Amynthas tsou Shen and Chang

Shen, Huei-Ping, Chang, Chih-Han & Chih, Wen-Jay, 2016, Four new earthworm species of the genus Amynthas (Megascolecidae: Oligochaeta) from southwestern Taiwan with re-description of Amynthas tungpuensis Tsai, Shen and Tsai, 1999, Journal of Natural History 50 (29 - 30), pp. 1889-1910 : 10-13

Amynthas tsou Shen and Chang , sp. nov.

( Figure 4 )

Type material

Holotype. Clitellate (mature) specimen (61 mm in length, dissected) collected 25 July 2013 from roadside slopes and ditches around Dinghu (elevation 1661 m), Alishan, Chiayi by H.T. Fang (TESRI-O-H-49) (voucher number: Ali005).

Paratypes. Seven clitellates and an aclitellate (same collection data as holotype, TESRI- O-P-44) (voucher numbers of specimens used for DNA barcoding analyses: Ali003, Ali004 and Ali006).

Other material

One clitellate collected 25 July 2013 along Beitzutong Forest Road (elevation 1541 m) near the borders of Jhuci and Alishan, Chiayi by H.T. Fang (coll. no. 2013 – 3); five clitellates collected 25 July 2013 along Fencihu Cedar Wooden Plank Trail (elevation 1418 m), Jhuci, Chiayi by H.T. Fang (coll. no. 2013 – 4) (voucher numbers of specimens used for DNA barcoding analyses: Ali014, Ali016 and Ali018); one clitellate and an aclitellate collected 16 August 2013 from roadside slopes and ditches around Dinghu (elevation 1662 m), Alishan, Chiayi by H.T. Fang (coll. no. 2013 – 8); one clitellate collected 1 October 2013 from roadside slopes and ditches around Dinghu (elevation 1662 m), Alishan, Chiayi by H.T. Fang (coll. no. 2013 – 9) (voucher number: Ali026); one clitellate collected 6 November 2013 from roadside slopes and ditches around Dinghu (elevation 1662 m), Alishan, Chiayi by H.T. Fang (coll. no. 2013 – 11) (voucher number: Ali027); one clitellate collected 28 April 2014 from roadside slopes and ditches around Dinghu (elevation 1664 m), Alishan, Chiayi by H.T. Fang (coll. no. 2014 – 1) (voucher number: Ali029); one clitellate collected 28 April 2014 from roadside slopes and ditches around Dinghu (elevation 1662 m), Alishan, Chiayi by H.T. Fang (coll. no. 2014 – 3) (voucher number: Ali031); three clitellates collected 28 April 2014 along Beitzutong Forest Road (elevation 1495 – 1650 m) near the borders of Jhuci and Alishan, Chiayi by H.T. Fang (coll. no. 2014 – 6); one clitellate collected 28 April 2014 along a hiking trail (elevation 1460 m) near Shihcho, near the borders of Jhuci and Alishan, Chiayi by H.T. Fang (coll. no. 2014 – 7) (voucher number: Ali036); two clitellates collected 28 April 2014 from roadside ditches around a parking lot at south end of a hiking trail in Longyun Farm (elevation 1486 m), Jhuci, Chiayi by H.T. Fang (coll. no. 2014 – 8); one clitellate collected 29 April 2014 along Fencihu Cedar Wooden Plank Trail (elevation 1407 m), Jhuci, Chiayi by H.T. Fang (coll. no. 2014 – 10).

Diagnosis

Small to medium; length (clitellates) 42 – 79 mm. Segments numbering 74 – 97. Setae 28 – 38 in VII, 30 – 42 in XX and 6 – 11 between male pores. First dorsal pore in 12/13 or 13/14. Spermathecal pores not visible or three pairs in 6/7 – 8/9, 0.28 – 0.30 body circumference ventrally apart. Preclitellar genital papillae paired and immediately anterior to setal line in VIII and IX. Male pores 0.24 body circumference ventrally apart in XVIII, each inconspicuous on a small, round or oval porophore with or without an anterior, posteromedial or one anteromedial and one posteromedial papillae. Spermathecae three pairs in VII – IX. Prostate glands vestigial in XVIII. Prostatic duct long, U-shaped, occupying XVII – XVIII. Accessory glands stalked, each corresponding to external genital papilla.

Description

External characters. Total length (clitellates) 42 – 79 mm. Weight 0.12 – 0.29 g. Segments numbering 74 – 97. Clitellum XIV – XVI, setae and dorsal pores absent, 1.10 – 2.61 mm in length and 2.02 – 2.80 mm in width. Prostomium epilobous. Setae minute, numbering 28 – 38 in VII, 30 – 42 in XX, and 6 – 11 between male pores in XVIII. First dorsal pore in 12/13 or 13/14. Spermathecal pores not visible or three pairs in intersegmental furrows of 6/7 – 8/9; distance between paired pores 0.28 – 0.30 body circumference ventrally apart. Preclitellar genital papillae usually paired and immediately anterior to setal line in VIII and IX ( Figure 4 a), occasionally with an additional pair in VII or X or papillae totally absent. Each papilla small, round, 0.25 – 0.35 mm in diameter. Female pore single, mid-ventral in XIV.

