A new athecate earthworm of the genus Amynthas Kinberg (Megascolecidae: Oligochaeta) from Taiwan with discussion on phylogeny and biogeography of the A. illotus species-group

Abstract

This paper describes a new species of athecate earthworm belonging to the illotus species-group of the genus Amynthas Kinberg from Taiwan. It is Amynthas hohuanmontis sp. nov. from Mt Hohuan at an elevation of 3000 m in the Central Mountain Range. The athecate earthworm Amynthas pusillus (Ohfuchi) from Ishigaki Island, Riukiu is found to be synonymous with Amynthas assacceus (Chen) from Hainan Island, China. Accordingly, the A. illotus species-group currently consists of A. hohuanmonti s sp. nov. from Taiwan, A. illotus (Gates) from Yunnan and Riukiu, A. assacceus (Chen) of Hainan and Riukiu, A. sheni (Chen) from Hong Kong and A. oyuensis (Ohfuchi) from Japan. Based on characters of particularly the porophore structure, the ® ve species are divided into two species-subgroups: the sheni species-subgroup of A. sheni and A. hohuanmonti s, and the assacceus species-subgroup of A. illotus, A. assacceus and A. oyuensis. The two subgroups might have diOE erentiated from two independent ancestors. The ® ve species show an arc-shaped distribution in the peripheral regions of the East Asian continent (Yunnan, Hainan, Hong Kong, Taiwan, Riukiu and Japan), suggesting them to be survivors from the Pleistocene ice ages.

Asian Invasive Earthworms of the GenusAmynthasKinberg in Vermont

“…Gates (1972a: 196) also surmized that his subsequent Amynthas youngi (Gates, 1932: 406) (with types either lost or in Calcutta Museum: 3077) may be one possible candidate for his species's H morph, although information was lacking for confirmation of this. Tsai et al (2002) give distribution of A. illotus as Yunnan (China) and Ishigaki Island, apparently overlooking the type locality and accepting Ohfuchi's records, even though the diagnosis of these latter specimens differed considerably from Gates's original. .…”

“…50 %). This diversity compares with approximately 41 species from Taiwan (with 18 native taxa); 105 from mainland China (82 native); 45 species from Korea (27 native, but other natives recently added); and 19 species (5 native) from the historical region of northeast China called Manchuria (these totals from Tsai et al 2000Tsai et al , 2001 who also give historical accounts and biogeographical notes for these regions). Gates (1972a) described about 174 mainly pheretimoid species from Myanmar (Burma), with much information on their relationships to other Oriental faunas.…”

“…Remaining members of the A. illotus species-group from other than Japanese reports are Amynthas assacceus (syn. pusillus: Ohfuchi, 1956, ?proasacceus Tsai et al, 2001; A. catenus Tsai et al, 2001 from Taiwan; A. hohuanmontis Tsai et al, 2002 from Taiwan;and A. sheni (Chen, 1935) from Hong Kong (but cf. A. corticis or A. robustus).…”

“…Amynthas assacceus: Sims & Easton, 1972: 236 (A. illotus species-group). Amynthas asacceus [sic, lapsus]: Tsai et al, 2001: 284 [syn. pusilla Ohfuchi, 1956 (non Ude)].…”

Three New Earthworms of the Genus Amynthas (Clitellata: Megascolecidae) from Nam Ha NPA, Laos

“…Other than the known athecal morphs of species with spermathecae (Gates, 1972), we can compare this species to other athecal species. First we will compare it to five athecal species, A. hohuanmontis Tsai et al, 2002, A. chilanensis Tsai et Tsai, 2007, A. bilineatus Tsai et Shen, 2007 (Goto et Hatai, 1899), and A. dageletensis Hong et Kim, 2005. Amynthas irregularis and A. dageletensis are Korean, and have manicate cecum unlike the present species, which has simple caeca.…”