Amynthas trapezoides Qiu & Sun

Sun, Jing, Zhao, Qi & Qiu, Jiang-Ping, 2010, Three new species of earthworms belonging to the genus Amynthas (Oligochaeta: Megascolecidae) from Hainan Island, China, Zootaxa 2680, pp. 26-32 : 26-28

Amynthas trapezoides Qiu & Sun sp. nov.

( Figs. 1 A, B)

Material. Holotype: One clitellate (C-HN008A): China, Hainan Province, Mt. Jianfeng (18°44.45’N, 108°50.32’E), 1020 m. elevation, soil, coll. J. P. Qiu and M. B. Bouché, 5 Jun. 2006. Paratype: Three clitellates (C-HN008B): Same data as for holotype. Other material: Seventeen semiclitellates (C-HN008C): Same data as for holotype.

Locality and habitat. The specimens were collected from a yellow cinnamon soil under the arbors of Jianfeng Mountain tropical rain forests, Hainan province, China.

Etymology. This species is named after its character of arrangement of spermathecal pores.

Diagnosis. Dimensions 147–155mm by 3.2–3.6mm at clitellum, segments 147–194. Setae 44– 54 /III, 52– 68 /V, 52– 70 /VIII, 58–66/XX, 54–60/XXV; 0 between male pores; 4–6 between spermathecal pores. Spermathecal pores in 6/7–7/8, arranged at corner of trapezoid near the mid-ventral line. Male pores on XVIII, with a complicated glandular region on ventral side of 1/2XVII–1/4XIX.

Description. Preserved specimens grayish on dorsum in segment I–V, and no pigment in other segments. Dimensions 147–155mm by 3.2–3.6mm at clitellum, segments 147–194; body cylindrical in cross-section, gradually tapered towards head and tail. Prostomium ½epilobous. Setae numbering 44–54 at III, 52–68 at V, 52–70 at VIII, 58–66 at XX, 54–60 at XXV; 0 between male pores; 4–6 between spermathecal pores, setal formula AA=1.1–1.2AB, ZZ=1.3–2.2ZY. Clitellum annular XIV–XVI, reddish-brown, or grayish-brown, or yellow-brown, or light yellow; setae cannot be seen externally in clitellum.

First dorsal pore 12/13. Two pairs of spermathecal pores in 6/7–7/8, ventral, arranged at corners of trapezoid, each on a small swollen forward extension of segments VII and VIII respectively. The first pair of spermathecal pores is very close to each other as compared to the second ones, being only 0.1 circumference ventrally apart. Male pores are paired in XVIII and the male pore region is very complex from 1/2XVII–1/ 4XIX, being twisted into a glandular ventral region which includes a small extended papillae in the front edge and a pair of closely situated protuberant male pores at perichaetine of XVIII, as well as a vertical trench between two male pores from 1/2XVIII to 17/18. This glandular region with three depression in upper place, left and right side near the bottom, has a clear dividing line at perichaetine of XVIII ( Fig. 1 A). Female pore single in XIV.

Septa 5/6–7/8 thick and muscular, 10/11–11/12 slightly thickened, 8/9–9/10 absent. Dorsal blood vessel single, continuous onto pharynx; esophageal hearts in X–XIII, the last two pairs of which are bigger than the anterior pairs. Gizzard in VIII–X, bucket-shaped, covered with white flocs; intestine enlarged gradually from XV and distinctly from XX; intestinal caeca simple, originating in XXVII and extending forward to XXV, horn-shaped sac with a slight incision on dorsal margins at the septa.

Ovaries in XIII, spermathecae paired in VII–VIII; ampulla heart-shaped or oval-shaped, about 2.2mm long, gradually slender duct as long as 0.33 ampulla; diverticulum shorter than main pouch by 0.5, slender, terminal 0.25 dilated into an oval-shaped chamber; no nephridia on spermathecal ducts ( Fig. 1 B). Male sexual system holandric, testis sacs two pairs, developed, ventral in X, XI, in close proximity to two sides on ventrum; seminal vesicles paired in each of XI and XII, anterior pair bigger in size and connected on dorsum, the latter pair separated from each other clearly; prostates in XVII–XXI, glands developed, coarsely lobate, prostatic duct irregular shaped, repeatedly curved, very close to ventral midline. No accessory glands were seen.

Remarks. Amynthas trapezoides sp. nov. keys to the tokioensis group which comprised eighteen species in Sims & Easton (1972). After Sims & Easton (1972), twenty more species were reported. They are A. platycorpus ( Thai,1982) , Metaphire jianfengensis ( Quan, 1985) , A. zhongi Qiu & Wang, 1991 , A. quadrapulvinatus Wu & Sun, 1997 , A. yongshilensis Hong & James, 2001 , A. alveolatus Hong & James, 2001 , M. geomunensis ( Hong & James, 2001) , A. eastoni Hong & James, 2001 , A. boletiformis Hong & James, 2001 , A. odaesanensis Hong & James, 2001 , A. righii Hong & James, 2001 , A. fasciiformis Hong & James, 2001 , A. sanchongensis Hong & James, 2001 , A. songnisanensis Hong & Lee, 2001 , A. ephippiatus Hong & Lee, 2001 , A. multimaculatus Hong & Lee, 2001 , A. mujuensis Hong & Kim, 2002 , A. yeoi Hong & Kim, 2002 , A. heshanensis Zhang & Qiu, 2006 , A. jiangmenensis Zhang & Qiu, 2006 . The appearance of Amynthas trapezoides sp. nov. is somewhat similar to that of A. quadrapulvinatus . They share some similar characters: two pairs of spermathecal pores in 6/7–7/8; absent septa in 8/9–9/10; heart-shaped ampulla or oval-shaped spermathecae. However, the new species can be distinguished from A. quadrapulvinatus in that it lacks pigment, has two pairs of closely spaced spermathecal pore in 6/7 and 7/ 8 in the form of a trapezoid, a special male pore region comprising of a glandular depression divided by a clear line, and two male pores which are very closely spaced, Amynthas quadrapulvinatus , on the other hand, has fulvous pigment, spermathecal pores which are equidistantly spaced, and a rectangular pad male pore region with two pairs of larger truncated additional papillae that were 0.2 body circumference ventrally apart. Moreover, the new species is twice as long as A. quadrapulvinatus .

Figures

FIGURE 1. (A) Ventral view showing spermathecal pores, female pores and male pores of Amynthas trapezoides sp. nov.; (B) spermatheca of Amynthas trapezoides sp. nov.