Two new species of Tanaopsis ( Tanaidacea : Tanaopsidae ) from Admiralty Bay ( Antarctica ) , with an identification key

Two new species of family Tanaopsidae, genus Tanaopsis, from Admiralty Bay (Antarctica) are herein described. Tanaopsis brevicorpus sp. nov. displays antennule article 1 about 1.5 times as long as wide, carapace as long as first three pereonites, both rami of uropod biarticulate with fusion line, and pleotelson short, more than twice longer than wide. Tanaopsis bamberi sp. nov. resembles other Antarctic species T. kerguelenensis in its habitus, antennule long and uropod uniarticulate. However, the new species can be distinguished from it by a combination of characters that includes maxilliped basis with long seta arising from tubercles; inner margin of cheliped fixed finger with three smooth sub-terminal spines; uropod subequal to pleotelson in length, and uropodal endopod about twice as long as exopod. (JLS) Laboratório de Carcinologia, Museu Nacional, Universidade Federal do Rio de Janeiro. Quinta da Boa Vista, s/n, 20940-040 Rio de Janeiro, Brazil. E-mail: julianasegadilha@gmail.com. * Corresponding author (CLAS) AEE (Laboratório de Ecologia Aquática e Evolução), CIIMAR (Centro Interdisciplinar de Investigação Marinha e Ambiental), Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal; Fundação Capes, Ministério da Educação do Brasil, 70040-020 Brasília, DF, Brazil. E-mail: katelas@hotmail.com


Introduction
The monotypic family Tanaopsidae Błażewicz-Paszkowycz and Bamber, 2012 is characterized mainly by the pleon being laterally convex and wider than pereon, and the cheliped fixed finger having a bifid terminal spine.The systematics of the genus Tanaopsis Sars, 1899 is confused.The genus was first described in the family Tanaidae Dana, 1849, then transferred to Paratanaidae Lang, 1949 by Lang (1949) and later relocated to Leptognathiidae Sieg, 1976by Sieg (1976).The Paratanaoidea phylogeny performed by Larsen and Wilson (2002), and then revised by Bird and Larsen (2009), placed Tanaopsis as genus incertae sedis mainly due to the cheliped fixed finger with bifid terminal spine and coxa of pereopod-1 with a developed spur, which do not allow its inclusion in other family (Błażewicz-Paszkowycz and Bamber, 2012).Currently the genus includes 14 described species (Anderson, 2013) and it is distributed through shallow waters to bathyal and even abyssal depths, usually in muddy-sand or mud (Bird and Bamber, 2000).
This work is based on Antarctic species of Tanaopsis and, herein, we describe two new species (T.bamberi sp.nov.and T. brevicorpus sp.nov.) and, additionally, an identification key to all species of the genus, based on female characters is given.

Material and Methods
Specimens were collected from about 50-500 m depth in Admiralty Bay (South Shetland Islands, Antarctic), during the austral summer of 2005 and 2010 (Tab.1).The sediment was collected using a box corer, washed in a mesh size of 0.5 mm, fixed in 4% borax buffered formalin and subsequently preserved in 70% alcohol.
Material examined.Holotype.Diagnosis: Female.Antennule elongated, first and second articles 2.7 and 1.6 times as long as wide, respectively.Antenna with six articles, second and third articles with simple setae, seta on second article longer than on third article.Inner distal margin of cheliped fixed finger with three smooth spines.Uropodal exopod and endopod uniarticulate and endopod long with 2.5 times as long as exopod.

Etymology:
The name is dedicated to the late Dr. Roger Bamber in recognition of his great contribution to tanaidacean knowledge.Description: Female paratype, 4.5 mm (dissected).
