A new deepwater species of Calliopiidae , Halirages helgae ( Crustacea , Amphipoda ) , with a synoptic table to Halirages species from the northeast Atlantic

Halirages helgae sp. nov. is recorded from the shelf slopes of the Norwegian Sea at depths of 1000 to 2600 m in the Arctic cold water masses. A total of 50 specimens were found at five stations. The species differs from other known species in the genus Halirages Boeck, 1871 by the bilobed posterior margin of pereonite 7. A synoptic table to the northeast Atlantic species of Halirages is provided.


Introduction
MAREANO, a programme to develop a Marine Areal database for Norwegian waters, was initiated in 2005 and conducts physical, biological, and environmental mapping of the sea bottom within Norwegian waters (Fig. 1). The programme procures information for an ecosystem-based management of Norway's coastal and offshore regions. MAREANO (www.mareano.no) is an ongoing program, and one of the aims is to increase the knowledge of marine benthic species. A new calliopiid species has been found at five of the stations; we suggest placing the new species in the genus Halirages.

Material and methods
Altogether 17 cruises have been undertaken from 2005 through 2013 in the MAREANO program; they included 1013 video stations, of which 252 were physically sampled using a van Veen grab; 246 of these stations also included sampling with a beam trawl and 201 with a Rothlisberg-Piercy (RP) sledge. The survey area up until 2013 has covered 130,000 km 2 ; it has included the shelf and slope off the coast of Nordland and Troms counties, parts of the SE Barents Sea and the banks off mid-Norway. The material for this study was collected in 2008 and 2010. All samples were processed on board to facilitate further handling and sorting. RP samples were decanted before being sieved at 4 mm, 1 mm, and 0.5 mm.
Only the decanted fractions were identified for this study. The samples were fixed in 4% borax-buffered formalin and transferred to 75% ethanol after sorting in the lab. All material has been deposited in the Bergen University Museum, Norway (ZMBN). Permanent slides were made with Faure's medium, and drawings were made with a tablet (Wacom Bamboo CTH-470) and Adobe Illustrator (Version CS 5.1) as shown by Coleman (2003). Length measurements are from tip of rostrum to tip of telson. A total of 50 specimens were found at five stations. The specimens are placed in the genus Halirages for the following reasons: labrum rounded apically and acute dorsally, labium with small inner lobes, length of mandible palp article 3 about half that of article 2. Coxal plates small, coxa 1 not expanded distally. Gnathopods 1 and 2 subequal, propodi subrectangular, ischium of pereopod 7 with a small posterodistal process, second epimeral plate with small tooth on posteroventral corner, third epimeral plate smooth. Pereonite 7 with bilobed posterior margin. The uropods of all examined specimens were badly damaged, and only peduncles and proximal parts of rami were available for study.

Diagnosis
Head with short rostrum, anteroventral corner with small projecting tooth. Eyes present, but very small, whitish in alcohol. Article 3 of mandible palp about half the length of article 2. Pereonite 7, and in large animals (> 11 mm) also pereonite 6 and pleonite 2, with weakly bilobed posterior margin. Length of dactylus on first and second gnathopod about half that of propodus palm. Carpus longer than propodus. Epimeral plate 2 with small tooth posteroventrally, and epimeral plate 3 with posterior corner rounded. Uropods 1 and 2 biramous, with strong setae. Telson entire, longer than wide, acute.

Etymology
The species is named in memory of Helga Ringvold, for encouraging her children in their future endeavours.

