Amynthas gracilis gracilis (Kinberg, 1867)

Blakemore, Robert J., 2013, Jeju-do earthworms (Oligochaeta: Megadrilacea) - Quelpart Island revisited, Journal of Species Research 2 (1), pp. 15-54 : 26-27

Amynthas gracilis gracilis (Kinberg, 1867)

[ Fig. 8A ]

Material examined. IV000251208 from Cheonji-yeon Falls, 13 th June, 2012. Mature specimen sketched and dissected providing DNA sample (w63).

Description. (Jeju specimen in summary). Genital marking discs median to male pores, postsetally with small stalked glands corresponding internally. Spermathecal pores in 5/6/7/8, first dorsal pore in 11/12. Septa 7/8 present to base of gizzard, 8/9 absent. Spermathecae in 6-8, with saccular ampulla on muscular duct with thin diverticula stalk having small, spherical bulb. Holandric. Prostates glands well developed in 18. Intestinal caeca incis- ed ventrally. Typhlosole absent.

Remarks. The current specimen complies morphologically with current concepts of “ A. gracilis ” (e.g., by Gates, 1972; Sims & Gerard, 1999; Blakemore, 2010b), another cosmopolitan species from tropical and warm temperate localities. Blakemore (2010b) noted that Amynthas bouchei , A. omodeoi and A. edwardsi all by Zhao & Qiu in Zhao et al., 2009 from Hainan, China in the same “ hawayanus species-group”, are possible syns. nov. of A. gracilis . Sims & Easton (1972: 176, 214) remarked that gracilis was the type-species of the monotypic genus Nitocris Kinberg, 1867 , a pre-occupied name, and made it representative of their “ hawayanus species-group” while noting that the precise identity of the type-series could not be established as the specimens are immature.

Kinberg’s original description, in full, was: “ N. gracilis n. Lobus cephalicus longitudinem partis mediae superioris segmenti buccalis aequans; segmenta 89-91; longitudo 42-66 mm. Rio de Janeiro, in horto botanico.”

The current specimen complies with earlier descriptions although it lacks the GMs frequently seen in some or all of 6-8,9 near the spermathecal pores in 5/6/7/8 and in groups of up to eleven (or twelve) median to male pores and sometimes on 17 and 19 too ( Gates, 1972: 189; Sims & Gerard, 1999: 130). Without reference to DNA data, this would reasonably be the first record from Korea. However, a potential sub-species is tentatively described below that differs from the more familiar concept of the cosmopolitan A. gracilis , yet its DNA - at least for the part of the COI gene - agrees 100% with the current specimen. At the same time, the only previously A. gracilis barcodes from Japan seem to indicate slight differences (Appendix). Morphology and DNA are recorded, leaving the outcome of the issue of correct identity and taxonomic relationship of either taxon flagged for future reference.

Figures

Fig. 8. A.?Amynthas gracilis gracilis spermatheca from 7rhs, male field and caeca from 27rhs; B. Amynthas gracilis insularum sub-sp. nov. holotype showing ventral aspect; prostomium and pygidium, spermathecae, prostate in situ and caecum in 27 with [boxed] enlargement of male pore 18lhs.