Amynthas acinus, Hong & James, 2009

Hong, Yong & James, Samuel W., 2009, Some new Korean Megascolecoid earthworms (Oligochaeta), Journal of Natural History 43 (21 - 22), pp. 1229-1256 : 1248-1250

Amynthas acinus sp. nov.

( Figure 11 )

Type material

Holotype: Clitellate (NIBRIV0000120472) specimen: Korea, Jeollanam-do, Damyanggun, Mt Chuwol , 200–600 m, soil and litter layers in forest, 3 August 2000, Y. Hong coll.

Etymology

The epithet acinus, Latin for “berry-shape”, refers to the shape of the ampulla pouch.

Diagnosis

Three pairs of two spermathecal pores VI–VIII close to 5/6/7/8, 0.24 mm circumference apart; male pores 0.31 mm circumference apart, ochre-coloured patches laterally VI, VII and VIII.

Description

Worm unpigmented. Dimensions 128 mm by 7.0 mm at segment X, 7.0 mm at XXX, 6.8 mm at clitellum; body cylindrical throughout, segments 98. Setae regularly distributed around segmental equators, numbering 28 at VII, setae may be present in ochre genital patches but very hard to see, 75 at XX, regular; 11 between male pores, size and distance regular; setal formula AA: AB: YZ: ZZ = 1.5: 1: 2: 3 at XIII. Female pore single in XIV, 1.1 mm oval shape. First dorsal pore 12/13.

Male field with large 2.6 × 2.2 mm egg-shaped raised pads, narrow end medial; each pad extending from 17/18 to 18/19, with transverse seminal groove from approximate lateral edge of broad end of pad to medial edge, 0.31 mm circumference apart; male pores at medial ends of grooves, raised above body wall level. Three pairs of two spermathecal pores VI, VII, VIII close to 5/6, 6/7 and 7/8 on mid-lateral, small, flat-top spots, pore opening appears black, spermathecal pores 0.24 mm circumference apart. Ochre-coloured genital patches laterally VI, VII and VIII. Genital markings lacking.

Septa 5/6–7/8 thick, 8/9, 9/10 absent, 10/11–13/14 thin with some muscle. Gizzard small in VIII–X. Intestine begins in XV, lymph glands from XV. Typhlosole low simple fold from XXVII. Intestinal caeca simple, originating in XXVII, extending anteriorly about to XXIII, each consisting of a finger-shaped sac with seven or eight pouches on ventral margin. Oesophageal hearts X–XIII, IX lateral.

Ovaries in XIII. Four spermathecae in each of VI, VII, VIII in paired groups of two; each ampulla berry-shaped pouch, with conspicuous blood vessel; ducts short, thin, as long as ampulla, slender tapered digitate diverticulum longer than duct; no nephridia on spermathecal ducts, densely crowded nephridia on body wall of VII, VIII. Male sexual system holandric, testes and funnels enclosed in dorsally united, ventrally separate sacs. Seminal vesicles, two pairs XI and XII. Prostates XVIII extending to XVI–XX; short thick ducts, both glandular portions divided into leaflets. Genital papillae glands lacking.

Remarks

Amynthas acinus sp. nov. is polythecal, unlike all other Korean Amynthas and bournei - group members, which are bithecal. Amynthas acinus sp. nov. has four spermathecae per segment, in paired groups of two. This point is very interesting for Amynthas systematics. Amynthas acinus sp. nov. has ochre-coloured genital patches, dense crowds of nephridia in the location of the ochre genital patches, ventral margin pockets on the caeca, spermathecae in VI–VIII, and united testes sacs. It has very unique spermathecae. All Korean Amynthas have paired spermathecae, but the species has four spermathecae per segment. In this way, it is similar to other polythecate members of other Pheretima -complex genera, though polythecy is unusual in this group.

Figures

Figure 11. Amynthas acinus sp. nov.: ventral view and spermathecae.