First record and a new species of Foxiphalus Barnard, 1979 (Crustacea: Amphipoda: Phoxocephalidae) from the Atlantic Ocean, with two new records of the family from northeastern Brazil

. A new species of Foxiphalus Barnard, 1979 is described. The material examined was collected as part of the project “Avaliação da biota bentônica e planctônica da Bacia Potiguar e Ceará” (BPOT), off northeastern Brazilian continental slope on the state of Rio Grande do Norte at depths ranging from 135 to 283 meters. Foxiphalus potiguara sp. nov. is recognized among its congeners by: rostrum slightly exceeding the article 2 of antenna 1; lower lip outer lobes with strong shoulder cusps; maxilliped inner plate with two apical robust setae; gnathopod 2 carpus shortened; pereopod 5 basis tapering distally; and epimeral plate 3 posterior margin weakly crenulated. This is the first record of Foxiphalus for the Atlantic Ocean and we provide an amended diagnosis of the genus and an identification key to its world species. In addition, two new records of Phoxocephalidae are reported from northeastern Brazil: Heterophoxus shoemakeri Andrade & Senna, 2020 and Metharpinia dentiurosoma Alonso de Pina, 2003.

Until now, Foxiphalus has been only recorded in cold waters from the northern Pacific Ocean, ranging from Alaska, in North America, to Panama, in Central America, mostly on shallow waters, but also in slightly greater depths up to 324 meters (Barnard & Karaman, 1991;Jarret & Bousfield, 1994).
The family Phoxocephalidae has lately been studied in more detail in Brazil, accounting many new species and new records from southeast and southern Brazilian waters (Andrade & Senna, 2019a, b;Andrade & Senna 2020a, b, c, d).
Currently there are 28 species of the family recorded from Brazilian waters. Here, we report two new records of phoxocephalids from northeastern Brazil: Heterophoxus shoemakeri Andrade & Senna, 2020 and Metharpinia dentiurosoma Alonso de Pina, 2003. We also describe a new species of Foxiphalus, being the first record of the genus for the Atlantic Ocean, with material from the Potiguar Basin, northeastern Brazil. In addition, we provide an amended diagnosis of the genus and an identification key to world species of Foxiphalus.

MATERIAL AND METHODS
The material was collected off the Potiguar Basin (BPOT), Rio Grande do Norte state, across the shelf break to the upper slope from 135 to 283 meters by Van Veen grabs on the scope of the project "Avaliação da Biota Bentônica e Planctônica da Bacia Potiguar e Ceará" developed by the Brazilian Oil Company "Petróleo Brasileiro S/A (Petrobrás)" onboard the R/V Seward Johnson.
The basin is located at the eastern end of the Brazilian Equatorial Margin (Fig. 9), comprising both emerged and submerged segments. Most of it is distributed in the state of Rio Grande do Norte and partially in the state of Ceará (Mohriak, 2003), covering approximately 38,500 km², distributed between the continental shelf and the continental slope, up to 2,000 meters depth (Bertani et al., 1990).
The type-material is deposited at the Crustacea Collection of the Museu de Oceanografia Prof. Petrônio Alves Coelho da Universidade Federal de Pernambuco (MOUFPE), Brazil. For the taxonomic study, appendages and mouthparts were dissected and mounted in glycerin gel slides, drawn under an optical microscope with camera lucida, Leica DM E, and digitally prepared with CorelDRAW 2018. The setal/spine classification used in this work follows Watling (1989). The nomenclature of gnathopod palm is based on Poore & Lowry (1997). Based on literature review and observation of other important characters on the new species, we decided to amend the previous diagnosis from Jarret & Bousfield (1994) and new characters are highlighted in bold. The previous identification key available for Foxiphalus from Jarret & Bousfield (1994) was not complete, accounting only regional species. Thus, we present an updated identification key for all world species, as well as using better established and stable characters for an easier distinction of the species within Foxiphalus. Distribution and bathymetric range: The species has previously been found off the coast of the states of Rio de Janeiro, Santa Catarina and Rio Grande do Sul (Andrade & Senna, 2020a) between 25 and 128 m depth.

