AMBLER: SPECIES OF MUNIDOPSIS OFF OREGON 



and slightly convex; pair of large, blunt, gastric 

 spines, one pit behind each gastric spine, each pit 

 surrounded by a small bare area; dorsal carapace 

 surface densely covered with setae except for bare 

 spots posterior to pits on gastric area, on cervical 

 groove, and on anterior boundary of cardiac re- 

 gion; with setae removed dorsal surface fairly 

 smooth except for rounded tubercles of posterior 

 branchial area; one blunt ridge at unarmed poste- 

 rior margin. 



Rostrum 22'7f of carapace length, triangular in 

 dorsal view, horizontal in lateral view, covered 

 with setae, bluntly carinate dorsally. 



Abdomen densely pubsecent, unarmed; second, 

 third, and fourth somites with two blunt trans- 

 verse ridges. 



Sternum with few setae and small tubercles; 

 with transverse setose ridge opposite legs. 



Eyestalks immovable; long, stout, pubescent in- 

 ternal eye spine much longer than diameter of the 

 cornea. 



Basal segment of antennular peduncle with one 

 long spine midventrally, one long spine mid- 

 dorsally, and an inner toothed process. 



Basal segment of antennal peduncle covered 

 with setae, bearing outer ventral tooth and stout, 

 inner, ventral spine. Second segment with large, 

 outer, ventral spine and small, inner, ventral 

 tooth. 



Inner margin or merus of third maxilliped has 

 three main spines, the posterior two have two 

 points. 



Cheliped shorter than carapace length; densely 

 pubescent; epipods on chelipeds only; ischium 

 with dorsal and ventral spine at meral articula- 

 tion and a ventral row of six to seven small spines 

 (including spine at meral articulation); merus 

 with five spines at carpal articulation, dorsal row 

 of six spines (including spine at carpal articula- 

 tion), and two spines on the inner margin; carpus 

 with four spines at chela articulation and one 

 spine on inner dorsal surface; chela without 

 spines. 



Remarks. — Paratypes differ only slightly from 

 holotype (Table 3). The chelipeds of four paratypes 

 (USNM 134658, USNM 171339, OSUBI 00177, 

 and OSUBI 00178) are relatively longer than 

 those of the holotype and two other paratypes 

 (OSUBI 00179 and OSUBI 00180), as shown by 

 the ratio of carapace length to cheliped length in 

 Table 3. In two specimens (OSUBI 00180 and 

 USNM 134658), the lateral carapace margins 

 posterior to the cervical groove have jagged edges 

 instead of being smooth. The number of spines on 

 the inner edge of the merus of the third maxilliped 

 is constant except for one maxilliped of USNM 

 134658. 



The number of spines on the cheliped segments 

 is usually constant. Only the holotype has five 

 spines at the carpal-meral articulation — the 

 paratypes have four. There are four to five spines 

 of the dorsal row on the merus; usually there are 

 four on the paratypes. The number of spines on the 

 ventral row of the ischium is variable, ranging 

 from three to six. The dorsal inner spine on the 

 carpus is always present, but is greatly reduced on 

 paratype OSUBI 00179, and on OSUBI 00177 

 there are two spines. 



A rhizocephalan parasite is present under the 

 abdomen of USNM 171339. 



Munidopsis cascadia was compared with the 

 type of M. bermudezi. Munidopsis cascadia has 

 stouter, blunter gastric spines, no spines on the 

 lateral margin of the carapace, convex rather than 

 a straight lateral margin of the carapace, and 

 more pubescence. 



Etymology. — Munidopsis cascadia is named from 

 Cascadia Basin since all the specimens were found 

 there. 



Distribution. — Only seven specimens of M. cas- 

 cadia are known, all from Cascadia Basin at 

 2,743-2,926 m. Munidopsis bermudezi has only 

 been found in the Atlantic Ocean (Chace 1942; 



Table 3. — Morphometry of Munidopsis cascadia. 



Measurement (mm) 



USNM 

 '171338 



USNM 

 1 34658 



USNM 

 171339 



OSUBI 

 00177 



OSUBI OSUBI OSUBI 

 00178 00179 00180 



Carapace length 54 45 38 51 



Rostrum length 14 13 10 15 



Anterior carapace width 36 21 18 23 



Posterior carapace width 38 27 25 32 



Cheliped length 43 41 33 49 



Chela length 21 19 14 24 



Carapace length/ cheliped length 1.26 1.10 1.15 1.04 



37 



9 

 17 

 24 

 35 

 12 



1.06 



27 



8 



12 

 16 

 22 

 10 



1.23 



47 

 13 

 23 

 36 

 37 

 17 

 1.27 



'Type-specimen. 



23 



