Description of a new earthworm belonging to the genus Amynthas (Oligochaeta: Megascolecidae) from Taiwan and its infraspecific variation in relation to elevation

This paper describes the sexthecal earthworm Amynthas tessellatus, new species, from the Central Mountain Range of Taiwan. It shows wide ranges of vertical (altitude) variation in the characters of reproductive organs, such as the number and location (segment) of genital papillae, the stalk length of accessory glands, the spermathecal stalk length/ampullar length ratio, and the diverticular stalk length/seminal chamber length ratio. Based on genital papillae and accessory glands, A. tessellatus consists of two distinctive geographical populations; Amynthas tessellatus tessellatus, new subspecies, at high elevations of 1000 m to 3200 m, and Amynthas tessellatus paucus, new subspecies, at low elevations of 700 m to 1100 m. In the postclitellar region, A. tessellatus tessellatus has genital papillae with sessile accessory glands in XVII, XVIII and XIX, whereas A. tessellatus paucus has genital papillae with stalked accessory glands in XVIII.