Amynthas hengchunensis, James & Shih & Chang, 2005

James, Samuel W., Shih, Hsi-Te & Chang, Hsueh-Wen, 2005, Seven new species of Amynthas (Clitellata: Megascolecidae) and new earthworm records from Taiwan, Journal of Natural History 39 (14), pp. 1007-1028 : 1015-1016

Amynthas hengchunensis sp. nov.

( Figure 2G, H )

Holotype: adult collected at Nanrenshan , Kending, Pingtung County, Taiwan, 22 ° 059030N, 120 ° 509070E; 150 m, 28 April 1999 by H.- T. Shih, NMNS 4054-006 .

Other material examined. One adult, Nanrenshan, Kending, Pingtung County, Taiwan, October 1998, Chung-Chi Huang coll., NMNS 4054-007 ; one adult , Kending , Hengchun, Pingtung County, Taiwan, 4 February 1998, Chi-Yuan Huang coll., NMNS 4054-008 ; one adult , Santaishan , Hengchun, Pingtung County, Taiwan, 22 ° 029120N, 120 ° 459560E; 93 m, 31 March 1999, H.- T. Shih coll., NMNS 4054-009 ; two adults , Kending , Hengchun, Pingtung County, Taiwan, 21 ° 549170N, 120 ° 519330E; 45 m, 6 January 2000, H.- T. Shih coll., NMNS 4054-010 .

Etymology

This species is named after Hengchun Peninsula, Pingtung County, Taiwan, where it was discovered.

Description

Dimensions 200–252 mm by 9–11 mm at segment x, 9.5–11 mm at xxx, 8–9.5 mm at clitellum; body cylindrical throughout, segments 138–148. Setae regularly distributed around segmental equators, numbering 120–170 at vii, 140–164 at x, 170–208 at xxv; size uniform; setal formula AA:AB:YZ:ZZ51.7:1:1:3 at xxv. Female pore single in xiv. Prostomium epilobic, with tongue open. Unpigmented, first dorsal pore 12/13. Clitellum annular xiv–xvi; setae invisible externally.

Male pores minute on low conical porophores at posterior extension of spatulate longitudinally orientated genital marking surrounded by epidermal folds, lateral fold close to male pores enlarged to form flap or hood partially covering male porophore; 26–28 setae between male pores, pores 0.33 circumference apart on setal line 20. Spermathecal pores dorso-lateral in 5/6/7/8/9, 0.37–0.40 circumference apart dorsally, segmental edges posterior to pores thickened ( Figure 2G ).

Septa 5/6/7/8 thinly muscular, 8/9 membranous, 9/10 absent, 10/11–13/14 thickly muscular; gizzard viii. Intestinal origin 1/2xv; typhlosole simple fold from xxiv gradually to full size xxviii, one-fifth lumen diameter. Intestinal caeca conical, margins smooth, xxvii– xxiii; lymph gland from xv; blood glands in v. Oesophageal hearts x–xiii, very small links to dorsal vessel xi–xiii; commissural vessels vii, ix lateral, viii to gizzard; supraoesophageal vessel xi–xiv; extraoesophageal vessels join ventral oesophageal wall in x, prior to this receive vessels from ventral posterior face of gizzard; posterior latero-parietal vessels from body wall of xiv–xvi, septum 13/14 to ventral oesophageal location of extraoesophageal vessels in xiii.

Male sexual system proandric, testes, funnels in ventrally joined sac in x. Seminal vesicles large in xi, with small dorsal lobe; seminal vesicles, other contents of xi enclosed in thin sac. Prostates large in xviii, four main lobes, each lobe served by two to five small ductlets radiating fan-like from ental end of prostatic duct; ducts stout, straight, muscular, narrowing towards body wall; vasa deferentia join duct at duct–glandular portion junction; vasa deferentia non-muscular.

Ovaries in xiii. Paired spermathecae vi–ix; ampulla ovate, duct shorter than ampulla, diverticulum small ovate chamber, stalk slender composed of entally widening hairpin loops not enclosed in membrane ( Figure 2H ); no nephridia on spermathecal ducts.

Remarks

Amynthas hengchunensis is similar to A. formosae (Michaelsen, 1922) with respect to proandry, the enclosure of the contents of xi in a sac, being octothecal in vi–ix, the general form of the spermathecae, the body size, the intestinal origin, and the very large number of setae in the anterior segments. In contrast, A. hengchunensis has many more setae, especially in the post-clitellate segments, and has spermathecal pores more ventrally placed. Other differences ( A. hengchunensis features given) include the male field possessing a flap partially covering the male porophore, much shorter caeca, and lack of membranous covering of the diverticulum stalk. This species is the second proandric Amynthas known from Taiwan, with three more described below. Amynthas hengchunensis also has a different prostatic duct structure from that encountered in most Amynthas , the only one similar to it being A. formosae . The ordinary Amynthas prostatic duct has a multiple approximately dichotomous branching pattern, with occasional trichotomies. In the present species, and the next three described below, numerous ductlets of equal size join the large prostatic ducts at the same point, creating a single polytomy. This polytomy may form from two or more groups of ductlets, or as in A. chaishanensis , which is described later in this paper, one undivided fan of ductlets.

Figures

Figure 2. (A) Ventral view of Amynthas nanrenensis holotype, with detail of the male pore; (B) spermatheca of Amynthas nanrenensis; (C) ventral view of Amynthas monsoonus holotype; (D) spermatheca of Amynthas monsoonus; (E) ventral view of Amynthas huangi holotype; (F) spermatheca of Amynthas huangi; (G) left lateral view of segments i–ix and ventral view of xiv–xix of Amynthas hengchunensis, with detail of male pore; (H) spermatheca of Amynthas hengchunensis.