Body (Fig. 1A) about six times as long as wide.Cephalothorax subtriangular, 1.1 times as wide as long, shorter than first three pereonites combined; with one lateral simple medial seta in each side; rostrum rounded.Pereonites.All pereonites wider than long, with slightly rounded corners.Pereonite 1 shortest, about 0.32 as long as carapace.Pereonite 3 longer than pereonites 2 and 6 and shorter than pereonite 5. Pereonite 4 longest.Pleonite 5 longest.Pleotelson longer than two last pleonites combined (about 35% length of pleon), with two pairs of simple and one pair of plumose terminal setae; apex pointed.
Antennule (Fig. 1B) about as long as cephalothorax.Article 1 narrow, about 2.75 times as long as wide, inner proximal margin with one simple seta, one distal inner simple seta and four plumose and one outer simple seta.Article 2 about Dissections were made in glycerin using chemically-sharpened tungsten wire needles.Body length was measured from the tip of the cephalothorax to the apex of the pleotelson.Terminology follows Larsen (2003).Three specimens from each new species collected in Admiralty Bay were dissected and habitus and appendage drawings were made from one dissected specimen from each one, excepted the labium of T. brevicorpus sp.nov., which was recovered from another specimen dissected.
The type materials and the other specimens are deposited at the collection in the National Museum, Universidade Federal do Rio de Janeiro, Brazil (MNRJ).
(Figs. 1-2)  1.6 times as long as wide, with four inner distal plumose and two simple setae.Article 3 shortest, as long as wide, with two outer distal simple and one plumose seta.Article 4 slender, about 3.8 times as long as wide, with one aesthetasc and seven simple terminal setae.Antenna (Fig. 1C) about 0.9 times as long as antennule.Article 1 broader than following articles, naked.Article 2 longer than article 3, about 1.3 times as long as wide, with one inner distal simple seta and one outer distal long simple seta.Article 3 as long as wide, with one outer distal simple seta.Article 4 narrow and longest, about 4.5 times as long as wide and 1.3 times longer than the last two articles together, with two subdistal plumose setae and three distal simple setae.Article 5 about 3.5 times as long as wide, longer than article 2, with one distal simple seta.Article 6 minute, with six terminal setae.
Cheliped (Fig. 2A, B).Basis about 1.7 times as long as wide, shorter than carpus, attached to cephalothorax via large sclerite.Merus triangular, with one long simple seta ventrally.Carpus about 1.3 times as long as wide, no carpal shield, with two long simple ventral setae and two minute setae dorsally.Propodus about 1.8 times as long as wide, with one simple seta near dactylus insertion.Fixed finger having delicate bifid terminal spine, with three inner and two outer simple setae and inner margin with three smooth sub-terminal spines.Dactylus slightly longer than fixed finger, with weak crenulations on dorsal margin and with two spines ventrally.
Pereopod 1 (Fig. 2C).Coxa with prominent spur with simple seta.Basis long (about 5.6 times as long as wide), with one minute seta dorsally.Ischium with one ventral simple seta.Merus apparently naked, 1.1 times as long as wide.Carpus slightly longer than merus, with two simple setae distally.Propodus as long as merus and carpus combined, with four simple terminal setae and dorsal microtrichia.Dactylus more than half as long as unguis, combined longer than propodus.
Pereopod 2 (Fig. 2D).As pereopod 1 except coxa without prominent spur.Basis 4.75 times as long as wide, with two minute plumose setae dorsally.Merus as long as wide, with one distal simple seta.Carpus with three setae distally.Propodus shorter than merus and carpus combined, with row of microtrichia along outer margin.
Pereopod 3 (Fig. 2E).As pereopod 2 except basis 3.75 times as long as wide, with one ventral and one plumose seta dorsally.Propodus with row of microtrichia along outer margin.
Pereopod 4 (Fig. 2F).Stouter than pereopods 1-3.Coxa absent.Basis about 2.7 times as long as wide, with one plumose seta ventrally.Ischium short, with two simple setae ventrally.Merus 1.3 times as long as wide, with two long feathery distal spines.Carpus longer than merus, with one pointed and two round feathery spines and one distal simple seta.Propodus shorter than merus and carpus combined, with one plumose seta dorsally, three serrated spiniform terminal setae and row of microtrichia along outer margin.Dactylus 1.2 times as long as unguis.
