Amynthas xuanchengensis Jin & Li, 2024

Jin, Qing, Li, Jiali, Jiang, Jibao & Qiu, Jiangping, 2024, Four new earthworm species of the genera Amynthas and Metaphire (Oligochaeta, Megascolecidae) from Hunan and Anhui provinces, China, ZooKeys 1210, pp. 247-271 : 247-271

Amynthas xuanchengensis Jin & Li sp. nov.

Fig. 4

Material examined.

Holotype. • 1 clitellate ( AH 201517-06 ), China, Anhui Province, Xuancheng City (30.89694 ° N, 118.48889 ° E), 860 m elevation, black sandy soil under shrubbery in front of the house, 11 October 2015, Y Dong, Z Yuan, MS Chen and YL Wang . Paratype. • 1 clitellate ( P 1 CJHUSH 190521800 Q 6-03 ), China, Hunan Province, Chenzhou City (26.16809 ° N, 113.05648 ° E), 79 m elevation, sandy soil under weeds beside roadways, 21 May 2019, JB Jiang, JL Li and Y Wang .

Diagnosis.

Size small. Spermathecal pores in 5 / 6 and 6 / 7, separated by 1 / 3 of body circumference. Male pores in XVIII, separated by 1 / 4 of body circumference, each on the top of a slightly raised, circular porophore. Spermathecae two pairs in VI and VII, ampulla heart-shaped, duct is thick and ~ 1 / 2 of ampulla. Diverticulum as long as main pouch (duct and ampulla together), terminal 1 / 2 dilated into ovoid-shaped seminal chamber. Intestinal caeca are simple. Prostate glands are developed.

External characters.

No dorsal or ventral pigmentation. Dimensions 26–32 mm by 1.5–2.0 mm at clitellum, segments 60–65. The dorsal midline is not clearly visible. First dorsal pore of all examined individuals in 12 / 13. Prostomium 1 / 2 epilobous. Clitellum annular, taupe, in XIV – XVI, smooth, setae invisible externally. Setae numbering 32–40 at III, 36–44 at V, 40–48 at VIII, 50–54 at XX, 56–58 at XXV; 4 between male pores; setal formula, aa = 1.0–1.4 ab, zz = 1.4–2.0 zy. Male pores one pair in XVIII, separated by 1 / 4 body circumference, each on the top of a slightly raised, circular porophore (Fig. 4 A ). Female pore single in XIV, oval, milky white. Spermathecal pores two pairs in 5 / 6 and 6 / 7, ventral, not clearly, milky white porophore in center, separated by 1 / 3 body circumference.

Internal characters.

Septa 5 / 6–7 / 8 thick and muscular, 10 / 11–12 / 13 slightly thickened, 8 / 9 and 9 / 10 absent. Gizzard spherical in IX – X. Intestine enlarged distinctly from XV. Intestinal caeca paired in XXVII, extending anteriorly to XXVI, simple, smooth on both sides (Fig. 4 C ). Four esophageal hearts in X – XIII, not well developed. Male sexual system holandric, testis sacs two pairs, in X and XI, well developed, left and right lobes separated on the ventral side. Seminal vesicles two pairs, extending in XI and XII, well developed, left and right lobes separated on the ventral side. Prostate glands well developed, inserting in XVIII and extending to XVI and XIX, coarsely lobate, prostatic duct U-shaped, slightly thicker at the distal part (Fig. 4 B ). No accessory glands observed. Spermathecae two pairs in VI – VII, ampulla heart-shaped, ~ 0.7 mm long in holotype; ampulla duct is thick and ~ 1 / 2 of ampulla. Diverticulum as long as main pouch (duct and ampulla together), terminal 1 / 2 dilated into ovoid-shaped seminal chamber. No accessory glands observed (Fig. 4 D ).

Etymology.

The species is named after its type locality.

Remarks.

