Amynthas quinqueconvexus, 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 : 1237-1238

Amynthas quinqueconvexus sp. nov.

( Figure 5 )

Type material

Holotype: Clitellate (NIBRIV0000120466) specimen: Korea, Gyeongsangbuk-do, Gujosa , 5 August 1971, G.S. Kim coll.

Etymology

The epithet quinqueconvexus, Latin for “containing five”, with regard to the appearance of the male pore region.

Diagnosis

Spermathecal pores in VI, VII, above lateral margin; male pores equatorial at centres of large hardened male discs, discs ovate to nearly circular; four other pairs of pads in XVII, XIX–XXI, 0.23 mm circumference apart.

Description

Brown dorsal pigment. Dimensions 182 by 8.5 mm at segment X, 6.7 mm at XXX, 7.1 mm at clitellum; body cylindrical throughout, segments 133. Setae regularly distributed around segmental equators, numbering 66 at VII, 87 at XX; 15 between male pores, regular spacing; setal formula AA: AB: YZ: ZZ = 8.5: 3: 2.5: 5 at XIII. Female pore single in XIV, 1.2-mm circle. First dorsal pore 12/13.

Male pores equatorial at centres of large hardened male discs, discs ovate to nearly circular, each with curved transverse groove posterior to male pore, shorter semi-circular groove anterior to male pore; paired male pads in XVII, XIX, XX, XXI; XVII, XIX slightly smaller than XVIII, decreasing in size posteriorly, 0.23 mm circumference apart. Male pads appear to be darkened areas roughly triangular with apex towards mid-ventral line. Spermathecal pores in VI, VII, above lateral margin, inconspicuous, spermathecal pores region swelled slightly. Genital markings absent.

Septa 5/6, 6/7, 7/8 thick, 8/9 – 9/10 absent, 10/11 – 13/14 thick, muscular. Gizzard globular in VIII – X. Vascularized low oesophageal lamellae XIII, XIV. Intestine begins XV, lymph glands from XXVII. Typhlosole medium height from XXVII. Intestinal caeca simple, originating in XXVII, extending anteriorly to about XXIII, each consisting of a finger-shaped sac, each finger with 10 serriform outgrowths on ventral margin. Hearts X – XIII oesophageal, IX lateral.

Ovaries in XIII. Paired spermathecae in VI, VII; each ampulla a pear-shaped small pouch with apical appendix; ducts as long as ampulla, diverticula club-shaped, stalked; no nephridia on spermathecal ducts. Male sexual system holandric, testes sacs of X enclose hearts of X, testes sacs XI enclosing seminal vesicles, hearts of XI; both pairs of sacs joined dorsally, ventrally; however, dorsal connection section of X not filled with sperm. Seminal vesicles small, two pairs in XI, XII; sperm ducts slightly muscular. Prostates just in XVIII small; thick short ducts, both glandular portions consisting of one main lobe, each lobe divided into seven or eight leaflets. Large paired muscle bands traversing coelom from mid-ventral to near mid-dorsal in XIV–XII.

Remarks

The present species has a peculiar male pore region, with paired pads within XVII– XXI. The ampullae of the spermathecae are different from other Korean Amynthas because there is an apical appendix. Also this species is large-bodied, but it has only two pairs of spermathecae, unlike the other large species, which have four pairs. The species has different testes sac structure from the other Korean species with spermathecae in VI and VII, and also different from the morrisi -group members. Compared to the canaliculatus -group of species (intrasegmental spermathecal pores in VI, VII), this species has simple rather than manicate caeca (as in A. canaliculatus ) and has genital markings unlike A. rallus ( Gates 1936) and A. rallidus ( Gates 1936) . On the other hand the last two share some similarities of the testes sacs with the present species, but they are also considerably smaller (30–66 mm), and have red pigmentation. Amynthas benigmus ( Chen 1946) has low simple testes sacs and only one papilla pair placed medial to the male pores.

Figures

Figure 5. Amynthas quinqueconvexus sp. nov.: ventral view and spermathecae.