Pleopods (Fig. 2I).Well-developed.All pleopods similar in structure, with unequal rami.Basal article short, as long as wide.Endopod subrectangular with all setae distal, with one outer and eleven plumose inner setae.Exopod subovate with 32 plumose setae on entire outer margin; no gaps between the most proximal and the other setae.
Remarks: The main differences between the species of Tanaopsis are shown in Tab. 2. Tanaopsis bamberi sp.nov.resembles T. boonwurrungi and T. canaipa recorded from Australia and T. kerguelenensis from Antarctica, particularly in these species having antennule long (article 1 more than twice as long as wide), pleotelson long and uropod endopod more than 2.5 times longer than exopod.However, T. bamberi sp.nov.has more stout body (4.9 times); maxilliped basis with seta longer than endite and arising from tubercles; maxilliped endite with seta short and subdistal and inner margin of cheliped fixed finger with three smooth sub-terminal spines.Also, T. bamberi sp.nov. is distinct from T. antarctica, T. chotkarakde, T. graciloides (Lilljeborg, 1864), T. oios, T. profunda, T. rawhitia and T. rugaris Błażewicz-Paszkowycz et al., 2013 by the antennule article 2 rectangular and longest (about 2.7 times as long as wide) and the uropod endopod without segmentation or fusion line.The new species distinguish from T. cadieni, T. gallardoi and T. laticaudatus by the maxilliped endite having a short subdistal seta instead of being absent and the uropod endopod and exopod uniarticulate instead of biarticulate.
Moreover, T. curtus has carapace 1.1 times as long as the first three pereonites (T.bamberi has carapace 0.7 times as long as pereonites 1-3) and has maxilliped basis seta absent.Finally, T. bamberi sp.nov. is immediately distinguished from all of these taxa, except T. boonwurrungi and T. kerguelenensis, by its antennule article 1 and article 2 longest (about 2.75 and 1.6 times as long as wide, respectively) and both rami of uropod uniarticulate, without a fusion line.Etymology.Named after the body stout of the new species, with the lowest proportion length/ width among Tanaopsis species (4.1 times).
Body (Fig. 3A, B).Body about four times as long as wide.Cephalothorax triangular, 1.1 times as wide as long, as long as first three pereonites combined; with one lateral simple medial seta in each side; rostrum rounded; eyelobes absent.Pereonites.All pereonites with slightly rounded corners and with one seta in each lateral margin.Pereonite 1 shortest, about 0.25 as long as carapace.Pereonite 3 as long as pereonites 2 and Antennule (Fig. 3C).About 0.9 times as long as cephalothorax.Article 1 longest but as short as the rest of antennule, about 1.45 times as long as wide, inner distal margin with six plumose and one long simple setae and one outer distal simple seta.Article 2 half length of article 1, about 1.1 times as long as wide, with three inner distal plumose and two simple setae and one outer distal simple seta.Article 3 shortest, as long as wide, with one outer distal plumose and two simple setae.Article 4 slender, about 3.2 times as long as wide, with one aesthetasc and eight simple terminal setae.
Antenna (Fig. 3D).About 0.9 times as long as antennule, with six articles.Article 1 broader than following articles, naked.Article 2 as long as article 3, about 1.  as the last two articles, one medial and five distal plumose setae and three distal simple setae.Article 5 three times as long as wide, longer than article 3, with one single distal seta as long as fourth article.
