On the immature biology of Pseudocoladenia dan sadakoe (Sonan & Mitono), with a discussion of the systematic status of this rare taxon (Lepidoptera: Hesperiidae)

Although Pseudocoladenia dan is a common skipper throughout much of its distributional range, the race sadakoe (Sonan & Mitono) inhabiting Taiwan has not been recorded since its description. Pseudocoladenia dan sadakoe was found to be associated with Achyranthes bidentata var. japonica and another unidentified Achyranthes species, as opposed to A. aspera and A. bidentata var. bidentata, which are used as the primary hosts by the populations of P. dan in neighboring mainland China and the other regions. The host associations may explain the rarity of this skipper in Taiwan because A. bidentata var. japonica is an uncommon herb growing in montane broad-leaved forests. By constrast, A. aspera is a weedy species found in disturbed habitats. Preliminary results show that P. dan sadakoe is bivoltine, and may have a different preference for host plants between generations. A discussion on the systematic status of P. dan sadakoe and a synonymic list are also given.