and redescription of Lebbeus armatus (Owen, 1839), long synonymized with L. groenlandicus (Fabricius, 1775), and description of one new species from the southwestern Sea of Okhotsk, Hokkaido, Japan (Crustacea: Decapoda: Caridea: Thoridae), Zootaxa 3905 (4), pp. 451-473 : 452-462

Lebbeus armatus ( Owen, 1839)

Figs. 1–6

Hippolite armata Owen, 1839: 88 , pl. 27, fig. 2.

Hippolyte aculeata .— Brandt 1851: 118 (in part).

Hetairus groenlandica .— Brashnikov 1907: 155, fig. 19.— Derjugin & Kobjakova 1935: 112, 142.— Kobjakova 1936: 222; 1937: 108; 1958: 227.

Spirontocaris groenlandica .— Balss 1914: 45.— Yokoya 1933: 24.— Urita 1942: 16.

Lebbeus groenlandica .— Vinogradov 1950: 203, pl. 14, fig. 53.— Igarashi 1969: 5, pl. 5, fig. 15.— Adrianov & Kussakin 1998: 264.

Lebbeus groenlandicus .— Holthuis 1947: 9 (in part).— Kubo 1960: 105, pl. 52, fig. 1; 1965: 616, fig. 978.— Miyake et al. 1962: 123.— H.S. Kim & Park 1972: 203, pl. 4, fig. 6.— Motoh 1972: 31, 42, pl. 9, figs. 1, 2; 2008: 18.— Hayashi 1976: 17; 1992a: 120; 1992b: 344 (key), fig. 232; 1992c: 439, figs. 233f, 234f. — H.S. Kim 1976: 143; 1977: 274, pl. 25, 26, fig. 53a–c, textfigs. 113, 116; 1985: 67.— Miyake 1982: 53, pl. 18, fig. 3.— Takeda 1982: 25, fig. 73.— Komai 1991: 72; 1994: 82; 2008: 257, fig. 21.16.— Komai et al. 1992: 193; 2004: 122 (table 1).— Chace 1997: 51.— Cha et al. 2001: 112, unnumbered fig.— Sokolov 2001: 109, fig. 7.— Motoh & Toyota 2005: 34, fig. 3-10.— Motoh & Yamaguchi 2009: 216, fig. 3E.— De Grave & Fransen 2011: 425 (part).— J.N. Kim 2012: 37, fig. 16, pl. 12.— Komatsu 2014: 190.

