Tissue & Cell 35 (2003) 441–446 Spermiogenesis and sperm ultrastructure in Cichla intermedia with some considerations about Labroidei spermatozoa (Teleostei, Perciformes, Cichlidae) I. Quagio-Grassiotto a,∗ , F.N. Antoneli a,b , C. Oliveira a a Departamento de Morfologia, Instituto de Biociˆ encias, Universidade Estadual Paulista—UNESP, CP 510, CEP 18618-000 Botucatu, SP, Brazil b Departamento de Biologia Celular, Instituto de Biologia—Universidade Estadual de Campinas—UNICAMP, CEP 13.083-970 Campinas, SP, Brazil Received 24 February 2003; received in revised form 7 July 2003; accepted 10 July 2003 Abstract Spermiogenesis and spermatozoal structure were studied in Cichla intermedia, a primitive species of Neotropical cichlids. The analysis shows that spermiogenesis is characterized by chromatin compaction, flagellum development, nuclear rotation, nuclear fossa formation and residual cytoplasm elimination. In the spermatozoa, the head is round, the nucleus contains highly condensed filamentous clusters of chromatin and an acrosome is absent. The nuclear fossa is slightly eccentric and shows a projection that penetrates into the nuclear outline. The proximal centriole is located in the initial segment of the nuclear fossa. The midpiece and the cytoplasmic channel are long. The mitochondria, about 10 in number, are round or slightly elongated, disposed in two layers around the initial segment of the flagellum. The flagellum has a classical 9 + 2 axoneme and two lateral fins. The data available show that no characteristics of spermiogenesis or spermatozoa are exclusively found in members of the suborder Labroidei. However, three characteristics seem to be exclusively observed in Cichlidae: (1) compact filamentous clusters of chromatin; (2) slightly eccentric nuclear fossa; and, (3) number of mitochondria. © 2003 Elsevier Ltd. All rights reserved. Keywords: Ultrastructure; Spermiogenesis; Fish; Teleostei; Cichlidae 1. Introduction The families Cichlidae, Pomacentridae, Embiotocidae, and Labridae have been recognized as a natural group, the suborder Labroidei, on the basis of the structure of some hypopharyngeal characters (Kaufman and Liem, 1982; Lauder and Liem, 1983). According to these authors, Po- macentridae is the sister group of all other Labroidei; the Cichlidae the sister group of Embiotocidae and Labridae; and Embiotocidae the sister group of Labridae. However, molecular data have not corroborated the monophyly of this class (Streelman and Karl, 1997). Cichlidae is a freshwater fish family distributed through- out Asia, Africa, Central and South America (Nelson, 1994). In contrast to the numerous and well known African lake species, cichlids are generally riverine in the Neotropical region (Kullander, 1998). In a morphological study of the group, Kullander (1998) suggested that the Neotropical ci- ∗ Corresponding author. Tel.: +55-14-6802-6264; fax: +55-14-6802-6322. E-mail address: morfologia@ibb.unesp.br (I. Quagio-Grassiotto). chlid genus Retroculus is the sister group of all the remain- ing species, followed by Cichla and Crenicichla, which are also sister groups. Studies of the spermiogenesis and spermatozoal struc- ture in several Perciformes species have shown that the group displays a great variety of spermatozoon types and structures and spermiogenesis processes (Mattei, 1991; Jamieson, 1991). No phylogenetic study of this kind of data—spermatozoa—has so far been conducted with the Cichlidae and the evolution of the identified characters re- mains unknown. Considering the relative basal condition of the genus Cichla in the Neotropical cichlid phylogeny (Kullander, 1998) and the relative lack of knowledge on spermiogenesis and spermatozoal structure in Neotropi- cal cichlids, these characteristics are here analyzed in the species Cichla intermedia and compared with the data available on the order Perciformes. 2. Material and methods Cichla intermedia adult male specimens were collected from the Volta Grande reservoir, Minas Gerais, Brazil 0040-8166/$ – see front matter © 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0040-8166(03)00068-5