Amynthas hongyehensis Tsai CF and Shen, 2010

Tsai, Chu-Fa, Shen, Huei-Ping & Tsai, Su-Chen, 2010, Four new species of Amynthas earthworms (Oligochaeta: Megascolecidae) from the Central Mountain Range of southern Taiwan, Journal of Natural History 44 (21 - 22), pp. 1251-1267 : 1263-1266

Amynthas hongyehensis Tsai CF and Shen , sp. nov.

( Figure 4 )

Type material

Holotype. Clitellate (195 mm in length, dissected) collected 16 March 2000 along the Yenping Forest Road (elevation 950 m) near Hongyeh Village , Taitung County by C.F. Tsai, S.C. Tsai, H.P. Shen, S. T. Chang, H.S. Fang, H.P. Yang, and T. J. Lin (TESRI-O-H-34).

Paratype. One clitellate (amputated, same collection data as holotype, TESRI-O- P-29).

Other material

One clitellate (dissected) collected 16 March 2000 along the Yenping Forest Road (elevation 1000 m) near Hongyeh , Taitung County by the same collectors as for the holotype (coll. no. 2000-27-Shen) .

Diagnosis

Medium earthworm; length (clitellates) 140–195 mm. Segments numbering 87–136. Setae 52–57 in VII, 65–78 in XX, and 12–14 between male pores. Spermathecal pores three pairs, small, buried deeply in intersegmental furrows of 6/7–8/9, 0.26–0.29 body circumference ventrally apart. Male pores 0.23–0.24 body circumference ventrally apart in XVIII, each on a round, white porophore 0.55–0.8 mm in diameter, surrounded by one or two shallow skin folds. Two pairs of large, round genital papillae, each 0.6–0.85 mm in diameter, with depressed centre of 0.3–0.45 mm in diameter, located slightly medially to male porophores at presetal portions in XVIII and XIX. Genital papillae absent in preclitellar region. Spermathecae three pairs in VII–IX; ampulla large, oval or peach-shaped, surface wrinkled, with a short, stout stalk. Diverticulum with an oval-shaped seminal chamber and a slender stalk. Seminal vesicles large, two pairs in XI and XII. Prostate glands large, folliculated in XVII– XX. Prostatic duct long, U-shaped in XVII–XVIII. Accessory glands sessile, each oval-shaped, corresponding to its external genital papilla.

Description

External characters. Total length (clitellates) 140–195 mm. Weight 2.64–4.06 g. Segments numbering 87–136. Clitellum XIV–XVI, setae and dorsal pores absent, length 5.35–6.33 mm and width 5.28–5.42 mm. Prostomium epilobous. Three annulets (secondary segments) per segment in VII–XIII. Setal number 52–57 in VII, 65–78 in XX, and 12–14 between male pores in XVIII. First dorsal pore in 11/12. Spermathecal pores three pairs, small, buried deeply in intersegmental furrows of 6/7–8/9 ( Figure 4A ), distance between paired pores 0.26–0.29 body circumference ventrally apart. Genital papillae absent in the preclitellar region. Female pore single, midventral in XIV.

Male pores paired in XVIII, 0.23–0.24 body circumference ventrally apart. Each pore on a round, white porophore 0.55–0.8 mm in diameter, surrounded by one or two shallow skin folds. Two pairs of large, round genital papillae, each 0.6–0.85 mm in diameter, slightly larger or as large as the porophore, with depressed centre 0.3– 0.45 mm in diameter, located slightly medially to the porophore at the presetal portions in XVIII and XIX ( Figure 4B ), and an additional pair in XX for paratype.

Preserved specimens purple brown on head and dorsum, light brown on ventrum, and dark purple brown around clitellum. Setal ring white, distinctive.

Internal characters. Septa 5/6–7/8 and 10/11 thick, 11/12–13/14 muscular. Nephridial tufts thick on anterior faces of 5/6/7. Gizzard in VIII–X, large, yellowish in colour. Intestine enlarged from XVI. Intestinal caeca paired in XXVII, extending anteriorly to XXIII or XXIV, each simple, slender, slightly wrinkled ( Figure 4G ). Oesophageal hearts in XI–XIII.

Spermathecae three pairs in VII–IX, ampulla large, oval or peach-shaped, surface wrinkled, each 2.66–3.65 mm long and 1.63–2.54 mm wide, with a short, stout spermathecal stalk 0.35–0.57 mm in length. Diverticulum with an oval-shaped seminal chamber and a slender stalk 1.2–1.65 mm in length that are about twofold to more than threefold of the spermathecal stalk length ( Figure 4C ).

Holandry. Testes large, two pairs in ventrally joined sacs in X and XI. Vas efferens connected in XII on each side to form a vas deferens. Seminal vesicles two pairs in XI and XII, large, occupying the full compartment, anterior pair larger, each vesicle with a round, finely folliculated dorsal lobe, darker in colour ( Figure 4D ). Prostate glands large, lobed, folliculated, in XVII–XX. Prostatic duct long, U-shaped in XVII–XVIII ( Figure 4E ). Accessory glands sessile, each oval-shaped, about 0.55 mm long, corresponding to its external genital papilla ( Figure 4F ).

Etymology

The name hongyehensis is given to this species with reference to the nearest village of its type locality.

Remarks

Amynthas hongyehensis sp. nov. is found on the east slope of the Central Mountain Range at elevations of 950–1000 m in southern Taiwan. It is a sexthecate earthworm belonging to the sieboldi species-group of the genus Amynthas ( Sims and Easton 1972) , and morphologically fairly similar to peregrine Amynthas hupeiensis (Michaelsen, 1895) . Amynthas hongyehensis is distinguishable from A. hupeiensis in that it has paired presetal genital papillae between the setal line and intersegmental furrows in XVIII and XIX (or an additional pair in XX), whereas A. hupeiensis has paired genital papillae in the intersegmental furrows of 17/18 and 18/19 ( Chen 1933; Tsai 1964). Furthermore, A. hupeiensis has a much higher setal number than A. hongyehensis with 100–121 in VIII and 79–88 in XX for the former ( Tsai 1964) and 52–57 in VII and 65–78 in XX for the latter. Amynthas hupeiensis has a very long diverticulum ( Chen 1933, p. 253, fig. 19E), while that of A. hongyehensis is much shorter than its ampulla.

Figures

Figure 4. Amynthas hongyehensis sp. nov. Holotype (TESRI-O-H-34) (195 mm): (A) ventral view of spermathecal pore region (sp, spermathecal pore); (B) ventral view of male pore region (gp, genital papilla; mp, male porophore); (C) dorsal view of right spermathecae (amp, ampulla; dv, diverticulum); (D) dorsal view of right seminal vesicles (sv) (dl, dorsal lobe); (E) dorsal view of right prostate gland; (F) accessory gland (ac) under prostatic duct (pd); (G) dorsal view of right caecum.