SYSTEMATICS AND BIOLOGY OF THE STROMATEID FISHES OF THE GENUS PEPRILUS 1 MICHAEL H. HORN 2 TABLE OF CONTENTS Abstract 1 65 Introduction 166 Materials and Methods 169 Systematics 170 Genus Peprilus 170 Key to the Species of Peprilus 173 Peprilus meclius 175 Peprilus ovatus 182 Peprilus simillimus 185 Peprilus snyderi 189 Peprilus burti 192 Peprilus triacanthus 197 Peprilus paru .. 202 Aspects of Functional Morphology . 210 Aspects of Life History and Ecology .. 220 Evolutionary Relationships and Zoogeography 239 Acknowledgments 252 Summary 254 Literature Cited 255 ABSTRACT A complete revision is presented of the genus Peprilus, one of the three genera of the family Stromateidae. The nominal genera Poronotus and Palometa are placed in the synonymy of Peprilus. Seven species 1 This paper is based on a thesis presented to Harvard University in partial fulfillment of the requirements for the Ph.D. in Biology. 2 Museum of Comparative Zoology, Harvard University. Present Address: Department of Bi-ology, California State College, Fullerton, Cali-fornia 92631. are recognized, and one, Peprilus ovatus from the northern Gulf of California, is newly described. Several aspects of functional morphology are considered. The vertebral column, skull, and pectoral fins appear to ossify earlier than the caudal skeleton and median fins, a sequence interpreted as being correlated with an early planktonic life followed by an independent nektonic existence. Vertebral number is relatively constant within a species and is considered to be of possible selective value in main-taining a certain body form. The absence of pelvic fins, the long pectoral fins which are used extensively for propulsion in adult fishes, and the compressed body, may all be correlated with the continuous swim-ming habit of these fishes, especially those larger than 100 mm SL. An hypothesis is proposed that the swimbladder is of hydro-static advantage to juvenile fishes which hover under jellyfish medusae and that it becomes nonfunctional in larger fishes which swim continuously. The scales are highly deciduous, and the skin is underlain by an extensive canal system, the function of which is unknown. The alimentary canal includes a small mouth with nipping teeth, a toothed, muscular pharyngeal sac which shreds food material, and numerous pyloric caeca and a long intestine which provide a great absorptive area. Considerations of life history and ecology generally are of four species: P. triacanthus, P. buiii, P. paru, and P. simillimus. Spawn-Bull. Mus. Comp. Zool., 140(5): 165-262, September 165
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