Liljeborgia fissicornis (M. Sars, 1858 )

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 : 2109-2120

Liljeborgia fissicornis (M. Sars, 1858)

( Figures 13–19 )

Gammarus fissicornis M. Sars, 1858, p. 147 (type locality = Vadsø, Northern Norway, 20–30 fathoms); Bate, 1862, p. 380 (English translation of M. Sars’s diagnosis).

Iduna fissicornis ; Boeck 1861, p. 656.

Gammarus pallidus (Lilljeborgia) ; Goës, 1866, p. 529, pl. 40, fig. 27.

Lilljeborgia fissicornis ; Boeck, 1871, p. 75; Boeck, 1876, p. 499, pl. 18, fig. 10 (in part); von der Brüggen, 1909, p. 23; Stephensen, 1931, p. 222 –225 (in part); Stephensen, 1938, p. 196 –197 (in part).

Liljeborgia fissicornis ; Stebbing, 1906, p. 230 –232 (in part).

Not G. [ Gammarus ]? pallidus Bate, 1857, p. 145 .

Not Lilljeborgia fissicornis ; G.O. Sars, 1890 –1895, p. 534, pl. 189 (= L. ossiani sp. nov.).

Material examined

Svalbard, Storfjord , R / V Jan Mayen, sta. 823–94, 76°52.4′ N, 018°52.4′ E, 93 m, Beyer sledge, 25 July 1994: 7 specimens, leg. Wim Vader, TSZCr 9870 ; Svalbard, Erik Eriksenstredet , R / V Jan Mayen, sta. 834–97, 79°02.6′ N, 23°36.1′ E, 107 m, Sneli sledge, 11 September 1997: 1 specimen, TSZCr 10480 ; Svalbard, R / V Jan Mayen, sta. 869–97, 78°13′ N, 019°28′ E, 111 m, Sneli sledge, 13 October 1997: 1 specimen, TSZCr 10655 ; Svalbard, R / V Jan Mayen, sta. 196–03, 78°52.2′ N, 022°13.4′ E, 120 m, 23 September 2003: 1 female, leg. C. d’Udekem d’Acoz, TSZCr 12536; Barents Sea, AKVAPLAN-NIVA, R / V Jan Mayen, cruise Barentshavet 02, sta. 427, 73°03′ N, 019°48′ E, 415 m, 30/04/2002: 1 large female, leg. H.C. Trannum, TSZCr 12417; Barents Sea, AKVAPLAN-NIVA, R / V Jan Mayen, cruise Barentshavet 02, sta. 382, 75°55′ N, 028°12′ E, 201 m, 25 April 2002: 2 medium-sized specimens (of which one has been dissected and fully illustrated), leg. H.C. Trannum, TSZCr 12392; Barents Sea, AKVAPLAN-NIVA, R / V Jan Mayen, cruise Barentshavet 02, sta. 329, 72°26′ N, 034°17′ E, 277 m, 18 April 2002: 1 specimen, leg. H.C. Trannum, TSZCr 12485; Barents Sea, AKVAPLAN-NIVA, R / V Jan Mayen, cruise Barentshavet 02, sta. 312, 71°19′ N, 023°38′ E, 369 m, 16 April 2002: 1 male, leg. H.C. Trannum, TSZCr 12361; Barents Sea, AKVAPLAN-NIVA, R / V Jan Mayen, cruise Barentshavet 02, sta. 322, 71°19′ N, 031°06′ E, 252 m, 17 April 2002: 1 specimen, leg. H.C. Trannum, TSZCr 12364; Barents Sea, AKVAPLAN-NIVA, R / V Jan Mayen, cruise Barentshavet 02, sta. 425, 73°24′ N, 018°32′ E, 458 m, 30 April 2002: 1 specimen (tooth of Ep 3 less strong than usually, but otherwise normal), leg. H.C. Trannum, TSZCr 12424; northern Norway, west of the county of Finnmark, R / V Johan Ruud , sta. 303–05, 71°00.26′ N, 025°21.56′ E, 161 m, sand with tunicates and hydroids, RP sledge, 13 April 2005: 2 specimens, presumably males (Ep 3 with smaller tooth than usual), leg. C. d’Udekem d’Acoz, TSZCr 13790 .

