Meristic and Morphometric Analysis of Two Hagfish Species (Myxine affinis and Notomyxine tridentiger) from the Magellan Strait, Chile

Abstract

SUMMARY:Myxinoids in Chile are represented by the subfamilies Eptatretinae and Myxininae, with a total of 14 species, the identification is complex due to the low level of morphological differentiation that characterizes this taxonomic group. Worldwide, hagfish are species of commercial value, and in Chile many attempts have been reported to initiate small-scale fisheries. The aim of the present study is describe the hagfish species caught in an incipient fishery of the Magellan Strait. Samples were collected in the Magellan Strait during eight fishing expeditions from June 2009 to October 2010 in Bahía Lomas (53º48`S; 70°46'W) and Agua Fresca (53º23`S; 70°45'W). The samples were taken at two depths, 0-70 meters and 71-140 meters. Taxonomic keys were used to identify the species. All specimens were individuals from the Myxininae subfamily. From a total of 3946 hagfishes, 99 % (n=3905) were the species Myxine affinis and the remaining 1 % were Notomyxine tridentiger, both reported for Chilean and Argentinean Patagonia. The range of variation for meristic variables recorded in this research was wider than those reported in the literature. This could be explained by differences in sample size between the present study and those previously published. Body proportions and meristic variables were not species specific in Myxine sp, so there is a large overlap of ranges between species, which makes their diagnostic use not applicable. This research updates the information and extends the meristic ranges for both species. The esophageocutaneous duct (in N. tridentiger) and the number of fused teeth (bicuspid in M. affinis and tricuspid in N. tridentiger) are the morphological characters that allow a clear identification in the field of the two species.