Collossella suprema, Jóżwiak, Piotr & Błażewicz-Paszkowycz, Magdalena, 2007

Jóżwiak, Piotr & Błażewicz-Paszkowycz, Magdalena, 2007, Apseudomorpha (Malacostraca: Tanaidacea) of the ANDEEP III Antarctic Expedition, Zootaxa 1610, pp. 1-25 : 9-14

Collossella suprema n. sp.

( Figs 4–6 )

Material examined: Holotype (female partially dissected on slides) ( K 41404 ) ANTXXII/3, sta. PS67/154–9, 62º31.47'– 62º31.36'S, 64º39.45'– 64º39.25'W, 30 Mar 2005, depth 3804 m.

Etymology: suprema [Latin]: topmost, greatest. The name reflecting the impression by authors on seeing the species for the first time.

Male: Unknown.

Diagnosis: Perepod-1 lack exopod; propodus with eight spiniform setae on the ventral margin and two spiniform setae on the carpus of the same appendage. Three setae on pleopod basal article.

Description of female: body ( Figs 4 A, B) 15 mm long, 11.1 times as long as wide, with minute hyposphenians on pereonites. Carapace 10% of total body length, without rostrum. Pereonite-1 twice as wide as long; others pereonites longer than wide, rounded laterally in dorsal view, with one spine on each anterolateral sides and posterolateral with rounded apophysis above pereopod coxae; pereonite-2 1.3 times as long as wide; pereonite-3 subequal to pereonite-2; pereonite-4 as long as pereonite-6, 1.35 as long as wide; pereonite- 5 longest. Pleon 40% of body length. Pleonites subequal, trapezoidal in dorsal view, longer than wide. Pleotelson as long as combined length of pleonites 3, 4 and half of 5.

Antennule ( Fig. 5 A) about twice as long as carapace. Peduncle article-1 2.5 times as long as article-2, with one long and three short setae on outer margin and with two pinnate and two short setae on inner margin; article-2 with minute setae on outer margin and one pinnate seta distally. Peduncle article-3 0.75 times as long as article-2, with three minute setae. inner flagellum 7-articled, about as long as peduncle article-1. First four articles of outer flagellum with pair of small setae distally. Articles 3 and 6 with aesthetasc; articles 5 and 6 with one long seta distally; article-7 with six small setae. Outer flagellum 2-articled, shorter than article-1 of inner flagellum. outer flagellum article-2 with two setae distally.

Antenna ( Fig. 5 B) article-1 short, less than half length of article-2, naked, distally wider; article-2 longest, with one small seta on lateral margin. Squama with four setae distally; article-3 wider than long, with one long, simple seta innerdistally; article-4 four times as long as article-3, with one pinnate seta subdistally; article-5 as long as article-4, with four pinnate setae. Flagellum 6-articled, tip broken off; article-1 less than half length of peduncle article-5, with long seta outerdistally; articles 2 and 3 equal in length, each with two long setae outerdistally; article-4 slender, about as long as article-3, naked; articles 5 and 6 half as long as article-4, each with one simple seta distally.

Mouthpart. Labrum ( Fig. 5 C) hood shaped, with lateral margins covered by numerous simple setae and minute setation distally. Mandible ( Fig. 5 D) molar process longer than incisor, distally with minute setation. Palp of three articles; article-1 short; article-2 2.2 times as long as article-3, with six simple (two long and four short) and nine serrated setae on inner margin in distal half; article-3 with row of numerous serrated setae on ventral margin, two long serrated setae terminally and two serrated setae in middle. Labium ( Fig. 5 E) lobe with minute setation on inner margin (distal part). Palp with numerous simple setae on both margins; tipped by one strong seta. Maxillule ( Fig. 5 F) outer endite with ten spiniform setae distally; both margins with numerous simple setae. Inner endite with four setae (three plumose, one broken); palp ( Fig. 5 G) with two articles; distal article tipped by ten distally serrated setae. Maxilla ( Fig. 5 H) outer lobe of movable endite with two serrated setae on outer margin and with five serrated and one simple setae distally; inner lobe of movable endite with three simple and five serrated setae. Outer lobe of fixed endite with three simple, four serrated, one plumose and three multifurcate setae distally. Inner lobe of fixed endite with row of numerous simple setae and one serrated seta. Maxilliped ( Fig. 5 J) basis little wider than long, with two simple setae subdistally and numerous microtrichiae proximally. Endite ( Fig. 5 K) with row of eleven multifurcate setae distally and one plumose seta subdistally. Inner margin with row of eight plumose setae and six coupling hooks. Palp article-1 with one simple seta on outer margin and one simple and one plumose setae on inner margin; article-2 with row of simple and plumose setae on inner margin and one short seta on distoexternal margin; article-3 with six long setae on inner margin; article-4 tipped by seven (six long and one short) setae.

Epignath ( Fig. 5 I) basal plate naked, slender, setose on terminal half. Terminal seta sparsely setose, less than half as long as basal plate.

Cheliped ( Fig. 6 A) basis about twice as long as merus, with five short setae on ventral margin; merus rhomboidal, with two minute and one pinnate setae ventrally; carpus twice as long as merus, with one seta dorsodistally and six long setae ventrally; propodus massive, with four setae ventrally, two short setae dorsodistally and three long setae near dactylus insertion. Fixed finger with one large tooth near dactylus insertion and with short simple setae on serrated inner margin. Dactylus and unguis as long as carpus, unguis 0.3 times as long as dactylus; dactylus with three simple setae dorsally and weakly serrated inner margin. Exopod of three articles, article-3 with four plumose setae.

