New apseudomorph tanaidaceans (Crustacea, Peracarida, Tanaidacea) from the bathyal slope off New Caledonia Author Bamber, Roger N. Department of Zoology, The Natural History Museum, Cromwell Road, London SW 7 5 BD (United Kingdom) r. bamber @ nhm. ac. uk text Zoosystema 2007 29 1 51 81 journal article 10.5281/zenodo.5394163 1638-9387 5394163 Indoapseudes choristhema n. sp. ( Figs 8 ; 9 ) TYPE MATERIAL . — Holotype : New Caledonia , S to SW of Île des Pins , CALSUB, stn PL 19 , Cyana dive 1034/40, 22°46’S , 167°20’E , 416- 404 m depth, 10.III.1989 , coll. M. Segonzac, ♀ with oostegites (MNHN-Ta926). Paratypes : same data as holotype , 1 manca, paratype (MNHN-Ta927). — New Caledonia , between Lifou and Ouvéa, CALSUB, stn PL 15, Cyana dive 1030/36, 20°37.1’S , 166°58’E , 545- 317 m depth, 6.III.1989 , coll. A. Guille, 1 manca (MNHN-Ta928). — New Caledonia , BIOGEOCAL, stn DW 44, N.O. Charcot , 22°47.35’S , 167°14.50’E- 23°47.34’S , 167°14.80’E , 440-450 m depth, 30.VIII.1985 , 1 ♀ with oostegites, anterior fragment (dissected). TYPE LOCALITY . — Off New Caledonia , 22°46’S , 167°20’E . ETYMOLOGY. — From the Greek “ choris ”, without, and “ aisthima ”, feeling, with reference to the unique lack of antennal flagellum in this species. DESCRIPTION Female Body ( Fig. 8A ) strongly calcified, typical of the genus, tapering from anterior to posterior; small, holotype 4.9 mm long. Cephalothorax subrectangular, naked, 1.1 times as long as wide, with concave anterior margin without rostrum; eyelobes present, eyes without pigment. Six free pereonites; pereonite 1 short with convex lateral margins; pereonites 2 and 3 progressively longer, with anterolateral spine-like apophyses; pereonite 4 longest (twice as long as pereonite 1) with paired anterolateral and posterolateral spine-like apophyses; pereonite 5 1.5 times as long as pereonite 1, with posterolateral spine-like apophyses; pereonite 6 as long as pereonite 1 with midlateral spine-like apophyses and further dorsolateral pair near anterior margin. Pleon of five free subequal pleonites each with four spine-like apophyses across dorsal surface. Pleotelson pentagonal, longer than all pleonites together, 2.6 times as long as wide with pair of distal setae. Antennule ( Fig. 8B ) proximal peduncle article 4.6 times as long as wide, with numerous inner sharp ( holotype ) or rounded ( paratype ) apophyses, and smaller outer rounded apophyses in proximal half; outer distal corner extended into slender, rounded apophysis. Second article 0.15 times as long as first with distal crown of six simple setae; third article 1.2 times length of second, fourth article 1/3 length of second. Main flagellum of six segments subequal in length, distal segments narrower than proximal, first five segments with single aesthetasc, distal segment with five distal setae; accessory flagellum of three segments. FIG. 8. — Indoapseudes choristhema n. sp. : A , holotype ♀, dorsal; B , left antennule; C , right antenna; D , labrum; E , right mandible; F , left mandible (palp not shown); G , labium; H , maxillule. Scale bar: A, 1 mm; B, C, 0.3 mm; D-H, 0.15 mm. Antenna ( Fig. 8C ) with five-articled peduncle; proximal article wide, rounded, naked; second article with inner and outer spine-like apophyses and single subdistal outer setulose seta; squama absent. Third article 1/5 as long as second, fourth article twice as long as third with paired outer setae; fifth article just longer than fourth with three longer and three shorter distal setae. Flagellum absent. Labrum ( Fig.8D ) bilobed, rounded, laterally setulose. Right mandible ( Fig. 8E ) with tricuspid pars incisiva, lacinia mobilis not denticulate, setiferous lobe with five setae, pars molaris slender, blunt but with finely denticulate margin; palp of three articles, proximal article with simple proximal seta, second article as long as first with two longer denticulate inner setae and distal group of seven simple setae, third article shorter, with three simple and two denticulate inner subdistal setae and two longer denticulate distal setae. Left mandible ( Fig. 8F ) as right but with denticulate lacinia mobilis and sparse distal spines on pars molaris. Labium ( Fig. 8G ) with smooth outer margin, palp with two distal setae. Maxillule ( Fig. 8H ) inner endite