Amynthas dinganensis Qiu & Zhao

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 : 385-386

Amynthas dinganensis Qiu & Zhao , sp. nov.

( Fig. 1 , Table 2 )

Material. Holotype one clitellate (F-HN 201116 -04A), China, Hainan Province, Longmeng Town (19°26ʹ44ʺN, 110°22ʹ18ʺE), 739m a.s.l., soil, coll. J.P. Qiu, Q. Zhao, J.B. Jiang, D. Cluzeau, W.K. Zhang, 27 May 2011. Paratypes two clitellates (F-HN 201116 -04B, F-HN 201116 -05), same data as for holotype.

Locality and habitat. The specimens were collected under rubber plantation of Longmeng Town, Ding’an County, Hainan province, China.

Etymology. This species is named after its location.

Diagnosis. Dimensions 77–91.5 mm by 3.5–4.4 mm at clitellum, segments 107–138. Setae 40– 56 /III, 46– 56 / V, 48– 60 /VIII, 40–48/XX, 42–44/XXV; 10–13 between male pores; 30–32 between spermathecal pores. Spermathecal pores in 5/6–6/7, less than 0.5 circumferences ventrally apart. Male pores on XVIII, less than 0.5 body circumferences apart, ventrally placed and surrounded by several skin folds.

Description. Preserved specimens dorsally light brown before clitellum and brown behind clitellum, grey ventrally. One paratype specimen dorsally without pigmentation before clitellum and light red brown behind clitellum, pale ventrally. Dimensions 77–91.5 mm by 3.5–4.4 mm, segments 107–138; body cylindrical in crosssection, gradually tapered towards head and tail. Prostomium epilobous. Setae numbering 40– 56 /III, 46– 56 /V, 48– 60 /VIII, 40–48/XX, 42–44/XXV; 10–13 between male pores; 30–32 between spermathecal pores, setal formula AA=1.0–1.2AB, ZZ=1.0–1.5ZY. Clitellum annular XIV–XVI, grey or pale; setae not seen externally on clitellum. First dorsal pore 11/12. Two pairs of spermathecal pores in 5/6–6/7, ventral, eye-like, less than 0.5 body circumferences apart. A pair of round markings anterior to setae circle of VII, about 0.14 body circumferences apart. Genital markings absent in one paratype specimen. Male pores paired in XVIII, a little less than 0.5 body circumferences ventrally apart, surrounded by four to six circular folds. Irregular papillae present anterior to setae circles of XVII, XVIII and XIX, which constitute five to seven big gland protuberances. Female pore single in XIV.

Septa 5/6–7/8 comparatively thick and muscular, 10/11 thick (10/11 thin in one specimen of paratype), 11/ 12–12/13 thin, 8/9–9/10 absent. Dorsal blood vessel single, continuous onto pharynx; esophageal hearts in X–XIII, first pair small. Gizzard in IX–X, ball-shaped; intestine enlarged distinctly from XVI; intestinal caeca simple, originating in XXVII or XXVIII and extending forward to XXIV or XX, one or two big incisions on dorsal margins, smooth on ventrum. Spermathecae paired in VI–VII with a gradually tapering slender duct; ampulla elongated, heart-shaped, spermathecal duct as long as 0.67–0.75 main pouch; diverticulum as long as 0.66 to 0.8 of or a little longer than or equal to main pouch, terminal 0.33–0.5 enlarged as a clavate seminal chamber; stipitate accessory glands present in holotype. Male sexual system holandric, testis sacs two pairs in X–XI; seminal vesicles paired in XI–XII, developed, separate from each other ventrally, seminal vesicles not developed in one paratype specimen; prostates in XVIII or XVII–XVIII, degenerate, closely adherent to body wall, prostatic duct stout and long, U-shaped. Four ovoid accessory glands present in segment XVII–XVIII, attached to the body wall, without stalk.

Remarks. Amynthas dinganensis sp. nov. keys to the morrisi -group according to Sims and Easton (1972). After comparison of 27 Amynthas species reported from China and Southeast Asia with two pairs of spermathecal pores in 5/6–6/7 (Bai 1982, 1984; Chen 1933, 1936, 1938, 1946; Chen et al. 1975; Chen & Hsu 1977; Gates 1935; Hong 2007; Hong & James 2001, 2009; Michaelsen, 1927; Thai, 1982, 1984), we found that the present species is most similar to Amynthas varians (Chen, 1938) and Amynthas hainanicus (Chen, 1938) . They share the following characters: two pairs of spermathecal pores in 5/6–6/7, septa absent in 8/9–9/10, spermathecae heart-shaped, intestinal caeca simple. They differ from Amynthas dinganensis sp. nov. in body size, genital markings and genital papillae. The irregular papillae anterior to the setae circle of XVII, XVIII and XIX make Amynthas dinganensis different from others. Furthermore, Amynthas dinganensis is nearly two times bigger than Amynthas varians and Amynthas hainanicus , and it has one pair of round genital markings anterior to the setae circle in VII. In addition, it differs from Amynthas hainanicus because of its degenerative prostate gland, presence of accessory glands, short spermathecal diverticulum, and body pigment. The sequence of a 16S gene fragment of the holotype of Amynthas dinganensis (F-HN 201116 -04A) has been deposited in GenBank under the Accession No. JQ904530 ( Table 1 ).

Figures

FIGURE 1. Amynthas dinganensis sp. nov. A. Ventral body surface with spermathecal pores. B. Spermatheca. C. Ventral body surface with male pores. D. Intestinal caeca.