New earthworms belonging to the genus of Amynthas Kinberg (Megascolecidae: Oligochaeta) and Drawida Michaelsen (Moniligastridae: Oligochaeta) from Guangdong, China

This paper describes three new species of earthworm from Guangdong, China: Amynthas heshanensis sp. nov., Amynthas jiangmenensis sp. nov., and Drawida cheni sp. nov. The former two species both have two pairs of spermathecal pores in 6/7–7/8, and simple paired caecae in XXV. Four similar Amynthas species are reviewed. Drawida cheni sp. nov. has similar characters in external appearance (large body size, no dorsal pore, and no clitellum) with Drawida sulcata Zhong, 1986 from Yunnan, China. The species is distinguished from other Drawida species by the five gizzards, which are otherwise only found in D. syringa Chen, 1933, the smooth body without setae, the superficial male pores, and the female pores in 12/13.


Introduction
Spermathecae number and structure are usually species-specific, and have been commonly used as one of the diagnostic characters in the systematics of earthworms (Tsai et al. 2002). Although at least 12 nominal Amynthas species which possess two spermathecal pores in 6/7-7/8 have been reported from the Korean peninsula (Hong and James 2001;, there are only four such Amynthas earthworm species found in China. They are Amynthas biconcavus (Quan and Zhong 1989), Amynthas zhongi (Qiu et al. 1991), Amynthas quadrapulvinatus (Wu and Sun 1997), and Amynthas acidophila (Chen 1946). Here we describe two new Amynthas species from Guangdong, China.
As for the genus Drawida Michaelsen, about 16 nominal earthworm species have been recorded in China. They are D. gisti Michaelsen, 1931, D. gisti nanchanginna Chen, 1933, D. gisti anchingiana Chen, 1933, D. linhaiensis Chen, 1933, D. sinica Chen, 1933, D. syringa Chen, 1933, D. glabella Chen, 1938, D. omeisna Chen, 1946, D. sulcata Zhong, 1986, D. changbaishanensis Wu and Sun, 1996, D. koreana Kobayashi, 1938, D. jeholensis Kobayashi, 1940, D. nemora Kobayashi, 1940, D. japonica Michaelsen, 1892, D. japonicus f. siemsseni Michaelsen, 1910, and D. grahami Gates, 1935. However, no species of this genus has been reported from the mainland of Guangdong, except for Hainan Island (in the territory of Guangdong until 1988). For the sake of examining the correlation between earthworm community and vegetation succession, we conducted a survey in the Hilly Land Interdisciplinary Experimental Station of the Chinese Academy of Sciences (22u419N, 112u549E) where different pure or mixed tree plantations grow, and Mt. Dinghu (23u099210-23u119300N, 112u309390-112u339410E), which has been regarded as an oasis at the Tropic of Cancer in the mid-part of Guangdong Province, with an area of 11.33 km 2 , and elevation ranging from nearly 100 to 700 m.
Earthworms were collected with 0.4% formalin solution, and preserved in 10% formalin solution. All materials were deposited in the Laboratory of Environmental Biology, School of Agriculture and Biology, Shanghai Jiaotong University, China.

Type material
Holotype: a mature specimen ( Spermathecal pore: two pairs in 6/7-7/8, ventral, inconspicuous externally. Genital markings not present. Male pore: one pair in XVIII, 0.4 body circumference ventrally apart from each other, each on the top of a capsula-like porophore surrounded by several circular folds. Genital papillae not present ( Figure 1A).
Spermathecae two pairs in VII-VIII, ampulla oval-shaped, about 2 mm long. The duct is so short as to be inconspicuous. Diverticulum curved, a little longer than the ampulla plus duct, terminal one-quarter dilated into a long chamber ( Figure 1B). No accessory glands observed.
Holandry: testis sac two pairs, small, in X-XI, separated from each other. Seminal vesicles paired in XI-XII, well developed, with large conspicuous dorsal lobes. Prostate glands developed, extending from XVII to XXII. Prostatic duct slender, slightly curved at the distal part. No accessory glands present.

Locality and habitat
The specimens were collected from vegetable plots near the orchard (elevation 40 m) of Heshan station, one of the core stations of the Chinese Ecological Research Network (CERN) of the Chinese Academy of Sciences, which is located in Heshan County, Guangdong Province, China.