Amynthas xuanchengensis sp. nov., with two pairs of spermathecal pores in 5 / 6 and 6 / 7, can be assigned to Amynthas morrisi group ( Sims and Easton 1972) with 55 species included in this group ( Sun et al. 2009, 2015, 2021; Shen et al. 2014; Jiang et al. 2015; Hong 2017), such as Amynthas nanulus ( Chen & Yang, 1975) ( Chen et al. 1975) , Amynthas parvus ( Chen & Hsu, 1977) , Amynthas piagolensis Hong & James, 2001 , Amynthas diaoluomontis Qiu & Sun, 2009 , Amynthas endophilus Zhao & Qiu, 2013 . Amynthas xuanchengensis sp. nov. is very similar to Amynthas endophilus Zhao & Qiu, 2013 by lacking pigmentation, first dorsal pore in 12 / 13, clitellum in XIV – XVI, the position of spermathecal pores and male pores, no papillae within spermathecal pore and male pore regions, simple intestinal caeca. However, the new species differs from A. endophilus by smaller body size and fewer setae. And beyond that, the ventral distance of spermathecal pores and male pores is 1 / 3 C and 1 / 4 C in A. xuanchengensis sp. nov., but 2 / 5 C and 1 / 3 C in A. endophilus ; spermathecal pores of A. xuanchengensis sp. nov. are inconspicuous, but obvious in A. endophilus ; male pores of A. xuanchengensis sp. nov. not surrounded by folds, but A. endophilus surrounded by four folds; prostate glands in XVI – XIX in A. xuanchengensis sp. nov., but XVII – XXI in A. endophilus ; spermathecae ~ 0.7 mm long, ampulla heart-shaped, duct is thick and ~ 1 / 2 of ampulla of A. xuanchengensis sp. nov., while spermathecae longer, ampulla elongated ovoid, duct a little shorter than ampulla in A. endophilus ; diverticulum as long as main pouch in A. xuanchengensis sp. nov., nevertheless shorter than main pouch in A. endophilus (Table 3 ).

Another similar species with two pairs of spermathecal pores in 5 / 6 and 6 / 7 is Amynthas fucatus Zhao & Qiu, 2013 . The two species share some similarities, such as clitellum in XIV – XVI, the position of spermathecal pores and male pores, invisible papillae within spermathecal pore region, and simple intestinal caeca. By contrast, the new species and A. fucatus can be separated on the basis of smaller body size and fewer setae at VIII. In addition, A. xuanchengensis sp. nov. is unpigmented, but dark red brown before clitellum and pale after clitellum in dorsum, pale red brown before clitellum and pale after clitellum in ventrum in A. fucatus ; the first dorsal pore of A. xuanchengensis sp. nov. in 12 / 13, but 11 / 12 in A. fucatus ; the ventral distance of spermathecal pores and male pores are 1 / 3 C and 1 / 4 C in A. xuanchengensis sp. nov., but 2 / 5 C and 2 / 5 C in A. fucatus ; spermathecal pores of A. xuanchengensis sp. nov. are inconspicuous, but obvious in A. fucatus ; male pores of A. xuanchengensis sp. nov. not surrounded by folds, but A. fucatus surrounded by three to five folds; invisible papillae within male pore region of A. xuanchengensis sp. nov., whereas two papillae on the inner side of male pore, another paired in XVIII in A. fucatus ; prostate glands in XVI – XIX of A. xuanchengensis sp. nov., while XV – XXI with accessory glands invisible in A. fucatus ; spermathecae ~ 0.7 mm long, ampulla heart-shaped in A. xuanchengensis sp. nov., nevertheless spermathecae longer, ampulla elongated ovoid in A. fucatus ; diverticulum is as long as main pouch, terminal 1 / 2 dilated into ovoid-shaped seminal chamber in A. xuanchengensis sp. nov., but diverticulum ~ 1 / 3 of main pouch, straight, terminal 3 / 4 dilated into virgulate seminal chamber in A. fucatus (Table 3 ).

