Comprehensive DescriptionRead full entry
[[ Genus Mystus Scopoli ]]
Mystus Scopoli, 1777 , is a diverse group of small- to medium-sized bagrid catfishes, from South Asia, with 23 of the 46 nominal species known from there (Talwar & Jhingran, 1991). Despite two previous studies (Jayaram, 1954; Jayaram & Anuradha Sanyal, 2003), the diversity and distribution of the group in South Asia is not well known. Phylogenetic relationships within the genus are also poorly understood, although Mo (1991) suggested there are two major lineages. Hardman (2005) recently confirmed the paraphyly of Mystus .
One group of species (considered Mystus s. str. by Roberts, 1994) can be easily distinguished from other congeners in having a very long adipose-fin base that spans almost the entire postdorsal distance. This group (hereafter referred to in the diagnoses as “congeners with a long-based adipose fin”), known from West, South and Southeast Asia, was revised by Roberts (1994), who considered the following eight species to be valid: M. pelusius (Solander, 1794) , M. cavasius (Hamilton, 1822) , M. singaringan (Bleeker, 1846) , M. bocourti (Bleeker, 1864) , M. bleekeri (Day, 1877) , M. rufescens (Vinciguerra, 1890) , M. rhegma Fowler, 1935 ZBK , and M. albolineatus Roberts, 1994 ZBK .
A considerable amount of variation in the number of rakers on the first gill arch has been observed in M. cavasius (see Roberts, 1994). We investigated patterns in this variation and recognize three distinct species, one of which is undescribed. Redescriptions of two of these species, Mystus cavasius and M. seengtee , from northern and southern India respectively, and the description of a new species, Mystus falcarius ZBK , from Myanmar form the basis of this study.