Amynthas laceratus, 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 : 1235-1236

Amynthas laceratus sp. nov.

( Figure 4 )

Type material

Holotype: Clitellate (NIBRIV0000120465) specimen: Korea, Jeollabuk-do, Wanju-gun, Mt Unjang , litter layers in forest, 4 September 2000, Y. Hong coll. 1 paratype: 1 clitellate (NIBRIV0000120477): Same data as for holotype.

Etymology

The name laceratus is Latin for a little mangled, with regard to the diverticulum being coiled with a short muscular stalk.

Diagnosis

Spermathecal pores in VI, VII, close to 5/6/7, 0.29–0.33 mm circumference apart; male pores in setal lines within deeply invaginated area medial to lateral edge, resembling volcanic crater, 0.22–0.23 mm circumference apart.

Description

Red–brown dorsal pigment. Dimensions 74–97 mm by 4.4–4.7 mm at segment X, 4.7–5.0 mm at XXX, 3.8–4.8 mm at clitellum; body cylindrical throughout, segments 64–81. Setae regularly distributed around segmental equators, numbering 55 at VII, 57 at XX; 13–15 between male pores, size and distance regular; setal formula AA: AB: YZ: ZZ = 3: 2: 2: 4 at XIII. Female pore single in XIV, 0.5 mm oval shape. First dorsal pore 12/13.

Male pores equatorial within deeply invaginated areas medial to lateral edges of approximately circular thickened areas, resembling volcanic crater, each with small white spot at centre, some flanked by two to four very small longitudinal wrinkles, 0.22–0.23 mm circumference apart, distance between male pores 3.8 mm. Spermathecal pores ventral in VI, VII, close to 5/6 and 6/7, spermathecal pores 0.29–0.33 mm circumference apart, small white spot surrounding pore openings, which appear black. Genital markings not present in spermathecal segments.

Septa 5/6–7/8 thin, 8/9, 9/10 absent, 10/11–13/14 thin. Gizzard moderately globular in VIII–X. Typhlosole absent. Intestinal caeca simple, originating in XXVII, extending anteriorly about to XXIII, each consisting of a finger-shaped sac. Oesophageal hearts three pairs in XI–XIII, IX lateral in left side.

Ovaries in XIII. Paired spermathecae in VI, VII; ampulla large pouch, irregular shape, ducts thick, as long as ampulla, diverticulum coiled and kinked with short muscular stalk, somewhat longer than ampulla; no nephridia on spermathecal ducts. Male sexual system holandric, testes and funnels in ventral paired sacs in X, XI. Seminal vesicles large in XI, XII. Prostates XVIII extending to XVI–XX; having long muscular ducts with a hairpin bend, both glandular portions consist of two main lobes.

Remarks

Amynthas laceratus sp. nov. and the next two species, which have intrasegmental spermathecal pores on VI and VII close to 5/6, 6/7, key out to the canaliculatus -group in Sims and Easton (1972). Members of the Korean canaliculatus -group all have simple intestinal caeca, but A. canaliculatus (Gates, 1932) has manicate caeca. The other canaliculatus -group species are A. rallus ( Gates, 1936) , A. rallidus ( Gates, 1936) and A. benigmus ( Chen, 1946) . The present species differs from other species in the canaliculatus -group and the morrisi -group by lacking genital papillae and by having the male pores at the bottoms of crater-like invaginations. Korean canaliculatus -group species consist of two sub-groups, one with spermathecal pores well within VI, VII containing the following species A. seungpanensis (Song and Paik, 1970) , A. plantus ( Song and Paik, 1973) , A. cuneatus Hong and James, 2001 , A. gongjuensis Hong and Kim, 2002 , A. vicinus Hong and James, 2001 , A. oviformis Hong and James, 2001 , A. jindoensis Hong and James, 2001 and A. jangbogoi Hong and James, 2001 . The other sub-group has spermathecal pores on VI, VII closer to 5/6, 6/7, similar to the morrisi -group, and contains the following species: A. fibula typica ( Kobayashi, 1936) , A. fibula ranunculus ( Kobayashi, 1936) , A. bithecus ( Kobayashi, 1936) , A. sopaikensis ( Song et Paik, 1973) , A. piagolensis Hong et James, 2001 , A. taebaekensis Hong et James, 2001 , A. bubonis Hong et James, 2001 and A. deogyusanensis Hong et James, 2001 .

Figures

Figure 4. Amynthas laceratus sp. nov.: ventral view and spermathecae.