Taxonomic analysis
Here we report it for the continental slope of the state of Rio Grande do Norte at 278 and 283 m depth.
Remarks: This species was recently described with material from off the coasts of the Brazilian states of Rio de Janeiro, Santa Catarina and Rio Grande do Sul. The individuals found here agree with its original description although some subtle differences can be noticed such as setation patterns. This is the deepest and northernmost record of the species and its first record to northeastern Brazil.

Subfamily Phoxocephalinae G.O. Sars, 1891
Genus Foxiphalus Barnard, 1979 Type species: Foxiphalus obtusidens (Alderman, 1936) Diagnosis: After Jarret & Bousfield (1994), amendments in bold. Pigmented eyes very small to medium in female, medium to large in male. Rostrum fully hooded, unconstricted. Antenna 1, peduncle article 2 shorter than 1. Antenna 2, peduncle article 1 and 2 variously ensiform, article 3 with one lateral seta, article 4 facial robust setae in three distinct rows, anterior margin with few setae only, or also with robust seta, article 5 with one or two clusters of facial setae and one or two distal calceoli on the anterior margin in male; flagellum medium in the male and elongated with alternately calceolate articles in the male. Mandible incisors broad with at least two teeth, left lacinia mobilis with at least two teeth, right lacinia mobilis simple, bifid or absent, molar with five to 10 robust setae, accessory setal row medium to strong; palp slender, article 2 weakly setose, article 3 apex oblique and truncate, bearing cluster of setae. Upper lip epistome occasionally with sharp anterior process. Lower lip broad, with distinct shoulder cusps. Maxilla 1 inner plate with up to five apical setae, outer plate with one apical robust seta enlarged. Maxilla 2 outer plate usually broader than inner. Maxilliped inner plate with one or two apical robust setae; outer plate slender, short, not reaching half of palp article 2, dactylus slender. Gnathopods 1-2 dissimilar, propodus longer than respective carpus; palms acute. Gnathopod 2 carpus posterior margin short. Pereopods 3-4 carpus posterior margin with distal long robust seta, propodus with robust setae distally. Pereopod 5 basis broad, propodus longer than carpus, posterior margin setose, dactylus slender. Pereopod 6 basis broad, merus usually narrow and without facial rows of robust setae. Pereopod 7 copulatory spines in males slender, subequal, straight or slightly curved, prox-imally serrated, distally setulose or smooth. Uropod 1 peduncle with displaced robust seta present, rami with few dorsal robust setae, bearing apical nail. Uropod 2 peduncle with dorsal row of robust setae, outer ramus with few dorsal robust setae, inner ramus with robust seta or naked. Uropod 3 inner ramus of variable length in females, subequal and setose with plumose setae in males. Telson lobes with at least one apical robust seta on each side and single plumose seta.
Epimeral plate 1 (Fig. 6A) anterior margin with two plumose setae, anteroventral corner with a row of three plumose setae extending to facial margin. Epimeral plate 2 (Fig. 6B) anterior margin with two plumose setae, facial margin with a row of six plumose setae. Epimeral plate 3 (Fig. 6C) anterior margin with two plumose setae, ventral margin with two setae, posterior margin weakly crenulated, with eight setae. Urosomite 1 (Fig. 1A) bearing a ventral tuft of setae. Uropod 1 (Fig. 6D) peduncle longer than rami, about 2.8× longer than wide, dorsomedial margin with one slender and five