Amynthas conchipapillatus 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 : 28-30

Amynthas conchipapillatus Qiu & Sun sp. nov.

( Figs. 2 A, B)

Material. Holotype: One clitellate (C-HN009A): China, Hianan Province, Mt. Diaoluo (18°40.05’N, 109°53.27’E), 394 m. elevation, soil, coll. J. P. Qiu and W. X. Zhang, 7 Jun. 2006. Paratype: one clitellate (C- HN009B): same data as for holotype.

Locality and habitat. The specimens were collected from cinnamon sandy soil under the banana and arbor forests of Diaoluo Mountain, Hainan province, China.

Etymology. This species is named after its papilla, which looks like a conch.

Diagnosis. Dimensions 42–49mm by 1.5–2.0mm at clitellum, segments 106–115. Setae 40/III, 54– 64 /V, 50– 52 /VIII, 38–48/XX, 40–50/XXV; 5 between male pores; 8 between spermathecal pores. Spermathecal pores in 5/6, 0.2 circumference ventrally apart. Male pores paired in XVIII, each situated on ventral side of a shellfish-like, convex and smooth surface.

Description. Preserved specimens lacking pigment on dorsum and ventrum, clear dorsal midline of the distinct vessel after XXII. Dimensions 42–49mm by 1.5–2.0mm at clitellum, segments 106–115; body cylindrical in cross-section, gradually tapered towards head and tail. Secondary annulations conspicuous only in III. Prostomium ½epilobous. Setae numbering 40 at III, 54–64 at V, 50–52 at VIII, 38–48 at XX, 40–50 at XXV; 5 between male pores; 8 between spermathecal pores, setal formula: AA=1.2–2AB, ZZ=1.3ZY. Clitellum annular XIV–XVI, raised, orange, setal annulet particularly obvious on ventrum while setae invisible.

First dorsal pore in 12/13. One pair of spermathecal pores in 5/6, intersegmental, ventral, eye-like, 0.2 circumference ventrally apart. Genital markings not present. Male pores paired in XVIII, each situated on ventral side of a shellfish-like, convex and smooth surface. There are only 5 setae between the two so called shellfish. ( Fig. 2 A). Female pore single in XIV.

Septa 5/6–7/8 thick, 10/11–12/13 slightly thickened, 8/9–9/10 absent. Dorsal blood vessel single, continuous onto pharynx; esophageal hearts in X–XIII. Gizzard in VIII–X, ball-shaped, covered with some pale floc in IX–XX; intestine enlarged distinctly from XX; intestinal caeca simple, originating in XXVII and extending forward to 1/3 XXIV, a bigger incision on dorsal margins.

Ovaries in XIII, spermathecae paired in VI with a gradually tapering slender duct; ampulla heart-shaped or oval-shaped, about 1.2mm, spermathecae duct as long as ampulla; diverticulum shorter than main pouch by 0.2, no kinks, terminal 0.25 dilated into a pear-shaped chamber; no nephridia on spermathecal ducts ( Fig. 2 B). Male sexual system holandric, testis sacs two paires in X–XI, anterior pair developed, second pair silvery, they are all separated from each other on ventrum; seminal vesicles paired in each of XI and XII, anterior pair more developed than posterior pair; prostates in XVII–XIX, undeveloped, thin, closely adherent to body wall, prostatic duct n-shaped. Accessory glands lacking.

Remarks. Amynthas conchipapillatus sp. nov. keys to the minimus group with one pair of spermathecal pores intersegmental in 5/6. This group is composed of seventeen species. After Sims & Easton (1972), four species were recorded in China, A. lumbricatus ( Zhong, 1986) , A. bisemicircularis ( Ding, 1985) , M. plesiopora ( Qiu, 1988) , A. tetrapapillatus Quan & Zhong, 1989 , but they differ from the present species in the form of the male pore region. Also, it is easy to distinguish Amynthas conchipapillatus sp. nov. from the similar species A. mutus ( Chen, 1938) and A. infantilis ( Chen, 1938) which both have one pair of spermathecal pores in 5/6. Amynthas conchipapillatus has distinct characteristics such as a special pair of papilla in male pore region, closely arranged spermathecal pores; small prostate glands and so on, whereas A. mutus has only one small papilla on XIX behind each male pore and occasionally another on XVII in line with the former, and the distance between spermathecal pores is slightly longer than half of the body circumference. The papillae in the male pore region of A. infantilis have the following characteristics: 3 papillae placed ventro-medially on XIX–XXI, but in most cases placed ventro-laterally, with one in front of and another behind each male pore on XVIII and XX. Its prostate gland is well developed.

Figures

FIGURE 2. (A) Ventral view showing spermathecal pores, female pores and male pores of Amynthas conchipapillatus sp. nov.; (B) spermatheca of Amynthas conchipapillatus sp. nov.