WILLIAMS: NEW MARINE DECAPOD CRUSTACEANS 



grasping. For mobile animals of this morphologi- 

 cal makeup, the most likely feeding methods in 

 the stated environments would seem to be bacte- 

 rial concentration, along with secondary preda- 

 tion and scavenging. 



ANOMURA: GALATHEIDAE 

 Munidopsis alvisca new species 



Figure 8 



Materm/. —USNM 234294, 9 Holotype, 

 USNM 234301, 9 Paratype, Guaymas Basin, 

 Golfo de Cahfornia, 27°00'N, lir25'W, 2,008 m, 

 Aluin Dive 1616, 8 August 1985, pilots J. Hardi- 

 man and R. Wilkes, observer J. F. Grassle. From 

 J. F. Grassle, Woods Hole Oceanographic Institu- 

 tion, Woods Hole, MA. 



USNM 234295, 6 Paratype, Explorer Ridge, 

 Magic Mountain, 49°45.6'N, 130°16.16'W, 1,818 

 m, Pisces IV Dive P-1494, Coll. No. 1877, Gulati 

 Gusher-base, 1 July 1984, pilots-observers. Wit- 

 combe, Johnson, Tunnicliffe. USNM 234296, 9 

 ovig. Paratype, Explorer Ridge, Upper Magic 

 Mountain, 49°45.5'N, 130°16.1'W, 1,812 m, 

 Pisces IV Dive P-1497, Coll. No. 1873, Lunch 

 Hour Vent, 4 July 1984, pilots-observers. Shep- 

 herd, Juniper, Johnson. USNM 234297, 9 ovig. 

 Paratype, same. Coll. No. 1875, Crab Vent. 

 USNM 234298, 9 ovig. Paratype, same. Coll. No. 

 1875. USNM 234299, 2 9 ovig. Paratypes, Juan 

 de Fuca Ridge, Limbo Vent ( = 3 m from Holland's 

 Hillock Axial Seamount), 45°55'N, 130°03'W, 

 1,545 m, Pisces IV Dive P-1732, Coll. No. 1934, 2 

 August 1986, pilots-observers, K. Shepherd, 

 R. Embley, J. Franklin. From Verena Tunnicliffe, 

 Biology Department, University of Victoria, B.C., 

 Canada. 



Measurements in mm. — Holotype 9, carapace 

 length including rostrum 23.7, margin of orbit to 

 posterior edge of carapace 18.6, maximum cara- 

 pace width 15.7; Paratype 9 234301, same, 27.9, 

 20.8, 17.3; Paratype 6 234295, same, 13.8, 10.2, 

 8.4. 



Description. — Carapace (Fig. 8a, c) exclusive 

 of rostrum distinctly longer than broad, moder- 

 ately arched transversely; anterior and posterior 

 cervical grooves apparent, depression in anterior 

 part of cardiac region; short moderately devel- 

 oped rugosities on each anterior branchial region, 

 but more distinct and transversely developed 



rugae on each posterior branchial region, with 

 tendency to being continuous across anterior and 

 central part of cardiac region; posterior margin 

 with median concavity. Rostrum narrowly tri- 

 angular, concave dorsal surface smoothly curv- 

 ing to upturned tip exceeding eyestalks by more 

 than twice their length, distinct carina bearing 

 almost imperceptible scalelike rugae diminish- 

 ing to obsolescence on gastric region. Frontal 

 margin with broad angle lateral to eyestalk 

 followed by concave raised and sparsely orna- 

 mented margin ending in antennal spine followed 

 in turn by almost rectangular but acute antero- 

 lateral angle. Lateral plate obliquely rugose, pro- 

 jecting anteriorly below antennal peduncle, its 

 rather angular tip minutely but bluntly bi- 

 spinose. 



Abdomen (Fig. 86) unarmed; transverse ridge 

 of segments 2 and 3 smooth, that of segment 4 

 obsolescent; segments 5 and 6 smooth. 



Eyes (Fig. 8a , c ) moderate in size; well exposed, 

 smoothly ovate cornea cupped within broad based 

 movable ocular peduncle extended into elongate 

 mesiodorsal spine, directed obliquely upward at 

 low angle and ornamented with tiny irregular 

 obsolescent spinules, and much shorter mesioven- 

 tral spine. 



Basal article of antennular peduncle with dis- 

 tal margin irregularly crenulate, slender dorso- 

 lateral spine and broader lateral spine flanked by 

 cluster of irregular small spinules, an obsolescent 

 mesiodorsal spine present. Antennal peduncle 

 with fixed basal article extended into stout, flat 

 ventral spine and shorter crenulate lateral spine; 

 succeeding articles short, second bearing stout 

 lateral angle, third unarmed, fourth with scal- 

 loped distal margin, its dorsomesial projection 

 spinelike. 



Third maxilliped (Fig. 8e ) with ischium shorter 

 than merus, bearing mesial crest armed with 

 finely uniform, evenly spaced corneous teeth. 

 Basis with 2 low spines in line with crest on is- 

 chium. Merus with obsolescent spine at pos- 

 teromesial corner, mesial margin usually with 

 another at level of propodo-carpal joint, followed 

 after an interval by an obscure tubercle, and then 

 by a more prominent spine at base of convex dis- 

 tal margin; stronger spine at anterolateral cor- 

 ner; lateral margin broadly arched. Carpus, 

 propodus, and dactyl folded on merus-ischium 

 and about as long as those two articles together, 

 dense setation on dorsal surface of each, and dis- 

 tally on prehensile surface of propodus and 

 dactyl. Sternite (Fig. 8d) at base of third maxil- 



279 