Amynthas xuanchengensis sp. nov. appears to be closely related to A. infuscuatus Jiang & Sun, 2015 in the combined characters of ventrum pigmentation, first dorsal pore in 12 / 13, clitellum in XIV – XVI, the position and characteristics of spermathecal pores, invisible papillae within spermathecal pore region, the position of male pores, simple intestinal caeca, and ampulla heart-shaped. Conversely, they still have some differences, such as body size, dorsum pigmentation, and setae number. Amynthas xuanchengensis sp. nov. smaller, without pigment on dorsum, but purple before VIII; pale brown after VIII in A. infuscuatus ; four setae between male pores of A. xuanchengensis sp. nov., but 8–10 setae in A. infuscuatus ; the ventral distance of male pores is 1 / 4 C in A. xuanchengensis sp. nov., but 1 / 3 C in A. infuscuatus ; spermathecal pores of A. xuanchengensis sp. nov. are inconspicuous, but obvious in A. infuscuatus ; male pores of A. xuanchengensis sp. nov. surrounded by no folds, but A. infuscuatus surrounded by three or four folds; invisible papillae within male pore region of A. xuanchengensis sp. nov., whereas two papillae on the inner side of male pore in A. infuscuatus ; prostate glands in XVI – XIX of A. xuanchengensis sp. nov., while XVI – 1 / 2 XX with accessory glands invisible in A. infuscuatus ; spermathecae ~ 0.7 mm long, duct is thick and ~ 1 / 2 of ampulla in A. xuanchengensis sp. nov., but spermathecae longer, duct slender, twice as long as ampulla in A. infuscuatus ; diverticulum is as long as main pouch, terminal 1 / 2 dilated into ovoid-shaped seminal chamber in A. xuanchengensis sp. nov., but diverticulum longer than main pouch, slender, terminal 1 / 3 dilated into swollen seminal chamber in A. infuscuatus (Table 3 ).

Amynthas xuanchengensis sp. nov. and Amynthas zonarius Sun & Qiu, 2015 share some common characters in pigmentation, first dorsal pore in 12 / 13, clitellum in XIV – XVI, the characteristics of spermathecal pores, invisible papillae within spermathecal pore region, the position of male pores, simple intestinal caeca. In contrast, A. xuanchengensis sp. nov. differs from A. zonarius in smaller body size and fewer setae. Additionally, the ventral distance of spermathecal pore and male pores are 1 / 3 C and 1 / 4 C in A. xuanchengensis sp. nov., but 2 / 5 C and 1 / 3 C in A. zonarius ; male pores of A. xuanchengensis sp. nov. surrounded by no folds, but A. zonarius surrounded by five folds; invisible papillae within male pore region of A. xuanchengensis sp. nov. whereas one or two papillae on the inner side of male pore, sometimes another two on XVIII in A. zonarius ; prostate glands in XVI – XIX in A. xuanchengensis sp. nov., while XVI – 1 / 2 XX with accessory glands invisible in A. zonarius ; spermathecae ~ 0.7 mm long, ampulla heart-shaped, duct is thick and ~ 1 / 2 of ampulla in A. xuanchengensis sp. nov., whereas spermathecae longer, ampulla ovoid, duct as long as ampulla in A. zonarius ; ovoid-shaped seminal chamber in A. xuanchengensis sp. nov., but band-shaped seminal chamber in A. zonarius (Table 3 ).

In terms of pigmentation, clitellum, setae number, the positions of spermathecal pores and male pores, inconspicuous spermathecal pores, invisible papillae within spermathecal pore and male pore regions, simple intestinal caeca. Amynthas xuanchengensis sp. nov. is somewhat similar to Amynthas baikmudongensis Hong, 2017 . On the contrary, the new species is easily distinguished from A. baikmudongensis by body size, prostate glands, the characteristics of male pores, spermathecae, and diverticulum (Table 3 ).

Figures

Figure 4. A. xuanchengensis sp. nov. A ventral view showing spermathecal pores, and male pores B prostate glands C intestinal caeca D spermathecae. Abbreviations: sp, spermathecal pores; mp, male pores.