Pereopod-1 ( Fig. 6 B) coxa with large acute apophysis directed forward ( Fig. 4 B); basis about as long as combined length of merus and carpus, three times as long as wide, with two small setae ventrally and three simple and one pinnate setae on dorsal margin; ischium with simple seta; merus about twice as long as carpus, with row of 11-13 setae on ventral and dorsal margin respectitvely, massive spiniform seta distoventrally; carpus 1.4 times as long as wide, with numerous simple setae, two spiniform setae distoventrally; propodus little shorter than carpus with row of eight spiniform setae ventrally; dactylus 0.7 times as long as propodus, with simple seta dorsally, ventral margin with small teeth; unguis broken. Exopod absent.

Pereopod-2 ( Fig. 6 C) coxa with simple seta; basis about as long as combined length of ischium, merus and carpus, with two pinnate setae distoventrally, one pinnate seta dorsally and some minute setae on both margins; ischium with two simple setae; merus 0.7 as long as carpus, with one pinnate seta distodorsally and four simple (one long and three short) setae distoventrally; carpus with row of long setae ventrally and dorsodistally, and three pinnate setae dorsally; propodus as long as merus, with numerous long setae on ventral margin, distal part of dorsal margin with row of simple setae, one short serrated seta distally; dactylus 0.8 times as long as propodus, with three simple setae (one near insertion of unguis).

Pereopod-3 ( Fig. 6 D) relatively similar to pereopod-2.

Pereopod-4 ( Fig. 6 E) similar to pereopod-2, but carpus and propodus with setae distally only.

Pereopod-5 ( Fig. 6 F) similar to pereopod-4, but basis with two pinnate setae dorsally and one pinnate seta ventrally; merus with two simple setae; propodus distal setae not exceeding unguis.

Pereopod-6 ( Figs 6 G, G’) basis as long as combined length of merus, carpus and propodus, with two pinnate setae dorsally and minute setae ventrally; ischium naked; merus 0.7 times as long as carpus, with three short simple setae; carpus with simple setae distally and subdistally; propodus little shorter than merus, with one pinnate seta on dorsal margin, ventral margin with strong setae at middle, row of short spiniform setae and two serrated setae distally; dactylus 0.7 as long as propodus, with two short setae near unguis insertion; dactylus and unguis as long as propodus.

Pleopods ( Fig. 6 H) in five pairs; basal article longer than rami, with three plumose setae on ventral margin. Rami subequal. Exopod 2-articled; article-1 short, with one plumose seta; article-2 about 4.3 times as long as article-1, with numerous (about 15) plumose, long setae. Endopod with about thirteen long, plumose setae.

Uropod ( Fig. 6 I) peduncle three times as long as wide, with two short simple setae subdistally; endopod of six articles; exopod of four articles, distal setae broken; article-2 of endopod with two simple and two pinnate setae distally; article-3 with long seta exceeding distal of article-5; article-6 with four long setae terminally.

Distribution: The species is known only from type locality Drake Passage (62º31.47'– 62º31.36'S, 64º39.45'– 64º39.25'W) from the depth 3804 m.

Remarks: Collossella suprema shows much affinity with the congeneric C. bicornis ( Kudinova-Pasternak, 1973) shearing a similar body form, blunt rostrum, two articled exopod of antennule, compact cheliped with robust chela and short carpus. The incomplete drawings supplementing the ambiguous description given by Kudinova-Pasternak (op. cit.) inhibit a full comparison here. However the same stage (female with rudimental oostegites) of the new species and C. bicornis are compared. Collossella suprema lacks of exopod on pereopod-1 which occurs in C. bicornis . Furthermore it has eight spiniform setae on the ventral margin of perepod-1 propodus and two spiniform setae on the carpus of the same appendage. C. bicornis has only six propodal spiniform setae there and no spiniform setae on carpus. Some other subtle differences include the presence three setae on the pleopod basal article of the new species in contrast to one in C. bicornis , and the naked chela dorsal margin in C. suprema that bears a few setae in C. bicornis . Also, the maxilliped endite has six couplers in C. suprema and only four in C. bicornis .

Figures

FIGURE 4. Collossella suprema n. gen. n. sp. Holotype female. A, Body dorsal view; B, Body lateral view; C, Details of carapace. Scale line = 1 mm.

FIGURE 5. Collossella suprema n. gen. n. sp. Holotype female partially dissected. A, Antennule; B, Antenna; C, Labrum; D, Right mandible; E, Labium; F, Maxillule; G, Palp of maxillule; H, Maxilla; I, Epignath; J, Maxilliped; K, Maxillipedal endite. Scale line = 1 mm for A, B; 0.1 mm for C-K.

FIGURE 6. Collossella suprema n. gen. n. sp. Holotype female partially dissected. A, Cheliped; B, Pereopod- 1; C, Pereopod- 2; D, Pereopod- 3; E, Pereopod- 4; F, Pereopod- 5; G, Pereopod- 6; G', magnification of carpus (distal part), propodus and dactylus of pereopod- 6; H, Pleopod; I, Uropod. Scale line = 1 mm.