Article 6 minute, with six simple terminal setae.Mouthparts.Labrum not recovered.Labium (Fig. 3E) with outer distal process, with few setules.Mandibles (Fig. 3F, G) with distal margins crenulated and molar thin and tapering.Left mandible (Fig. 3F) incisor with rounded and bloated tip; lacinia mobilis well-developed, with crenulations.Right mandible (Fig. 3G) incisor not bifurcated, weakly calcified.Maxillule (Fig. 4A, B) endite with several fine setules on lateral margins, six apical pinnate setae; palp with two distal simple setae.Maxilla (Fig. 4C) triangular, naked.Maxilliped (Fig. 4D) basis partly fused, with two long simple setae on distal margin; endite not fused, with two short simple setae arising from tubercles; palp article 1 naked; article 2 with two inner and one outer simple setae and two medial rows of minute setules; article 3 trapezoidal, with four inner simple setae and two distal rows of minute setules; article 4 slender than the others, with six simple terminal setae and four distal rows of minute setae.Epignath not recovered.
Cheliped (Fig. 4E, F).Basis about 1.6 times as long as wide, as long as carpus, attached to cephalothorax via large sclerite, with dorsodistal simple seta.Merus triangular, with one long simple seta ventrally.Carpus about 1.3 times as long as wide, no carpal shield, with two long simple ventral setae and two minute setae dorsally.Propodus two times as long as wide, with five simple setae and two groups of minute setae near dactylus insertion.Fixed finger having delicate bifid terminal spine, with three inner and two outer simple setae and inner margin with one   large sub-terminal spine.Dactylus as long as fixed finger, with crests on outer margin, two simple setae and two spines ventrally.
Pereopod 1 (Fig. 4G).Coxa present, with prominent spur with long simple seta.Basis long (about 4.7 times as long as wide), with one minute dorsal seta.Ischium short, with one ventral simple seta.Merus naked, 1.3 times as long as wide.Carpus longer than merus, with three simple setae distally.Propodus as long as merus and carpus combined, with row of minute setae along outer margin and four spiniform terminal setae.Dactylus half as long as unguis.Dactylus and unguis combined longer than propodus.
Pereopod 2 (Fig. 4H).As pereopod 1 except coxa without prominent spur.Basis 3.4 times as long as wide, with two plumose setae dorsally.Merus as long as wide, with medial rows of minute setules.Propodus longer than merus and carpus combined, with three spiniform terminal setae and medial rows of minute setules.Dactylus less than half as long as unguis.
Pereopod 3 (Fig. 4I).As pereopod 1 except coxa without prominent spur, basis 4.4 times as long as wide, with one inner and one outer plumose seta.Carpus with two distal simple setae.
Pereopod 4 (Fig. 5A).Shorter than pereopod 1-3.Coxa absent.Basis about 2.4 times as long as wide, with one long plumose seta ventrally.Ischium short, with two simple setae ventrally.Merus 1.3 times as long as wide, with medial rows of minute setules and two pointed processes and one simple seta distally.Carpus longer than merus, with one pointed process, two tubercles and one simple seta distally.Propodus shorter than merus and carpus combined, with one long plumose seta dorsally, three spiniform terminal setae and row of minute setae along outer and inner margins.Dactylus about two times as long as unguis.
Pereopod 5 (Fig. 5B).As pereopod 4 except basis 3 times as long as wide, with two inner and one outer plumose setae.Merus twice as long as wide, with two simple setae distally.Dactylus about as long as unguis.
Pereopod 6 (Fig. 5C).As pereopod 4 except basis 2.1 times as long as wide, naked.Merus with two pointed processes distally.Carpus with two pointed processes and one simple setae distally.Propodus tipped by five serrated spiniform setae.Dactylus as long as unguis.
Pleopods (Fig. 5D).Well-developed.All pleopods similar in structure, with unequal rami.Basal article short, 1.1 times as wide as long.Endopod subrectangular with all setae distal, with one outer and ten plumose inner setae.Exopod sub-ovate with 24 plumose setae on entire posterior margin; no gaps between the most proximal and other setae.
