Amynthas fluviatilis Zhao and Sun, 2013

Zhao, Qi, Sun, Jing, Jiang, Jibao & Qiu, Jiangping, 2013, Four new species of genus Amynthas (Oligochaeta, Megascolecidae) from Hainan Island, China, Journal of Natural History (J. Nat. Hist.) 47 (33 - 34), pp. 2175-2192 : 2183-2185

Amynthas fluviatilis Zhao and Sun , sp. nov.

( Figure 2 )

Type material

Holotype: Clitellate specimen (C-HN014-01), 121 mm long, 3.2 mm wide, 119 segments. Setae numbers: 52/III, 56/ V, 40/ VIII, 46/XX, 55/XXV; 22( VI) between spermathecal pores, 5( XVIII) between male pores, collected in Jianfengling National Nature Reserve , south-west Hainan, (18 ◦ 43 ′ 58 ′′ N, 108 ◦ 53 ′ 10 ′′ E), at an altitude of 890 m. Collected by J. P. Qiu, M. Bouche, J. X. Li and W. X. Zhang.

Etymology

This species is named after its habitat near the river.

Diagnosis

Spermathecal pores two pairs, in 5/6–6/7, about 0.33 circumference apart. Small genital markings posterior to each pore. Male pores 0.33 circumference apart, ventrally placed, each on top of a tiny conical porophore, surrounded by five skin folds. A small papilla posterior to the left male pore. Another small papilla present in the middle of XVIII ventrally above setae line.

Description

Preserved specimens light brownish dorsally; no pigmentation before clitellum, but light brownish after clitellum ventrally. Dimensions 121 mm by 3.2 mm; segments 119. Setae sparsely paired, regularly distributed around segmental equators, their numbers: 52 at III, 56 at V, 40 at VIII, 46 at XX, 55 at XXV; 22(VI) between spermathecal pores, 5(XVIII) between male pores; setal formula AA = AB, ZZ = 1.3ZY. Female pore single in the ventral centre of XIV, ovoid, brown. First dorsal pore in 11/12. Prostomium 1/2 epilobous. Clitellum in XIV–XVI, ring-shaped, purplish, markedly glandular; setae invisible.

Male pores paired in XVIII about 0.33 body circumference apart, ventrally placed, each on the centre of a slightly raised, tiny conical porophore, surrounded by five skin folds. A small papillae posterior to the left male pore. Another small papillae present in middle of XVIII ventrally above the setae line. Spermathecal pores two pairs in 5/6–6/7, ventral, eye-shaped, distance between them about 0.33 body circumferences apart. Two tiny genital markings posterior to each pore, but three tiny markings posterior to the left pore in 6/7.

Septa 8/9, 9/10 absent; 6/7–7/8 comparatively thick and muscular; 10/11–12/13 thin but slightly thicker than those following. Gizzard barrel-shaped, in IX–X. Intestine starting enlarged in XV. Intestinal caeca simple, small, originating in XXVI, extending anterior to 1/2XXIV, dark brownish, with one slight incision on terminal dorsal margin, smooth ventrally. Oesophageal hearts four pairs, in X–XIII.

Spermathecae two pairs, in VI–VII; ampulla ovoid, duct slender, a little shorter than ampulla, diverticulum short, as long as 0.25 of main pouch, ental 0.25 swollen, serving as seminal chamber, whitish in appearance. Testis-sacs paired in X and XI. Seminal vesicles paired in XI and XII, the first pair slender, the second more developed. Prostate gland in 1/2XVII–1/3XX, coarsely lobated, composed of some grey-brown vesicular capsule, its duct well-developed, U-shaped, and proximally appreciably enlarged. An accessory present in VII.

Remarks

Amynthas fluviatilis sp. nov. also keys to the morrisi -group according to Sims and Easton (1972). In appearance, Amynthas fluviatilis sp. nov. is somewhat similar to Amynthas incongruus ( Chen, 1933) . Both of them are moderate species with pigmentation. They have two pairs of spermathecal pores in 5/6–6/7, simple intestinal caeca, and no septa in 8/9–9/10. Furthermore, their spermathecae are similar. They have an ovoid ampulla with a duct a little shorter than the ampulla. Their diverticulum is small; there is an accessory gland around the prostate. But Amynthas fluviatilis sp. nov. has no accessory gland around the spermathecae, and its seminal vesicles are developed. A pair of small papillae is present in the middle of XVIII ventrally above the setae line in Amynthas fluviatilis sp. nov., which is similar to some individuals of Amynthas incongruus . However, there is only a small papilla posterior to the left male pore in Amynthas fluviatilis sp. nov. while three to seven small genital papillae occur around the male pores in Amynthas incongruus . In the spermathecal regions there are only two or three small genital markings posterior to each spermathecal pore in Amynthas fluviatilis sp. nov. while there are usually paired small genital markings pre- and/or post-setal in VI and/or VII in Amynthas incongruus . Occasionally, there are no genital markings in Amynthas incongruus ( Table 3).

Figures

Figure 2. Amynthas fluviatilis sp. nov.; (A) ventral body surface with spermathecal pores; (B) spermatheca; (C) ventral body surface with male pores; (D) intestinal caeca.