New records of the family Agathotanaidae (Crustacea: Tanaidacea) in the Antarctic, with remarks on Arthrura monacantha (Vanhöffen, 1914) Author Jóźwiak, Piotr Author Błażewicz-Paszkowycz, Magdalena text Zootaxa 2011 2785 32 52 journal article 10.5281/zenodo.203296 0f43fb52-9eab-4a57-90ae-c5ad902f7c9c 1175-5326 203296 Paragathotanais ipy n. sp. Figures 6–9 Material examined: Holotype : female, ZMH K- 42686, ANTXXII/3, PS67/110-8, 65° 0.52'− 65° 0.68' S , 43° 2.09'− 43° 2.16' W , depth 4696−4698 m , 10 Mar 2005 . Paratypes : two females (one dissected on slides and one partially dissected), ZMH K- 42687( ZMH K- 42696 for specimens dissected on slides), ANTXXII/3, PS67/059-5, 67° 29.74'– 67° 29.61' S , 0° 1.93'– 0° 2.19' W , depth 4655 m , 14 Feb 2005 ; one male (partially dissected on slide), ZMH K- 42697, ST-EBS-2, 59° 30.42'– 59° 30.40' S , 27° 18.15'– 27° 18.47' W , depth 1019–1038 m , 28 Mar 2006 . Diagnosis: body elongate, 9.7 times as long as wide; maxillipedal endites relatively long (reaching the end of palp article 2), with pair of simple setae distally, palp article 3 with two setae; pereopod 1 propodus with long seta distally; pereopods 1−3 merus naked; pereopods 4–6 ischium with one seta; uropod endopod article as long as basal article. Etymology: IPY is the acronym of the International Polar Year. Description of female. Body ( Fig. 6 A) 2.3 mm long, almost ten times as long as wide. Carapace elongate, 20% of total body length, 1.6 times as long as wide. Pereonites without hypospheniae; pereonites 1 to 6 with length/width ratio 1.0; 1.1; 1.3; 1.2; 1.3 and 1.0 respectively. Pleon about 15% of total body length; pleonites equal; fifth pleonite with lateral simple setae. Pleotelson with two pairs of setae distally. Antennule ( Fig. 6 B) 4-articled; article 1 longest, about as long as rest of articles together, with one simple and two bipinnate setae distally; article 2 half as long as article 1, with two simple setae distally; article 3 trapezoidal, with two distal setae; article 4 tipped with one minute and four long, simple setae. Antenna ( Fig. 6 C) 6-articled; article 1 broken off; article 2 naked; article 3 square, with one distal seta; article 4 longest, 3.6 times as long as article 3, with two setae distally; article 5 short and naked; article 6 very short, tipped by four long setae. Mouthparts : labrum ( Fig. 6 D) hood-shaped, with dense setation. Left mandible ( Fig. 6 E) with spiniform lacinia mobilis , incisor crenulated and well calcified; molar reduced to insignificant bulge. Maxillule ( Fig. 6 G) with ten spiniform setae terminally. Labium ( Fig. 6 H) with minute setation and one spine distally. Maxilliped ( Fig. 6 I) endites tapering distally, each with pair of distal, simple setae. Palp article 1 naked; article 2 with three setae on inner margin; article 3 with two setae on inner margin; article 4 with four long setae terminally and one subdistal short seta. Cheliped ( Fig. 7 A) sclerites fused; merus 2.5 times as long as wide, with ventral seta; carpus 1.8 times as long as wide, with two setae ventrally and two setae dorsally; one tubercle on distal margin; propodus with one seta on inner side near dactylus insertion and one seta on ventral margin; fixed finger with two setae on inner margin, tipped by well calcified spine; dactylus robust 2.5 times as long as wide tipped with well calcified spine. Pereopod 1 ( Fig. 7 B) basis 4.7 times as long as wide, naked; ischium with one seta; merus naked; carpus 1.2 times as long as merus, with two robust setae distally; propodus elongate, 1.3 times as long as merus, with one spiniform seta and one long seta distoventrally; dactylus little longer than unguis, both together as long as carpus. Pereopod 2 ( Fig. 7 C) basis partially broken, naked; ischium with simple seta; merus naked; carpus 1.2 times as long as merus, with two long and one short, robust setae distally; propodus 1.3 