Amynthas retortus Sun and Jiang 2016, sp. nov.
Creators: name: Sun, Jing
name: Jiang, Jibao
name: Hu, Feng
name: Qiu, Jiangping
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Clitellata
Opisthopora
Megascolecidae
Amynthas
Amynthas retortus

description: Amynthas retortus Sun and Jiang sp. nov.
(Figure 2 (a–d))
Type material
Holotype: One clitellate (C-SC201102-15A) specimen: China, Sichuan Province, Mt. Emei (29°35 ′ 29 ″ N, 103°17 ′ 12 ″ E), 1300 m elevation, woods and bamboo, in black cinnamon soil, 27 July 2011, J. Sun, J.B. Jiang, X.D. Lei and H.W. Feng coll. Paratype: One clitellate (C-SC201102-15B): Same data as for holotype.
Etymology
The species name comes from the twisted shape of the spermathecal diverticulum.
Diagnosis
Three pairs of spermathecal pores in 6/7–8/9; each male pore on an oval-shaped pad with an elliptical glandular flat-top pad in the centre, surrounded by three circular ridges inside and five circular ridges outside, a pair of small round genital papillae medial to two male porophores postsetally on XVII; two bud-like accessory glands observed medial to each prostatic duct; spermathecal diverticulum shorter than main spermathecal axis by 0.17, distal 0.5 dilated and twisted into a zigzag-shaped seminal chamber; genital markings beneath the left spermathecae on VIII and IX and the right spermathecae on IX.
Description
External characters. Preserved specimens light brown on dorsum, and lacking pigment on ventrum. Mid-dorsal line pigmented. Dimensions 36–37 mm by 3.0– 3.6 mm at clitellum, segments number 61–74. Body cylindrical in cross section, gradually tapered towards head and tail. Secondary annulations absent. Prostomium ½ epilobous. First dorsal pore in 13/14. Clitellum annular in XIV–XVI, lacking pigment, smooth, no visible setae externally, and dorsal pore absent on clitellum. Setae uniformly distributed, dorsal breaks more distinct than ventral, 20–24 at III, 36–39 at V, 40 at VIII, 40–48 at XX, 36–42 at XXV; 2–5 between male pores; 6–7/VII, 6/VIII between spermathecal pores, setal formula AA = 1.2–1.4AB, ZZ = 1.6–1.8ZY. Spermathecal pores three pairs, in 6/7–8/9, intersegmental, cannot be seen externally, one tiny genital papilla on VII and two similar papillae on VIII (Figure 2 (a)). Male pores paired in XVIII, a little less than 0.33 of circumference ventrally apart, each on an oval-shaped pad with an elliptical glandular flat-top pad in the centre, surrounded by five circular ridges inside and three circular ridges outside. One small round genital papilla medial to each male porophore, and postsetally on XVII (Figure 2 (b)). Female pore single, mid-ventral in XVI.
Internal characters. Septa 5/6–7/8 and 10/11–11/12 slightly thickened, 8/9–9/10 absent. Dorsal blood vessel single, continuous onto pharynx; esophageal hearts four pairs in X–XIII, developed. Gizzard barrel-like, in VIII–X; intestine beginning to swell in XV; intestinal caeca simple, originating in XXVII and extending forward to XXIII, fingershaped sac, smooth on ventral and dorsal margin (Figure 2 (c)). Male sexual system is holandric. Testis sacs two pairs, ventral in X and XI. Seminal vesicles paired in XI and XII, developed, each is enclosed in the front of testis sacs, separated ventro-medially. Prostate glands developed, coarsely lobate, botryoidal, in XVI–XXII, ducts short and stout. Two bud-like accessory glands observed medial to each prostatic duct root. Female organs: Ovaries in XIII. Spermathecae paired in VII–IX, about 1.5 mm long; ampulla ball-shaped, with long duct as long as 0.67 ampulla; diverticulum shorter than main spermathecal axis by 0.17, slender, distal 0.5 dilated and twisted into a zigzag shaped seminal chamber; no nephridia on spermathecal ducts, stalked genital marking beneath the left spermathecae on VIII and IX and the right spermathecae on IX (Figure 2 (d)).
Remarks
A. retortus sp. nov. keys to the Amynthas sieboldi group (Sims and Easton 1972). The new species appears similar to Amynthas cruratus (Chen, 1946) in the characters of the pigment, the density of setae, the location of spermathecal pores, intestinal caeca shape and prostate gland. But it is distinct when the following characteristics are regarded: the body size, the arrangement of male pores and male pore region genital papillae, spermathecal diverticulum chamber, seminal vesicles and accessory glands aspect (Table 1).
Twenty species were added to the Amynthas sieboldi group after 1972. They are Amynthas heterogens (Chen and Hsu), Amynthas contingens (Zhong and Ma 1979), Amynthas daulis daulis (Zhong and Ma 1979), Amynthas daulis fanjinmontis Qiu, 1992, Amynthas saccatus Qiu and Wang, Amynthas binoculatus Tsai, Shen and Tsai, Amynthas sexpectatus Tsai, Shen and Tsai, Amynthas tayalis Tsai, Shen and Tsai, Amynthas tungpuensis Tsai, Shen and Tsai, Amynthas moakensis Hong and Kim, Amynthas fenestrus Shen, Tsai and Tsai, Amynthas tantulus Shen, Tsai and Tsai, Amynthas carnosus lichuanensis Wang and Qiu, Amynthas huangi James, Shih and Chang, Amynthas monsoonus James, Shih and Chang, Amynthas hongyehensis Tsai, Shen and Tsai, Amynthas apapillatus Zhao and Qiu, A. arenulus, Amynthas dongyinensis Shen, Chang and Chih and A. longicaeca. So, the other two similar species – A. saccatus and A. tungpuensis – were also put into Table 1. A. saccatus and the new species were both collected in Southwest China, and they both have concentric ridges on the male pore region. Moreover, the genital papillae always appear in the male pore and spermathecal pore region. However, they have some differences in the characteristics of the body size, the spermathecal seminal chamber and so on. A. tungpuensis and A. retortus sp. nov. have similar characters in male pore porophores and intestinal caeca, but the genital papilla of spermathecal pore and male pore region, the accessory glands, the shape of spermathecae and body size are very different. The partial COI sequence of the holotype of A. retortus sp. nov. has been deposited in the NCBI GenBank with accession number KF205479 (specimen C-SC 201102 -15A).
description: Published as part of Sun, Jing, Jiang, Jibao, Hu, Feng & Qiu, Jiangping, 2016, Four new earthworms of the genus Amynthas (Oligochaeta: Megascolecidae) from Mount Emei, Sichuan Province, China, pp. 2499-2513 in Journal of Natural History 50 on pages 2505-2507, DOI: 10.1080/00222933.2016.1193649, http://zenodo.org/record/3994511