Amynthas huizhouensis Sun & Jiang, 2025

Sun, Jing, Wang, Ding-Yi, Qiu, Jiang-Ping, Jiang, Ji-Bao & Liu, Man-Qiang, 2025, Three newly discovered species of Amynthas earthworms (Oligochaeta: Megascolecidae) from Jiangxi Province and adjacent regions of China, Zootaxa 5729 (2), pp. 283-314 : 299-301

Amynthas huizhouensis Sun & Jiang , sp. nov.

( Figures 4–5 )

Type material. Holotype. One clitellate specimen (P1CJJXNN210513057 R01-01 A) was collected from Huitang Village , Hutang Township , Yichun City, Fengcheng City, Jiangxi Province, China ( 28°17′21″ N, 115°36′50″ E), at 56 m asl, in fluvo-aquic and alluvial soils, within a camphor tree plantation on a hilly terrain. The ground temperature was 18°C at the time of collection on May 13, 2021. Collectors: X. X. Qi, D. Wu, K. H. Jiao, C. Z. Zhang, X. Gong, M. G. Xu, and Y. Zhang.

Paratypes. A total of 20 specimens are presented in Table 4.

Etymology. The species was initially collected from the Xiangtou Mountain National Nature Reserve, located within Huizhou City, Guangdong Province, China. The Chinese name of this species is šḣḭŝē.

Diagnosis. New species, length 68–78 mm, diameter 2.1–4.1 mm, segments 95–137, small to medium size. Prostomium ½ proepilobous. First dorsal pore at 12/13. Setal numbers: 40–56/III, 46–60/V, 52–68/VIII, 48–58/XX, 48–60/XXV. Three pairs of spermathecal pores in 5/6–7/8. Genital markings, when present, 1 or 2 pairs on VII or VIII. Male pores spaced approximately 0.33 total circumference ventrally apart. A single or a pair of genital papillae anteriorly and slightly medial to each male porophore, passing through intersegmental furrow of 17/18. Intestinal caeca simple. Prostate gland underdeveloped. Three pairs of spermathecae in VI–VIII, with the first and second pairs longer than third pair. Diverticulum straight, slender, without distal expansion.

Description.

External morphology. Preserved specimens exhibit a light yellowish-brown coloration on the dorsal and ventral surfaces. A pigmented mid-dorsal line observed posterior to the clitellum. Specimens measure 68–78 mm in length and 2.1–4.1 mm in width at the clitellum, with 95–137 segments. Secondary annulations present on the posterior third of the body segments. The prostomium ½ proepilobous. The first dorsal pore located in intersegmental furrow 12/13. The clitellum annular, smooth, and extends from segments XIV to XVI, without pigmentation, but with 6, 8, and 10 setae on the ventral surfaces of segments XIV, XV, and XVI, respectively. Dorsal pores absent within the clitellar region. Setae uniformly distributed, with 40–56 setae on segment III, 46–60 on segment V, 52–68 on segment VIII, 48–58 on segment XX, and 48–60 on segment XXV. Additionally, 18–20 and 18–22 setae present on segments VI and VII, respectively, between the spermathecal pores, while 11–13 setae are present between the male pores. The setal formula AA = 1.1–1.2AB, ZZ = 1.8–2.0ZY. Three pairs of spermathecal pores present in intersegmental furrows 5/6–7/8, separated by approximately one-third of the total body circumference and located on the ventral surface, with milky white margins around each pore ( Fig. 4A ). Genital papillae absent in spermathecal pore region. Male pores located on the ventral surface of segment XVIII and separated by approximately one-third of total circumference. Each pore situated on a rounded, glandular porophore raised on a pad-like area ( Fig. 4B ). Two transversely arranged, round papillae positioned anterior and slightly medial to each male pore porophore, traversing the intersegmental furrow 17/18. A single female pore located mid-ventrally on segment XIV, milky-white, elliptical in shape, and situated within a slight depression.

Internal morphology. Septa 8/9–9/10 absent; septa 5/6–7/8 thickened and muscular, while septa 10/11–13/14 thicker than those of the posterior segments. A single dorsal blood vessel extending continuously to the pharynx. Four pairs of esophageal hearts present in segment X–XIII, with the first pair more slender than the others. A ballshaped gizzard present in segments VIII–X; intestinal enlargement is observed in segment XV; the intestinal caeca simple, originating in segment XXVII and extending anteriorly to segment XX, forming finger-shaped sacs with smooth dorsal and ventral margins ( Fig. 4C ). Testis-sacs present in segments X and XI, and appear as small, oval structures, with two lobes divided ventro-medially. Underdeveloped seminal vesicles present in segments in XI and XII, and separated ventro-medially. The prostate gland underdeveloped and appears as a small, continuous, blocklike structure, extending from the posterior half of segment XVI to segment XVIII. The prostatic duct small, located in segment XVIII, and U-shaped, with the dorsal side thinner than the ventral side ( Fig. 4D ). Accessory glands absent in segment XVIII in the holotype and most paratypes; however, one stalked accessory gland present medial to the prostatic duct in segment XVIII of paratype GD201107-13. Paired spermathecae present in segments VI–VIII; the first and second pairs measure approximately 2.7 mm in length, with bar-shaped ampullae that thickened anteriorly. The spermathecal duct equal in length to the ampulla, with indistinct boundaries between the two structures. The third pair of spermathecae about 2.0 mm in length and with a heart-shaped ampulla clearly demarcated from the duct. The duct moderately thick and approximately twice the length of the ampulla. The first and second pairs of diverticula approximately half the length of the main spermathecal axis, while the third pair approximately three-fifths of the length of the main spermathecal axis. All the diverticula straight and slender, lack distal expansion, and the spermathecal ducts without nephridia ( Fig. 3E ). Accessory glands absent in the spermathecal region.

Morphological variations. Compared to those of the holotype, the paratype specimens exhibit variations in the number and position of papillae in both the spermathecal and male pore regions ( Table 5, Fig. 5 ).

Figures

FIGURE 3. Amynthas yichunensis Sun & Jiang, sp. nov. Ventral views of paratypes: A–D, spermathecal pore regions; E–K, male pore region. Specimen codes: A and F, P1CJJXNN210607920R03-02; B and I, P1CJJXNN210518936R05-01; C and J, P1CJJXNN210609889R03-02; D and K, P1CJJXNN210609889Q01-02; E. P1CJJXNN210604061R01-02; G. P1CJJXNN210520933R02-01; H. P1CJJXNN210525940R02-01. Scale bars = 1 mm. Abbreviations: sp (spermathecal pore), mp (male pore), gp (genital papilla).

FIGURE 4. Amynthas huizhouensis Sun & Jiang, sp. nov. Holotype (P1CJJXNN210513057R01-01A). A. Ventral view of spermathecal pore region. B. Ventral view of male pore region. C. Intestinal cecum. D. Prostate gland. E. Spermathecae Scale bars = 1 mm. Abbreviations: sp (spermathecal pore), mp (male pore), gp (genital papilla).

FIGURE 5. Amynthas huizhouensis Sun & Jiang, sp. nov., Ventral views of paratypes: A and C, spermathecal pore regions; B, male pore region. Specimen codes: A, P1CJJXNN210513057R01-01B; B and C, P1CJJXNN210604061Q04-02. Scale bars = 1 mm. Abbreviations: sp (spermathecal pore), mp (male pore), gp (genital papilla).