Remarks
Amynthas heshanensis is somewhat similar to Amynthas zhongi (Qiu et al. 1991), Amynthas sanchongensis (Hong and James 2001), Amynthas paiki , and Amynthas taebaekensis (Hong and James 2001). However, it is easy to distinguish Amynthas heshanensis from A. zhongi by the larger body size, the much shorter spermathecal duct, and the XXV originating caecae, from Amynthas sanchongensis, Amynthas paiki, and Amynthas taebaekensis by the simple structure of male pores, the absent genital markings and papillae, and the simple XXV originating caecae. Amynthas sanchongensis has a distinct lateral cresentic groove on the apex of the porophore. Amynthas paiki has two pre-setal pairs of genital papillae in XVIII, pre-setal paired sets of two genital markings in segments VII and VIII, and its caecum is manicate, each consisting of six to seven finger-shaped sacs, originating from XXVII. Amynthas taebaekensis has only one pair of post-setal genital papillae in XVIII.
Male pore: one pair in XVIII, on the centre of a slightly raised, transverse, ellipse-like porophore, 0.3 body circumference apart from each other, surrounded by several circular folds. Genital papillae not present (Figure 2A).
Holandry: testis sac two pairs, small, in X-XI, separated from each other. Seminal vesicles paired in XI-XII, small. Prostate gland well developed, the duct much thickened, enlarged at mid-length. No accessory glands present.

Locality and habitat
The holotype was collected at an abandoned nursery near the orchard (elevation 40 m) in Heshan station (112u549E, 22u419N), one of the core stations of the Chinese Ecological Research Network (CERN) of the Chinese Academy of Sciences, which is located in Heshan County, Guangdong Province, China.

Remarks
Amynthas jiangmenensis is closely related to Amynthas heshanensis sp. nov. However, they differ markedly in the structures of the male porophore and spermathecae. In addition, seminal vesicles of A. jiangmenensis were smaller than those of A. heshanensis sp. n.

Type material
Holotype: a mature specimen (

External characters
Body large, smooth, with yellowish pigment, slightly sharp at head end and blunt at the caudal part. Dimensions 110-185 mm by 9-11 mm at segment X, segments number 165-174. Annulets are conspicuous in IV-XXIX segments. Prostomium prolobous.
Clitellum not observed. Dorsal pores absent, and setae are also invisible externally. Spermathecal pore: one pair in 7/8 intersegmental furrow, ventral, 0.4 body circumference apart from each other, each on the centre of a longitudinally orientated, flat elliptical whitish glandular membrane patch. Genital markings not present.
Male pore: one pair in 10/11 intersegmental furrow, 0.4 body circumference ventrally apart from each other, slightly swollen, each on the centre of a large, longitudinally orientated, flat elliptical whitish glandular membrane patch. Genital papillae not present.
Female pore: one pair in 12/13, 0.4 body circumference ventrally apart from each other. Segment XII is distinctly short ( Figure 3A).

Internal characters
Septa 5/6-8/9 greatly thickened, muscular. Gizzards five in XII-XXII segments (in XII-XIV, XV-XVI, XVII-XVIII, XIX-XX, and XXI-XXII, respectively), same size, shining on the surface with whitish vertical fibres. Intestine enlarged distinctly at segments XXIV-XXVI, just behind the last gizzard. Oesophageal hearts greatly thickened, black in VI-IX. Meganephridia present, beginning at least from VI, about 20-30 mm long, pairs in each segment close to the anterior septum. There are a few brownish black dots on the surface of segments anterior to VII.
Testis sac: one pair, about 6 mm long, 3.5 mm wide, yellowish, each suspended in middle part of septum 9/10. Ovarian chambers are in XI-XII, about 3.5 mm, vertical long pouchshaped or palm-like.
Spermathecae one pair in VIII, ampulla oval-shaped, yellowish, about 2.5 mm long, 1.2 mm wide, narrowly attached to the surface of septum 7/8 with a short connective tissue; from its lower side a duct arising, gradually narrowing and making a number of great coils from its median part, about 23 mm in total length, spermathecal atrium inconspicuous or absent (not certain). No accessory glands are present ( Figure 3B).

Remarks
In appearance Drawida cheni sp. nov. is somewhat similar to Drawida sulcata Zhong, 1986 from Yunnan, China. They share similar characters of external appearance, large body size, absent dorsal pore, absent clitellum, oval-shaped testis sac and ampulla, and convoluted duct. However, the new species is distinguished from D. sulcata and other species by the five gizzards which otherwise can only be found in D. syringa Chen, 1933, the absent genital papillae, inconspicuous thumb-shaped spermathecal atrium, as in Drawida nemorus Kobayashi, 1936 whose spermathecal duct also terminates without any trace of atrial dilatation. Furthermore, Drawida cheni sp. nov is characterised by the smooth body without setae, the intestine origin immediately behind the last gizzard, the female pore in 12/13, and the superficial male pore covered by a glandular membrane patch, with no atrium or penis present.
The name cheni is given after Prof. Chen Y., who made great contributions to the earthworm systematics of China.