Amynthas wenchangensis Qiu & Zhao, 2018

Zhao, Qi, Yao, Xuanzhu, Lan, Yaqiong, Xu, Junxian & Qiu, Jiangping, 2018, New earthworm species of the genus Amynthas from Hainan Island, China (Megascolecidae, Clitellata), Zootaxa 4496 (1), pp. 279-286 : 279-281

Amynthas wenchangensis Qiu & Zhao , sp. nov.

( Figure 1 )

Type material. Holotype. One clitellate specimen (HN201518-04), China, Hainan Province, Tanniu Town, Hanjiapo (19°41'44"N, 110°44'06"E), 30 m a.s.l., soil, coll. J.P. Qiu, Q. Zhao, J.B. Jiang, L.L. Zhang, Y. Dong, M.S. Chen, June 4, 2015 . Paratypes. Four clitellate specimens (HN201518-02, HN201518-03, HN201518-05, HN201518-06), same data as for holotype .

Locality and habitat. The specimens were collected in brown sandy soil on the edge of a grassland, Hanjiapo, Tanniu Town , Wenchang City, Hainan province, China.

Etymology. This species is named after the city where the species was found, Wenchang City.

Diagnosis. Two pairs of spermathecal pores in 5/6–6/7, eye-like, about 0.33 circumferences ventrally apart. Male pores each on a round protuberance in XVIII, about 0.33 body circumferences apart, six small genital papillae above and four below the setae circle in XVIII between male pores, another 4 small papillae in the middle of XIX above the setae circle, sometimes five genital papillae present between male pores and another four small papillae above and below the setae circle in XIX.

Description. Preserved specimens dark brown dorsally, light brown ventrally before XXV, light brown dorsally, no pigment ventrally after XXV. Dorsal line invisible. Dimensions 78–83.5 mm by 3.0 mm at clitellum, segments 119–148; body cylindrical in cross section. Prostomium 1/2 epilobous. Setae numbering: 32– 36/III, 36– 40/V, 40– 44/VIII, 40/XX, 44/XXV; 0 between male pores; 16 (VII) between spermathecal pores. Setal formula AA=2.0 AB, ZZ=1.0 ZY. Clitellum annular XIV–XVI, dark brown, setae and dorsal pore visible. First dorsal pore in 9/10. Two pairs of spermathecal pores in 5/6–6/7, ventral, eye-like, about 0.33 body circumferences apart ( Fig. 1B ). Male pores each on a round protuberance in XVIII, about 0.33 body circumferences apart, surrounded by several skin folds ( Fig. 1A,B ). Seven small genital papillae above and four below the setae circle in XVIII between male pore, another four small pre-setal papillae in the middle of XIX ( Fig. 1A ). In two paratype specimen (HN201518-02, HN201518-03), five genital papillae present between male pores and four small papillae in XIX, pre- and post-setal ( Fig. 1B ). Septa 8/9, 9/10 absent, before 8/9 thick and muscular, 10/11 thick. Esophageal hearts in X–XIII. Gizzard in IX–X, ball-shaped. Intestine enlarged distinctly from XV. Intestinal caeca simple, originating in XXVII, extending anteriorly to XXIV. Spermathecae small, paired in VI–VII; the first ampulla bean-sprout like, spermathecal duct slender, as long as 0.6 of main pouch, diverticulum in zigzag fashion, as long as 0.75 of main pouch ( Fig. 1D ); the second ampulla heart-shaped, spermathecal duct slender, as long as ampulla, diverticulum in zigzag fashion, equal to main pouch; or spermathecae very large, ampulla heart-shaped, spermathecal duct half as long as ampulla, diverticulum straight, half as long as main pouch, terminal third enlarged as club-shaped seminal chamber (HN201518-02) ( Fig. 1E ); or diverticulum straight, as long as 1.25 of main pouch, terminal 0.6 enlarged as zonal seminal chamber (HN201518-03) ( Fig. 1F ). Male sexual system holandric, testis sacs two pairs in X–XI, slender, undeveloped; seminal vesicles paired in XI–XII, the first pair developed, the second pair small. Prostates degenerated in XVIII (on the right of holotype), or disappeared (on the left of holotype), or prostates developed in XVII–XVIII (some of paratypes), prostatic duct U-shaped in XVIII ( Fig. 1G ).

Remarks. Amynthas wenchangensis sp. nov. keys to the Amynthas morrisi -group as defined by Sims & Easton (1972). All species in this group were compared, including 49 Amynthas species listed from China and Southeast Asia ( Beddard 1892; Chen 1933, 1936, 1938, 1946; Gates 1968; Jiang et al. 2015; Kobayashi 1936, 1938; Michaelsen 1927; Sun et al. 2015; Zhao et al. 2009, 2013, 2015). The new species is most similar to Amynthas endophilus Zhao et al., 2013 . They share the following characters: moderately large individuals, septa 8/9–9/10 absent, male pores each on a round protuberance in XVIII, surrounded by several skin folds. No genital markings, intestinal caeca simple. Furthermore, the spermathecae of A. endophilus are similar to those of one paratype ( Fig. 1F ). However, there are also distinct differences between them. Irregular genital papillae are present in the new species while they are absent in A. endophilus . The first dorsal pore in the new species is forward in 9/10. No pigmentation in A. endophilus compared to the dark or light brown pigmentation of new species. Prostates are developed in A. endophilus , however, they are degenerate in XVIII or absent, or developed in XVII–XVIII in the new species. Interestingly, sperm was observed in the seminal chambers of all specimens, which suggests that the new species might evolve in the direction of parthenogenesis under severe environment. In view of slight but nonetheless clear-cut differences, we decided to give new species status to our specimens.

Figures

FIGURE 1. Amynthas wenchangensis sp. nov. A. Ventral body surface with male pores. B. Ventral body surface with male pores and different arrangement of genital papillae. C. Ventral body surface with spermathecal pores. D–F. Spermathecae. G. Prostate.