Description
Body. Up to 13 mm long. Pereonites 1-5 smooth, dorsal posterior margin of pereonite 7 slightly bilobed ( Fig. 2B) (also on pereonite 6 and pleonite 2 on some large specimens greater than 11 mm long). Head (Fig. 3A). Rostrum short; corner of cephalic lobe with small projecting tooth; eye small (can be difficult to see in preserved specimens), reniform.
AntennA 1 (Fig. 3B). Flagellum broken in all examined specimens. Peduncle of article 1 longer than article 2, article 3 about ⅓ length of article 2, which has a posterodistal process. Eight articles remaining in flagellum, with one short seta on three of them.
mAxiLLA 1 (Fig. 4A). Inner plate with 9 plumose setae; outer plate with 11 spines of which 5-6 are bifurcate; palp 2-articulate and well developed, article 1 expanded distally, article 2 tapering and with 2 rows of 5-6 spines, one row apically and the other slightly lower. Left article 2 with long marginal spines and margino-facial setae, right article 2 with a row of 6-7 stout, conical marginal spines with margino-facial row of setae.
mAxiLLA 2 (Fig. 4B). Outer plate longer than inner plate, both plates with long setae apically. Upper and inner plate with posterior setae, on inner plate the setae also reach posterodistal area.   (Fig. 4C). Broad and covered with numerous setae; inner plate short with short setae apically and on inner margins, three apical teeth; outer plate slender with long setae apically and on inner margins; palp articles 2-3 elongate, article 2 longest; article 3 with long setae apically and on inner margins; dactylus stout, about half length of article 3.
GnAthopods 1 And 2 ( Fig. 5A and 5B). Quite similar in shape: both coxae sub-quadrate and smooth; bases rectangular with a few short setae; ischia narrow; meri longer than wide, with group of setae apically; propodi shorter than carpi, subovate, carpi subtriangular with rows of setae along posterior margin, propodi subtriangular. Gnathopod 1 carpus length / width ratio 3.0, of propodus 1.9. Gnathopod 2 carpus length / width ratio 2.7, of propodus 1.9; carpus setae along hind margins and palms, with groups of setae along inner face, palm of gnathopods 1 and 2 similar and slightly excavate; dactyli on both gnathopods about half length of propodus palm, with dentate inner margin.
pereopods 3-7 (Fig. 6A-E). Coxa 3 sub-quadrate and smooth, coxa 4 posteriorly excavate, coxae 5 and 6 longer than wide, coxa 7 elliptic and smallest of all coxae; bases of pereopods 5-7 broad and posteriorly smooth. Articles of pereopods 4-7 missing on all specimens except paratype 2, which has one pereopod 7 that includes carpus; ischium short and square-shaped, merus with setae along both margins and long setae apically, carpus with setae on both margins, 7 times as long as wide, and 1.5 times as long as merus.
CoLour pAttern. Colour of live specimens unrecorded.

Distribution
This species has only been found in the northeast Atlantic, off northern Norway. It has been recorded at some of MAREANO's deepest stations, from 997 to 2,609 m, and only in cold water masses (NSAIW, Norwegian Sea Arctic Intermediate Water) (Buhl-Mortensen et al. 2012), with mud as the dominant sediment.

Discussion
The entire calliopiid family is in need of revision. Both Stephensen (1931) and d'Udekem d'Acoz (2012) stated that the differences between Halirages and Apherusa are blurred. It can also be difficult to separate Halirages and Haliragoides morphologically (Sars 1895;Stephensen 1931; M. Thurston pers. comm.), but differences regarding cephalic lobes, antennal calceoli and the rami on uropod 3 have been suggested as characters useful for separating them. The head of Halirages helgae sp. nov. has a small projecting tooth anterodistally. The damaged antennae show no calceoli (only females have been found, and according to Stephensen (1931) and d'Udekem d'Acoz (2012) calceoli are probably present in all males in Halirages but not always in the females).
The species fits more or less the characters of the genus Halirages, and in the present confused systematic situation, it is preferable to assign it to this genus.
As many Calliopiidae, Halirages helgae sp. nov. is a brittle species. The specimens differ somewhat in size (3-13 mm) and probably include both juveniles and adults. The species seems to be morphologically closest to H. mixtus Stephensen, 1931 andH. gorbunovi Gurjanova, 1946, based on the absence of dorsal spines. One should, however, take into consideration that thorough descriptions are lacking for both species, and that H. gorbunovi is only known from its two mutilated type specimens, which actually look similar to H. quadridentatus G.O. Sars, 1877(d'Udekem d'Acoz 2012. The examined specimens of H. helgae sp. nov. have a bilobed posterior margin on pereonite 7 and differ from H. gorbunovi in the fact that coxae 1 and 2 are not ventrally serrate, and that H. helgae sp. nov. has eyes. The telson on H. mixtus is emarginate and the posterior margin of epimeron 3 serrate, whereas the telson of H. helgae sp. nov. is triangular with a blunt tip, and the posterior margin of the third epimeron is smooth. Apart from H. mixtus and H. gorbunovi, six other species within Halirages are described from the northeast Atlantic: H. fulvocinctus (M. Sars, 1858), H. quadridentatus, H. nilssoni Ohlin, 1895, H. caecus Kamenskaya, 1980, H. cainae d'Udekem d'Acoz, 2012, and H. stappersi d'Udekem d'Acoz, 2012 Halirages helgae sp. nov. differs from all these species by the bilobed posterior margin of pereonite 7. The posteroventral corner of epimeral plate 2 is toothed and that of epimeral plate 3 rounded. See the synoptic table (Table 1) for a more detailed compilation of how the characters are distributed.
It can be debated whether the species Haliragoides abyssi Gurjanova, 1951 (we have not been able to study this as no specimens were available for study) should be transferred to the genus Halirages due to the dissimilarity it shows with the two other Haliragoides species, described by Sars (1883)   H. helgae sp. nov. would still differ from it by the presence of eyes, a bilobed posterior margin on pereonite 7, and a mandibular palp with article 3 half the length of article 2 (Table 1).