Abstract:  Subspecies is a subunit of species, and its status is questioned because of different definitions and subjectivity in taxonomy. However, all attempts either to replace the subspecies by a different terminology or to abandon it altogether have been found unacceptable in taxonomic practice. Subspecies, as a part of the natural process, are also an important part of biodiversity, and with certain uniqueness, they also have values in conservation. Based on subspecies concepts and characteristics, it is proposed that two principles, geographical isolation (such as allopatric distribution) and differences in phenotype, should be applied in subspecies taxonomy. In this article, we reviewed the application and problems of the two principles with the rare butterflies of Teinopalpus as examples, collected the data of geographic distribution, morphological descriptions of subspecies taxonomy or related literatures of this butterfly genus, and summarized the status, problems and causes in the subspecies taxonomy of this genus. From 1843 to 2007, eight subspecies were recorded in T. imperialis and its sister species T. aureus, respectively. However, some subspecies were applied simultaneously in one administrative region, such as T. i. imperialis, T. i. himalaicus and T. i. behludinii all were applied in Sichuan Province of China, and two subspecies were recorded together in Zhejiang Province of China, indicating uncertainties in subspecies application. Considering that both the two sister butterflies were distributed (sympatric) in Southeast Asia, the geographical isolation between subspecies was then determined by comparing the consistency of locations of their holotype specimens in biomes and ecoregions. The niche differentiation in T. imperialis (over three biomes) could be higher than that in T. aureus (with only one biome). According to the isolation of ecoregion, we suggest that the subspecies taxonomy of T. imperialis should be revised as the seven subspecies T. i. imperialis, T. i. himalaicus, T. i. miecoae, T. i. behludinii, T. i. imperatrix (including T. i. bhumipholi), T. i. gillesi and T. i. gerritesi in T. imperialis, and that of T. aureus as T. a. aureus (including T. a. wuyiensis, T. a. guangxiensis and T. a. nagaoi), T. a. eminens (including T. a. laotiana), T. a. shinkaii and T. a. hainani. Due to the lack of reference specimens, the information available for morphological comparison is limited and incomplete (such as only unisexual comparison in morphology), so it could lead to over-subspecialization. In rare butterflies, subspecies problems such as over-subspecialization and uncertainty would affect management in conservation, since governors usually make decision after weighing costs and effectiveness and identifying priorities in regions or species in conservation. Therefore, subspecies taxonomy should not be recommended until more definitive information available.

Key words: Butterflies, subspecies, taxonomy, geographic isolation, phenotype, conservation