48 U.S. NATIONAL MUSEUM BULLETIN 234 



The tentacles are long and slender, flattened on the oral surface, 

 and bear short, strongly curled clubs. A broad membrane on the 

 dorsal surface originates proximal of the club and extends to the tip. 

 The club bears about 12 to 14 rows of small suckers whose presence 

 or absence of dentition could not be discerned. 



The male holotype bore a number of spermatophores. One of these 

 (fig. 7) is long and slender, with a very small and tightly coiled reser- 

 voir; it does not correspond to any of the spermatophores known 

 from other species of Euprymna. 



The color in alcohol is yellowish brown. Dorsally the head and 

 mantle bear few but large dark-brown chromatophores; ventrally 

 the chromatophores are more numerous and smaller. The aboral 

 surface of all the arms bear large pigment spots, a single row on I, II, 

 and III but liberally scattered over the surface of IV. Several large 

 chromatophores on the aboral surface give the arms a barred effect. 



Measurements and indices of the holotype of Euprymna phenax 

 Voss, 1962 are: 



Holotype Holotype 



There is no gladius. 



There is a well-developed saddle-shaped luminous organ on the 

 ink sac. 



Discussion. — This unique specimen must be considered, because of 

 its several peculiarities, to represent a new species of Euprymna. 

 This decision was arrived at after a great deal of deliberation inasmuch 

 as our knowledge of the various nominal species of this genus is scanty 

 and the species poorly defined. It is axiomatic that only the males 

 of the genus show any real specific differences, and according to Adam 

 (1954) even these differences are apparently not consistent. How- 

 ever, all the other species possess four rows of suckers on the mid- 

 portion of the arms in contrast to only two in the present species, and 

 all have at least some of the suckers abruptly enlarged in the males 

 whereas this one does not. 



In summary, E. phenax may be immediately separated from morsel, 

 berryi, scolopes, and stenodactyla by the presence of biserial suckers, 

 the more simplified hectocotylus and apparent lack of any enlarged 

 suckers on the arms. It may also be separated by the structure of 

 the spermatophore. 



