Short Communication 1 Department of Evolutionary Ecology, Max-Planck Institute for Evolutionary Biology, Plo ¨n, Germany; 2 Biology Department, and Center for Natural Sciences and Environmental Research (CENSER), College of Science, De La Salle University, Manila, Philippines; 3 AUF Center for Planning, Research, and Development, Angeles University Foundation, Angeles City, Philippines Multivariate analyses of the biometric features from Philippine sardines – implications for the phylogenetic relationships of the freshwater Sardinella tawilis (Teleostei, Clupeomorpha)* I. E. Samonte 1,2 , R. A. Canlas 2 , K. Alvia 2 , T. Carvajal 2 and R. C. Pagulayan 3 Abstract Philippine sardines are members of the commercially important Sardinella genus (Family Clupeidae). Sardines are mostly marine species with a very few exception like the Philippine freshwater sardine, Sardinella tawilis, of Lake Taal. This species is believed to have immigrated from Balayan Bay some 250 years ago. To determine the relationship of freshwater S. tawilis to the marine forms, 35 biometric features were investigated. The variables were subjected to univariate (mean, standard deviation and coefficient of variance) and multivariate analyses [Principal Component Analysis (PCA) and Hierarchical Cluster Analysis]. Results from univariate tests revealed that the number of ventral fin ray can discriminate Sardinella lemuru from the rest of the sardines. Multivariate PCA, on the other hand, showed discrete separation of the marine sardines. Sardinella tawilis, however, cannot be clearly separated from the marine species, Sardinella albella. The same clustering was recovered in HCA, thus providing evidence that S. albella is the closest marine relative of the freshwater S. tawilis. Key words: Sardinella tawilis – multivariate analyses – Hierarchical Cluster Analysis – biometrics – Lake Taal – PCA Introduction Sardines are moderately small, silvery fishes that live in the shallow depths of coastal water or occasionally in estuaries. They are known for their oily flesh and their two-lobed non- functional lung (Pileggi and Thomson 1979). Sardines have compressed streamlined body, a single soft-rayed dorsal fin, and protruding thin deciduous scales (Munro 1955). This group of fish belongs to the genus Sardinella of the family Clupeidae (Order Clupeomorpha; Class Teleostei). In the Philippines, there are seven Sardinella species (Conlu 1986). These are Sardinella albella (Saal), Sardinella brachysoma (Sabr), Sardinella fimbriata (Safi), Sardinella lemuru (Sale), Sardinella longiceps (Salo), Sardinella melanura (Same) and the recently reclassified Sardinella tawilis (Sata), formerly a member of the Harengula genus (FishBase 1995). Like other members of the family Clupeidae, Philippine sardines mostly thrive in marine environments where they mainly move in large schools feeding on planktons. The only exception is the freshwater S. tawilis which is endemic to Lake Taal. This species was separated from its marine relatives when it was trapped in Lake Taal, a caldera lake formed from the collapse of a large volcanic crater and by subsistence. Its morphometry has been modified by a series of volcanic eruptions in 1754 (Hardgrove 1991). This 10th century lake empties its water to Balayan Bay through the narrow Pansipit River located southwest of the lake (Kira 1995). Delineation of species within the Sardinella genus is mostly based on morpho-anatomical features, which in many cases, is quite confusing because of their great similarity with each other. Taxonomists have tried to resolve this problem by using rigid criteria for discriminating species that can be derived by subjecting biometrics data through descriptive univariate- and multivariate analyses. Multivariate analyses, such as Principal Component Analysis (PCA), allow comparison of taxonom- ically similar species with increased precision by considering many biometric variables simultaneously. These tests have already been applied to facilitate morphology-based identifi- cation of fish (Beacham 1985; MacCrimmon and Clayton 1985; Ungaro et al. 2001; ErkÕahan et al. 2003; Escala and Miranda 2003) and even in the determination of morpholog- ical variation that exists in fish parasites (Jousson and Bartoli 2001; Bell et al. 2002). In this study, biometric measurements from the different sardines were subjected to univariate and multivariate analyses to distinguish each of the sardines and to infer the relationship of the freshwater sardine, S. tawilis, to the marine sardines. Materials and Methods Fish A total of 236 individuals belonging to six different species of Philippine sardines were used in this study. The marine sardines, Saal, Sabr, Safi, Sale were each represented by 35 individuals, whereas only 29 individuals of Salo were included in the study. These fish were caught from Balayan Bay and Cebu Bay. Two populations of S. tawilis, each represented by 35 individuals, were collected from the northern (Talisay) and southern (Agoncillo ⁄ San Nicholas) basins of Lake Taal. These two subpopulations of Sata, designated as SataT and SataA, respectively, were sampled to determine whether morphologic data would support genetic differ- entiation previously reported by Samonte et al. (2000). Initial identification of the fish was based on the key to classification of clupeiods species (Munroe et al. 1999). * This paper is dedicated to Prof. Dr. Dr. h. c. Diether Sperlich on the occasion of his 80th birthday. Accepted on 21 November 2008 Ó 2009 Blackwell Verlag GmbH J Zool Syst Evol Res doi: 10.1111/j.1439-0469.2008.00517.x J Zool Syst Evol Res (2009) 47(1), 21–24