Two new tanaidaceans (Crustacea: Peracarida) from Portuguese submarine canyons (NE Atlantic, West Iberian Margin)

The Tanaidacea are ubiquitous and amongst the most abundant taxa in the deep sea. However, their diversity in submarine canyons remains largely unknown. Here, two new species and a new genus of Paratanaoidea are described. Paranarthrura cousteaui sp. nov. is distinguished by the combination of the following characters: post-cheliped sclerites not fused, presence of one seta in the maxilliped endite, one long midventral seta in cheliped, one penicillate seta in the basis of pereopods 4–6, uropod endopod bi-articulated and uropod exopod shorter than endopod article 1. This species was found at the upper reaches of three Portuguese canyons, Cascais, Setúbal and Nazaré Canyons, and the adjacent open slope, between 897 and 1001 m water depths. Tirana vallis gen. et sp. nov. presents a combination of the characters that define the other two genera of Paranarthrurellidae, Paranarthrurella and Armatognathia, but also unique characters within the family: the antenna, cheliped and uropod are more elongate than the rest of the species; the pereopods 4–6 carpus spines reach at least half of the length of the propodus and the propodus of pereopods 4–6 have ramified subdistal spines. This species was found at the middle reaches of Setúbal Canyon (3214–3219 m water depth).


Introduction
Submarine canyons are deep-sea geomorphic features distributed along continental margins worldwide, with high variability of topographic, hydrographic, sedimentological and biogeochemical conditions (Tyler et al. 2009;Harris & Whiteway 2011). This morphological and ecological heterogeneity results in variations of the diversity patterns of the macrofaunal assemblages along the canyons (e.g., Almeida et al. 2018) and submarine canyons have been defi ned as areas of organic matter accumulation with a high density of benthic biomass compared with the open slopes (Vetter & Dayton 1998;Duineveld et al. 2001;Cunha et al. 2011). However, despite the fact that Tanaidacea Dana, 1849 are amongst the dominant taxa in benthic macrofaunal assemblages (e.g., Cunha et al. 2011;Gunton et al. 2015), only one study focusing on tanaidaceans from submarine canyons has been published to date (Sganga & Roccatagliata 2016).
The knowledge of the deep-sea Tanaidacea along the Portuguese margin is scarce: except for the Gulf of Cadiz and Horseshoe Continental Rise, where tanaidacean fauna have been the subject of taxonomic studies (Błażewicz-Paszkowycz et al. 2011a, 2011bEsquete & Cunha 2017, few published works (Norman & Stebbing 1886;Stephensen 1915;Băcescu 1978) and repository datasets (IFREMER 2020; Orrel 2020) have added localized records to the area. In 2006, two research cruises were carried out aiming at a multidisciplinary study of three of the largest marine canyons from the Portuguese margin: Nazaré, Cascais and Setúbal (Fig. 1). The benthic macrofauna samples revealed a great diversity and heterogeneity of the assemblages (Cunha et al. 2011), and particularly of tanaidaceans. The forty tanaid species recorded in the Portuguese canyons will be reported elsewhere but from these, two were identifi ed as new for science are herein formally described as a new species belonging to the family Agathotanaidae Lang, 1971 and a new species and new genus of the family Paranarthrurellidae Błażewicz, Jóźwiak & Frutos, 2019. The family Agathotanaidae is currently composed of 56 species belonging to seven genera (WoRMS 2020), 13 of which have been found in the Northeast Atlantic as the outcome of two exhaustive works (Bird & Holdich 1988;Bird 2010). This is not considered a strictly deep-sea family, because