Liljeborgia charybdis, d & d & Acoz & Vader, 2009

d, Cédric, d, Udekem, Acoz & Vader, Wim, 2009, On Liljeborgia fissicornis (M. Sars, 1858) and three related new species from Scandinavia, with a hypothesis on the origin of the group fissicornis, Journal of Natural History 43 (33 - 34), pp. 2087-2139 : 2099-2108

Liljeborgia charybdis sp. nov.

( Figures 7–12 )

Lilljeborgia fissicornis ; Stephensen, 1931, p. 222 –225 (in part).

Material examined

Norwegian Sea, R / V “Akademik Mstislav Keldysh”, cruise 33, sta. 3318, wreck-site of the nuclear submarine “Komsomoletz”, 73°40.03′ to 73°41.74′ N, 013°23.56′ to 013°35.52′ E, 1550–1600 m depth, Sigsbee trawl at 2.5 m, 25 June 1994: 5 specimens (1 dissected female holotype + 4 paratypes), leg. E. Vinogradov, TSZCr 10180 .

Description

Rostrum well-developed, narrow, with acute tip. Eye absent.

A1. Major flagellum with 34 articles in male and 30 in female; accessory flagellum with 22 articles in male and in female.

A2. Fourth article of peduncle with short slender ventrolateral and dorsomedial spines; fifth article without spines; flagellum with 25 articles in male and 23 in female.

Epistome. Rounded, barely protruding in lateral view.

Md. Left lacinia mobilis large with anterior margin with four rounded teeth; right lacinia mobilis distinctly smaller than left one, with anterior margin smooth; one spine of left incisor process bifid, distal one of normal stoutness; article one of palp shorter than article two (ratio length article one: article two = 0.75); article one 3.98 times as long as wide; article two with setae on tip and all along distal half, 5.71 times as long as wide; article three 4.86 times as long as wide, 0.59 times as long as article two.

Mx1. First article of palp without setae; second article of palp with six strong setae (not forming transverse rows) on upper margin, 12 spines on ventral and apical margins (most proximal ones slender, distal ones stout) and 14 facial setae; outer plate with 10 slender weakly denticulate spines; inner plate with a single seta on tip.

Mx2. Outer plate with about 11 short setae on upper margin.

Mxp. Palp with dactylus fairly stout, with ventral margin distinctly convex, 0.58 times as long as article three; article three of palp with three transverse rows of thin dorsomedial setae; outer plate with 18 normally spaced spines on medial border (these spines are rather long and slender), and about 15 strong medioventral setae; inner plates with six well-developed anterior spines and 23 marginal and submarginal strong but non-spiniform setae.

Gn1. Coxa broadly triangular, with concave posterior border, with or without posterior tooth and without anterior tooth; merus and carpus with confluent groups of setae; merus with small acute distal tooth; tip of carpus reaching propodal group of strong spines (as seen in outer view); propodus 1.88 times as long as wide; group of spines on the proximal 0.26 of propodus (emergence of most distal spine on outer side used as reference point); one of these spines is rather long; palm border forming a regular curve, without teeth, with hooked spines of outer row narrowly spaced (about 91 hooked outer spines); dactylus with 0 (male) or 1 (female) tooth.

Gn2. Coxa triangulo-elliptic with small posterior tooth and no anterior tooth; merus and carpus with confluent groups of setae; merus with small acute distal tooth; tip of carpus almost reaching propodal group of strong spines; propodus 1.87 (female) or 1.79 (male) times as long as wide; group of spines on the proximal 0.20 (female) and 0.27 (male) of propodus (emergence of most distal spine on outer side used as reference point); in male these spines are short and arise from a strong protrusion; palm border curved and convex in female but almost straight (barely convex) and curving abruptly near the tip in male, without teeth; medial setae of palm short, with hooked spines on outer row in females; these spines are narrowly spaced (87 hooked spines and nine outer setae in female); dactylus of normal width, with six (male) or five (female) teeth and toothed on 0.3 of length.

P3. Coxa quadrato-elliptic, narrow, with small posterior tooth and minute anterior notch; merus 1.70 times as long as carpus and 1.31 times as long as propodus; carpus 4.50 times as long as wide; propodus 7.94 times as long as wide; dactylus of normal length and stoutness with its two borders slightly curved, 0.64 times as long as carpus and 0.51 times as long as propodus; posterior border of merus with one short seta; carpus with four groups of one or three setiform spines (of which some are long) on posterior border (longest spine in distal group; this spine is 1.19 times as long as width of carpus and 0.26 times as long as carpus length), and one tiny setule at the tip of anterior border; propodus with seven groups of one or three spines (of which the longest ones are setiform) and on posterior border (longest setiform spines 1.57 times as long as width of propodus and 0.20 times as long as length of propodus); anterior border of propodus with distal group of six well-developed spiniform setae and three isolated setae more proximally.

