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U.S. NATIONAL MUSEUM BULLETIN 258 



Figure 4. — Pleonexes aptos, new species, holotype, female, 6.0 mm., station 48-H-l: a, 

 mandible; b, head and antennae; c, lower lip; d, maxilla 1; e, maxilliped;/,£,A, uropods 1, 

 2, 3. Male, 7.0 mm., station 48-H-10: *, antenna 2. 



Holotype.— AHF No. 633, female, 6.0 mm. 



Type locality. — Carmel Point, California, December 30-31, 1963, 

 station 48-H-l, in algae collected below water at low tide. 



Relationship. — This species is closely related to Pleonexes gam- 

 maroides Bate (see Sars, 1895, pi. 207) but differs by (1) the some- 

 what more truncated lateral cephalic lobe; (2) the shorter peduncles 

 of antennae 1 and 2 on the female; (3) the fifth article of the peduncle 

 of antenna 2 on the female being shorter than article 4 ; (4) the smaller 

 mandibular palp, with article 3 shorter than 2; (5) the smaller female 

 gnathopods and male first gnathopod with their very oblique palms 

 and short posterior margins of the sixth articles; (6) the presence of 

 distinctly produced, small posterodistal lobes each armed with a 

 seta on the second articles of pereopods 3-5; (7) the ampithoid-like 

 lower lip; (8) the larger striated distal spines of the sixth articles 

 on pereopods 3-5; (9) probably differences in the spination of the 

 outer ramus of uropod 3 (unclear in P. gammaroides) . 



Pleonexes ferox Chevreux (see Chevreux and Fage, 1925) is a poor 

 example of the genus and probably should be removed to Ampithoe. 

 Its pereopods 3-5 are not as strongly modified in their distal expan- 

 sions or spination as in either P. gammaroides or P. aptos and the 

 telson is rounded and lacks distal protusions. The female gnathopods 

 of P. aptos are more like those of P. ferox than of P. gammaroides but 