some populations of well-known species, such as Paranarthrura subtilis Hansen, 1913 and Agathotanais ingolfi Hansen, 1913 have been found at depths shallower than 200 m (Bamber 1986;Bird 2010). Morphological distinction of Agathotanaidae from Anarthruridae Lang, 1971 has been historically controversial, and its taxonomic status has been changing between family, subfamily and tribe (Lang 1971;Sieg 1983Sieg , 1986aLarsen & Wilson 2002). Currently, Agathotanaidae is accepted as a distinct family, not based on specifi c characters or apomorphies but rather on a particular combination of characters that also occur in species belonging to Anarthruridae, making it diffi cult to discern between the two families (Bird 2004). These diffi culties were refl ected in the status of the genus Paranarthrura, which was described by Hansen (1913) as a Tanaididae Nobili, 1906, and subsequently moved to the family Anarthruridae by Lang (1971), to the tribe Anarthrurini Lang, 1971by Sieg (1986b, the tribe as well as two sampling sites located in the upper slope ( Fig. 1) September, 2006) was conducted by the Royal Netherlands Institute for Sea Research (de Stigter et al. 2007). Samples where extracted using a NIOZ boxcore equipped with a cylindrical coring barrel of 30 cm diameter (sampling area 0.07 m 2 ) and 55 cm in length. Cruise CD179 (RSS Charles Darwin, 14 th April-17 th May 2006) was conducted by the National Oceanography Centre, Southampton (Billet et al. 2006). Samples were collected using a NOC-UKORS Megacore equipped with 12 megacorer tubes (100 mm diameter) (in ST CD179_21-1) or 9 megacorer + 3 multicores (in ST CD179_21-2). In all cruises the sample material was sieved (1 mm, 500 μm and 300 μm) and fi xed immediately in 10% buffered formalin diluted in seawater, or in 96% ethanol (in the case of cruise 64PE252) (see Cunha et al. 2011 more details on sampling). Specimens were dissected whenever necessary, mounted in slides with glycerol and examined under a Leica MZ 125 stereoscope and an Olympus BX50 microscope. Length measurements were made axially at the longest part of the structure.
The body length was measured from the tip of the rostrum to the tip of pleotelson. Identifi cation of developmental stages follows Bird & Holdich (1988, 1989. All setae mentioned in the descriptions are simple unless otherwise specifi ed. 'Penicillate' setae are those with setules densely covering their distal part, forming a terminal plume. 'Plumose' setae are those entirely covered by setules, form their insertion in the cuticle to the terminal end. 'Setulose' setae are those with setules only on the posterior half middle of the seta. If not commented, illustrations are performed in dorsal view. This terminology is used according to Esquete et al. (2012Esquete et al. ( , 2016. Illustrations were done under a camera lucida, and modifi ed with Adobe Illustrator CS6 software. Type material has been deposited in the Museo Nacional de Ciencias Naturales, Madrid, Spain (MNCN); further material is at the Biological Research Collection of Departamento de Biologia, Universidade de Aveiro (COBI-DBUA).  Phylum Arthropoda Latreille, 1829Subphylum Crustacea Brünnich, 1772Class Malacostraca Latreille, 1802Order Tanaidacea Dana, 1849Suborder Tanaidomorpha Sieg, 1980Superfamily Paratanaidoidea Lang, 1949 Family Agathotanaidae Lang, 1971 Genus Paranarthrura Hansen, 1913 Paranarthrura cousteaui sp. nov. urn:lsid:zoobank.org:act:3AFA3BE0-25D4-4FDC-B03F-57B7F75F27D1 Figs 2-5

Etymology
This species is named in honour to Jacques-Yves Cousteau (1910-1997, for his life-long intensive work in raising awareness to the sea life and great contributions to the knowledge of the marine environment.