Material examined. Sea of Okhotsk: off Kitami Monbetsu, Hokkaido, 44°48’N, 143°21’E to 44°44’N, 143°26’E, 142– 138 m, 17 November 1991, RV “Hakuyo-maru”, trawl, 2 females (cl 32.0, ca. 32.0 mm), 1 ovigerous female (cl 35.2 mm), NSMT-Cr 1585; off Kitami Monbetsu, 44°53.48’N, 143°22.28’E, 144–148 m, 16 November 1991, RV “Hakuyo-maru”, trawl, 1 male (cl 27.0 mm), NSMT-Cr 1598; off Kitami Monbetsu, 44°48.7’N, 143°36.5’E to 44°44.8’N, 143°42.4’E, 153–156 m, 16 November 1991, RV “Hakuyo-maru”, trawl, 1 ovigerous female (cl 29.3 mm), NSMT-Cr 1609. Pacific side of Hokkaido: off Kushiro, March 1961, 1 ovigerous female (cl 28.0 mm), NSMT-Cr 1692. Sanriku: off Miyako, Iwate Prefecture, depth not recorded, December 1982, commercial trawler, coll. T. Komai, 1 female (cl 17.4 mm), HUMZ-C 00023; same locality, January 1987, commercial trawler, 1 male (cl 15.0 mm), HUMZ-C; Sea of Japan: Peter the Great Bay, off Vladivostok, depth not recorded, trawl, coll. Y. M. Yakovlev, 1 male (cl 14.4 mm), 2 females (cl 24.0, 32.3 mm), CBM-ZC 3821; Musashi Bank, 44°40.48’N, 140°02.38’E to 44°39.53’N, 140°02.83’E, 198–206 m, 28 May 2011, RV “Tansei-maru”, KT 11-9 cruise, stn M2, beam trawl with 3 m span opening, 1 female (cl 7.8 mm), NSMT-Cr 22577; off Otaru, Hokkaido, ca. 150–200 m, 21 June 2003, commercial trap, coll. Y. Matsuzawa, 1 ovigerous female (cl 28.4 mm), CBM-ZC 7356; off Hokkaido, 200–250 m, April 2004, commercial trap, coll. Y. Matsuzawa, 1 female (cl 36.7 mm), CBM-ZC 7914; North Yamato Bank, 43°23.0’N, 135°05.0’E, 150–200 m, 30 May 1996, trawl, coll. Y. M. Yakovlev, 2 females (cl 18.6, 19.2 mm), CBM-ZC 4990; off Togi, Noto Peninsula, Ishikawa Prefecture, 20 May 2007, commercial trap, 2 males (cl 22.6, 24.5 mm), IMNH; Wakasa Bay, Fukui Prefecture, 36°06.03’N, 135°35.44’E to 36°06.63’N, 135°37.13’E, 336–338 m, 31 May 2009, RV “Tanshu-maru”, stn T 111, otter trawl, 2 females (cl 26.0, 28.7 mm), NSMT-Cr 22576; off Hamada, Shimane Prefecture, 35°53.59’N, 131°28.46’E, 35°53.50’N, 131°26.62’E, 342– 329 m, 9 May 2009, RV “Tanshu-maru”, otter trawl, 1 female (damaged, not measured), NSMT-Cr 22574; SE of Oki Islands, 35°54,83’N, 133°50.71’E to 35°53.33’N, 133°50.64’E, 206 m, 2 June 2009, RV “Tanshu-maru”, otter trawl, 1 male (cl 30.5 mm), 1 female (cl 34.0 mm), NSMT-Cr 22575; NW of Hinomisaki, Izumo, Shimane Prefecture, ca. 150 m, 1994, trawl, 2 males (cl 21.5, 22.8 m), 1 female (cl 21.8 mm), CBM-ZC 12596.

Redescription. Adult females. Body ( Figs. 1 , 2 A, B) robust; integument firm, surface with dense short pubescence on entire carapace and depressions on pleonal pleura; tips of spines or teeth frequently darkly pigmented generally.

Rostrum ( Figs. 2 A) directed forward or slightly ascending, nearly straight or slightly curving dorsally, far overreaching distal end of antennular peduncle but not reaching distal margin of antennal scale, 0.6–1.0 times as long as carapace, with dagger-like distal part; dorsal margin armed with 2 or 3 widely spaced small teeth in proximal 0.6–0.7, followed by 4 prominent, crested postrostral teeth; ventral margin armed with 2–4 small teeth in distal 0.4, ventral lamina moderately developed, outline of ventral margin gently convex; lateral carina conspicuous in proximal 0.6. Carapace ( Figs. 1 A, B, 2A, 3A) with high middorsal carina extending to posterior margin of carapace; postrostral teeth noticeably increasing in size anteriorly, anteriormost tooth strongest, distally overhanging rostral base, posteriormost tooth arising at 0.7 length of carapace; supraorbital tooth very strong, arising at rostral base, slightly curving dorsally in lateral view and slightly laterally in dorsal view, its dorsal margin carinate and fairly elevated (thus, surface between rostrum and supraorbital tooth forming deep channel), ventral margin slightly sinuous or convex in lateral view, merging into postrostral ridge; deep excavation just ventral to base of supraorbital tooth merging into orbit; suborbital lobe prominent, roundly subtriangular, inner margin keeled; anterolateral margin between antennal and pterygostomial teeth deeply notched at base of antennal tooth and then convex; antennal tooth very strong, far overreaching suborbital lobe, distinctly buttressed; pterygostomial tooth also strong, directed forward; postorbital region deeply depressed; branchial ridge clearly delimited, continuing to ridge supporting antennal tooth.

