Amynthas gracilis insularum

Blakemore, Robert J., 2013, Jeju-do earthworms (Oligochaeta: Megadrilacea) - Quelpart Island revisited, Journal of Species Research 2 (1), pp. 15-54 : 28

Amynthas gracilis insularum sub-sp. nov.

[ Fig. 8B ]

Material examined. IV0000251309, holotype (H) mature specimen sketched and dissected also providing DNA sample ( WO55 resampled as w31). Collected from Cheonji-yeon Falls , Seogwipo, 13 th June, 2012 by RJB .

Etymology. Latin for “of the islands” (latinized genitive plural).

Description. Length 110 mm, segments 86. Colour light brownish with darker mid-dorsal line, clitellum buff in 14-16. Prostomium epilobous. First dorsal pore in 10/11. Setae, larger and fewer in 4-7,8 (as in A. gracilis proper), number approximately 20 in 5 up to about 60 after clitellum. Spermathecal pores in 5/6/7/8 ca. 0.25-0.3 C. Female pore on 14. Male pores superficial 0.3 C apart on 18 with approximately 16 setae intervening. Genital markings in tight triplets, posterio-median to male pores on 18, with corresponding branched glands internally.

Internally, tufted nephridia occur in 5 and 6. Septa 8/9 /10 are aborted around muscular gizzard. Hearts in 10-13. Holandric, but iridescence not noted. Seminal vesicles are in 11 & 12 with pseudovesicles in 13 & 14. Spermathecal ampulla spherical, duct tapers with ental diverticulum as thin stalk and slightly dilated terminal portions. Oesophagus dilated and vascularized in 11-13, intestine begins in 15. Caeca single, incised ventrally and dorsally ruggose from ca. 27.

Remarks. Differences from A. gracilis proper possibly are a reduced first segment, dorsal pore more anteriorly in 10/11, slight difference in shape of spermathecae, distinct distribution of genital markings between male pores on 18 (a triumvirate rather than characteristically in series laterally) and caeca that are ‘quasi-pinnate’, rather than incised on ventral edges. As with the sympatric specimen described above, GMs are lacking between spermathecal pores.

DNA data in Appendix indicates agreement with specimens from Okinawa identified as “ Amynthas gracilis ” but some slight genetic separation is apparent for other specimens from the Japanese mainland. No other COI data is yet available on GenBank thus the current name awaits confirmation from further data and comparison with the fifteen or so historical names included, in whole or in part, in the nominal taxon’s synonymy.

A similar species is Amynthas papulosus (Rosa, 1896) and the closeness of its relationship also requires consideration.

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.