Uropod (Fig. 5E).Shorter than pleotelson.Basal article shorter than exopod, naked.Exopod biarticulate (with fusion line), half of endopod, with one simple medial seta and two long setae apically.Endopod biarticulate (with fusion line), with two plumose setae medially, one simple subdistal seta and tipped by two plumose and three long simple terminal setae.
Manca paratype 1.3 mm (Fig. 3B).Smaller than female and similar in morphology.Antennule, antenna and uropod have the same number of article as adults and cheliped has the same structure (even the tip of fixed finger) as full developed females, been the only difference between them: pereonites and pleotelson slightly wider than in adults.
Male paratype, 3.2 mm.Not dissected.Sexual dimorphism present.Feeding male.Body (Fig. 6A) about 5.5 times as long as wide.Cephalothorax triangular, 1.2 times as wide as long; rostrum rounded; eyelobes absent.Pereon.Pereonites lesser than female; pereonite 1 shortest, about 0.3 as long as carapace.Pereonite 4 longest, 2.0 times as wide as long.Pleon.Pleonites developed about 30% of body length.Antennule (Fig. 6B) 4.75 times as long as wide, as long as cephalothorax, with seven articles; article 1 longest, inner distal margin with six plumose and one long simple setae and one outer distal simple seta; article 2 half length of article 1, with two inner medial plumose and one long simple setae; article 3 short, with one inner and two outer distal simple setae; articles 4-6 densely packed with aesthetascs; article 7 slender, with one aesthetasc, four short and three long simple terminal setae.Maxilliped developed, not recovered.Cheliped (Fig. 6C, D) same as in female.Uropod (Fig. 6E) exopod uniarticulate, less than half of endopod, with two long setae on the tip.Endopod biarticulate (with fusion line), with twelve plumose setae proximally, two plumose setae medially and tipped by two plumose and five simple terminal setae.Pleopods (Fig. 6F) well-developed.Endopod with one outer and ten plumose inner setae.Exopod with 17 plumose inner setae; no gaps between the most proximal and other setae.
Remarks.Tanaopsis is a morphologically conservative genus (Bird and Bamber, 2000), being reported variations only by Lang (1967) in pleon shape of T. graciloides females.Thus, the few variations found in species are considered for this to be new for science.
Tanaopsis brevicorpus sp.nov.resembles T. antarctica, T. cadieni, T. chotkarakde, T. laticaudatus and T. profunda, however differs from these species by having carapace about as long as first three pereonites; pleotelson short (2.35 times as long as wide); proportions of uropod and pleotelson (0.85 times) and exopod of uropod with fusion line.
The new species is distinct from T. boonwurrungi, T. canaipa, T. graciloides, T. kerguelenensis, T. oios, T. rawhitia and T. rugaris by maxilliped endite with short seta and arising from tubercles; inner margin of cheliped fixed finger with one large spine; pleotelson short and uropod both rami with fusion line.Tanaopsis curtus has the carapace longer than pereonites 1-3 (1.15 times) and maxilliped basis seta absent.Furthermore, in comparison with T. gallardoi, T. brevicorpus sp.nov.has less slender antennule article 2, maxilla triangular instead of with two lobes, both rami of uropod having fusion line (semi-fused articles) and uropod about half length of pleotelson in place of subequal.
Bathymetric distribution.55-500 m.Sieg and Dojiri (1991) gave a key to the species then known.In this key were included T. laticaudatus as a synonym of T. graciloides and excluded T. gallardoi (before as Leptognathia gallardoi).A key to all species of the genus Tanaopsis up to now (16 species including T. bamberi sp.nov.and T. brevicorpus sp.nov.) is given.

Table 1 .
Study area and their sites and geographic coordinates containing Tanaopsis bamberi sp.nov.and Tanaopsis brevicorpus sp.nov.BP: Botany Point.
3 times, with one outer distal long simple seta.Article 3 square, with one outer distal long simple seta.Article 4 longest, about 4.2 times as long as wide, and 1.3 times as long