RADULAR TEETH OF INDO-PACIFIC MOLLUSCIVOROUS SPECIES OF CONUS: A COMPARATIVE ANALYSIS

Species determination in the gastropod genus Conus, heretoforeexclusively based on shell morphology and color pattern, hasled to considerable uncertainty and disagreement. We proposethat qualitative and quantitative radular tooth characters arepotentially useful in differentiating species as well as geographicsubspecies and will improve the taxonomic base. Molluscivorousspecies of Conus, sometimes placed in the subgenera Cylinder, Textilia,Darioconus, and the nominal subgenus, are taxonomically amongthe most difficult. We thus examined intra- and interspecificvariation in radular morphology of 11 of these species, C. ammiralis,C. araneosus, C. bandanus, C. canonicus, C. episcopatus, C. marmoreus,C. nodulosus, C. omaria, C. pennaceus, C. textile, and C. victoriae,and intra- and interregional variations in radular morphologyof C. pennaceus from three geographic regions. Taxonomicallyuseful qualitative characters include presence/absence of one ortwo barbs and a blade, and whether the row of denticles comprisingthe serration is continuous or interrupted. Useful metric charactersinclude the ratios of first barb, second barb, blade, serration,shaft width and base width to tooth length, the ratio of toothlength to shell length, the ratio of shaft width to base width,and the degree of curvature of the teeth. Univariate analysisof variance (ANOVA and unplanned pairwise comparison tests)distinguished 53 of the 55 possible species pairs from eachother by at least one character. Multivariate analysis of variance (MANOVA)indicated statistically significant differences between thespecies in the other two pairs. In C. pennaceus, ANOVA and unplannedpairwise tests differentiated Hawaiian from Indian Ocean samples,and MANOVA differentiated those from Maldives and Sumatra. Thediscrete radular characters sort the 11 species into three groups,and these are consistent with the distribution patterns of thequantitative characters. Radular tooth characters are thus potentiallyuseful in differentiating species and subspecies and shouldbe combined with other character sets in generating future phylogenetichypotheses. ¹ Present address: Department of Pathobiology, University of Pennsylvania,019104-6068, USA ² Author for correspondence: e-mail: kohn{at}washington.edu (Received 23 October 1999; accepted 25 January 1999)