Radular teeth of Indo-Pacific molluscivorous species of Conus: A comparative analysis

Species determination in the gastropod genus Conus, heretofore exclusively based on shell morphology and color pattern, has led to considerable uncert ainty and disagreement. We propose that qualitative and quantitative radula r tooth characters are potentially useful in differentiating species as wel l as geographic subspecies and will improve the taxonomic base. Molluscivor ous species of Conus, sometimes placed in the subgenera Cylinder; Textilia, Darioconus, and the nominal subgenus, are taxonomically among the most dif ficult. We thus examined intra- and interspecific variation in radular morp hology of 11 of these species, C. ammiralis, C. araneosus, C. bandanus, C. canonicus C. episcopatus, C. marmoreus, C. nodulosus, C. omaria, C. pennace us, C. textile, and C. victoriae, and intra- and interregional variations i n radular morphology of C. pennaceus from three geographic regions. Taxonom ically useful qualitative characters include presence/absence of one or two barbs and a blade, and whether the row of denticles comprising the serrati on is continuous or interrupted. Useful metric characters include the ratio s of first barb, second barb, blade, serration, shaft width and base width to tooth length, the ratio of tooth length to shell length, the ratio of sh aft width to base width, and the degree of curvature of the teeth. Univaria te analysis of variance (ANOVA and unplanned pairwise comparison tests) dis tinguished 53 of the 55 possible species pairs from each other by at least one character. Multivariate analysis of variance (MANOVA) indicated statist ically significant differences between the species in the other two pairs. In C. pennaceus, ANOVA and unplanned pairwise tests differentiated Hawaiian from Indian Ocean samples, and MANOVA differentiated those from Maldives a nd Sumatra. The discrete radular characters sort the II species into three groups, and these are consistent with the distribution patterns of the quan titative characters. Radular tooth characters are thus potentially useful i n differentiating species and subspecies and should be combined with other character sets in generating future phylogenetic hypotheses.