Methods for the Taxonomic Study and Description of Skates (Rajidae)

Abstract

Recent studies show the need for defined methods of systematically studying and describing skates. Disc width is proposed as the basis for proportional measurements of various parts of the disc, tail, fins, and head; of distances between certain spines; and of dimensions of ocellus. Methods are proposed for measurements of the cranium and the egg-capsule, and for counting vertebrae, pelvic radials, tooth rows, numbers of spines, rows of alar and malar hooks, and turns in the valvular intestine. Suggestions are given for description of spines, of prickles in various specific regions, of coloration, of cranium, of clasper, and of egg-capsules.