Description
Preparatory male (MNCN 20.04/12538) BODY ( Fig. 2A-B). Well calcifi ed, 6.2 times as long as wide (holotype length: 2.1 mm; width 0.33 mm). Cephalothorax without eyes or eye lobes, subrectangular posteriorly, narrower anteriorly, 0.20 of body length. Rostrum ( Fig. 2A, C) absent. Pereon 0.62 of body length, pereonites decreasing in width posteriorly. Pereonites 1-6: 0.5, 0.6, 0.6, 0.9, 0.9 and 0.7 times as long as wide respectively, each with hyposphaenium ( Fig. 2B); pereonites 2-6 subhexagonal. Coxal setae visible in dorsal view. Pleon 0.14 of body length, with fi ve free pleonites. Pleonite 5 longest, 0.3 times as long as previous, with anterodorsal and lateral seta (Fig. 2B). Pleotelson semicircular, 0.04 of body length, carrying a pair of setae in posterior margin. Uropods not visible in dorsal view. ANTENNULE (Fig. 2C). Four-articled. About as long as cephalothorax, 5.2 times as long as wide. Article 1, 2.8 times as long as wide, with one subdistal seta and three short medial penicillate setae on outer margin. Article 2, 2.1 times as long as wide, with one short subdistal seta on inner margin, one long dorsodistal penicillate seta, and one long subdistal seta on outer margin. Article 3, 0.9 times as wide as long, with two distal setae on inner margin and one subdistal seta on outer margin. Article 4, 2.7 times as long as wide, with six long and one short distal setae. ANTENNA (Fig. 2D, ventral view). Six-articled, 7.5 times as long as wide. Article 1 fused with body, not visible on dorsal view. Article 2, 1.4 times as long as wide, with dorsodistal seta. Article 3, 1.1 times as long as wide, with dorsodistal seta. Article 4 longest, 3.9 times as long as wide, with three subdistal setae. Article 5 naked, 2.8 times as long as wide. Terminal article 0.3 times as long as previous, with fi ve distal setae.   ( Fig. 4D) basis fused, elongate, 1.6 times as long as wide, with one seta near the palp insertion. Endites not fused, with one inner distal short seta each. Palp article 1, 1.5 times as long as wide, naked. Article 2, 1.0 times as long as wide, with three inner setae, one of them longer. Article 3, 1.4 times as long as wide, 1.5 times as long as previous, with three inner setae. Article 4, 2.1 times as long as wide, distally setulose, with four simple and two pinnate setae.

MOUTHPARTS. Labrum
CHELIPED (FigS 4E, 5A-B). Attached via ventral pseudocoxa, naked, 1.4 times as long as wide. Basis 1.2 times as long as wide, seta not seen. Merus subtriangular, 0.9 times as long as wide, with midventral seta. Carpus 1.7 times as long as wide, with two midventral setae, short and long, and two short middorsal and posterodorsal setae. Propodus 2.0 times as long as wide, ventral protuberance with one ventral seta and inner row of three setae near ventral margin. Cutting edge of fi xed fi nger coarse, not distinct claw, with three setae, near dactylus insertion. Dactylus and unguis not fused, together 3.3 times as long as wide. Dactylus with one simple dorsal seta.
PEREOPOD 1 (Fig. 5C). Coxa with seta. Basis 4.1 times as long as wide, naked. Ischium wider than long, naked. Merus twice as long as wide, with ventrodistal spine, reaching about half-length of carpus. Carpus 2.6 times as long as wide, bearing three serrate spines: one dorsodistal and two ventrodistal. Propodus slightly curved, 4.7 times as long as wide, ventral margin proximally with four spinules, bearing three subdistal simple setae, two ventral, and one dorsal. Dactylus and unguis together 1.1 times as long as propodus, unguis 0.53 times as long as dactylus.
PEREOPOD 2 (Fig. 5D). Coxa with anterior seta. Basis naked, 6.2 times as long as wide. Ischium wider than long, with ventral seta. Merus 1.7 times as long as wide, with long, ventrodistal simple spine, as long as carpus. Carpus 2.0 times as long as wide, bearing three serrate spines, one dorsodistal and two ventrodistal. Propodus slightly curved, 3.7 times as long as wide, with small dorsodistal spiniform apophysis, ventral margin with four spinules, bearing one subdistal simple spine. Dactylus and unguis combined 1.3 times as long as propodus, unguis 0.6 times as long as dactylus.
PEREOPOD 3 (Fig. 5E). Similar to pereopod 2, except for: basis 3.9 times as long as wide. Merus 2.1 times as long as wide, with spine reaching just 80% length of carpus. Carpus 2.7 times as long as wide. Propodus 3.5 times as long as wide. Dactylus and unguis combined 1.5 times as long as propodus.
PEREOPOD 4 (Fig. 5F). Coxa with anterior seta. Basis 3.2 times as long as wide, with one midventral penicillate seta. Ischium wider than long, with two ventral setae. Merus 1.7 times as long as wide, bearing two ventrodistal simple spines (both 50% length of carpus). Carpus 2.4 times as long as wide, bearing three subdistal serrate spines. Propodus 3.1 times as long as wide, with dorsodistal spiniform apophysis, two ventrodistal and one dorsodistal simple spines. Dactylus and unguis combined 1.7 times as long as propodus, unguis 0.5 times as long as dactylus.
