McMillan: Three species of hagflsh from the Galapagos Islands 



113 



called "labial barbels," which are immediately adja- 

 cent to the oral opening, very similar in size and 

 shape in all hagfish, and are not considered species 

 signifcant. The other three pairs of long, slender bar- 

 bels are usually measured, and sometimes used as a 

 species character. Because many of the barbels on 

 these specimens were curled and accurate measure- 

 ments difficult to repeat, this character has not been 

 included in Table 1. Multicusp pattern, and counts 

 of GP and slime pores have proved to be more accu- 

 rate and less variable intraspecifically than color or 

 barbel size, and thus more important as species char- 

 acters. The most significant features of taxonomic im- 

 portance in this study are the counts of gill pouches, 

 prebranchial slime pores, and multicusps. "First" and 

 "last" refer to anteriormost and posteriormost, and tail 

 pore counts are the sum of cloacal and caudal slime 

 pores; other terms used are from Wisner and McMillan 

 ( 1990, 1995). The water passes fi-om the the nasophary- 

 geal duct through the pharynx, through each afferent 



branchial duct (ABD) to the gill pouch, and exits 

 through each efferent branchial duct (EBD) to its cor- 

 responding external opening (GA). Any excess water 

 passes out of the body through the slightly larger duct 

 known as the pharyngocutaneous duct (PCD), which 

 is ordinarily confluent with, or occasionally just poste- 

 rior to the last GP on the left side. The numbers of gill 

 apertures are not shown in the table because the num- 

 ber of GA is normally the same as that of GP in the 

 genus Eptatretus; however, GA count is given in each 

 species description and in the key because the aper- 

 tures are readily counted by external examination and 

 thus provide a useful character for identification in the 

 field. In most Eptatretus, including the three species 

 described in the present study, the number of bran- 

 chial pores is one less than the number of gill 

 apertures, and each pore is slightly below and poste- 

 rior to each GA anterior to the PCD. The next slime 

 pore, usually found above and behind the PCD, is the 

 first in the trunk pore series. 



Key to the species of Eptatretus of the Galapagos Islands 



la Five or six gill pouches and apertures each side; multicusps 10 (3 in each anterior row and 2 in each 

 posterior row) total cusps 44; prebranchial slime pores 12-13, trunk pores 44-46, tail pores 14-15, 

 total pores 76-77 E. grouseri, new species 