with four distal setae and slight outer apophysis, outer endite with 10 distal spines, inner and outer margin sparsely setose; palp of two articles, subdistally with six setae ending in setulose “club”, longer distal seta simple. Maxilla (not figured) with rostral row of 23 setae and two inner simple spines; endites with simple setae. Maxilliped ( Fig. 9A ) with simple setae; basis naked, endite with simple outer distal setae and four stout inner spines, paired subdistal setae slender, elongate, simple; basis naked; palp proximal article with single outer distal seta; second article outer margin coarsely denticulate, inner margin with two parallel rows of eight setae; third article with inner apophysis bearing two rows of four setae; distal article with seven setae. Epignath ( Fig. 9B ) large, complex, cup-shaped, with setulose distal seta. Cheliped ( Fig. 9C ) basis 2.5 times as long as wide, dorsal and ventral margins with spine-like apophyses including larger mid-ventral and ventrodistal apophyses; exopodite absent (only one cheliped available); merus quadrangular, with ventrodistal denticulations, few setae; carpus slender, 3.7 times as long as wide, dorsodistal spine-like apophysis, whole ventral margin with fine, rounded denticulations; propodus slender, twice as long as wide, with short simple setae along ventral margin; fixed finger with finely crenulate cutting edge, longer simple proximal seta; moveable finger slender with fine crenulations along cutting edge. Pereopods all similar to each other. Pereopod 1 ( Fig. 9D ) coxa with slight setose apophysis; basis slender, 5.5 times as long as wide, with row of rounded dorsal apophyses interspersed with fine, simple setae; ischium with single, fine mid-ventral seta; merus 0.3 times as long as basis, widening distally, sparsely setose as figured; carpus 1.6 times as long as merus, propodus 0.75 times as long as carpus; carpus and propodus bearing two ventral rows of triangular spines and simple dorsal setae as figured; propodus with dorsodistal spine and cluster of four setae, one being simple, three recurved and distally setulose. Dactylus stout with single inner and outer setae, unguis distinct, stout. Pereopod 2 ( Fig. 9E ) as pereopod 1 but with two inner setae on dactylus, single simple distal seta on propodus. Pereopod 3 ( Fig. 9F ) as pereopod 2 but with two denticulate distal setae and mid-dorsal plumose sensory seta on propodus. Pereopod 4 ( Fig. 9G ) propodus with distal crown of six denticulate setae; pereopod 5 with only two, pereopod 6 ( Fig. 9H ) with three simple distal setae on propodus. Pleopods absent. Uropod endopods missing on all specimens. Exopod ( Fig. 9I ) of three segments, proximal segment shortest, distal segments subequal, distal segment with paired simple distal setae; basis with two outer setae. Male Unknown. REMARKS There are three species of Indoapseudes which have been described previously: I. brycesoni Băcescu, 1977 , from Dar es salaam at 0-25 m depth (the type species of the genus), I. secundus Guţu, 1997 from the Celebes Sea at 6 m depth, and I. macabre B FIG. 9. — Indoapseudes choristhema n. sp. : A , maxilliped and endite; B , epignath; C , left cheliped (drawn in situ ); D -F , pereopods 1 to 3 respectively; G , distal articles of pereopod 4; H , distal articles of pereopod 6; I , left uropod basis and exopodite. Scale bar: A, I, 0.15 mm; B, D-H, 0.3 mm; C, 0.4 mm. Bamber, 2005 from Esperance Bay, SW Australia at 18 to 26 m depth. The latter two have a small, central pointed rostrum while I. brycesoni has a denticulate down-curved rostrum ( Băcescu 1977 ); the present species has no rostrum. All three of the previous species have an exopodite on the cheliped, unlike I. choristhema n. sp. ; further, I. secundus and I. macabre have a squama on the antenna (unlike I. choristhema n. sp. ), and all three of the previously known species have an antennal flagellum. The lack of an antennal flagellum in I. choristhema n. sp. is particularly unusual not only for this genus but for any apseudomorph tanaidacean.While the present species, from 400 to 545 m depth, is by far the deepest of the species discovered so far, it is hard to interpret the reduced antenna as an adaptation to a deeper water habitat. Subfamily PAGURAPSEUDINAE Guţu, 1981