PEREOPOD 5 (Fig. 5G). Similar to pereopod 4, except for: basis 3.6 times as long as wide. Merus 1.84 times as long as wide. Carpus with an extra distal simple seta. Unguis broken PEREOPOD 6 (Fig. 5H). Similar to pereopod 4, except for: Basis 3.7 times as long as wide. Merus 1.6 times as long as wide, bearing two ventrodistal serrate spines. Carpus 2.8 times as long as wide. Propodus 3 times as long as wide, with dorsodistal spiniform apophysis, two distal serrate spines in dorsal margin and two distal serrate spines in ventral margin. Dactylus and unguis together 1.4 times as long as propodus. PLEOPODS (Fig. 2B, F). Rudimentary, uniramous, naked and fused to pleonites, with faint fusion line. UROPODS (Fig. 2B, E). Biramous. Exopod fused to protopod, with long and short distal setae, not reaching beyond mid-length of endopod article 1. Endopod bi-articulated, 2.7 times as long as wide. Article 1, 1.5 times as long as wide, with two distal setae on outer margin, one of them penicillate. Article 2, 1.0 times as long as wide, bearing one subdistal long setae on inner margin and four distal setae, one of them shorter.

Remarks
For most of the species of Paranarthrura the males were described with their original description, exceptions being Paranarthrura bacescui Kudinova-Pasternak, 1986, Paranarthrura coimbrai Larsen & Bird, 2013, Paranarthrura fortispina Sieg, 1986 and Paranarthrura meridionalis Sieg, 1986 (see Kudinova-Pasternak 1986;Sieg 1986b;Larsen et al. 2013). However, males of P. fortispina were later described (Jóź wiak & Błażewicz-Paszkowycz 2011). The presence of pleopods is common and one of the main differences with females, together with the body length and relative size of the pleon. Because of the poor condition of the neuter specimens in our collection, we describe P. cousteaui sp. nov. from a preparatory male holotype. Paranarthrura cousteaui sp. nov. is distinguished from the other species of the genus by the unique combination of the following characters: post-cheliped sclerites unfused; presence of one long midventral seta in cheliped carpus; presence of dorsal seta on cheliped dactylus; presence of one penicillate seta in the basis of pereopods 4-6; one seta in the maxilliped endite uropod endopod bi-articulated and uropod exopod shorter than endopod article 1.
Paranarthrura angolesis from the South East Atlantic shares with P. cousteaui sp. nov. the following characters: post-cheliped sclerites not fused, presence of serrate spines on pereopods and number and relative length of uropod endopod article; it can be distinguished from the new species by the endopod with "setose setae" (sensu Guerrero-Kommritz et al. 2002), a more slender chela (2.5 times as long as broad, instead of 2.1) and four setae on maxilliped articles 2 and 3 instead of three. Paranarthrura bispinosa from the Gulf of Mexico, shares with P. cousteaui sp. nov. the short uropod exopod not as long as endopod article 1 and penicillate setae on the basis of the pereopods 4-5 and the presence of distoventral spiniform apophysis in pereopods 2-3 propodus; it differs by the maxilliped endites fused to basis, presence of several penicillate setae on antennule (fi ve in article 1 and two in article 2) and antenna (three in article 3 and one in article 4), cheliped chaetotaxy (absence of midventral seta in merus, subdistal setae in carpus and dorsal in propodus, and presence of one midventral seta in carpus and one dorsal seta in dactylus) and slender chela. Paranarthrura tenuimanus also from the Gulf of Mexico, has very short setae on maxilliped endite, no long seta on cheliped carpus and no dorsal spine on dactylus.
Paranarthrura cousteaui sp. nov. can be distinguished from species with a two-articled uropod endopod from other geographic locations as follows: P. arctowskii from the Antarctic has post-cheliped sclerites unfused medioventrally two setae on maxilliped endite, and a longer uropod exopod; and P. bacescui from the Indian Ocean show relatively longer uropod endopod segments.

