| Summary: | 碩士 === 國立東華大學 === 海洋生物多樣性及演化研究所 === 101 === The genus Okamejei is a group of fishes with high the high morphological conservatism and is difficult to be identified. Four species of Okamejei were recognized from Taiwan during this study: Okamejei acutispina, O. boesemani, O. hollandi, and O. kenojei. Among them, O. acutispina with three morphological forms present: O. acutispina 1, O. acutispina 2 and O. acutispina 3. The record of O. meerdervoortii was questionable due to lacking of voucher. The result supports O. keonjei is a member of Dipturus or other genus. The status of three morphological forms of O. acutispina will need more detailed investigations. This study is aimed to use the statistical analysis to test the morphological variation of species which will provide a standard of describing the species. Three methods of statistical analysis are used from 45 (or 44) external morphological characters for all 6 OTUs: (1) Multiple Regression Analysis, in original data, 8 characters in males and 16 characters in females are different significantly (p<0.05); in proportional data, 16 characters are different significantly in both sexes. Six stable characters in all males, 3 stable characters in all females and 11 stable characters in both sexes are found. (2) Principal Components Analysis, only O. boesemani and O. hollandi are well-separated in both sexes; O. kenojei, O. acutispina 1, O. acutispina 2, O. acutispina 3 are grouped together, with the snout to maximum width (WSM), snout length (LSN) and cloaca to D1 (DD1C) are best influential in males; and snout to maximum width (WSM), cloaca to caudal origin (DCC) and nasal curtain length (LNC) are best influential in females. (3) Discriminant Analysis, using progressive discriminatory analysis to select the important characters of the discrimination. Ten characters are used to establish the Fisher's model and the correct recognition rate is 83.2% in males, with the caudal-fin length (LC) and tail (width) at D1 origin (WTD1) are best influential; and 86.7% in females, with cloaca to D1 (DD1C), mouth width (WM) and tail (width) at D1 origin (WTD1) are best influential. The results of this study would well distinguish the species of Okamejei and can be used in other ray groups.
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