Abstract:

This study investigated the diversity of fish species in the Nangunhe, Nanpenghe, Yongde Daxueshan and Lancangjiang nature reserves in Southwest Yunnan, China. The β diversity index, current and ancient endemic and monotypic taxa of inhabitants were used to compare the differences in present and historic fish species and genera composition among the nature reserves. The mechanisms behind difference in fish species diversity among the nature reserves were also investigated. We recorded 85 extant native species, belonging to 6 orders, 13 families, and 45 genera. There are four endemic genera and 18 endemic species being observed in Nujiang River system in China. The genera Aspidoparia and Neonoemacheilus and five endemic species occurred in these three nature reserves (Nangunhe, Nanpenghe, Yongde Daxueshan reserves). There have been 31 genera occurred only in the Lancangjiang River system in China, but the only genus observed in the Lancangjiang Nature Reserve was Ambastaia. In China twenty species were observed only in Lancangjiang Nature Reserve, three of which were only found in this reserve. Among the three nature reserves within the Nujiang river system, only one monotypic genus Anguilla and no monotypic species were observed. No monotypic genera or species were observed in the Lancangjiang Nature Reserve. Comparisons of observed species and groups with fossil records show that the current fishes of Yunnan are species and groups that evolved in the later Tertiary and Quaternary periods, and there are no old or relic species currently present. The β diversity index showed that fish diversity was greatest in the Lancangjiang Nature Reserve, and the lowest in the Nangunhe Nature Reserve. However, the fish diversity representation and protected status in the three nature reserves located within the Nujiang River system are higher than those in the Lancangjiang Nature Reserve. The existence of monotypic species and taxa in the three nature reserves within the Nujiang River system reflects the importance of fisheries protection within these reserves. Geographical location, the length, heterogeneity, number of river branches in the reserve explained difference in fish diversity among the four nature reserves. In order to provide protection to the greatest number of fish species, the first branches in the upper, middle and lower regions of the river system should be designated as reserves.

Key words: fish diversity, monotypic, endemic, βdiversity index, Southwest Yunnan