P4. Coxa of normal width (1.25 times as long as wide), with anterior and posterior border slightly converging downwards, with ventral border almost straight, with two normally developed teeth on posterior border and no anteroventral tooth; merus 1.70 times as long as carpus and 1.34 times as long as propodus; carpus 4.20 times as long as wide; propodus 7.00 times as long as wide; dactylus of normal length and stoutness with its two borders slightly curved, 0.67 times as long as carpus and 0.53 times as long as propodus; posterior border of merus with one isolated seta; carpus with three groups of one or two long setiform spines on posterior border (longest setiform spine 1.15 times as long as width of carpus and 0.28 times as long as carpus length); propodus with nine groups of one to three spines (the longest are setiform) on posterior border (longest setiform spines 1.61 times as long as width of propodus and 0.23 times as long as length of propodus); anterior border of propodus with distal group of five well-developed spiniform setae and two groups of short setae more proximally.

P5. Basis very narrow (2.32 times as long as wide), anteriorly distinctly and regularly convex, posteriorly straight; anterior border with conical spines, posterior border with nine (male and female) distinct but not especially strong, non-erect teeth (posterodistal angle not included), tip of distal tooth very close to or overreaching posterodistal angle, distal border straight (junction between posterior and distal borders forming a right angle) and not at all produced into a lobe; merus with anterior groups of very short spines; carpus with three anterior groups of very short spines, which are not intermixed with setae and no posterior spines (except apical group which is reduced to a spinule); carpus 0.57 times as long as merus; propodus with four anterior short slender spines (two spines are rubbed off in illustrated specimen) (some of which paired with a seta in non-illustrated specimen); medial border with scar of six groups of one or two setae; propodal apical tuft of setae well developed (in non-illustrated specimen); dactylus distinctly curved and fairly stout, 0.35 to 0.38 times as long as propodus.

P6. Basis very narrow (2.37 times as long as wide), anteriorly proximally weakly convex and posteriorly straight; anterior border with conical spines, posterior border with 11 (male) to 10 (female) distinct but not especially strong, non-erect teeth (posterodistal angle not included), tip of distal tooth slightly overreaching posterodistal angle, distal border straight (junction between posterior and distal borders forming a right angle) and not at all produced into a lobe; merus with anterior and posterior groups of very small spines; carpus with anterior and posterior groups of small spines (one anterior intermixed with short setae); carpus 0.58 times as long as merus; propodus with five tiny anterior spines (in non-illustrated specimen); medial border with scar of four groups of three to four setae; propodal apical tuft of setae reduced to a single seta; dactylus weakly curved and fairly stout, 0.32 times as long as propodus.

P7. Upper part of posterior border of coxa produced into a tooth; basis proximally barely expanded, very narrow (2.10 times as long as wide), anteriorly weakly convex and posteriorly very slightly concave; anterior border with conical spines, posterior border with eight (male) to seven (female) distinct teeth (posterodistal angle not included), tip of distal tooth overreaching posterodistal angle, distal border nearly straight (slightly concave) (junction between posterior and distal borders forming a very obtuse, scarcely distinct angle) and not at all produced into a lobe; merus and carpus with rather short anterior and posterior spines; carpus same length as merus; propodus of P7 2.71 times as long as propodus of P6; propodus with four anteromedial spinules, and three posteromedial spinules; propodal apical tuft of setae lacking; dactylus nearly straight, distally not notched, fairly slender, short, 0.16 times as long as propodus.

Pleonite 1. Posterodorsal area produced into one large tooth; Ep1 with small posteroventral tooth, with posterior border distinctly convex; without setae.

Pleonite 2. Posterodorsal area produced into one large tooth; Ep2 with small posteroventral tooth, with posterior border distinctly convex.

Pleonite 3. Posterodorsal area produced into a small tooth; Ep3 with small posteroventral tooth (of which the ventral margin is regularly and strongly convex), with posterior border straight on all its length and joining the posteroventral tooth after forming a shallow notch.

Urosomite 1. With crest-like carina, posteriorly terminated into a strong posterodorsal tooth obliquely pointing upwards; ventrolateral border with two spines; peduncle of U1 with nine dorsolateral spines: eight regularly spaced and short and rather slen- der ones spread on all length of peduncle and a long and strong distal one, with six dorsomedial spines (which are slender and fairly short) regularly spaced all along its length; outer ramus with 15 short and rather slender outer spines and nine very short medial spines; inner ramus with six very short spines on outer border and nine short spines on medial border.