Male pores paired in XVIII, about 0.24 body circumference ventrally apart, each pore inconspicuous on a small, round or oval porophore with or without an anterior, posteromedial, or one anteromedial and one posteromedial papillae ( Figure 4 b – d), surrounded by two or three circular folds. For 28 specimens examined, one papilla anterior to each male porophore in eight specimens, one posteromedial to each male porophore in five specimens, one anteromedial and one posteromedial to each male porophore in two specimens, one anteromedial and one posteromedial to right male porophore and one posteromedial to left male porophore in two specimens, one posteromedial to right male porophore only in two specimens, one anterior to left male porophore only in one specimen, papillae absent in eight specimens. Each papilla small, round, 0.20 – 0.30 mm in diameter. Occasionally papillae closely paired in presetal XVIII or XVIII – XIX, immediately adjacent to intersegmental furrows ( Figure 4 d).

Preserved specimens dark brown on dorsum, dark orange brown or pinkish brown on clitellum, and greyish brown on ventrum.

Internal characters. Septa 5/6 – 7/8 and 10/11 – 13/14 thick, 8/9/10 absent. Nephridial tufts on anterior faces of 5/6/7. Gizzard large, round in VIII – X. Intestine enlarged from XVI. Intestinal caeca paired in XXVII, each simple, long, stout, extending anteriorly to XX or XXI. Oesophageal hearts in XI – XIII.

Spermathecae three pairs in VII – IX, each ampulla elongated oval-shaped, surface slightly wrinkled, 1.00 – 1.50 mm long and 0.50 – 0.65 mm wide, with a slender to stout spermathecal stalk 0.40 – 0.65 mm in length. Diverticulum with a slender stalk and a slightly swollen terminal knob, 0.50 – 0.67 mm in length. Accessory glands stalked, mushroom-like, 0.55 – 0.65 mm in total length, each corresponding to external genital papilla ( Figure 4 e).

Holandry: testes round, two pairs in ventrally joined sacs in X and XI. Seminal vesicles two pairs in XI and XII, transversely elongated oval-shaped, each vesicle with a round dorsal lobe. Prostate glands vestigial in XVIII ( Figure 4 f,g), wrinkled and lobed. Prostatic duct long, U-shaped, occupying XVII – XVIII, stouter toward distal end. Accessory glands stalked, about 0.5 mm in total length, each corresponding to external genital papilla.

DNA barcodes

GenBank accession numbers KU232782 (Ali005, holotype), KU232780 , KU232781 and KU232783 (Ali003, 0 0 4 and 0 0 6, respectively, paratypes), KU232784 , KU232785 , KU232786 , KU232787 , KU232788 , KU232789 , KU232790 and KU232791 (Ali014, 0 16, 0 18, 0 26, 0 27, 0 29, 0 31 and 0 36, respectively).

Etymology

The name tsou is given to this species with reference to the native Tsou Tribe living in the Alishan area, Chiayi, southwestern Taiwan.

Remarks

The variable papilla arrangements around male porophore of Amynthas tsou sp. nov. is fairly similar to that of A. tungpuensis ( Figure 6 ). Both species are members of the sieboldi - group ( Sims and Easton 1972), and sympatric in the Alishan area, Chiayi, southwestern Taiwan. However, A. tungpuensis is larger, 63 – 160 mm in length, and has higher setal number with 35 – 48 in VII and 46 – 59 in XX and large prostate glands occupying four or five segments in XV – XX (this study). In addition, preclitellar genital papillae of A. tsou are usually paired in presetal VIII and IX, never as two transverse rows as in A. tungpuensis . Furthermore, the two species are genetically distinguishable ( Figure 1 ). The male pore structure of A. tsou also looks similar to Amynthas mutabilitas Shen, 2012 found at elevations of 410 – 1350 m on the east slope of the Central Mountain Range and Coastal Mountain Range in eastern Taiwan. The two species are distinctively different since A. mutabilitas has spermathecae from absent (athecate) to two pairs in VI and VII (quadrithecate) and prostate glands from large in XVI – XXI to vestigial in XVIII ( Shen 2012).

The preclitellar papilla arrangement of A. tsou resembles that of Amynthas douliouensis sp. nov., also a member of the sieboldi -group. Amynthas douliouensis is larger with body length of 78 – 120 mm, and has higher setal number with 40 – 45 in VII and 48 – 57 in XX and large prostate glands in XVI – XX. Also, the two species can be differentiated based on molecular analyses ( Figure 1 ).

Figures

Figure 1. Neighbour-joining tree of representatives of Amynthas mutabilitas, Amynthas tungpuensis and the four new species based on the cytochrome c oxidase subunit I (COI) gene and Kimura ’ s twoparameter model and rooted using Amynthas polyglandularis. 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. For A. tungpuensis, numbers of spermathecae are in parentheses.

Figure 4. Amynthas tsou sp. nov. (a) Ventral view of spermathecal pore region of holotype (TESRI-O- H- 49) (voucher number: Ali 005) (gp, genital papilla; sp, spermathecal porophore). (b) Ventral view of male pore region of holotype (mp, male porophore). (c) Ventral view of male pore region of a 61 - mm paratype (TESRI-O-P- 44) (voucher number: Ali 003). (d) Ventral view of male pore region of a 57 - mm clitellate (coll. no. 2013 – 9) (voucher number: Ali 026). (e) Dorsal view of right spermathecae of holotype (amp, ampulla; dv, diverticulum; ag, accessory gland). (f) Dorsal view of left prostate gland of holotype (pd, prostatic duct). (g) Dorsal view of right prostate gland of holotype. Scale bar 1 mm.

Figure 6. Amynthas tungpuensis Tsai, Shen and Tsai, 1999. (a) Ventral view of spermathecal pore region of a 77 - mm clitellate (coll. no. 2013 – 4) (voucher number: TP 20) (gp, genital papilla; sp, spermathecal pore). (b) Ventral view of spermathecal pore region of a 76 - mm clitellate (coll. no.