Amynthas hsiyinensis Shen and Chih, 2013

Shen, Huei-Ping, Chang, Chih-Han & Chih, Wen-Jay, 2013, Five new earthworm species of the genera Amynthas and Metaphire (Megascolecidae: Oligochaeta) from Matsu, Taiwan, Journal of Natural History (J. Nat. Hist.) 48 (9 - 10), pp. 495-522 : 501-504

Amynthas hsiyinensis Shen and Chih , sp. nov.

( Figure 4 )

Type material

Holotype. Clitellate (128 mm in length, dissected) collected 31 August 2012 from roadside ditches (elevation 15 m), Chingshuiao, Hsiyin by H.P. Chen and H.H. Huang (TESRI-O-H-39) (voucher number: MTS 124).

Paratypes. Two clitellates (same collection data as holotype, TESRI-O-P-34).

Other material

Seven clitellates collected 28 June 2012 from Chingshuiao (elevation 15 m), Hsiyin by H.P. Chen and W.J. Chih (coll. no. 2012–74) (voucher number of specimen used for DNA barcoding analyses: MTS 116); one clitellate collected 31 August 2012 from roadside ditches outside Stronghold No. 33 (elevation

40 m), Hsiyin by H.P. Chen and H.H. Huang (coll. no. 2012–125) (voucher number: MTS 126).

Diagnosis

Small to medium; length (clitellates) 85–145 mm. Segments numbering 123–129. Setae 69–74 in VII, 75–78 in XX, and 20–27 between male pores. First dorsal pore in 12/13. Spermathecal pores two pairs in 7/8/9, 0.31–0.33 body circumference ventrally apart. Preclitellar genital papillae small, 10–20 arranged in a transverse row in each of postsetal VIII, presetal IX and presetal X. Male pores about 0.34 body circumference ventrally apart in XVIII, each inconspicuous on a small, round porophore with two small papillae immediately adjacent to it: one anteromedial and the other posteromedial. Numerous tiny genital papillae arranged closely and rather irregularly in several transverse rows between male porophores. Spermathecae two pairs in VII and VIII. Diverticulum coiled. Seminal vesicles large, two pairs in XI and XII. Prostate glands large in XVI–XX or XVI–XXI. Prostatic duct long, S-shaped or U-shaped in XVIII–XIX. Accessory glands short-stalked, round or mushroom-like, corresponding to external genital papillae.

Description

External characters. Total length (clitellates) 85–145 mm. Weight 1.11–3.12 g. Segments numbering 123–129. Clitellum XIV–XVI, setae and dorsal pores absent, 5.02–6.27 mm in length and 3.85–5 mm in width. Prostomium epilobous. Setae minute, number 69–74 in VII, 75–78 in XX, and 20–27 between male pores in XVIII. First dorsal pore in 12/13. Spermathecal pores two pairs in intersegmental furrows of 7/8/9; distance between paired pores 0.31–0.33 body circumference ventrally apart. Preclitellar genital papillae small, round, arranged in a transverse row in each of postsetal VIII, presetal IX and presetal X ( Figure 4A ). Number of papillae 16–20 in postsetal VIII, 11–19 in presetal IX and 10–15 in presetal X. Female pore single, mid-ventral in XIV.

Male pores paired in XVIII, about 0.34 body circumference ventrally apart. Each pore inconspicuous on a small, round porophore with two small papillae immediately adjacent to it: one anteromedial and the other posteromedial. The male porophore together with the genital papillae surrounded by two or three round or diamondshaped shallow skin folds ( Figure 4B ). Numerous tiny genital papillae arranged closely and rather irregularly in several transverse rows between male porophores, number of papillae about 140.

Preserved specimens dark brown on dorsum, brown to dark brown on clitellum, and greyish brown on ventrum.

Internal characters. Septa 5/6–7/8 thick, 10/11–13/14 muscular, 8/9/10 absent. Nephridial tufts thick on anterior faces of 5/6/7. Gizzard large, round in VIII–X. Intestine enlarged from XV. Intestinal caeca paired in XXVII, each long, simple, large, distal end bent in XXV or XXVI. Oesophageal hearts in X–XIII.

