Mamm. biol. 67 2002) 47±50 Mammalian Biology ã Urban & Fischer Verlag http://www.urbanfischer.de/journals/mammbiol Zeitschrift fu È r Sa È ugetierkunde Short communication Common dolphins genus Delphinus) in southeastern Brazil By M. C. DE O. SANTOS, S. ROSSO, and R. M. A. RAMOS Instituto de Biocie Ãncias, Universidade de Sa Äo Paulo, Sa Äo Paulo, and Universidade Estadual do Norte Fluminense, Campos, Rio de Janeiro, Brazil. Receipt of Ms. 05. 04. 2001 Acceptance of Ms. 26. 07. 2001 Key words: Delphinus, Cetacea, taxonomy, southeastern Brazil Common dolphins genus Delphinus) show a wide distribution in tropical and tempe- rate waters around the world Leather- wood and Reeves 1983; Jefferson et al. 1993). Since the publication on the evi- dence for the existence of two common dolphin species the short-beaked common dolphin, Delphinus delphis Linnaeus, 1758 and the long-beaked common dolphin, Delphinus capensis Gray, 1828) from the eastern North Pacific by Heyning and Per- rin 1994), a revision on skull morpho- metrics and colour patterns on specimens from this genus was urgently needed in other areas of its distribution. One of the evidences that could identify both species was regarded as the analyses of skull ros- tral ratios in adult specimens. This ratio in- volves the division of the rostral length by the zygomatic width see Perrin 1975). Prior to the revision made by Heyning and Perrin 1994), common dolphins in Brazilian waters were recognized as D. del- phis Pinedo et al. 1992; Hetzel and Lodi 1993). The main objective of this study was to re-evaluate this species taxonomy in southeastern Brazil based on rostral ra- tio analyses. A total of 16 skulls of common dolphins was analysed. These skulls were collected from 1986 to 1998, from dead, stranded spe- cimens found on the southern coast of Sa Äo Paulo SP) State and on the northern coast of Parana  PR) State 24°40'S±25°50'S), southeastern Brazil. The stranded speci- mens were reported in over approximately 115 km of beaches, ranging from Ilha Com- prida SP) to Ilha do Superagui PR) Fig. 1). These skulls are deposited at the ªMuseu de Zoologia ± Universidade de Sa Äo Pauloº MZUSP), at the ªMuseu do Instituto Oceanogra Âfico ± Universidade de Sa Äo Pauloº and at the ªLaborato Ârio de Eco- logia Marinha LabMar) ± Instituto de Bio- cie Ãncias, Universidade de Sa Äo Pauloº. The specimen data are given in table 1. These specimens were considered as physically mature based on the fusion of the premaxil- lae and the maxillae at the tip of the ros- trum Dailey and Perrin 1973). Age was estimated by counting the number of Growth Layer Groups GLGs) in dentin layers. The method was based on the analy- sis of decalcified and thin 40 lm) teeth sec- tions stained with Mayer's haematoxylin, following the recommendations of Perrin and Myrick 1980) and Hohn et al. 1989). The protocol details can be found in Ramos et al. 2000). Skull measurements were based on Perrin 1975). Statistical analyses involved the use of parametric and non- parametric tests based on Zar 1996). The 1616-5047/02/67/01-047 $ 15.00/0.