MORPHOLOGICAL COMPARISON OF MELLITA GRANTII AND MELLITA LONGIFISSA (ECHINODERMATA, ECHINOIDEA, FAMILY SCUTELLIDAE)"

Abstract

Ratios of morphological features of Mellita grantii and Mellita longifissa are compared using animals collected from the Northern Gulf of California and from Costa Rica. The two populations of these species can be recognized by differences in the mean value of nine.ratios; however, three ratios show no over-lap and so would be useful for distinguishing single specimens. The values for Mellita grantii Mortensqn 1948 were: length/width ratio 0.91 - 0.99; width/length ratio of lunule 5I 0.14 - 0.26; lunule 5I length/ total length 0.12 - 0.17. Mellita lonqifissa Michelin 1858 for the same measurements had ratios of 0.73 - 0.85; 0.08-0.12; and 0.25 - 0.33 respectively.