robust setae, dorsolateral margin with four robust setae, displaced robust setae present; both rami bearing one embedded apical nail; outer ramus slightly longer than inner, dorsal margin with four robust setae; inner ramus dorsal margin with two robust setae. Uropod 2 (Fig. 6E) peduncle longer than rami, about 2.1× longer than wide, dorsomedial corner with one robust seta, dorsolateral margin with seven robust setae; both rami bearing one embedded apical nail; outer ramus slightly longer than inner, dorsal margin with three robust setae; inner ramus dorsal margin with one robust seta. Uropod 3 (Fig. 6F) peduncle about 1.5× longer than wide, dorsomedial margin with one robust and one short seta, dorsolateral margin with one distal robust seta, ventral margin with a distal row of four robust setae; outer ramus 1.4× longer than inner, article 1, ventrally with three sets of two robust and one plumose seta, dorsal margin with three plumose setae, article 2 about 0.3× the length of article 1, bearing two apical plumose setae, inner ramus about 0.6× the length of outer, with few plumose setae, being two placed apically. Telson (Fig. 6I) about 85% cleft, each lobe with two dorsolateral plumose setae plus a short, one robust and one plumose seta apically.
Head (Fig. 7A-B) with large and ovate eyes, rostrum broad and unconstricted, slightly exceeding the article 2 of antenna 1. Antenna 1 (Fig. 7C) peduncle article 1 dorsal apex with one plumose and two smooth setae, ventral margin with 13 plumose setae and a distal row of setules; article 2 dorsal apex with two setae, ventral margin with eight pectinate setae, facial margin with two plumose and five pectinate setae, article 3 ventral margin with two setae, facial margin with four setae, being two plumose; primary flagellum 12-articulate; accessory flagellum 9-articulate. Antenna 2 (Fig. 7D) peduncle ar-ticle 3 bearing one long and one short facial seta, dorsal margin with a row of setules; article 4 facial robust setae formula: 3-4-3, dorsal margin with one robust, one long and eight smooth setae medially, proximally and distally with sets of setules, ventral margin with five plumose setae proximally and pectinate setae medially, distally with one displaced robust long seta; article 5 facial robust setae formula: 3-2, dorsal margin with four brushes of setules and one distal calceolous, ventral margin with few slender and plumose setae, facial margin with two distal robust setae; flagellum 28-articulate, with five calceoli.
Epimeral plate 1 (Fig. 8C) anteroventral corner with a row of four plumose setae, increasing in length, ventral margin almost straight, posterior margin convex. Epimeral plate 2 (Fig. 8D) anterior margin with seven sete, anteroventral corner weakly expanded, ventral margin with a shallow concavity, posterior margin with two notches, one of them bearing one seta. Epimeral plate 3 (Fig. 8E) anterior margin with seven short setae, ventral margin with three setae, posterior margin with 11 pectinate setae. Uropod 3 (Fig. 8F) peduncle ventral margin with five distal robust setae, dorsal margin with one short and one robust seta; outer ramus slightly longer than inner, article 1 ventral margin with three sets of one ro-  Andrade, L.F. et al.: A new species of Foxiphalus from Brazil Pap. Avulsos Zool., 2022;v.62: e202262055 9/13 bust and one long plumose seta, dorsally covered with plumose setae, article 2 about 0.2× the length of article 1, beating two apical plumose setae, inner ramus strongly setose with plumose setae, with two apical plumose setae.