Description

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

A1. Major flagellum with 28 articles in male and 25 in female; accessory flagellum with 18 articles in male and in 14 to 15 in female.

A2. Fourth article of peduncle with short slender ventrolateral and dorsomedial spines; fifth article without spines; flagellum with 23 articles in male and 20 in female.

Epistome. Rounded, slightly protruding in lateral view.

Md. Left lacinia mobilis large with anterior margin with 5 rounded teeth; right lacinia mobilis slightly smaller than left one, with anterior margin strongly denticulate and with one large lateral triangular tooth; spines of incisor process not bifid, distal one of normal stoutness; article one of palp shorter than article two (ratio length article one / article two = 0.78); article one 3.70 times as long as wide; article two with setae on tip only, 5.88 times as long as wide; article three 5.50 times as long as wide, 0.70 times as long as article two (measurements made on right palp).

Mx1. First article of palp without setae; second article of palp with eight strong setae (not forming transverse rows) on upper margin, 12 slender spines on ventral and apical margins and nine facial setae; outer plate with 10 strongly denticulate spines of normal stoutness; inner plate with a single seta on tip.

Mx2. Outer plate with about 10 short and medium-sized setae on upper margin.

Mxp. Palp with dactylus fairly stout, with ventral margin distinctly convex, 0.77 times as long as article three; article three of palp with three transverse rows of thin dorsomedial setae; outer plate with 16 closely spaced spines on medial border (these spines are of normal length and stoutness), and 12 to 15 strong medioventral setae; inner plates with five well-developed anterior spines and 15 to 16 marginal and submarginal strong but non-spiniform setae.

Gn1. Coxa broadly triangular, with distinctly concave posterior border, with small posterior tooth, with or without small anterior tooth; merus and carpus with more or less distinct groups of setae; merus with small acute distal tooth; tip of carpus almost reaching propodal group of strong spines (as seen in outer view); propodus 1.83 times as long as wide; group of spines on the proximal 0.36 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 (56 to 73 hooked outer spines); dactylus with seven teeth.

Gn2. Coxa triangulo-elliptic with small anterior and posterior teeth; 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 1.88 times as long as wide; group of spines on the proximal 0.30 of propodus (emergence of most distal spine on outer side used as reference point); these spines are well developed and arise from a weak protrusion; palm border curved and convex in both sexes, with hooked spines on outer row narrowly spaced (about 95 hooked spines); dactylus of normal width, with 10 to 11 teeth and toothed on 0.5 or 0.6 of its length.

P3. Coxa quadrato-elliptic, rather narrow, with small anterior and posterior tooth; merus 1.61 times as long as carpus and 1.23 times as long as propodus; dactylus long, rather stout with its two borders slightly curved, 0.71 times as long as carpus and 0.54 times as long as propodus; carpus 4.23 times as long as wide; propodus 6.89 times as long as wide; posterior border of merus with three isolated short setae; carpus with three setiform spines (of which two are paired with a short seta) on posterior border (longest spine in distal group; this spine is 1.89 times as long as width of carpus and 0.43 times as long as carpus length), and a tiny setule at the tip of anterior border; posterior border of propodus with five groups (proximal group rubbed off in illustrated specimen) of one or three setiform spines (longest setiform spines 2.12 times as long as width of propodus and 0.31 times as long as length of propodus); anterior border of propodus with distal group of four well-developed spiniform setae and one tiny setule more proximally.

P4. Coxa of normal width (1.28 times as long as wide), with anterior and posterior border nearly parallel, with ventral border distinctly convex, with four normally developed teeth on posterior border and one normally developed anteroventral tooth; merus 1.58 times as long as carpus and 1.17 times as long as propodus; carpus 4.04 times as long as wide; propodus 6.72 times as long as wide; dactylus not very long, rather stout with its two borders slightly curved, 0.71 times as long as carpus and 0.57 times as long as propodus; posterior border of merus with three isolated setae; carpus with two isolated short setae followed by two groups of one or two setiform spines (each associated with a setule) on posterior border (longest spine in distal group; this spine is 1.89 times as long as width of carpus and 0.45 times as long as carpus length); propodus with five groups of one to three spines (the longest are setiform) on posterior border (longest setiform spines 2.09 times as long as width of propodus and 0.31 times as long as length of propodus); anterior border of propodus with distal group of five well-developed spiniform setae and one tiny setule more proximally.

