Amynthas hohuanmonti, Tsai, Shen & Tsai, 2002

Tsai, Chu-Fa, Shen, Huei-Ping & Tsai, Su-Chen, 2002, A new athecate earthworm of the genus Amynthas Kinberg (Megascolecidae: Oligochaeta) from Taiwan with discussion on phylogeny and biogeography of the A. illotus species-group, Journal of Natural History 36 (7), pp. 757-765 : 758-761

Amynthas hohuanmonti s sp. nov.

(®gure 1)

Type material

HOLOTYPE. A mature (clitellate) specimen (dissected) collected 20 October 1999 from Mt Hohuan (elevation 3000 m) near the High Altitude Experimental Station of the Taiwan Endemic Species Research Institute along Rd. 14A in Hualien Prefecture near the border of Nantou Prefecture by C. F. Tsai, S. C. Tsai, H. P. Shen, T. J. Lin and C. Y. Chang (coll. No. 1999-17- Shen).

PARATYPES. Four mature specimens (dissected, same collection as holotype).

Other material

Three mature specimens (one specimen dissected) collected 8 July 1999 from the same locality as holotype (coll. No. 1999-9- Shen). The collection was lost in the earthquake of 21 September 1999 .

External characters

Length (mature) 73±113 mm, clitellum width 3.41±4.40 mm, weight 1.07 ±2.91 g. Prostomium tanylobous. Segment number 85 ±103. Secondary furrows produce three annuli per segment in VI ±XIII. First dorsal pore in 12/13. Setae 32±41 in VII, 42±46 in XX, 9±11 between male pores in XVIII. Clitellum XIV±XVI, length 2.47±5.34 mm, which is 0.72±1.21 times longer than width, smooth, dorsal pores absent, setae absent.

Spermathecal pores absent. Genital papillae absent in preclitellar region. Female pore single, medio-ventral in XIV.

Male pores paired in XVIII, ventro-lateral, distance apart 0.26±0.29 circumference. Porophores (protuberances bearing male apertures) small, papilla-like or indistinct; male apertures invisible, but each with two genital papillae, one anterior and one posterior, or with three papillae, one anterior, one posterior and one lateral, and then surrounded by four to six circular folds. Each papilla round, centre ¯at or slightly convex, 0.21±0.27 mm in diameter, surrounded by a circular fold. In addition, a horizontal row of genital papillae, one to three (usually two) in number, just medial to each of the male pore regions, immediately posterior to setal line, each papilla similar in size and structure to those associated with the male pores (®gure 1A).

Preserved specimens light greyish brown on dorsum, light grey on ventrum, dark brown around clitellum.

Internal characters

Septa 5/6±7/8 comparativel y thick, 8/9/10 absent, 10/11±12/13 thick. Gizzard round in IX and X. Intestine enlarged from XV. Intestinal caeca paired in XXVII, each simple, surface slightly wrinkled, extending anteriorly to XXIV±XXII. Esophageal hearts enlarged in XI±XIII.

Spermathecae absent. Accessory glands absent in preclitellar region.

Holandry: sperm sacs two pairs in XI, or anterior pair in 10/11 (partly in X and XI) and posterior in XI, each small, round or oval-shaped. Seminal vesicles paired in XI and XII, surface smooth or folliculate, yellow in colour, each with a granulate dorsal lobe (®gure 1B). Prostate glands vestigial, small, nodule-like or absent, but prostatic ducts normal, large, C- or S-shaped. Accessory glands round, stalked, corresponding to the genital papillae in XVIII (®gure 1C±F).

Remarks

Amynthas hohuanmonti s sp. nov. is easily distinguishable from other nominal species of the A. illotus species-group by body size, porophore structure, number and arrangement of genital papillae, and size of prostate glands ( table 1). Based on the size, genital papillae and male pore structure, A. hohuanmonti s is closely related to A. sheni of Hong Kong ( Chen, 1935). However, A. hohuanmonti s has two or three postclitellar papillae at each of the male pore regions and a horizontal row of one to three postsetal papillae medial to the pore (®gure 1A), whereas A. shen i has a single postclitellar papilla medial to each male pore ( Chen, 1935). Also, the former has no preclitellar genital papillae, whereas the latter has paired preclitellar papillae in VIII. The prostate glands of A. hohuanmontis are small and vestigial, or absent (®gure 1C±F), while A. sheni has normal, large prostate glands ( Chen, 1935). The other three species, A illotus , A. assacceus and A. oyuensis , have no genital papillae ( table 1).

The name hohuanmontis is given to this species from its type locality at Mt Hohuan (elevation 3000 m) in Central Taiwan. The mountain is primarily covered with yushan cane ( Yushania niitakayamensis Hay ) grassland on rocky substratum. Pine trees are also common. The topsoil is very thin. In winter snow often covers the mountain in this subtropical island.