Urosomite 2. With dorsal border forming a large triangular tooth pointing obliquely upwards; peduncle of U2 with four to six regularly spaced and fairly short (except the distal one which is long) slender dorsolateral spines, with three dorsomedial spines; outer ramus with six to seven short outer spines and five very short medial spines; inner ramus with eight short spines on outer border and eight short to well-developed spines on medial border.

Urosomite 3. With a pair of long posterodorsal styliform spines; lateral projection usually produced into a tooth; outer ramus of U3 without spines; inner ramus with five to six very short spines on outer side, with five to seven very short spines on medial side.

Telson. Cleft on 0.54 of its length; medial tooth of each lobe reaching 0.34 of outer tooth; inter-teeth spine just overreaching tip of outer tooth, 0.17 times as long as telson; apical teeth of telson without setae.

Colour pattern

Unknown.

Size

Up to 28 mm.

Depth range

The types were found at 1700 m. The specimens from West Greenland, Ingolf sta. 25, 1096 m and from southwest Iceland, Ingolf sta. 80, 1761 m reported by Stephensen (1931) are presumably L. charybdis sp. nov. because he indicates the occurrence of a posterodorsal tooth on the third pleonite of these deep-sea specimens. Such a disposition also exists in L. ossiani sp. nov., but the latter has never been recorded deeper than 446 m and is presumably absent from the deep sea.

Distribution

Northern Norway (present material), West Greenland (?) and southwest Iceland (?) ( Stephensen 1931, as L. fissicornis ).

Etymology

From the Latin noun Charybdis, -is, sea monster of the Greek mythology, which is said to dwell in the Straits of Sicily at the edge of a sea chasm. The name, which is a genitive, alludes to the deep sea, which is the habitat of the species, and also to the type locality. Indeed the type specimens were collected close to the wreck of the nuclear submarine “Komsomoletz”, which can be considered as a deep-sea monster, just like the mythological Charybdis.

Remarks

It is possible that a third deep-sea Liljeborgia species of the group fissicornis is present in European Arctic waters. Indeed, Oldevig (1959) records a large (27 mm) “ L. fissicornis ” from the “Svenska Djupet” (78°19′ N, 008°41′ E, 2700 m), which is said to exhibit a combination of characters incompatible with L. charybdis sp. nov. and L. caliginis sp. nov. According to Oldevig (1959), in this specimen, “the 3rd segment of the metasom has no dorsal spine, the hind corner of Ep. 3 is rounded and without a toothlike process, and the dactylus of both P. 1 and P. 2 is even, not serrated on the inner edge”.

Figures

Figure 7. Liljeborgia charybdis sp. nov., female, holotype, Norwegian Sea, R/V Ak. Mstislav Keldysh, cruise 33, sta. 3318, TSZCr 10180. (A) Head, antennae and anterior part of thorax; (B) anterior part of head and epistome; (C) lower lip; (D) left Md; (E) tip of left Md; (F) tip of right Md; (G) left Mx1; (H) left Mx2.

Figure 8. Liljeborgia charybdis sp. nov., female, holotype, Norwegian Sea, R/V Ak. Mstislav Keldysh, cruise 33, sta. 3318, TSZCr 10180. (A) Mxp; (B) right outer plate of Mxp; (C) inner plate.

Figure 9. Liljeborgia charybdis sp. nov., Norwegian Sea, R/V Ak. Mstislav Keldysh, cruise 33, sta. 3318, TSZCr 10180. A–D, female, holotype; E, F, male, paratype. (A) Right Gn1; (B) palm of right Gn1; (C) left Gn2; (D) palm of right Gn2; (E) chela of left Gn2 (outer view); (F) chela of right Gn2 (medial view).

Figure 10. Liljeborgia charybdis sp. nov., female, holotype, Norwegian Sea, R/V Ak. Mstislav Keldysh, cruise 33, sta. 3318, TSZCr 10180. (A) Right P3; (B) articles 5–7 of right P3; (C) right P4; (D) articles 5–7 of right P4.

Figure 11. Liljeborgia charybdis sp. nov., female, holotype, Norwegian Sea, R/V Ak. Mstislav Keldysh, cruise 33, sta. 3318, TSZCr 10180. (A) Left P5; (B) distal part of basis of left P5; (C) articles 6 and 7 of left P5; (D) left P6; (E) distal part of basis of left P6; (F) articles 6 and 7 of left P6; (G) right P7; (H) distal part of basis of right P7; (I) articles 5–7 of left P7; (J) telson.

Figure 12. Liljeborgia charybdis sp. nov., female, holotype, Norwegian Sea, R/V Ak. Mstislav Keldysh, cruise 33, sta. 3318, TSZCr 10180. (A) Pleon in lateral view; (B) left U1; (C) peduncle of right U1; (D) left U2; (E) right U3.