GAMMARIDEAN AMPHIPODA 119 



A. Palmar process near dactylar hinge on male gnathopod 2 bi- or trifid; tooth 



at posteroventral corner of third pleonal epimeron small, posterior edge 



smooth 



Elasmopus rapax form I of Bahia de Los Angeles (Barnard, 1962b, fig. 16) 



B. Palmar process near dactylar hinge of male gnathopod 2 simple; tooth at 



posteroventral corner of third pleonal epimeron large, posterior edge 



serrate 



Elasmopus rapax of Alamitos Bay, California (Barnard, 1962b, fig. 17) 



C. Palmar process near dactylar hinge of male gnathopod 2 simple, middle 



palmar tooth immediately adjacent to hinge process; tooth at postero- 

 ventral corner of third pleonal epimeron large, posterior edge serrate 

 (some male specimens have gnathopod 2 palm and medial surface of 

 article 6 slightly hollowed as in Elasmopus pocillimanus [Bate]) 

 Elasmopus rapax form I of Tiburon Island ("Velero" sta. 1042) 



1. Inner ramus of uropod 3 narrower and shorter than outer ramus .... 2 



2. Male gnathopod 2 palm bearing only a process near dactylar hinge. Dense 



palmar setae fully lining palmar margin; telson with narrowly-incised 

 apices and 4-5 spines, medial apices sharp; pereopodal dactyls weakly 

 constricted; pereopod 5 with closely serrate posterior edge bearing tiny 

 setules Elasmopus antennatus (see J. L. Barnard, 1962b, fig. 12) 



2. Male gnathopod 2 palm bearing a middle process 3 



3. Telsonic apices in adults not truncate, incised, with medial portions pro- 



truding and subacute, spines short, few (2-3) in number and somewhat 



displaced laterally. 



Male gnathopod 2 with a ridge, not a projecting process at defining 

 corner, dense setae on posterior edge of article 6, not on palm; article 2 

 of pereopod 5 closely serrate and with minute setules on posterior edge; 

 third pleonal epimeron slightly convex posteriorly, smooth, rounded- 

 quadrate at posteroventral corner; pereopodal dactyls poorly constricted 

 Elasmopus rapax mutatus J. L. Barnard (1962b, fig. 18) 



3. Telsonic apices strongly truncate, broad, bearing 6-8 long spines in adults . 4 



4. Male gnathopod 2 palm defined by projecting process, middle process an 



asymmetrical cone, setae scattered throughout palm and posterior edge 

 of article 6; third pleonal epimeron of the "antennatus" morphology with 

 moderately upturned tooth at posteroventral corner; pereopodal dactyls 

 weakly constricted; pereopod 5 with posterior edge of article 2 closely 

 serrate, bearing minute setules and an occasional long seta 

 Elasmopus holgurus J. L. Barnard (1962b, figs. 14, 15) 

 4. Male gnathopod 2 defined by small ridge bearing one spine, dense setae 

 along posterior edge of article 6 and fully along palm to hinge process; 

 posterior edge of article 2 on pereopod 5 deeply crenuloserrate (like pereopod 

 4 of Elasmopus pectenicrus [Bate]) . 



A. Third pleonal epimeron with slightly convex posterior edge, rounded- 



quadrate at posteroventral corner, sparsely serrate posteriorly; pereopodal 

 dactyls strongly constricted; middle process of male gnathopod 2 palm 



short, broad, truncate Elasmopus rapax serricatus, 



n.ssp., of California, Bahia Magdalena and form II of Tiburon Island 



B. Third pleonal epimeron of the "antennatus" morphology, posterior edge 



slightly convex, smooth, with medium-sized posteroventral tooth; 

 pereopodal dactyls moderately constricted; middle palmar process of 

 male gnathopod 2 very long and pointed 



Elasmopus rapax form II of Bahia dc Los Angeles (SIO-62-216) 



280-102 0-69— 9 



