Taxonomic resolution of sawfish rostra from two private collections

• Main Authors: Seitz, JC, Hoover, JJ
• Format: Article
• Language: English
• Published: Inter-Research 2017-06-01
• Series: Endangered Species Research
• Online Access: https://www.int-res.com/abstracts/esr/v32/p525-532/

Management and recovery of endangered sawfishes are challenged by the uncertainty of species determination. Frequently, dried rostra (saws) are the only material available to represent an historical occurrence, yet traditional methods of species identification of data-deficient rostra (rostral tooth counts) are unreliable. We evaluated the utility of morphometric characters for the identification of specimens from 2 private collections totaling 41 rostra and representing 4 species: Anoxypristis cuspidata, Pristis pectinata, P. pristis, and P. zijsron. Rostra were acquired as available and the sample is likely representative of sawfishes globally. Data on 9 morphometric and meristic variables were collected, 5 of which were evaluated using principal component analysis (PCA). PCA of the mensural data accounted for 87% of the variance with the first 2 principal components. Principal component 1 (PCI) was explained by 4 variables and PCII by a single variable. This indicated that all 5 variables were taxonomically important. Spatial relationships of points were consistent with putative identifications based on available data. Knifetooth sawfish (A. cuspidata), smalltooth sawfishes (P. pectinata and P. zijsron), and largetooth sawfishes (P. pristis) formed 3 distinct clusters with minimal overlap along PCI. P. pectinata and P. zijsron were separated from each other along PCII, as were the P. microdon (nom. dub.) (Indian and Pacific) and P. perotteti (nom. dub.) (Atlantic) populations of P. pristis. The results demonstrate the utility of analyzing private collections of historically traded rostra. Cumulatively, such collections represent a global fauna sampled over many decades with potential for characterizing phenotypic variation in sawfish at interspecific and intraspecific levels on a greater geographic and temporal scale than targeted modern sampling of specific populations. Further, PCA provides an objective way of classifying data-deficient rostra to species, greatly increasing the research value of these specimens.