Pleon ( Figs. 1 A, 2B) dorsally rounded; first to fifth pleura each with shallow but distinct depressions to receive overlapping pleura. First pleomere with anterolateral margin slightly sinuous; pleuron usually with 2 (rarely 3) strong, subequal ventral teeth (ventral margin between teeth deeply concave). Second pleomere with deep transverse groove on tergum, posterior section slightly higher than anterior section; pleuron usually with 3 teeth (rarely 4 or 5), middle tooth strong, others small, sometimes abraded in large specimens. Third pleomere with posterodorsal margin fairly produced posteriorly; pleuron usually with 3 (rarely 4) ventral teeth, second tooth strongest. Fourth pleuron usually with 2–4 (most frequently 3) ventral teeth, second tooth elongate. Fifth pleuron usually with 2 (rarely 3) strongly unequal ventral teeth, posteroventral one elongate. Sixth pleomere 2.2 times as long as fifth pleomere and 1.3 times as long as high; posterodorsal margin slightly produced and bilobed ( Fig. 3 C); posterolateral process terminating in slender tooth ( Fig. 3 D); posteroventral angle strongly flared laterally, with strong tooth ( Fig. 3 C). Telson ( Fig. 3 C) about 1.9 times as long as sixth pleomere, 3.2 times longer than greatest width, gradually tapering posteriorly; dorsal surface deeply sulcate medially, proximally with prominent protuberance bearing tuft of short setae posteriorly ( Fig. 3 D); dorsolateral ridge distinct, with row of 6 or 7 spines on either side; posterior margin terminating in blunt to acute point, with 2 pairs of small spines (mesial pair stronger than lateral pair) and tufts of setae at base of median tooth ( Fig. 3 E).

Eye ( Figs. 2 A, 3A) subpyriform with eyestalk narrowing proximally; cornea small, slightly wider than eyestalk, its maximum width 0.15 of carapace length; ocellus present.

Antennular peduncle ( Figs. 2 A, 3A) reaching midlength of antennal scale. First segment longer than distal two segments combined, dorsodistal margin armed with 1 very strong, obliquely erect tooth; stylocerite elongate, faintly sinuous, reaching distal end of antennular peduncle, bearing small, low protuberance proximolaterally. Second segment about 0.6 length of first segment, armed with l strong dorsolateral distal tooth. Third segment short, armed with 1 strong dorsodistal tooth. Upper flagellum with thickened aesthetasc-bearing portion about 0.3 of carapace length; lower flagellum longer than upper flagellum, articles each with few short setae on distal margin.

Antenna ( Figs. 2 A, 3A, F) with basicerite bearing strong ventrolateral distal tooth directed slightly laterally; dorsolateral distal angle also produced into strong tooth distinctly shorter than ventrolateral distal tooth. Carpocerite falling short of midlength of antennal scale. Antennal scale 0.8 times as long as carapace and about 2.5 times as long as wide; lateral margin nearly straight or faintly sinuous; dorsal surface with blunt median ridge accompanied by narrow, deep groove laterally; distolateral tooth far overreaching rounded distal margin of lamella, supported by longitudinal keel extending to base of antennal scale. Flagellum slightly shorter than body.

Mouthparts typical for genus.

