jviarine isopods of the submarine canyons 



of the southern californian 



continental shelf 



by George A. Schultz 



INTRODUCTION 



The geographical, physical and biological aspects of the submarine 

 canyons of the continental shelf off the coast of southern California 

 have been described in earlier parts of this volume. Isopods were col- 

 lected in 10 of the 15 canyons. Many benthic species were obtained 

 since the specimens were obtained with a Campbell grab bottom sampler 

 operated from the Hancock Foundation research vessel Velero IV. The 

 method of collecting subjected some specimens to fragmentation, result- 

 ing in loss of legs and other damage. However all individuals could 

 easily be placed in existing genera or differentiated from the existing 

 genera or species, and they were all placed in their appropriate taxo- 

 nomic categories. Twenty-five species in eighteen genera, of which 

 fifteen species and two genera are new to science, were identified. Of 

 the ten known species, six have been reported only from California, one 

 is known from Alaska to southern California, and only three can be 

 considered cosmopolitan. 



Table 1 lists in systematic order the species identified from all of 

 the canyons ; Table 2 lists the species by canyon. The systematic ar- 

 rangement used is that of Menzies (1962 a, b). 



In the ten canyons sampled, an average of five species per canyon 

 was found. Many species were common to several canyons — Halio- 

 phasma geminata to five, Ilyarachna ocarina and Gnatliia crenulatifrons 

 to four, and other species to three or fewer. The three named species 

 have been called "common mud bottom" species by Menzies and 

 Barnard (1959). Tanner and Santa Cruz canyons yielded nine species 

 each ; most of those from Santa Cruz had been described, but seven 

 of the nine species from Tanner were new to science. The other can- 

 yons yielded fewer species, and San Clemente Canyon yielded only one. 

 No isopods were found in Dume, Hueneme, Monterey, Mugu Canyons 

 or the San Diego trough. Some of the species described here, plus addi- 



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