Spermathecae two pairs in VII and VIII, each with a wrinkled, peach-shaped or elongated oval-shaped ampulla 1.35–1.55 mm long and 1.64–2 mm wide, and a short, stout spermathecal stalk about 0.5 mm in length. Diverticulum heavily coiled with a slender and straight proximal part. Accessory glands short-stalked, round or mushroom-like, about 0.75 mm in length, each corresponding to external genital papilla ( Figure 4C ).

Holandry: testes oval, two pairs in ventrally joined sacs in X and XI. Seminal vesicles large, surface smooth, two pairs in XI and XII, occupying the entire segmental compartment, anterior pair rectangular-shaped, posterior pair transversely elongated oval-shaped, each vesicle with a round dorsal lobe at the middle of the dorsal end. Prostate glands large in XVI–XX or XVI–XXI ( Figure 4D ), wrinkled and lobed. Prostatic duct long, S-shaped or U-shaped in XVIII–XIX. Accessory glands short-stalked, about 0.75 mm long, similar to those in the preclitellar region, corresponding to external genital papillae ( Figure 4D ).

DNA barcodes

GenBank accession numbers KC897052 (MTS 124, holotype), KC897051 and KC897050 (MTS 116 and 126, respectively)

Etymology

The name hsiyinensis is given to this species with reference to its type locality in Hsiyin , Matsu .

Remarks

Amynthas hsiyinensis sp. nov. is only found on the island of Hsiyin. It is quadrithecate with two pairs of spermathecal pores in intersegmental furrows of 7/8/9. It is fairly similar to Amynthas polyglandularis ( Tsai, 1964) from northern Taiwan and Amynthas kinmenensis Shen et al., 2013 from Kinmen. Both species are quadrithecate with spermathecal pores in 7/8/9 and have numerous small genital papillae. Amynthas hsiyinensis and A. polyglandularis have more similar preclitellar and postclitellar papilla arrangements with papillae more concentrated mid-ventrally, whereas the papillae of A. kinmenensis are laterally distributed ( Table 1). However, papilla arrangement around the male pore is different in A. hsiyinensis and A. polyglandularis with one anteromedial and one posteromedial papilla for the former, and four to nine papillae surrounding each male pore for the latter ( Tsai 1964). In addition, number of papillae in mid-ventral XVIII is much higher in A. hsiyinensis than in A. polyglandularis ( Table 1). Furthermore, molecular analyses show that A. polyglandularis is more closely related to A. kinmenensis than to A. hsiyinensis ( Figure 2 ). It is possible that the three species were derived from a common ancestor and have gone through allopatric speciation. Further phylogenetic analyses are required to test this hypothesis.

Amynthas omeimontis ( Chen, 1931) and Amynthas kinfumontis ( Chen, 1946) from Sichuan, China also have spermathecal pores in 7/8/9 and numerous small genital papillae. However, A. omeimontis has manicate intestinal caeca and about 40 to 50 small papillae closely arranged in rows in presetal XI ( Chen 1931). Also, it has much lower setal number with 38–46 in VI–VIII, 40–44 in XX, and 10–12 between male pores ( Chen 1931). Amynthas kinfumontis is similar to A. hsiyinensis in having long, simple intestinal caeca and transverse rows of genital papillae in VIII or IX ( Chen 1946). However, A. kinfumontis has one presetal and one postsetal row of papillae in VIII or IX, one row of papillae along the intersegmental furrow of 18/19, and papillae in presetal XIX. Furthermore, it has large accessory glands with long stalk and much lower setal number with 40–44 in VI–IX, 44–48 in XXV, and 10–12 between male pores ( Chen 1946).

Figures

Figure 2. Neighbour-joining tree of the five new species and several other Amynthas based on cytochrome oxidase c subunit I (COI) gene and rooted using Metaphire californica. Specimens from this study and sequences retrieved from GenBank are shown by their voucher numbers and GenBank accession numbers, respectively. Numbers around nodes are bootstrap values above 50.

Figure 4. Amynthas hsiyinensis sp. nov. Holotype (TESRI-O-H-39) (voucher number: MTS 124). (A) Ventral view of spermathecal pore region (gp, genital papilla; sp, spermathecal pore); (B) ventral view of male pore region (mp, male porophore); (C) dorsal view of left spermathecae (amp, ampulla; dv, diverticulum; ag, accessory gland); (D) dorsal view of left prostate gland. Scale bar 1 mm.