FISHERY BULLETIN: VOL. 87, NO. 4, 1989 



Mariana Back Arc Basin. USNM 240198. Holo- 

 type ¥ (ovig.). Burke Field, 18°11'N, 

 144°43'E, 3,680 m, Alvin Dive 1837, 28 

 April 1987, Pilot Salzig, Observers Hessler, 

 France.— USNM 240199. Paratypes, 2 ¥ (ovig.), 

 1 •:/, same.— USNM 240200. Paratype ?. Illium, 

 18°15'N, 144°42'E, 3,620 m, Alvin Dive 1829, 14 

 April 1987, Pilot Tibbets, Observers Craig, 

 Farley.— USNM 240201. Paratype ?. 18°11'N, 

 144°43'E, 3,727 m, Alvin Dive 1847, 8 May 

 1987, Pilot Salzig, Observers J. and D. Hawkins; 

 transferred to collection of the Zoological Lab- 

 oratory, Kyushu University (ZLKU). The 

 material was graciously donated to us by R. 

 Hessler, Scripps Institution of Oceanography, 

 LaJolla, CA. 



Measurements in mm. — Holotype ? (ovig.), 

 carapace length including rostrum 52.1, margin 

 of orbit to posterior edge of carapace 38.0, maxi- 

 mum carapace width 30.8; same (respectively). 

 Paratypes USNM 240199, f (ovig.) 33.9, 25.6, 

 21.8, i (ovig.) 36.0, 25.8, 21.1, / 26.2, 19.0, 15.3; 

 USNM 240200, . 40.7, 30.2, 26.0; USNM 240201, 

 ?38.0, 28.1, 23.7. 



Description. — Carapace (Fig. la-c) exclusive of 

 rostrum distinctly longer than broad, moderate- 

 ly arched transversely; anterior and posterior 

 cervical gi'ooves apparent, transverse depres- 

 sion in anterior part of cardiac region. Rostrum 

 almost horizontal, narrow to moderately broad 

 triangular, lateral margin with denticles on 

 distal third, tip exceeding eyestalks by more 

 than their length, variably obscure to distinct 

 dorsal carina bearing obsolescent tiny tubercles 

 that merge into median tubercles on gastric 

 region. Slightly raised concave frontal margin 

 sweeping to antennal spine followed by irregu- 

 larly oblique margin leading to acutely spined 

 anterolateral angle. Gastric region somewhat in- 

 flated but slight posterolateral concavity at 

 either side defining meso-metagastric area; an- 

 terior gastric region bearing moderate spine on 

 either side of midline, and lateral to each another 

 variably developed spine in moderately arched 

 transverse row; remainder of gastric region 

 lightly rugose. Anterior branchial region bearing 

 strong anterolateral spine followed by 5 or 6 

 successively diminishing lateral spines, and scat- 

 tered moderate tubercles dorsally. Short rugae 

 and obscure tubercles clustered behind juncture 

 of anterior and posterior cervical grooves. Pos- 

 terior branchial region bearing strong antero- 

 lateral angle, sometimes spiniform, and distinct 



oblique and transverse rugae laterally; rugae 

 with tendency to being transversely continuous 

 across central part of cardiac region. Posterior 

 margin concave, preceded by narrow raised rim 

 with slightly cupped crown. Lateral plate ob- 

 liquely rugose, projecting anteriorly below an- 

 tennal peduncle; rugosities on anterodorsal 

 margin minutely serrated, and angular anterior 

 tip bearing minute spine. 



Abdomen (Fig. la) unarmed; transverse ridge 

 of segments 2 and 3 smooth, divided into narrow 

 anterior and broader posterior parts by concave 

 trough, that of segment 4 obsolescent; segments 

 5 and 6 smooth, 6 slightly raised posteriorly in 

 middle, posteromedian margin strongly pro- 

 duced, overreaching lateral lobe on each side. 

 Telson divided into 8 plates (Fig. 2a), length- 

 width ratio 0.79 ± SD 0.052, n = 6, midlateral 

 plate markedly convex on distolateral margin. 



Eyes (Figs. 16, c, 3a) moderate in size; well 

 exposed, smoothly ovate cornea cupped within 

 movable broad-based ocular peduncle; peduncle 

 extended into sti'ong mesiodorsal spine directed 

 horizontally or obliquely upward at very low 

 angle and ornamented with tiny, irregular, 

 obsolescent spinules; a much shorter lateral 

 spine near base of cornea; behind that an alate 

 basal process, either acutely spined or multi- 

 spinose at tip, posterolaterally paralleling con- 

 cave frontal margin. 



Basal article of antennular peduncle with 

 distal margin irregularly crenulate; slender dor- 

 solateral carina continued into anterior spine, 

 below it a broader anterior spine directed ob- 

 liquely laterad, flanked by inflated surface bear- 

 ing cluster of irregular small spines or spinules; 

 mesiodorsal spine much smaller. Antennal 

 peduncle with fixed basal article extended into 

 stout, flat ventral spine with subdivided mesial 

 margin and shorter, sometimes crenulate, 

 lateral spine; succeeding articles short, second 

 bearing appressed lateral angle, third with ser- 

 rate distal margin, fourth with scalloped distal 

 margin. 



Third maxiUiped (Fig. Id) with ischium short- 

 er than merus; bearing mesial crest armed with 

 finely uniform, evenly spaced corneous tipped 

 spines and a distodorsal spine. Basis with 3 or 4 

 corneous spines similar to and in line with crest 

 on ischium. Merus with 6 irregular acute spines 

 on flexor margin and strong spine at distodorsal 

 corner. Carpus, propodus, and dactyl folded on 

 merus-ischium and about as long as those 2 

 articles together, flexor surface of each bearing 

 dense setation mesially, and distally on propodus 



900 