Third maxilliped ( Fig. 4 A) relatively stout, reaching or slightly overreaching distal margin of antennal scale by ultimate segment. Ultimate segment about 2.2 times as long as penultimate segment (= carpus), somewhat depressed dorsoventrally, tapering to rounded distal end only in distal 0.2; dorsal, lateral and ventral surfaces partially obscured by with numerous setae, and also with minute spiniform setae; mesial surface with numerous transverse tracts of stiff setae, also grooming apparatus; distal part circumscribed by small, darkly pigmented spines ( Fig. 5 A). Carpus short, with scattered minute spiniform setae and tufts of short transverse rows of stiff setae on dorsal and lateral surfaces; mesial surface with numerous transverse tracts of stiff setae, forming grooming apparatus. Antepenultimate segment strongly depressed in proximal half, distal part subtrigonal in cross section; lateral surface with scattered minute spiniform setae and row of longer spiniform setae on blunt longitudinal ridge; distal margin with conspicuous tooth dorsally and stronger tooth laterally, and with row of spiniform setae on either side of dorsodistal tooth and around base of distolateral tooth ( Fig. 5 B).

Strap-like, terminally hooked epipods present on third maxilliped to third pereopod, corresponding setobranchs present on first to fourth pereopods.

First pereopod ( Fig. 4 B) stout, reaching midlength of antennal scale by tip of fingers. Dactylus about 0.7 times as long as palm, terminating in 2 darkly pigmented corneous claws ( Fig. 5 E); fixed finger terminating in single corneous claw ( Fig. 5 E); both fingers each with 1 darkly pigmented, flattened spines proximal to base of terminal claw(s) on either side ( Fig. 5 E). Palm ( Fig. 5 C) subcylindrical, about twice as long as wide. Carpus widened distally, cup-like, slightly shorter than palm, lateral surface with scattered minute spiniform setae, distomesial margin with deep notch; grooming apparatus consisting of short, obliquely longitudinal row of setae on ventromesial surface of palm and several short transverse rows of setae on mesial surface of carpus ( Fig. 5 D). Merus slightly narrowing proximally, with small tubercle proximodorsally and with several sets of minute spiniform setae on proximal half of ventral margin, dorsodistal margin slightly produced, lateral surface with numerous scattered minute spiniform setae. Ischium with blunt ventrodistal angle, ventrolateral surface with minute spiniform setae.

Second pereopod ( Fig. 4 C) slender, overreaching antennal scale by about 0.3 length of carpus. Carpus divided into 7 articles, third article longest.

Third pereopod ( Fig. 4 D) overreaching antennal scale by length of dactylus; dactylus ( Fig. 5 F) 0.3–0.35 times as long as propodus, stout (about 2.5 times as long as wide), terminating in strong, darkly pigmented unguis, armed with 4–6 darkly pigmented accessory spines on flexor margin, these accessory spines noticeably increasing in size distally, distalmost spinule subconical, making tip of dactylus biunguiculate; propodus with numerous darkly pigmented spinules, arranged in irregular 3 or 4 rows, on ventral surface; carpus slightly less than half length of propodus, slightly widened distally, armed usually with 1 or 2 small spines on lateral surface; merus armed with lateroventral row of 8–15 spines extending over entire length, and 1–7 smaller additional spines not aligned with lateroventral row; ischium also with 1 small lateral spine. Fourth pereopod ( Fig. 4 E) falling far short of distal margin of antennal scale by tip of dactylus; merus with lateroventral row of 7–10 spines and 0–6 smaller additional non-aligned spines particularly on ventral surface; ischium unarmed or armed with 1 lateral spine. Fifth pereopod ( Fig. 4 F) generally similar to preceding pereopods, but merus shorter and carpus and propodus combined longer; not reaching midlength of antennal scale; propodus with brush-like grooming setae distally; carpus with 1 or 2 small spines on lateral surface; merus armed with lateroventral row of 6–9 spines and 0–3 additional smaller spines not aligned; ischium unarmed.

Protopods of pleopods in spawning molts each with deep ventrolateral lobe distally terminating in subacute or blunt point.

Uropod ( Fig. 3 G) with protopod bearing sharp posterodorsal tooth, posterolateral angle terminating in strong tooth. Exopod with small spine just mesial to strong posterolateral tooth; dorsal surface with distinct longitudinal carina lateral to midline. Endopod with distinct median carina and scattered minute setae on dorsal surface.

