Amynthas dentiformis Sun & Jiang, 2018

Sun, Jing, Jiang, Ji-Bao, Bartlam, Scott, Qiu, Jiang-Ping & Hu, Feng, 2018, Four new Amynthas and Metaphire earthworm species from nine provinces in southern China, Zootaxa 4496 (1), pp. 287-301 : 293-296

Amynthas dentiformis Sun & Jiang , sp. nov.

( Figure 4 )

Type material. Holotype: One clitellate (C-YN 201105 -02A) specimen, China, Yunnan Province, Xishuangbanna National Natural Reserve (22°02'25"N, 100°23'17"E), 846 m asl, in tropical monsoon forest, latosolic red soil, 19 Jul. 2011, J. B. Jiang, J. Sun, H. W. Feng and X. D. Lei coll. Paratypes: A total of 23 specimens, as follows: One clitellate (C-YN 201105 -02B), same data as for holotype. Three clitellates (C-FJ 201112 -01), China, Fujian Province, Meihuashan National Natural Reserve (25°14'59"N, 116°50'09"E), 810 m asl, topsoil below reed in Midsubtropical evergreen broad-leaved forest, red soil, 13 Jul. 2011, J. B. Jiang, J. Sun, H. W. Feng and X. D. Lei coll. Five clitellates (C-GX201301-01), China, Guangxi Province, Shiwandashan National Natural Reserve (21°29'09"N, 107°34'12"E), 130 m asl, in northern tropical evergreen monsoon forest, sandy red soil with abundant organic matter, 11 May 2013, J. P. Qiu, Y. Hong, J. B. Jiang, L. L. Zhang and Y. Dong coll. One clitellate (C- GX201306-02), China, Guangxi Province , Shiwandashan National Natural Reserve (21°50'50"N, 107°53'23"E), 553 m asl, in northern tropical evergreen monsoon forest, mountain red soil, 13 May 2013, J. P. Qiu, Y. Hong, J. B. Jiang, L. L. Zhang and Y. Dong coll. Six clitellates and seven aclitellates (C-SCCZ2015003-01), China, Sichuan Province, Chongzhou City, jinjiang village (30°40'36"N, 103°40'59"E), 846 m asl, in warm temperate deciduous broad-leaved forest, brown soil, 22 Jun. 2015, J. Sun, Z. W. Yi and J. Yu coll.

Etymology. This species is named after its intestinal caeca, which show tooth-shaped sacs on the two margins.

Diagnosis. Medium-sized species; spermathecal pores two pairs in 7/8–8/9, without genital papillae; male pores always surrounded with two papillae, one anterior-medial to the male pore and another posterior-medial, and close to male pore; intestinal caeca have small sacs on the dorsal and ventral margins; prostate gland welldeveloped and occasionally with stalked accessory glands; spermathecal diverticulum shorter than the main spermathecal axis, distal ½ dilated into plump, heart-shaped, or elongated seminal chamber.

Description. External characters. Preserved specimens dark brown on dorsum and light brown or even lacking pigment on ventrum. Mid-dorsal line pigmented posterior to clitellum. Dimensions 1 29–151 mm by 6–6.1 mm at clitellum, segments 118–134. Secondary annulations conspicuous in segments VII–XIII and XVII–XIX. Prostomium ½ epilobous. First dorsal pore in 11/12. Clitellum annular in XIV–XVI, smooth, swollen, no visible setae on ventral side. Setal counts, however, are not significantly different. Satae uniformly distributed, setal breaks slightly more distinct on dorsum than ventrum, 44–46 at III, 46–64 at V, 47–66 at VIII, 60–68 at XX, 60–66 at XXV; 20– 38/VIII between spermathecal pores, 16–17 between male pores, setal formula AA=1.0–1.4AB, ZZ=1.2–2ZY. Spermathecal pores two pairs, in 7/8–8/9, intersegmental, about 0.4 of circumference ventrally apart, conspicuous, with an apron-like skin fold surrounding each pore ( Fig. 4A ). No genital papillae in this region. Male pores in XVIII a little more than 0.33 of circumference ventrally apart, each on a pad-like porophore, elliptical, raised, and glandular, surrounded by 3–4 skin folds. Male pore papillae always present within the porophore pad, one small, flat-topped papilla medial and anterior to the male pore on XVIII; another small, flat-topped papilla medial, posterior, and closer to the male pore ( Fig. 4B ). Single female pore mid-ventral in XIV, milk-white, elliptical, and slightly swollen.

Internal characters. Septa 8/9–9/10 absent, 5/6–7/8 and 10/11–13/14 thickened and muscular, 14/15–15/16 thicker than those following. Dorsal blood vessel single, continuous onto pharynx; esophageal hearts four pairs in X–XIII, the first pair less developed than the others. Gizzard bucket-shaped, in VIII–X; intestine swelling in XVI; intestinal caeca shaped between simple and complex, several small dentate sacs on dorsal and ventral margins, originating in XXVII and extending forward to XXIII ( Fig. 4C ). Male organs: Testis-sacs in X and XI; oval, separated ventro-medially. Seminal vesicles in XI, XII, moderately developed, the lobes connected ventro-medially with a tube. Prostate gland well-developed, coarsely lobate, in XVII–XX, distal end of its S-shaped duct is stout ( Fig. 4D ). No visible accessory glands on XVIII in holotype, but a stalked accessory gland medial to each prostate gland duct on XVIII in paratype C-SCCZ2015003-01. Female organs: Spermathecae paired in VIII–IX, about 3.7 mm long; ampulla oval and 3 mm long, duct stout; diverticulum 3.3 mm long, distal ¼ dilated into plump, heartshaped or elongated seminal chamber containing white twisted filler; no nephridia on spermathecal ducts ( Fig. 4E ).

DNA barcodes. GenBank accession numbers KF205445 (C-FJ 201112 -01A, holotype), NC720143 (C- YN 201105 -02, paratype), KY774379 (C-SCCZ2015003-01, paratype).

Remarks. Amynthas dentiformis sp. nov. keys to the Amynthas aeruginosus group ( Sims & Easton 1972). This group is diagnosed by the presence of two pairs of spermathecal pores intersegmental in 7/8–8/9 and a holandric male sexual system.

This relatively broadly distributed new species (Fujian, Guangxi, Yunnan and Sichuan provinces, China) is compared to three similar species in Table 1. These are the cosmopolitan Amynthas robustus (Perrier, 1872) , according to the record in Chang et al.(2009) and Gates (1972), and two Chinese endemic species, Amynthas triastriatus ( Chen, 1946) and Amynthas ultorius ( Chen, 1935) . These four species all have a medium to big body, similar pigment, the same spermathecal pore position and similarly shaped spermathecal seminal chamber. They may appear to have very similar male pore regions at first glance. However, each species has its own special characters. For example, the spermathecal pore region genital papillae do not exist in the new species, but are present in the three other species; the intestinal caeca are tooth-like on the ventral and dorsal margins in the new species, but simple in the other species. Furthermore, the length of spermathecal diverticulum, prostate glands, and accessory glands in spermathecal region and prostate gland region all show different characters in varying degrees.

Figures

FIGURE 4. Amynthas dentiformis sp. nov. A. Spermathecal pores (sp). B. Male pores (mp) and genital papillae (gp). C. Intestinal caecum. D. Prostate gland. E. Spermatheca.