Type species
Tirana vallis gen. et sp. nov.

Etymology
Following the steps of Błażewicz et al. (2019) for the species of the genus Paranarthrurella, we name the new genus after a folk dance from Portugal named 'tirana', object of great traditional and cultural value. Gender: feminine.

Remarks
The new genus presents a combination of the characters that defi ne the other two species of the family, Paranarthrurella and Armatognathia: It shares with Paranarthrurella an elongate body, maxilliped endites with slender gustatory cusps, and an uropod endopod article 1 about as long as article 2, and with Armatognathia it shares the presence of a distal spine in antenna article 2, presence of welldeveloped pleopods, and a molar with spiniform processes. Furthermore, females of (the new genus) have well-developed pleopods, which are present in Armatognathia and absent in most species of Paranarthrurella. Despite being described as "absent" in the diagnosis of Paranarthrurella provided by Błażewicz et al. (2019), illustrations of neuter specimens of P. rocknroll Błażewicz & Jóźwiak, 2019 and P. corroboree Błażewicz & Jóźwiak, 2019 show what seem to be rudimentary pleopods. However, those are signifi cantly different from the ones of Tirana gen. nov.
Tirana gen. nov. also presents unique characters within the family: the antenna article 4 is more elongate (10 times as long as broad) than in the other species of the family (4-5 times as long as broad); the cheliped is more slender (1.8 times as long as broad) than in the other species (< 1.6); the pereopods 4-6 carpus spines reach at least half of the length of the propodus; the propodus of pereopods 4-6 have ramifi ed subdistal spines; fi nally, the uropod rami are more slender than in the other species of the family (> 5.0 times as long as broad, while in the other species is < 4.0). Paratypes PORTUGAL • 1 manca, 1 juv., 1 ♀ (dissected); same collection data as for holotype; DBUA0002211.02.

Description of holotype
BODY (Fig. 6A-B). 8.9 times as long as wide (3.7 mm length, 0.5 mm width). Cephalothorax without eyes or eyelobes, elongate (1.3 times as long as wide) and subhexagonal, 0.15 of body length, narrower than pereon. Rostrum rounded. Pereon 0.63 of body length, pereonites 2-5 subhexagonal. Pereonites 1-6: 0.7, 0.9, 1.1, 0.9, 1.2 and 0.8 times as long as wide respectively. Coxal setae visible in dorsal view. Pleonites altogether shorter than last two pereonites together, 0.14 of body length. Pleonite 5 slightly longer than rest of them. All pleonites with a mediodorsal seta. Pleotelson 0.09 of body length, widest in its medial part, with posterior protuberance carrying four setae on distal margin. ANTENNULE (Fig. 6C). Five-articled. Article 1 longest and widest, 3.4 times as long as wide, with three outer penicillate setae in medial and distal position, respectively, three penicillate setae on subdistal outer margin, and one seta on subdistal inner margin. Article 2, 1.7 times as along as wide, with one seta on inner margin and three setae on outer margin (two of them penicillate), all subdistal. Article 3, as long as wide, with one long distal seta on outer margin and two on inner margin. Article 4, 4.4 times as long as wide, with one distal seta on inner margin. Article 5 minute, with fi ve terminal setae and one aesthetasc (not fi gured). ANTENNA (Fig. 6D, ventral view). Six-articled. Article 1 short and naked. Article 2, 2.1 times as long as wide, with one outer seta in medial margin and a dorsodistal spine. Article 3, 1.5 times as long as wide, with dorsodistal spine. Article 4 longest, 9.9 times as long as wide, with four subterminal setae, two penicillate. Article 5, 5.0 times as long as wide, with one long terminal seta. Article 6 minute, carrying fi ve terminal setae, two of them longer.