Eggs 2.4 x 2.0 mm in eyed stage, not counted.

Adult males. Generally similar to females except for sexual characters and smaller body size. Outer antennular flagellum ( Fig. 6 A) with thickened aesthetasc-bearing portion about 0.5 times as long as carapace; inner flagellum elongate ( Fig. 6 A) and stout, slightly tapering distally, 1.3–1.9 times as long as carapace; most articles wider than long. Endopod of first pleopod ( Fig. 6 B) rather abruptly tapering distally to terminal appendix interna in distal 0.3; mesial margin fringed with short simple setae; lateral margin sinuous, with row of moderately long plumose setae extending from base to distal 0.3. Appendix masculina of second pleopod ( Fig. 6 C) 0.7 length of appendix interna, rounded terminally, bearing numerous stiff setae on distal end to distal 0.6 of mesial surface.

Juvenile. Generally similar to adults, but additional small spines on meri of third to fifth pereopods not differentiated; minute spiniform setae on third maxilliped and pereopods also not differentiated.

Coloration in life. Carapace mottled with white and reddish brown. Pleon with brown or reddish brown transverse bands on whitish background (second to fifth pleomeres each with band). Telson whitish in anterior half, reddish brown in posterior half.

Size. Largest male cl 30.5 mm, largest female cl 36.7 mm, ovigerous females cl 28.0– 35.2 mm.

Distribution. Certain geographical range includes Kamchatka, Sea of Okhotsk, Sea of Japan, Pacific side of northern Japan extending from Hokkaido to Iwate Prefecture; 144– 338 m.

Variation. The number of ventral teeth on the second to fifth pleura of the pleon exhibits substantial variation not related to sex or size ( Table 1), although in some cases, the absence of tooth or teeth seems to be due to secondary loss caused by damage or abrasion. The second pleura usually bear three ventral teeth, although the number of the teeth on either side varies from three to five. The third pleura have three teeth at least on one side in all specimens examined. The fourth pleura have three or more teeth in vast majority of the specimens (83.3%). The fifth pleura bear two ventral teeth at least on one side in most specimens (95.8%).

Second pleura

Combination of number of teeth 2-3 3-3 3-4 4-5 Number of individuals 2 (8.3%) 19 (79%) 2 (8.3%) 1 (4.4%) Third pleura

Combination of number of teeth 2-3 3-3 3-4 Number of individuals 1 (4.5%) 19 (86.4%) 2 (9.1%) Fourth pleura

Combination of number of teeth 2-2 2-3 3-3 3-4 Number of individuals 4 (16.7%) 1 (4.2%) 14 (58.3%) 5 (20.8%) Fifth pleura

Combination of number of teeth 2-2 2-3 3-3 Number of individuals 20 (83.3%) 3 (12.5%) 1 (4.2%) Size-related variation is seen in the development of scattered minute spiniform setae on the surfaces of meral segments on the third maxilliped through the fifth pereopod and additional spines on the meri of the third to fifth pereopods: in juveniles, such spiniform setae or additional spines are not differentiated, but in large specimens, these setae or spines are prominent. The structure of the inner antennular flagellum exhibits noticeable sexual dimorphism as described and figured above, as in other congeneric species (e.g., Komai et al. 2004, 2012; Komai 2013).

