Amynthas tenuis Qiu & Jiang

Zhao, Qi, Jiang, Jibao, Sun, Jing & Qiu, Jiangping, 2013, Four new earthworm species and subspecies belonging to genus Amynthas and Metaphire (Oligochaeta: Megascolecidae) from Hainan Island, China, Zootaxa 3619 (3), pp. 383-393 : 386-387

Amynthas tenuis Qiu & Jiang , sp. nov.

( Fig. 2 , Table 2 )

Material. Holotype one clitellate (C-HN 201109 -08), China, Hainan Province, Mt. Wuzhi (18°54ʹ15ʺN, 109°41ʹ0 2ʺE), 861m a.s.l., soil, coll. J.P. Qiu, Q. Zhao, J.B. Jiang, D. Cluzeau, W.K. Zhang, 25 May 2011. Paratype one clitellate (C-HN 201110 -04), same data as for holotype except that elevation is 858 m a.s.l.

Locality and habitat. The specimens were collected from core area of Wuzhishan National Nature Reserve, tropical rain forest, Hainan province, China.

Etymology. This species is named after its slim body shape.

Diagnosis. Dimensions 48–56 mm by 2 mm at clitellum, segments 72–89. Setae 12–28/III, 24–28/V, 30– 36 / VIII, 24–32/XX, 28–30/XXV; 8 between male pores; 10 between spermathecal pores. Spermathecal pores in 5/ 6–6/7, a little less than 0.33 circumferences ventrally apart. Male pores on XVIII, about 0.33 body circumferences apart, ventrally placed on an ovoid porophore.

Description. Preserved specimens from light purple to light yellow brown or pale on dorsum, no colour on ventrum. Dimensions 48–56 mm by 2 mm, segments 72–89; body cylindrical in cross-section, gradually tapered towards head and tail. Prostomium 1/2 epilobous. Setae numbering 12–28/III, 24–28/V, 30– 36 /VIII, 24–32/XX, 28–30/XXV; 8 between male pores; 10 between spermathecal pores, setal formula AA=1.3–2AB, ZZ=1.3–1.5ZY. Clitellum annular XIV–XVI, no color or pale; 4 setae present in XVI or no setae ventrally. First dorsal pore in 12/ 13. Two pairs of spermathecal pores in 5/6–6/7, ventral, a little less than 0.33 body circumferences apart. Genital markings not present. Male pores paired in XVIII, about 0.33 body circumferences ventrally apart, placed on an ovoid porophore. Genital papillae not present in holotype, but two large ovoid genital papilla exist anterior and posterior of the ectal part of male pore in paratype. Female pore single in XIV.

Septa 5/6–6/7 comparatively thick, 7/8, 10/11–13/14 slightly thickened, 8/9–9/10 absent. Dorsal blood vessel single, continuous onto pharynx; esophageal hearts in X–XIII, first pair small. Gizzard in IX–X, elongated ballshaped; intestine enlarged distinctly from XV; intestinal caeca simple, originating in XXVII and extending forward to XXIV, smooth both on ventrum and dorsum. Ovaries in XIII, spermathecae paired in VI–VII, about 1.5-1.9 mm; ampulla heart-shaped, about 1.1 mm, spermathecal duct long and straight, distinctly separate from ampulla; length of diverticulum a little less than or 2/3 of the main pouch, terminal 1/10 enlarged as an irregular spherical chamber or terminal 0.67 enlarged as virgulate chamber; no nephridia on spermathecal ducts. Male sexual system holandric, testis sacs two pairs in X–XI, well-developed, separated ventrally; seminal vesicles paired in XI–XII, developed, separate from each other ventrally; prostates in XVII–XX, developed, prostatic duct in XVIII, n-shaped. Accessory glands present in XVIII, with a stalk.

Remarks. Amynthas tenuis sp. nov. is most similar to Amynthas infantilis (Chen, 1938) . Both species lack septa in 8/9–9/10 and first dorsal pores are in 12/13. Both of them have simple intestinal caeca and an accessory gland around the well-developed prostate glands. Both of them have an elongate ovoid spermathecal ampulla, and the diverticulum is shorter than the main pouch and with a spherical seminal chamber. However, they have distinct differences. Amynthas tenuis sp. nov. is more than 3 times bigger than Amynthas infantilis . It has two pairs of spermathecal pores in 5/6–6/7, while Amynthas infantilis has only one pair in 5/6. Amynthas tenuis sp. nov. has no genital markings, while Amynthas infantilis has both genital papillae and markings. The male pore is in XVIII in Amynthas tenuis while it is in XIX in Amynthas infantilis . The sequence of a 16S gene fragment of the holotype of Amynthas tenuis (C-HN 201109 -08) has been deposited in GenBank under the Accession No. JQ904531 ( Table 1 ).

Figures

FIGURE 2. Amynthas tenuis sp. nov. A. Ventral body surface with spermathecal pores. B. Spermatheca. C. Ventral body surface with male pores. D. Intestinal caeca.