Phylogenetic relationships of glyptosternoid fishes (Siluriformes: Sisoridae) inferred from mitochondrial cytochrome b gene sequences Zuogang Peng, a Shunping He, a, * and Yaoguang Zhang b a Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China b School of Life Science, Southwest China Normal University, Chongqing 400715, PR China Received 5 May 2003; revised 29 October 2003 Abstract To explore phylogenetic relationships among glyptosternoid fishes, we determined nucleotide sequences of the complete mito- chondrial cytochrome b gene region (1138 base pair). Thirteen species of glyptosternoid fishes and six species of non-glyptosternoids represent 10 sisorid genera were examined. Molecular phylogenetic trees were constructed using the maximum parsimony, minimum evolution, maximum likelihood, and Bayesian methods. Bayesian and maximum likelihood analyses support the monophyly of glyptosternoids, but our hypothesis of internal relationships differs from previous hypothesis. Results indicated that glyptosternoid is a monophyletic group and genera Glyptosternum and Exostoma are two basal species having a primitive position among it. Genera Euchiloglanis and Pareuchiloglanis form a sister-group. Then they form a sister-group with Pseudexostoma plus Oreoglanis. Our result also found that Pareuchiloglanis anteanalis might be considered as the synonyms of Parechiloglanis sinensis, and genus Euchiloglanis might have only one valid species, Euchiloglanis davidi. Ó 2003 Elsevier Inc. All rights reserved. Keywords: Sisoridae; Glyptosternoids; Cytochrome b; Phylogeny 1. Introduction The glyptosternoid fishes are freshwater catfishes belonging to the family Sisoridae in Siluriformes. They are mainly distributed in the water systems of the Qinghai-Tibet Plateau and East Himalayas. The main basins in which these fishes live include: Yaluzangbuji- ang (Tsaopo), Irrawady, Nujiang (Salween), Nanc- angjiang (Mekong River), Jingshajiang (upper stream of the Yangtze River), Yuanjiang (Red River), Nanpanji- ang (upper stream of the Pearl River), and Brahmaputra basin (He, 1996). They are highly adaptive to torrential environment. Its special distribution and phylogenetic interpretation would be helpful in determining the de- velopment of water systems in this area. There are nine genera of glyptosternoids in total with eight genera found in China, including genera Glyptosternum, Exostoma, Pseudexostoma, Oreoglanis, Pareuchiloglanis, Euchiloglanis, Parachiloglanis, and Glaridoglanis. The other genus Myersglanis is only found in India (Chu, 1979; Chu et al., 1999; Hora and Silas, 1952). Hora (1952) first studied systematics of glyptosternoids based on geographical distribution and adaptive structures, such as the maxillary barbells, ad- hesive organ. His conclusions suggested that Glyptos- ternum is the most primitive genus in the group, whose direct ancestor is Glyptothorax-like fish. Hora (1952) thought that glyptosternoids was originated in the Yunnan province of China, and that the various genera and species of the group diversified in a series of waves of tectonic movements in this region. In 1979, Chu di- vided this group into two clades: the first contains Glyptosternum-like genera, in which the lower labial-fold is interrupted; and the second includes Exostoma-like genera whose lower labial-fold is continuous, with the lips reflected and spreading to form a broad flat sucker. In 1996, one of us (H.S.P) re-examined the phylogeny of glyptosternoids based on 60 osteological characters (He, 1996). The resulted cladogram suggested that glypto- sternoids forms a monophyletic group with Glyptoster- num as the most primitive genus, and that some * Corresponding author. Fax: +86-27-87-87-5132. E-mail address: clad@ihb.ac.cn (S. He). 1055-7903/$ - see front matter Ó 2003 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2003.10.023 Molecular Phylogenetics and Evolution 31 (2004) 979–987 MOLECULAR PHYLOGENETICS AND EVOLUTION www.elsevier.com/locate/ympev