Remarks. Lebbeus armatus shares with L. groenlandicus and L. magnificus n. sp. several diagnostic characters, including the strong postrostral, antennal and pterygostomial teeth on the carapace, the suborbital lobe with a carinate inner margin, the presence of conspicuous ventral tooth/teeth on the first to fifth pleura, the prominent, laterally flared posteroventral teeth on the sixth pleomere, the presence of a prominent proximal protuberance on the dorsal surface of the telson, the possession of a strong tooth at the dorsolateral distal angle of the antennal basicerite, and the presence of a conspicuous tooth on the posterodorsal margin of the uropodal endopod. No other congeneric species have these characteristics, as far as known. Nevertheless, L. armatus is easily distinguished from these two species by many characters, including the possession of a dense covering of short setae on the carapace, extending to postrostral teeth, and on depressions of pleura of the second to sixth pleomeres, the extremely strong, crested postrostral teeth noticeably increasing in the size anteriorly (the first tooth is strongest and produced beyond the second tooth), the clearly delimited branchial ridge on the carapace, the usual possession of at least three pleural ventral teeth on the second to fourth pleomeres, the presence of lateral spines on the carpi of the third and fourth pereopods, and the presence of additional spines, not aligned with lateroventral row, on the meri of the third to fifth pereopods. These characters appear autapomorphic to L. armatus within the genus. In the latter two species, the carapace and pleon bear only sparse setae (in particular, postrostral teeth are glabrous); the postrostral teeth are generally weaker than in L. armatus , of which the first tooth is weaker than the second tooth; the branchial ridge on the carapace is obsolescent; the second to fourth pleomeres are armed with one (second) or at most two (third and fourth; of which the anterior tooth, if present, is minute to tiny) pleural ventral teeth; the carpi of the third and fourth pereopods are unarmed; there are no additional spines on the meri of the third to fifth pereopods. From L. groenlandicus , L. armatus further differs in the more numerous meral spines on the third to fifth pereopods (for details, see Table 2 ). From L. magnificus n. sp., L. armatus differs in the possession of two pleural ventral teeth on the fifth pleomere (versus usually three) and the less stout inner antennular flagellum in males.

The material studied by Owen (1839) is no longer extant (cf. Kim & Komai 2002; Sammy De Grave, personal communication). Nevertheless, Owen’s (1839) original description and figure of Hippolite armata clearly indicate the presence of three teeth on the ventral margins of the second to fourth pleonal pleura. Furthermore, not specifically mentioned in the text, the given figure (pl. 27, fig. 2) clearly shows the postrostral teeth noticeably becoming stronger anteriorly with the first tooth strongest, and the presence of a clearly delimited branchial ridge on the carapace. Consequently, I have little hesitation to resurrect L. armatus as a distinct species and refer the present East Asian material to the species.

There are many records of L. groenlandicus from East Asian waters (see synonymy), but references accompanied with figures or photos all matches L. armatus . Therefore, these East Asian records of L. groenlandicus are all referred to L. armatus . On the other hand, further study is needed to establish the specific identity of the records of L. groenlandicus from the Bering Sea to the west coast of North America ( Rathbun 1904; Butler 1980). Butler (1980) provided a rather detailed description and figure using specimens from British Columbia, Canada. According to his account, the Canadian specimens agree with L. armatus in the setose surfaces of the carapace and of the pleura of the pleon, and the postrostral teeth noticeably becoming stronger anteriorly, but still differs from L. armatus in the fewer pleural ventral teeth of the third and fourth pleomeres and the fewer meral spines on the third to fifth pereopods (seven to nine in the third, six to eight in the fourth, and six to eight in the fifth). It is highly likely that the northeastern Pacific population represents another, third species closely related to L. groenlandicus .

Comments on Hippolite cornuta are noteworthy. Krøyer (1842) and Brandt (1851) concluded that H. cornuta represented a male of Hippolyte aculeata (= L. groenlandicus ). In the descriptive text, Owen (1839) stated that “The abdominal segments terminate inferiorly in two spines, of which the posterior is the strongest;”, although the given figure seems to show the presence of only one tooth in the second pleuron and of two teeth on the first, third to fifth pleuron. As shown in this study, males of L. groenlandicus can have two ventral teeth in the first, third to fifth pleura and only one tooth in the second pleuron. The sampling locality of the type of H. cornuta was not indicated. The synonymy of H. cornuta with L. groenlandicus is maintained at present.

Characters/species L. groenlandicus L. armatus L. magnificus n. sp.

