PHARYNGEAL JAW MORPHOLOGY AND HOMOLOGY IN SICYDIINE GOBIES (TELEOSTEI, GOBIIDAE) AND ALLIES

An extremely large number of fifth ceratobranchial teeth, with highly modified, striated, and hooked tips were observed in the central and w estern Pacific sicydiine goby genus Stiphodon. A scanning electron mic roscopic study of the form and arrangement of fifth ceratobranchial te eth was conducted to assess the distribution of these modifications in sicydiine gobies and their putative close relatives. Our goals were t o explore a new set of characters in gobioid systematics, to test sicy diine monophyly, and to test hypotheses of relationships of sicydiine gobies. Sicydiines are hypothesized herein to be most closely related to the western Pacific Tukugobius and Rhinogobius, freshwater genera w ith which they share thickened pelvic-fin rays, no teeth on the anteri or portion of the fifth ceratobranchial bones, fifth ceratobranchial t eeth with differentiated and striated tips, and overlapping anterior r ami of the fifth ceratobranchial bones. The latter two characters occu r in some, but not all, sicydiines. The pantropical freshwater goby Aw aous, often classified with sicydiines, is not considered the closest relative of the subfamily. The highly modified fifth ceratobranchials of Stiphodon are similar to, and concluded here to be homoplasious wit h, those of the mudflat-dwelling New World goby Evorthodus and the Ind o-west Pacific oxudercine gobies, represented in this study by Pseudap ocryptes. (C) 1998 Wiley-Liss, Inc.(dagger).