MOUTHPARTS (described from paratype DBUA0002211.02). Labrum (Fig. 7A, ventral view) rounded, posteriorly setulated. Left mandible (Fig. 7B-C) incisor process naked, slightly concave; lacinia mobilis long and wide; molar process with rounded tip, wide on its basis, with several distal spiniform processes. Right mandible (not fi gured) as left but without lacinia mobilis. Labium composed of two lobes, quadrangular, naked (not fi gured). Maxillule (Fig. 7D) endite with row of spines on outer margin, distally with microtrichia, seven rounded-tip spines. Maxilla ovoid, naked (not fi gured). Maxilliped (Fig. 7E) basis narrower posteriorly, partially fused, with seta near palp insertion. Endites not fused, bearing one pair of slender gustatory cusps, and one pair of simple setae posteriorly to them. Palp 4-articled. Article 1 naked. Article 2 subtriangular with three inner setae. Article 3 longest, with three inner pinnate setae and one simple seta. Terminal article long with fi ve terminal and one subterminal pinnate setae. CHELIPED (Fig. 6G-H). Attached ventrally via large sclerite. Basis naked, 1.4 times as long as wide, posteriorly rounded. Merus naked, 1.3 times as long as wide with one medioventral seta. Carpus 1.8 times as long as wide, with two medioventral seta. Propodus robust, 1.8 times as long as wide, with inner row of seven setae. Ventral margin of fi xed fi nger with two pinnate setae near dactylus insertion and cutting edge crenulated with three setae. Dactylus robust, 2.1 times as long as wide, not fused with unguis. Dactylus and unguis together not reaching end of propodus and claw.
PEREOPOD 1 (Fig. 8A-A'). Coxa with seta. Basis 4.5 times as long as wide, with two mediodorsal setae. Ischium wider than long, with ventral seta. Merus 2.4 times as long as wide, with subdistal ventral seta and distoventral pinnate spine. Carpus 4.3 times as long as wide, with two ventrodistal pinnate spines and one distodorsal pinnate spine. Propodus 5.5 times as long as wide, ventral margin serrates with two dorsodistal spines, one of the setulose and the other simple, and one ventrodistal simple spine. Dactylus as long as unguis, naked, together as long as propodus.
PEREOPOD 2 (Fig. 8B-B'). Coxa with seta. Basis 4.5 times as long as wide, with three mediodorsal setae. Ischium wider than long, with ventral seta. Merus 2.5 times as long as wide, with long ventrodistal seta and pinnate spine. Carpus 3.5 times as long as wide, bearing one dorsodistal long pinnate spine and one short simple spine, and one ventrodistal long pinnate spine and one short simple spine. Propodus 6.1 times as long as wide, ventral margin serrated, with one one subdistal long seta, one subdistal short seta and one subdistal pinnate spine in dorsal margin and one pinnate spine in ventral margin. Dactylus and unguis naked, together about as long as propodus.
PEREOPOD 3 (Fig. 8C). Similar to pereopod 2, except for: seta from coxa not illustrated. Basis 4.1 times as long as wide, with one mediodorsal seta. Merus 2.8 times as long as wide. Carpus 3.6 times as long as wide. Propodus 5.6 times as long as wide.
PEREOPOD 4 (Fig. 8D). Coxa with seta. Basis 3 times as long as wide, with mediodorsal penicillate seta. Ischium wider than long, with two ventral setae. Merus 2.7 times as long as wide, with two ventrodistal pinnate spines. Carpus 2.3 times as long as wide, one dorsodistal, two in mediodistal and one ventrodistal pinnate spines. Propodus 6.2 times as long as wide, ventral margin serrated, with two dorsodistal and one ventrodistal pinnate spines. Dactylus and unguis naked, together 0.8 times as long as propodus.
PEREOPOD 5 (Fig. 8E-E'). As pereopod 4, except for: basis 5.0 times as long as wide. Merus 3.8 times as long as wide. Carpus 2.8 times as long as wide, with dorsodistal seta, and simple spine, and one dorsodistal and two ventrodistal pinnate spines. Propodus 6.0 times as long as wide with a mediodorsal penicillate seta, (not fi gured in Fig. 8E') one dorsodistal simple spine and two ramifi ed ventral-subdistal spines. Dactylus and unguis naked, together 0.7 times as long as propodus.