Etymology:
The specific epithet is given after the Potiguar Basin, type-locality of the new species. This name is derived from an indigenous Tupi word "poti'war" or "potiguar" that means "the one who eats shrimp". The epithet is used as a noun in apposition.

Distribution and bathymetric range:
The species is found off the coast of the state of Rio Grande do Norte, from 156 to 186 m depth (Fig. 9).
Remarks: Among the species of the genus, Foxiphalus potiguara sp. nov. is most morphologically similar to F. similis due to characters such as: lower lip outer lobes with strong shoulder cusps; mandible right and left incisors with three teeth, molar with five robust setae; maxilliped palp with slender nail; pereopod 5 merus and carpus narrow; uropod 1 peduncle with strong displaced robust setae; telson without dorsolateral robust setae. However, the new species can be distinguished by F. similis by the following (characters of F. similis in parenthesis): maxilla 1 inner plate with five apical setae (three to four apical setae); mandible molar as a hump with a triturative surface (as a hump, non-triturative); maxilliped inner plate with two apical robust setae (one apical robust seta); pereopod 5 basis narrow, tapering distally (broad, not tapering); male copulatory spine without distal setules (distally setulose); urosomite 1 of female with ventral tuft of setae (without); telson with each lobe bearing one apical robust seta (two robust setae). Furthermore, F. potiguara sp. nov., presents the longer rostrum withing the genus, slightly exceeding the apex of the second article of antenna 1, whereas the other species have it only reaching the apex of this article. In addition, F. potiguara sp. nov. has the largest discrepancy between gnathopods 1-2 among its congeners, being the second gnathopod stronger than the first. The new species also shares with only another species (F. aleuti) the presence of two apical robust setae on the inner plate of maxilliped. Thus F. potiguara sp. nov. can be distinguished by the latter by presenting: mandibular molar with less robust setae; gnathopods 1-2 with more shortened carpus and stronger propodus; pereopod 3 carpus posterior margin with longer distal long robust seta; uropod 3 outer ramus articles 1 and 2 longer in relation to the peduncle; telson lobes presenting only one apical robust seta.
It is important to highlight that during the analysis of the material, subtle and expected differences were found among the female individuals. However, it was possible to notice an interesting contrast between the inner and outer rami of the third uropod in relation to each individual's length, and consequently reflecting maturity stage. The smallest individual (female paratype MOUFPE 20004) presents a less setose uropod 3 (Fig. 6H), very short inner ramus on uropod 3 with one apical slender seta, about 0.3× the length of outer, and article 2 of outer ramus about 0.4× the length of article 1. A medium-sized individual (female paratype MOUFPE 15962) presents uropod 3 (Fig. 6G) more setose than the smaller one, with inner ramus about 0.4× the length of outer, bearing two apical plumose setae and article 2 of outer ramus about 0.3× the length of article 1. Whereas the bigger individual (female holotype MOUFPE 15999) presents a fully developed inner ramus on uropod 3 (Fig. 6F), reaching 0.6× the length of outer, bearing two apical plumose setae and article 2 of outer ramus about 0.3× the length of article 1.

Key to world species of Foxiphalus
Distribution and bathymetric range: This species was previously described with type-material from the coast of Buenos Aires, Argentina, at depths between 14 and 21 meters. Later, the species was found on samples off the coast of the Brazilian states of Rio de Janeiro, São Paulo and Santa Catarina ranging from 28 to 72 m depth. Here we report it for the continental slope of the state of Rio Grande do Norte at depths ranging from 135 to 173 meters.
Remarks: This species was recently redescribed with material from the coasts of the Brazilian states of Rio de Janeiro, São Paulo and Santa Catarina. The individuals found here agree with its original description although expected differences are observed such as setation due to maturity stages. This is the deepest and northernmost record of the species and its first record to northeastern Brazil.  Alonso de Pina, 2003 in the present study. Circle: record for H. shoemakeri; Star = records for F. potiguara sp. nov. and M. dentiurosoma; Triangle = records for M. dentiurosoma.

CONCLUSION
So far, the genus Foxiphalus had only been recorded mostly for shallow cold waters and deep sea in the Pacific Ocean, and despite the new finding reported here is in a warm tropical zone, the new species was found only in the continental slope. Thus, considering the past and new records of Foxiphalus, we can hypothesize that the genus has a wide bathymetric range, but more adapted to cold waters, even in the southern hemisphere.
The species H. shoemakeri and M. dentiurosoma have been previously recorded from southwestern Atlantic and in this study, we extend their distribution approximately 2.040 km towards north, and increase their depth range to 283 and 173 meters, respectively (Fig. 9). Accounting the latest findings regarding the phoxocephalids reported from Brazil it is expected that both species might also be found along the whole Brazilian coast.
The diversity of Phoxocephalidae in northeastern Brazilian waters is poorly known and the new species described here points out this evidence. We consider that new samplings and further taxonomical efforts combined with molecular studies must be applied as appropriate tools in order to fill these gaps in the marine Brazilian biodiversity.