Amynthas shengtangmontis Dong & Jiang

Dong, Yan, Law, Michelle Man Suet, Jiang, Jibao B. & Qiu, Jiangping P., 2019, Three new species and one subspecies of the Amynthas corticis - group from Guangxi Zhuang Autonomous Region, China (Oligochaeta, Megascolecidae), ZooKeys 884, pp. 23-42 : 23

Amynthas shengtangmontis Dong & Jiang sp. nov. Figure 4 , Table 4

Material.

Holotype: 1 clitellate (C-GX201312-03A): China, Guangxi Zhuang Autonomous Region, Dayao Mountain National Nature Reserve (23.97299°N, 110.11106°E), 1210 m asl, black sandy soil in bamboo forest, 15 May 2013, JP Qiu, Y Hong, JB Jiang, LL Zhang, Y Dong legit. Paratypes: 4 clitellates (C-GX201312-03A): same data as for holotype.

Diagnosis.

Dimension 100-134 mm by 4.2-5.1 mm at clitellum, 116-138 segments. First dorsal pore in 12/13. Setae numbering 26-28 at III, 24-32 at V, 26-32 at VIII, 33-40 at XX, 35-42 at XXV; 8-11 between male pores. Setae between spermathecal pores numbering 11-15 at VI, 10-13 at VII, 12-16 at VIII. Four pairs of spermathecal pores in 5/6-8/9. Four pairs of postsetal genital papillae arranged in VI–IX, 0.25 circumference ventrally apart from each other. One pair of male pores in XVIII, each on the top of a large raised, round porophore, surrounded by two circular ridges, with one presetal indented-topped genital papilla medial of each porophore. First ampulla of the three pairs is heart-shaped, duct stalked, diverticulum as long as main chain, U-shaped twist in the middle, terminal 4/5 dilated into a club-shaped seminal chamber. Ampulla of the fourth pair elongate-oval, duct as long as 1/6 ampulla, diverticulum as long as main chain, U-shaped twist in the middle, terminal 1/3 dilated into a chili-shaped seminal chamber. One round, semitransparent accessory gland presents near the medial area of each spermatheca. The prostate glands are developed.

Description.

External characters: Pigment from brown to no pigment on dorsum, from light brown to no pigment on ventrum. Dimensions 102 mm by 4.5 mm at clitellum, 117 segments. Prostomium ½ epilobous. First dorsal pore in segments 12/13. Setae numbering 26 at III, 26 at V, 29 at VIII, 36 at XX, 37 at XXV; 9 between male pores. Setae between spermathecal pores numbering 13 at VI, 12 at VII, 14 at VIII. Setal formula: AA = 1.0-1.4AB, ZZ = 2.0-2.2ZY. Clitellum annular, in XIV–XVI, setae not visible externally. Four pairs of spermathecal pores in 5/6-8/9, 0.40 circumference apart ventrally. Four pairs of genital papillae on VI–IX, 0.25 circumference ventrally apart from each other. One pair of male pores in XVIII, 0.40 circumference ventrally apart from each other, each on the top of a larger raised, round porophore, surrounded by two circular ridges, with one presetal indented-topped genital papilla medial of each porophore ( Figure 3A ). Singled female pore in XIV, pale grey.

Internal characters. Septa 5/6-7/8 thick and muscular, 10/11-11/12 slightly thickened, 8/9-9/10 absent. Gizzard bucket-shaped, wider below than above, in VIII–X. Intestine enlarged distinctly from XV. Intestinal caeca paired in XXVII, simple, smooth, extending anteriorly to XXI. Esophageal hearts in X–XIII. Ovaries in XIII, four pairs of spermathecae in VI–IX, 2.2-3.0 mm long. Spermathecae of two shapes: ampulla of the first three pairs heart-shaped, duct stalked, diverticulum as long as main chain, U-shaped twist in the middle, terminal 4/5 dilated into a club-shaped seminal chamber. The ampulla of the fourth pair elongate-oval, duct as long as 1/6 ampulla ( Figure 3C ), and diverticulum as long as main chain, U-shaped twisted in the middle, terminal 1/3 dilated into a chili-shaped seminal chamber ( Figure 3B ). One round semitransparent accessory gland presents near the medial area of each spermatheca. Holandric: two pairs of testis sacs in X–XI, separated from each other, well developed. Two pairs of seminal vesicles, in XI–XII, well developed. Prostate glands developed, thick, inserting in XVIII and extending from XV to XXII, coarsely lobate, prostatic duct U-curved, slightly thicker at the ental part. Two stalked accessory glands near the medial area of the distal part of the prostatic duct.

Etymology.

The species is named after the name of the collection site Shengtang Mountain, a famous peak of the Dayao Mountain National Nature Reserve.

Remarks.

Amynthas shengtangmontis sp. nov. keys to the corticis -group in Sims and Easton (1972). In terms of morphology, it is closely related to A. carnosus , A. corticis , and Amynthas pulvinus Sun & Jiang, 2013 (described from Hainan Island). Body size, body pigment, setal numbers, the first dorsal pore location, and simple intestinal caeca are similar among the four species.

In contrast, distance between the spermathecal pores and the male pores of the new species is 0.40C body circumference compared with 0.33C in A. carnosus , A. corticis , and A. pulvinus . In addition, there are eight postsetal genital markings on VI–IX in the new species, but the markings are present on V–VIII in A. carnosus , and there are more than two pairs of markings on VIII and IX in A. carnosus . The porophore of the new species is large, raised, round, and surrounded by two circular ridges, whereas the porophore is small in A. corticis and no genital markings apparent on the spermathecal pore region in A. pulvinus . Moreover, the new species has two different shapes of spermathecae, heart-shaped ampulla and diverticulum with club-shaped seminal chamber; and long-oval ampulla and diverticulum with chili-shaped seminal chamber, which are very different from those in the other species (Table 4 ).

Figures

Figure 3. A Ventral view showing spermathecal pores, female pores and male pores of Amynthas tortuosus sp. nov. B spermathecae of Amynthas tortuosus sp. nov. C illustration of the details of the male pore region.

Figure 4. A Ventral view showing spermathecal pores, female pores and male pores of Amynthas shengtangmontis sp. nov. B, C spermathecae of Amynthas shengtangmontis sp. nov. D illustration of the details of the male pore region.