Amynthas shengtangmontis minusculus Dong & Law

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 minusculus Dong & Law subsp. nov. Figure 5 , Table 4

Material.

Holotype: 1 clitellate (C-GX201316-02A): China, Guangxi Zhuang Autonomous Region, Dayao Mountain Nature Reserve (24.16658°N, 110.24313°E), 1285 m asl, black sandy soil under bryophytes beside road, 16 May 2013, JP Qiu, Y Hong, JB Jiang, LL Zhang, and Y Dong legit. Paratypes: 6 clitellate (C-GX201316-02B): same date as for holotype.

Diagnosis.

Dimensions 75-83 mm by 3.0-3.2 mm at clitellum, 75-87 segments. First dorsal pore in 11/12. Setae numbering 21-26 at III, 18-21 at V, 27-32 at VIII, 29-34 at XX, 36-40 at XXV; 5-7 between male pores; Setae between spermathecal pores numbering 9-11 at VI, 10-12 at VII, 10-12 at VIII. Four pairs of spermathecal pores in 5/6-8/9. Three pairs of postsetal genital papillae arranged in VI–VIII, 0.13 circumference apart ventrally. One pair of male pores in XVIII, each on the top of a raised, elliptic porophore surrounded by six circular ridges, with one small indented-topped genital papilla medial of each male pore. Ampulla heart-shaped; stout duct as long as 1/2 ampulla. Diverticulum as long as main pouch, terminal 1/2 dilated into a long club-shaped seminal chamber. Prostate glands developed.

Description.

External characters: Purple brown pigment on dorsum, no pigment on ventrum. Dimensions 83 mm by 3.2 mm at clitellum, 87 segments. Prostomium ½ epilobous. First dorsal pore in 11/12. Setae numbering 26 at III, 21 at V, 32 at VIII, 34 at XX, 38 at XXV; 6 between male pores; setae between spermathecal pores numbering 10 at VI, 11 at VII, 12 at VIII. Setal formula AA = 1.2-1.4AB, ZZ = 1.4-1.8ZY. Clitellum annular in XIV–XVI, setae not visible externally. Four pairs of spermathecal pores in 5/6-8/9, 0.40 circumference ventrally apart from each other. Three pairs of postsetal genital papillae arranged in VI–VIII. One pair of male pores in XVIII, 0.40 circumference apart ventrally, each on the top of a raised, elliptic porophore surrounded by six circular ridges, with one small indented-topped genital papilla in the center of each male pore ( Figure 4A ). Single female pore in XIIV.

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 IX–X. Intestine enlarged distinctly from XV. Intestinal caeca paired in XXVII, simple, smooth, extending anteriorly to 1/2 XXIV. Esophageal hearts in X–XIII. Ovaries in XIII, four pairs of spermathecae in VI–IX, heart-shaped, 2.2-2.7mm long, duct as long as 1/2 ampulla. Diverticulum as long as main pouch, terminal 1/2 dilated into a long club-shaped seminal chamber. Six semitransparent elliptical accessory glands observed near the ental part of the last three pairs spermathecae ( Figure 4B ). Holandric: two pairs of testis sacs, separated from each other, in X–XI, oval, the first pair extremely developed. Two pairs of seminal vesicles, in XI–XII, developed. Prostate glands, thick, inserting in XVIII and extending from XVI to XXI, developed, coarsely lobate; prostatic duct U-curved, long, slightly thicker at the ental part.

Remarks.

We compare A. shengtangmontis minusculus subsp. nov. with A. shengtangmontis shengtangmontis and find that they share similar characters of spermathecal pores, male pores, intestinal caeca, and prostate glands. However, there is a level of difference between them. For instance, A. shengtangmontis minusculus subsp. nov. has a smaller body size, fewer and more closely spaced genital papillae, longer spermathecal duct, accessory glands only observed in the spermathecal area. On the other hand, the first dorsal pore of A. shengtangmontis minusculus subsp. nov. is located in 11/12 compared to in 12/13 in A. shengtangmontis shengtangmontis . The pairwise distance of COI between A. shengtangmontis shengtangmontis and A. shengtangmontis minusculus subsp. nov. is 10.7%-11.4%, which is acceptable to differentiate subspecies.

Etymology.

The subspecies is named after its small body size, compared to the nominate species.

Figures

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.

Figure 5. A Ventral view showing spermathecal pores, female pores and male pores of Amynthas shengtangmontis minusculus subsp. nov. B spermathecae of Amynthas shengtangmontis minusculus subsp. nov. C illustration of the details of the male pore region.