PEREOPOD 6 ( Fig. 8F-F'). As pereopod 4, except for: basis 4.7 times as long as wide. Merus 2.3 times as long as wide. Carpus 2.9 times as long as wide Propodus 6.0 times as long as wide with a mediodorsal penicillate seta (not fi gured in Fig. 8E') three dorsodistal distal simple and two and two ramifi ed ventralsubdistal spines. Dactylus and unguis naked, together 0.7 times as long as propodus.  PLEOPODS (Fig. 6F). Present in all pleonites, all with same chaetotaxy. Protopod naked. Endopod long and narrow, 5.1 times as long as broad, with eight terminal long plumose setae and one subdistal seta on inner margin. Exopod long and narrow, 6.1 times as long as broad bearing seven long plumose setae. UROPODS (Fig. 6E). Biramous. Protopod naked, 1.5 times as long as broad. Endopod 2-articled, 2.3 times as long as protopod. Article 1 with two subdistal setae, one penicillate. Article 2, 1.2 times as long as article 1, with fi ve setae, two of them broken in holotype. Exopod 1.7 times as long as protopod. Article 1 with distal seta. Article 2, 1.8 times as long as article 1, with two distal setae, one of them broken in holotype.

Discussion
The genus Paranarthrura is well represented in the North-East Atlantic Ocean; seven out of 19 species have been found there (P. insignis, P. borealis Bird & Holdich, 1989, P. subtilis, P. crassa, P. lusitanus, P. intermedia and P. tridens Bird & Holdich, 1989) (Bird & Holdich 1989;Bird 2010). These species are present at different bathymetric ranges, and we can fi nd both euribathyal species, as P. insignis (385-5000 m) or P. intermedia (1400-4190 m), and species with a more restricted bathymetry, as P. subtilis (582-1739 m) or P. tridens (4426-4829 m). Paranarthrura cousteaui sp. nov. is the eighth species found in this region, so far recorded in the upper bathyal zone, between 897 and 1001 meters deep.
The family Paranatrhurellidae is currently composed of sixteen species, from which two are known from the North-East Atlantic, Paranarthrurella arctophylax (Norman & Stebbing, 1886) and P. voeringi (Sars, 1877). Paranarthrurella voeringi has been found from Faroe Islands in its lowest latitude to Svalbard archipelago in the North (Sars 1877;Jóźwiak et al. 2009;Błażewicz et al. 2019), while the northern limit of P. arctophylax is close to Iceland, and its southern limit is the Bay of Biscay (Norman & Stebbing 1886). Błażewicz et al. (2019) also found two additional Paranarthrurella species from north-east Iceland yet to be described.
Species of Armatognathia have been found exclusively in bathyal and abyssal zones from 3450 to 4892 meters, being Armatognathia shiinoi (Kudinova-Pasternak, 1973) the species found shallowest, occurring from 3450 to 3460 meters (Kudinova-Pasternak 1973), and Armatognathia swing Błażewicz & Jóźwiak, 2019 the deepest, occurring from 4713 to 4892 meters. On the other hand, Paranarthrurella can be considered a deep-sea euribathyal genus, as it contains species as P. voeringi found at 760 meters (Jóźwiak et al. 2009) as well as abyssal species like P. dissimilis (Lang, 1972), only known from its type location, the Sargasso Sea, at a depth of 6000 m (Lang 1972). Moreover, the species P. caudata (Kudinova-Pasternak, 1965) has been found in the hadal range from 7947 to 8006 m (Kudinova-Pasternak 1965). Occurring between 2314 and 3219 m deep, T. vallis gen. et sp. nov. is within this wide range and can be considered a bathyal species. It is the third formally described genus from Paranarthrurellidae and the fi rst species found in the margins of the Iberian Peninsula, therefore expanding the distribution of the family in the Easter Atlantic to the south. Original descriptions of some of the species mentioned here can be found in Kudinova-Pasternak (1973).
develop the cruises and obtain this samples. A. García-Herrero is supported by Erasmus + Programme, and P. Esquete is funded by national funds (OE), through FCT -Fundação para a Ciência e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. Thanks are due to FCT/MCTES for the fi nancial support to CESAM (UIDP/50017/2020+UIDB/50017/2020), through national funds. Thanks are due to the two anonymous referees whose comments greatly improved our manuscript.

Confl ict of interest
The authors declare that they have no confl ict of interest.