64 U.S. NATIONAL MUSEUM BULLETIN 260 



softly rounded. The prebuccal portions are like those of Woods Hole 

 specimens and not those of Sars or California. Pereopod 3 is stouter 

 in one of Gurjanova's specimens than in the other. There are small 

 differences in the shapes of article 2 of pereopods 3-5 in all popula- 

 tions discussed herein. 



These slim bits of evidence indicate that Orchomene pinguis is com- 

 posed of a large number of geographic races and perhaps ecopheno- 

 types. The complex of forms probably includes 0. mi7iuscula (Gur- 

 janova, 1962), which differs from all others by the broader posterior 

 lobe of coxa 4. Orcliomene minuta differs from O. pinguis in the con- 

 spicuous, convexly produced epistome and unexpanded coxa 1. The 

 Sakhalin form of O. minuta partially figured by Gurjanova (1962) 

 differs from "typical" 0. minuta in the slightly expanded coxa 1 and 

 the slender article 5 of gnathopod 2 and may have to be removed to 

 some other nomenclatural status. Orchomene intermedia Gurjanova 

 (1962) is the perfect intergrade between O. pinguis and 0. minuta 

 because it combines the expanded coxa 1 with a produced epistome. 

 It may be a hybrid between the two species. 



Sympatric relationships. — Seven other species of Orchomene occur 

 in California, not including Allogaussia recondita Stasek, which has 

 been assigned provisionally to Orchomene but which has an uncleft 

 telson. Orchomene pinguis differs from all of those species in the 

 extreme elongation and quadrate posterior lobation of coxa 6. The 

 other Calif ornian orchomenes are O. decipiens Hurley (1963), O. 

 holmesi Hurley (1963) , O. anaquela J. L. Barnard (1964a) , 0. paci-fica 

 (Gurjanova) (see J. L. Barnard, 1964a) , O. magdalenensis Shoemaker 

 (1942) , 0. ohtusa (Sars) { = 0. affinis Holmes, 1908, see J. L. Barnard, 

 1964a), and 0. tabasco^ new species. The juveniles of PseudoJcoroga 

 rima J. L. Barnard (1964a) superficially resemble 0. pinguis but 

 coxa 6 of the latter is characteristic. 



The following diagnosis of 0, pinguis is based on all forms so far 

 recorded, including that from California. The extent and complexity 

 of the diagnosis are indicative of the large number of species in 

 Orcliomene and the numerous characters of small and quantitative 

 extent which have been used to distinguish the species. 



Diagnosis of Orchomene pinguis. — Lateral cephalic lobes strongly 

 projecting, dorsal and ventral oblique margins fonning angle of less 

 than 90°, apex appearing grossly subacute but minutely rounded; 

 eyes present ; article 5 of antenna 2 much shorter than article 4 ; epis- 

 tomal margin ending flush with lobe of upper lip, straight or very 

 slightly convex ; article 1 of mandibular palp shorter than article 3 ; 

 some spines of outer lobe of maxilla 1 disjunct; coxa 1 distally ex- 

 panded, coxa 5 with subcorneal posterior lobe projecting below antero- 