times as long as merus, with ventral spiniform seta; dactylus little longer than unguis, both together about as long as propodus. Pereopod 3 ( Fig. 7 D) similar to pereopod 2. Pereopod 4 ( Fig. 7 E) basis 4.4 times as long as wide, with two bipinnate setae ventrally; ischium with simple seta; merus with two robust setae distally; carpus about 1.5 times as long as merus, with one short and three long robust setae; propodus little longer than carpus, with two setae ventrally and one dorsally; dactylus 0.7 as long as unguis; both together 1.4 times as long as propodus. Pereopod 5 ( Fig. 7 F) similar to pereopod 4. Pereopod 6 ( Fig. 7 G) similar to pereopod 4, but dactylus and unguis shorter (as long as propodus). Pleopod ( Fig. 7 H) poorly developed; endopod little longer than exopod; both rami rounded, naked. Uropod ( Fig. 7 I) very short, basis with small projection tipped by long seta; endopod uniarticled with one long, bipinnate seta subdistally and one bipinnate and five simple setae distally. Male. Body ( Fig. 8 A) 2.9 mm long, 9.3 times as long as wide. FIGURE 6. Paragathotanais ipy n. sp. , holotype female. A) body dorsal view; A') cephalothorax ventral view; A'') cephalothorax lateral view; paratype female B) antennule; C) antenna; D) labrum; E) left mandible; F) right mandible; G) maxillule endite; H) labium; I) maxilliped. Scale bars = 1 mm for A, = 0.1 mm for B-I. FIGURE 7. Paragathotanais ipy n. sp. , female. A) cheliped; B) pereopod 1; C) pereopod 2; D) pereopod 3; E) pereopod 4; F) pereopod 5; G) pereopod 6; H) pleopod; I) uropod. Scale bars = 0.1 mm. Carapace elongated, about 20% of total body length. Pereonites without hypospheniae, pereonites 1 to 6 with length/width ratio 0.7; 0.9; 0.9; 1; 0.9; 0.5 respectively. Pleon 24% of body length, pleonites equal in length, each with simple seta on lateral margin; pleonite 5 with pair of simple setae dorsally; pleotelson with two setae distally. Antennule ( Fig. 8 B) thicker than that of female, 4-articled; article 1 with one simple and three bipinnate setae distally on outer margin; article 2 0.4 times as long as article 1, with one simple and two bipinnate setae on outer margin and short seta on inner margin; article 3 about 0.6 times as long as article 2, with two distal setae; article 4 2.5 times as long as article 3, terminated by one minute and five long setae. FIGURE 8. Paragathotanais ipy n. sp. , male. A) body dorsal view; B) antennule; C) pleopod. Scale bars = 1mm for A, = 0.1 for B and C. FIGURE 9. Distribution map for Arthrura monacantha (Vanhöffen, 1914) and Paragathotanais ipy n. sp. Pleopod ( Fig. 8 C) well-developed, exopod little shorter than endopod, with one subdistal seta and six setae terminally; endopod with eight setae distally. Distribution: The species is known from the Weddell Sea from a depth range of 4696–4698 m , from the Scotia Sea at depth range 1019–1038 m , and east of Cape Norway from the depth 4655 m ( Fig. 9 ). Remarks: P. i p y n. sp. is the only species in Paragathotanais without setae on the merus of the first three pairs of pereopods, as well as a reduced molar in the mandible. The other distinctive characters are shared with some other members of the genus. The long seta on the propodus of pereopod 1 is present also in P. gracilis Bird & Holdich, 1988 ; P. medius Larsen, 2002 ; P. robustus Bird & Holdich, 1988 and P. ty p ic u s Lang, 1971 ; the single seta on the ischium of pereopods 4–6 are shared with P. medius and P. abyssorum Larsen, 2007 . It is worth mention that most paragathotanaids have two setae on the ischium of pereopods 4–6, but P. insolitus Guerrero-Kommritz, 2003 has none. A useful character for identification is the short endopod article of the uropod which the new species shares with P. nanus Bird & Holdich, 1988 and P. abyssorum ; the other members of the genus have the endopod article of the uropod clearly longer than the basis.