COHEN and RUSSO: VARUTION IN FOURBEARD ROCKLING 



this area, which we separate because it is geo- 

 graphically between the region to the south. 

 where fishes are mostly dark colored. 



Northern Atlantic. This region extends along 

 the western Atlantic coast from north of the vicin- 

 ity of Norfolk Canyon to the northern North 

 American limit of E. cimbrius occurrence. 



Greenland. A single specimen from West Green- 

 land is apparently the only known occurrence of £. 

 cimbrius from Greenland. 



Iceland. The region around Iceland. 



Europe. Although E. cimbrius occupies a con- 

 siderable area we have examined only a small 

 sample, mainly from Denmark and Norway. 



Africa. Two specimens from off the coast of 

 Mauritania ca. lat. 21°N are the most southerly 

 known. 



Color 



Enchvlyopus cimbrius from the Gulf of Mexico 

 and Southern Atlantic areas have on the average 

 more of the dorsal fin colored with dark pigment 

 than do fourbeard rocklings from other areas (Ta- 

 ble 1 ). We have attempted to quantify this charac- 

 ter by coding it on a 0-10 scale with representing 



Table l. — Frequency distributions of degree of dorsal fin pig- 

 mentation in Enchelyopus cimbrius from eight geographical 

 areas. = no dark pigment in dorsal fin; 10 = entire fin darkly 

 pigmented. 



a fin with no dark pigment and 10 representing a 

 fin that is completely dark. Values were subjec- 

 tively assigned by a single observer (Cohen). Fig- 

 ure 2A shows a New England fish that would be 

 coded as 1; Figure 2B shows the color pattern of a 

 fish from the Gulf of Mexico, which would be coded 

 as 6. Note that fish are morphologically inter- 

 mediate and most variable in the Intermediate 

 region'* where the mean is 3.8 and the standard 

 deviation is highest at 2.8. 



Two other pigment characters were noted; how- 

 ever, neither was quantified. Fish with light fins 

 lacked dark pigment in the groove along the base 

 of the row of filaments between the strong first 

 dorsal ray and the beginning of the normally de- 

 veloped dorsal fin ( Figure 3 A); fish with dark dor- 

 sal fins had varying amounts of dark pigment in 

 this region (Figure 3B). Also, in many Gulf, 

 Southern Atlantic, and Intermediate fish the body 

 was dusky; in most others the body was a rather 

 light straw color. 



Meristics 



Frequencies of both anal fin rays and dorsal fin 

 rays show a pattern similar to, though less pro- 

 nounced than, that shown by dorsal fin pigmenta- 

 tion in the western Atlantic (Tables 2, 3), with fish 

 from the Intermediate area being intermediate 

 between fish from the north and the south. Also, 

 for anal fin rays the standard deviation is larger in 

 fish from the Intermediate area than in adjacent 

 samples. These two characters differ from dorsal 

 pigmentation in having the highest mean in the 

 Iceland sample. 



Frequencies of pectoral fin rays and vertebrae 

 for North American samples from the Inter- 

 mediate area have nearly identical means in both 



■'Detailed descriptions of color variation in samples from Nor- 

 folk Canyon and comparisons with specimens from the northeast 

 coast of Florida have been presented by: P, Szarek. 1974 A 

 preliminary study of Norfolk Canyon Enchelyopus cimbrius. 

 Ichthyology Term Paper. Virginia Institute of Marine Science. 



Table 2. — Frequency distributionsof numbers of anal fin rays in Enchelyopus cimbrius from 



eight geographical areas. 



93 