Rostral shape dagger-like distal part dagger-like distal part dagger-like distal part

relatively small ( Fig. 7 A) relatively large ( Figs. 2 A, 6A) relatively small ( Figs. 10 A, 13A)

Figures

FIGURE 1. Lebbeus armatus (Owen, 1839), female (cl 36.7 mm), Sea of Japan off Hokkaido, CBM-ZC 7914. A, entire animal in lateral view; B, dorsum of carapace in lateral view, showing surface setation.

FIGURE 2. Lebbeus armatus (Owen, 1839), female (cl 19.2 mm), North Yamato Bank, Sea of Japan, CBM-ZC 4990. A, carapace and cephalic appendages, lateral view (setae omitted); B, pleon, lateral view (setae omitted). Scale bar: 5 mm.

FIGURE 3. Lebbeus armatus (Owen, 1839), female (cl 19.2 mm), North Yamato Bank, Sea of Japan, CBM-ZC 4990. A, anterior part of carapace and cephalic appendages, dorsal view (setae omitted); B, suborbital lobe, dorsolateral view; C, posterior part of sixth pleomere and telson, dorsal view (setae partially omitted); D, posterior part of sixth pleomere and proximal part of telson, lateral view (setae partially omitted); E, posterior margin of telson, dorsal view; F, left antennal scale, ventral view (setae omitted); G, left uropod, dorsal view (marginal setae on rami omitted). Scale bars: 5 mm for A, C, F, G; 2 mm for B, D; 1 mm for E.

FIGURE 4. Lebbeus armatus (Owen, 1839), female (cl 19.2 mm), North Yamato Bank, Sea of Japan, CBM-ZC 4990, left thoracic appendages in lateral view. A, left third maxilliped; B, first pereopod; C, second pereopod; D, third pereopod; E, fourth pereopod; F, fifth pereopod. Scale bar: 5 mm.

FIGURE 5. Lebbeus armatus (Owen, 1839), female (cl 19.2 mm), North Yamato Bank, Sea of Japan, CBM-ZC 4990. A, left third maxilliped, distal part of ultimate segment, dorsal view; B, same, distal part of antepenultimate segment, lateral view; C, left first pereopod, chela, extensor view; D, same, chela and carpus, mesial view; E, same, tip of fingers; F, left third pereopod, dactylus, lateral view. Scale bars: 2 mm for A – D, F; 0.5 mm for E.

FIGURE 6. Lebbeus armatus (Owen, 1839), male (cl 21.5 mm), NW of Hinomisaki, Izumo, Sea of Japan, CBM-ZC 12596. A, anterior part of carapace and cephalic appendages, lateral view (setae partially omitted); B, endopod of left first pleopod, ventral view; C, appendices interna and masculina of left second pleopod, mesial view. Scale bars: 5 mm for A; 2 mm for B; 1 mm for C.

FIGURE 7. Lebbeus groenlandicus (Fabricius, 1775), female (cl 16.4 mm), W of Greenland, HUMZ-C 1396. A, carapace and cephalic appendages, lateral view; B, pleon, lateral view (setae omitted); C, distal part of right antennal scale, dorsal view; D, left third pereopod, lateral view. Scale bars: 5 mm for A, B, D; 2 mm for C.

FIGURE 10. Lebbeus magnificus n. sp., holotype, ovigerous female (cl 24.0 mm), Kitami Yamato Bank, southwestern Sea of Okhotsk, CBM-ZC 12597. A, anterior part of carapace and cephalic appendages, right lateral view (setae partially omitted); B, same, dorsal view (marginal setae on antennal scales omitted; right stylocerite damaged); C, tergite of second pleomere, lateral view; D, third to sixth pleomeres, lateral view; E, posterior part of sixth pleomere, telson, and left uropod, dorsal view (marginal setae on uropodal rami omitted); F, posterior margin of telson, dorsal view (right spines broken off). Scale bars: 5 mm for A – E; 1 mm for F.