Metaphire tahanmonta, Chang & Chen, 2005

Chang, Chih-Han & Chen, Jiun-Hong, 2005, Three new species of octothecate pheretimoid earthworms from Taiwan, with discussion on the biogeography of related species, Journal of Natural History 39 (18), pp. 1469-1482 : 1475-1478

Metaphire tahanmonta sp. nov.

( Figure 4 )

Type material

Holotype: a mature (clitellate) specimen (dissected) collected 3 June 2002 from Mt Tahan , Pingtung County, south-west of the Central Mountain Range, in the south region of Taiwan ( Figure 1 ) by S. P. Wu (coll. no. 14-03993) . Paratypes: a mature (clitellate) specimen (undissected) collected 5 May 2003 from Paoshan, Kaohsiung County by C. H. Chang (coll. no. 14-05898), and a mature (clitellate) specimen (dissected) collected 5 May 2003 from Ernchituan, Kaohsiung County by C. H. Chang (coll. no. 14-05899) .

External characters

Length (mature) 291–408 mm, clitellum width 12.9–14.7 mm, segment number 122–191. Number of annulets (secondary segmentation) per segment three in 5–9, five in 10–13, and three in body segments behind 17. Prostomium prolobous. Setae 122–144 in 7, 134– 156 in 20, 24–30 between male pores. First dorsal pore in 12/13. Clitellum 14–16, smooth, saddle-shaped, length 12.8–15.5 mm, dorsal pore absent, setae absent. Spermathecal pores four pairs in 5/6–8/9, lateral, situated above the lateral-midline, distance between the paired pores about 0.55 body circumference ventrally apart. No genital papillae in the spermathecal region. Female pore single, situated on the medio-ventral in 14. Male pore paired, situated on setal line close to lateral border of 18. Each male pore area is slightly Cshaped, with the opening of the C facing the ventral setal line, bordered by a thick skin wall. The appearance of the anterior part of the skin wall is tubercular. The male pore area is enlarged, with length about twice the length of 18, extending to the setal line of 17 and 19, surrounded by circular folds. The male aperture is situated on the extended line of the ventral setal line, slightly posterior to the middle of the male pore area. A horizontal ridge extends from the setal line, backward to the male aperture. An oval pad is situated behind the setal line of 17, close to the anterior end of the male pore area. The oval pad is linked to the male aperture through a seminal groove. Genital papillae absent in the male pore area.

Live specimens dark purplish grey with metallic lustre on dorsum, reddish brown on ventral. Preserved specimens purplish brown on dorsum, light greyish brown on ventral.

Internal characters

Septa 5/6–7/8 thickened, 8/9 and 9/10 absent, 10/11–13/14 greatly thickened. Gizzard in 8– 10. Intestine enlarged from 15. Intestinal caeca paired in 27, simple, extending anteriorly to 23. Lateral hearts enlarged in 10–13.

Spermathecae four pairs in 6–9. Ampulla large, about 3.6–5.6 mm in length, with a stalk about 1.2–1.9 mm in length. The spermathecal diverticulum is short, usually shorter than one-third of spermathecae length, with a small oval seminal chamber on the tip. Nephridia tufted, attached to the post-segmental septa, surrounding the segmental chambers anterior to the 6/7 septum. Ovaries paired in 13, medio-ventral, close to the 12/13 septum.

Testis sacs paired in 10 and 11, the anterior pair oval, smooth, medio-ventral in front of 10/11, the posterior pair is much larger than the anterior one, filling the space between septa. Sperm ducts meeting in 12. Seminal vesicles paired in 11 and 12, the anterior pair included in the posterior testis sac, both pairs moderate in size. Prostate glands paired in 18, large, lobular, extending to 17.

Habitat and behaυiour

This species lives in the mountains between the altitudes of 500 and 2000 m, where the vegetation is evergreen broadleaf forest or deciduous broadleaf forest, according to the altitude and latitude. Because it can be found both in virgin forest and secondary forest, it might tolerate low levels of human activity. This species is an anecic species, having permanent vertical burrows. It is active around the upper layer of soil or on the ground at night. Although it is occasionally active after rain, it usually stays in the soil during the day. When resting, it is usually found more than 30 cm deep below the ground.

Remarks

Metaphire tahanmonta has a length greater than 300 mm, width over 10 mm, four pairs of spermathecae, and C-shaped male pores with an oval pad and a horizontal ridge. These characters are shared with M. paiaeanna . However, M. paiaeanna is protandric ( Tsai CF et al. 2000c), while M. tahanmonta is holandric. In pheretimoid earthworms, most species have a holandric condition, while rare species have a protandric condition ( Sims and Easton 1972; Easton 1979; Tsai CF et al. 2000c). Accordingly, it is reasonable to regard the holandric specimens as a different species.

Regarding body size, position of seminal vesicles, number of spermathecae, and holandry, M. tahanmonta shares the same characters with M. yuanpoaea . However, the male pores of the two species are very different. The male pore of M. tahanmonta has a horizontal ridge and only one oval pad, while that of M. yuanpoaea has no horizontal ridge and two oval pads on each side of the male aperture. Therefore, they are easily distinguished by their external characters.

The species name ‘‘ tahanmonta ’’ is given referring to Mt Tahan in Pingtung County, Taiwan, where this species was collected.

Figures

Figure 1. The map of Taiwan and surrounding areas. (A) The location of Taiwan in East Asia. (B) The map of the major mountain ranges and the distributions of the earthworm species discussed in this paper in Taiwan. Shei- Shan Mountain Range (a), Ali-Shan Mountain Range (b), Yu-Shan Mountain Range (c), Central Mountain Range (d), and Coastal Mountain Range (e) are the five major mountain ranges in Taiwan. Earthworm species, Amynthas formosae (solid circle), Metaphire bununa (open triangle), Metaphire paiaeanna (open star), Metaphire yuanpoaea (open circle), Metaphire nanaoensis (open square), Metaphire taiaeanensis (solid triangle), and Metaphire tahanmonta (solid star), showed different distributions in Taiwan.

Figure 4. Metaphire tahanmonta. (A) Male pore region (op, oval pad; sw, skin wall); (B) caecum; (C) spermathecae (dv, diverticulum; amp, ampulla); (D) testis sacs and seminal vesicles (ts, testis sacs; sv, seminal vesicles), seminal vesicles in 11 are embedded in the testis sacs and are not shown in this figure; (E) prostate gland.