Paragathotanais ipy, Jóźwiak, Piotr & Błażewicz-Paszkowycz, Magdalena, 2011

Jóźwiak, Piotr & Błażewicz-Paszkowycz, Magdalena, 2011, New records of the family Agathotanaidae (Crustacea: Tanaidacea) in the Antarctic, with remarks on Arthrura monacantha (Vanhöffen, 1914), Zootaxa 2785, pp. 32-52 : 42-46

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.

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.

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.

Figures

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.

FIGURE 8. Paragathotanais ipy n. sp., male. A) body dorsal view; B) antennule; C) pleopod. Scale bars = 1 mm for A, = 0.1 for B and C.

FIGURE 9. Distribution map for Arthrura monacantha (Vanhöffen, 1914) and Paragathotanais ipy n. sp.