WILLIAMS AND BABA: SQUAT LOBSTERS FROM THE PACIFIC OCEAN 



M. nitida (A. Milne-Edwards, 1880) of the 

 western Atlantic, and more distantly, M. vemlli 

 Benedict, 1902 of the eastern Pacific. Ambler 

 (1980:19) correctly differentiated, from M. 

 ciliata, the new species with "shorter, stouter 

 spines on the carapace and legs; shorter setae 

 covering the carapace and legs; rostrum with a 

 narrower base; and no extra spine between the 

 anterolateral and antennal spines, as sometimes 

 occurs in the Albatross specimens." However, 

 she regarded the differences between these 2 

 forms as racial or varietal rather than specific, a 

 view paralleling that of Faxon (1895:84), who 

 identified eastern Pacific specimens collected by 

 the Albatross as M. ciliata, and stated that dif- 

 ferences between M. nitida and M. ciliata "ap- 

 pear to be of racial or varietal, rather than speci- 

 fic, value." However, he reserved judgment 

 until the distribution of each might become bet- 

 ter known. It does appear that the specimens 

 seen by Faxon closely resemble M. ciliata, al- 

 though only those from Albatross stations 3392 

 and 3393 are now present in the MCZ crustacean 

 collection, and there is no record of specimens 

 from stations 3353 and 3363 in the MCZ crusta- 

 cean catalog^. There are minor differences in 

 spination of the walking legs of M. ciliata and 

 those of the available specimens seen by Faxon, 

 but before deciding the status of this eastern 

 Pacific material a search for the missing material 

 should be made. 



Munidopsis ciliata reaches noticeably larger 

 size as an adult than does M. lig)mria. Muni- 

 dopsis ciliata is characterized by much longer 

 and more slender spination, and much longer and 

 more prominent setae springing from rugosities 

 of the carapace and legs than on M. lignaria. 



Munidopsis nitida has well-developed acute 

 spines on legs and cephalothorax, but rugae are 

 far less prominent than in either M. ciliata or M. 

 lignaria, and unlike either of these has the ros- 

 trum upturned distally at a low angle. 



Munidopsis ciliata, M. lignaria, and M. 

 nitida have a distally trilobate margin on the 

 sixth abdominal segment (Fig. 2,f-h), each with a 

 convex lobe to either side and a broader median 

 lobe; the middle portion of the median lobe ofM. 

 lignaria usually has a very shallowly concave 

 distal margin, that of M. ciliata is slightly con- 

 vex and slightly arched dorsally, and that of M. 

 nitida is almost transversely straight except for 



'^Ardis B. Johnston, Harvard University Museum of Com- 

 parative Zoology, Cambridge, MA 02138, pers. commun. 

 October 1988. 



a slight concavity at either side where it joins the 

 respective lateral lobes. Munidopsis lignaria 

 has 8 plates in the telson (Fig. 2/) whereas the 

 other species have 10. The telson of M. lignaria 

 has a length-width ratio of 0.85 in the holotype, 

 and 0.83 in a much smaller paratype; that ratio in 

 M. ciliata is 0.70, and in M. nitida it is 0.72. 



The chelae of these 3 species are similar, hav- 

 ing close fitting, crenulate distal edges on the 

 tips of the spooned fingers, and a seirate disto- 

 lateral angle on the fixed finger. Width-length 

 ratios of the chelae are 0.50 in M. lignaria and 

 M. ciliata, and 0.41 in M. nitida. Both M. 

 lignaria and M. nitida have been collected in 

 association with wood (see material studied; Wil- 

 liams and Turner 1986), and Van Dover (1988) 

 found numerous wood fragments in the stomachs 

 of A/, lignaria collected off Mexico. The chelae of 

 the latter 2 species look as if they could be used 

 for boring, tunneling in, or shredding wood. 

 Thei'e are no published habitat data for M. 

 ciliata. However, Wolff (1979) recorded the as- 

 sociation of M. vicina Faxon, 1895, M. hender- 

 soniana Faxon, 1895, and Munidopsis sp. with 

 wood. The first two of these species, having 

 chelae similar to those discussed here (see Faxon 

 1895: pi. XVIII, fig. 2a and pi. XXIV, figs. 2, 2c) 

 were listed as utilizing wood for food, and the 

 third sheltering in it. 



Munidopsis verrilli, with which Ambler 

 (1980) also compared the new species, is much 

 more distant, being a larger species vrith con- 

 spicuously setose legs, relatively longer and 

 stronger cheHpeds lacking epipods, more coarse- 

 ly ornamented cephalothorax with rugosities in a 

 different pattern on both carapace and side 

 plates, a relatively shorter rostrum, and more 

 globose eyes from the margin of which the 3 

 spines project prominently at divergent angles, 

 to mention the most obvious differences. 



Etymology. — From the Latin "lignarius", of or 

 belonging to wood, for the association of the 

 species with pieces of wood. 



Munidopsus granosicorium New Species 



Figures 2/, 5 



Material studied.— USNM 240205. Holotype ? 

 (ovig.), eastern Pacific Ocean off Strait of Juan 

 de Fuca, 48°38.7'N, 126°57.6'W, 2,020 m, RV 

 Destiger, DWD-BMT 10, 11 September 1971. 



Measurements in mm. — Carapace length includ- 

 ing rostrum 9.7, margin of orbit to posterior 



907 