P5. Basis very narrow (1.90 times as long as wide), anteriorly distinctly and regularly convex, posteriorly straight; anterior border with conical spines, posterior border with 11 to 13 distinct but not especially strong, non-erect teeth, tip of distal tooth far from reaching posterodistal angle, distal border straight (junction between posterior and distal borders forming a curve) and not produced into a lobe; merus with anterior group and posterior groups of short spines; carpus with three or four anterior groups of rather slender and fairly short spines, and no posterior spines (except apical group); carpus 0.65 times as long as merus; propodus with at least two anterior short slender spines each followed by a tuft of moderately long setae; propodal apical tuft of setae well developed; dactylus distinctly curved and fairly stout, 0.32 times as long as propodus.

P6. Basis very narrow (1.98 times as long as wide), anteriorly distinctly convex and posteriorly straight; anterior border with conical spines, posterior border with 13 to 14 distinct but not especially strong, non-erect teeth, tip of distal tooth not reaching posterodistal angle, distal border straight (junction between posterior and distal borders forming a curve) and not produced into a lobe; merus and carpus with anterior groups of well-developed spines and posterior groups of small spines (not intermixed with short setae); carpus 0.65 times as long as merus; propodus with at least four anterior spines or pairs of spines followed by a tuft of moderately long setae (easily rubbed off); propodal apical tuft of setae well developed; dactylus weakly curved and fairly stout, 0.32 times as long as propodus.

P7. Upper part of posterior border of coxa angular; basis proximally expanded, very narrow (1.74 times as long as wide), anteriorly distinctly convex and posteriorly straight; anterior border with conical spines, posterior border with 10 to 12 distinct teeth, tip of distal tooth far from reaching to almost reaching posterodistal angle, distal border straight (junction between posterior and distal border forming a right angle, or a curve when the distal tooth is close to the tip) and not produced into a lobe; merus and carpus with rather well-developed anterior and posterior spines; carpus 1.16 times as long as merus; propodus of P7 1.88 times as long as propodus of P6; propodus with six to eight anterior groups of one to three fairly short spines, and five posteromedial isolated fairly short spines (associated with long thin setae, which are often rubbed off); propodal apical tuft of setae present and consisting of thin setae, which are often completely rubbed off; dactylus nearly straight, distally not notched, fairly slender, short, 0.28 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 slightly convex.

Pleonite 3. Posterodorsal area toothless and deeply notched; Ep3 with very large 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 without forming a notch or after forming a notch.

Urosomite 1. With crest-like carina, posteriorly terminated into a strong posterodorsal tooth obliquely pointing upwards; ventrolateral border with one to two spines; peduncle of U1 with nine to 11 dorsolateral spines: eight to 10 regularly spaced and short and rather slender ones spread throughout length of peduncle and a long and strong distal one, with four dorsomedial spines (which are rather stout and fairly short) regularly spaced all along its length; outer ramus with nine to 15 very short and rather stout outer spines and seven short medial spines; inner ramus with five very short spines on outer border and seven well-developed spines on medial border.

Urosomite 2. With dorsal border forming a large triangular tooth pointing obliquely upwards; peduncle of U2 with three to five regularly spaced and fairly short (except the distal one which is long) slender dorsolateral spines, with two dorsomedial spines; outer ramus with five well-developed outer spines and 0 to two very small medial spines; inner ramus with three short spines on outer border and five large 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 three large and stout spines on outer side, with five large and stout spines on medial side.

Telson. Cleft on 0.60 of its length; medial tooth of each lobe reaching at most 0.33 of outer tooth; inter-teeth spine overreaching tip of outer tooth by 0.30 of its length, 0.24 times as long as telson; apical teeth of telson without setae.

Colour pattern

Uniform pale brown. No difference of pigmentation at the place where eyes would have been expected (observations by the first author).

Size

Up to 24 mm.

