Taxonomic notes on the Asian frogs of the tribe Paini (Ranidae, Dicroglossinae): 1. Morphology and synonymy of Chaparana aenea (Smith, 1922), with proposal of a new statistical method for testing homogeneity of small samples ALAIN DUBOIS & ANNEMARIE OHLER Reptiles et Amphibiens, De ´partement Syste ´matique & Evolution, Muse ´um national d’Histoire naturelle, Paris, France (Accepted 4 November 2004) Abstract The species from northern Vietnam described as Rana fansipani Bourret, 1939 is shown to be a synonym of the species from northern Thailand described as Rana aenea Smith, 1922. The male secondary sex characters of this species are described in detail for the first time. Combined with a few other characters, they allow this species to be distinguished from the closely related Rana unculuanus Liu, Hu and Yang, 1960 from southern China. Both species should be placed in a subgenus Chaparana (Chaparana), a member of the tribe Paini of the subfamily Dicroglossinae of the Ranidae. In this study, we propose a new statistical method for testing homogeneity of small samples: this consists of considering the values obtained for each specimen and for each regression factor score as morphometric characteristics of this specimen within the frame of this analysis; these values, or some of them, can be used to compare subgroups of specimens by non-parametric tests such as the Mann– Whitney U test. Keywords: Anura, Chaparana, Chaparana aenea, Chaparana fansipani , Chaparana unculuanus, China, Dicroglossinae, male secondary sex characters, Paini, Ranidae, statistical method, Thailand, Vietnam Introduction This is the first of a series of papers dealing with the taxonomy of the frogs of the tribe Paini, a rather poorly-known group of frogs living, mostly in running waters, in the mountains of South and South-East Asia (Himalayas, mountains of northern Indochina and southern China) (Dubois 1976, 1992). Bourret (1939) established a new subgenus Chaparana and a new species Rana (Chaparana) fansipani for a single specimen of torrent frog collected on mount Fan Si Pan Correspondence: Alain Dubois, Reptiles et Amphibiens, USM 0602, De ´partement Syste ´matique & Evolution, Muse ´um national d’Histoire naturelle, 25 rue Cuvier, 75005 Paris, France. Email: adubois@mnhn.fr Journal of Natural History, 2005; 39(20): 1759–1778 ISSN 0022-2933 print/ISSN 1464-5262 online # 2005 Taylor & Francis Group Ltd DOI: 10.1080/00222930400023735