Depth range

120 to 458 m (present material). The type of M. Sars (1858) was found at 20–30 fathoms (i.e. 38–56 m, assuming that M. Sars was using Norwegian fathoms). The species has apparently been found at depths as shallow as 9 m ( Goës 1866).

Distribution

Northern Norway, Svalbard, Barents Sea (present material), presumably Jan Mayen ( Stephensen 1931: material collected at 100 m depth), New Siberian Islands ( von der Brüggen 1909), West Greenland (?) ( Hansen 1888).

Remarks

Hansen (1888: 142) gives no description of his “ L. fissicornis ” from West Greenland, but since it was large (20.5 mm) and collected on the continental shelf (98 fathoms), the most likely hypothesis is that it was a true L. fissicornis . It is not possible to determine the real identity of the L. fissicornis recorded by Chevreux (1900) from the Bay of Biscay (180 m depth) and from the Azores (1372 m) because the author gave no information on the morphology of his specimens.

The original description of G. fissicornis M. Sars, 1858 by M. Sars (1858: 147) is short and devoid of illustrations. However, it is very clear and leaves no doubt concerning the identity of the type material. Indeed, the unique specimen studied by M. Sars (1858) is said to have no posterodorsal tooth on the third pleonite, which agrees with the deep-water L. caliginis sp. nov. and “our” shallow-water L. fissicornis . It has been collected between 20 and 30 fathoms (between 38 and 56 m), i.e. at a shallow depth compatible only with L. ossiani sp. nov. and “our” L. fissicornis . Its size (3/ 4 inch, i.e. 18 mm) is much too big for L. ossiani sp. nov. but fits with the three other species. Finally, its type locality (Vadsø, North East Norway) lies within a broad area, where “our” L. fissicornis is common.

Figures

Figure 13. Liljeborgia fissicornis (M. Sars, 1858), male, Barents Sea, cruise Barentshavet 02, sta. 425, TSZCr 12424, habitus.

Figure 14. Liljeborgia fissicornis (M. Sars, 1858), female, Barents Sea, cruise Barentshavet 02, sta. 382, TSZCr 12392. (A) Head and cephalic appendages in lateral view; (B) rostrum and cephalic appendages in dorsal view; (C) lower lip; (D) left Md; (E) right Md; (F) lacinia mobilis of left Md; (G) lacinia mobilis of right Md; (H) left Mx1; (I) left Mx2.

Figure 15. Liljeborgia fissicornis (M. Sars, 1858), female, Barents Sea, cruise Barentshavet 02, sta. 382, TSZCr 12392. (A) Mxp; (B) dorsal side of inner plates of Mxp (setae indicated by their surface of insertion); (C) ventral side of right inner plate of Mxp.

Figure 16. Liljeborgia fissicornis (M. Sars, 1858), A–E, female, Barents Sea, cruise Barentshavet 02, sta. 382, TSZCr 12392; F, G, male, BH425, TSZCr 12424. (A) Left Gn1; (B) margin of palm of left Gn1 (detail); (C) dactylus of left Gn1; (D) left Gn2; (E) dactylus of left Gn2; (F) chela of left Gn1; (G) chela of left Gn2.

Figure 17. Liljeborgia fissicornis (M. Sars, 1858), female, Barents Sea, cruise Barentshavet 02, sta. 382, TSZCr 12392. (A) Left P3; (B) articles 5–7 of left P3; (C) left P4; (D) articles 5–7 of left P4.

Figure 18. Liljeborgia fissicornis (M. Sars, 1858), females; A–F, Barents Sea, cruise Barentshavet 02, sta. 382, TSZCr 12392; G, Svalbard, R/V Jan Mayen, st. 196, TSZCr 12536. (A) Left P5; (B) posterodistal corner of basis of left P5; (C) left P6; (D) posterodistal corner of basis of left P6; (E) left P7; (F) posterodistal corner of basis of left P7; (G) right pleopod 1; (H) coupling hooks of right pleopod 1; (I) telson.

Figure 19. Liljeborgia fissicornis (M. Sars, 1858), females; A–F, Barents Sea, cruise Barentshavet 02, sta. 382, TSZCr 12392; (A) Pleonites 1–3; (B) urosome in lateral view; (C) pleon in dorsal view; (D) left U3.