Four new earthworm species of the genus Amynthas (Oligochaeta: Megascolecidae) from Kinmen, Taiwan
Author
Shen, Huei-Ping
Author
Chang, Chih-Han
Author
Li, Chi-Lun
Author
Chih, Wen-Jay
Author
Chen, Jiun-Hong
text
Zootaxa
2013
3599
5
471
482
journal article
10.11646/zootaxa.3599.5.4
6bf9d0d6-4c9c-4ba2-b274-f6bff5ea307a
1175-5326
218667
6F355903-94C7-4BD7-8E98-E9D6770DD2FF
Amynthas taiwumontis
sp. nov.
(
Fig. 4
)
Holotype
:
Clitellate (mature) specimen (
133 mm
in total length, dissected) collected
1 May
2008
in front of Haiyin Temple (elevation
207 m
), Mt. Taiwu, Kinmen by C. L. Li and Y. H. Lin (cat. no. 14-07399).
Other material.
2 specimens
altogether. One aclitellate (cat. no. 14-07398) and one semi-clitellate (cat. no. 14-07400), same collection data as
holotype
.
Diagnosis.
Small to medium; length
133–151 mm
. Segments numbering 131–142. Setae
74–97 in
VII,
73–89 in
XX, and 16–22 between male pores. First dorsal pore in 11/12. Spermathecal pores small, four pairs in 5/6–8/9, 0.25–0.28 body circumference ventrally apart. Male pores 0.22–0.29 body circumference ventrally apart in XVIII, each inconspicuous on a round, slightly elevated porophore. Genital papillae absent. Spermathecae four pairs in VI–IX. Seminal vesicles small, two pairs in XI and XII, each vesicle with a round or elongated oval dorsal lobe. Prostate glands large, occupying four to nine segments in XVI–XXIV. Prostatic duct C- or S-shaped in XVIII–XIX. Accessory glands absent.
FIGURE 4.
Amynthas taiwumontis
sp. nov.
Holotype (cat. no. 14-07399): (A) ventral view of male pore region (mp, male porophore); (B) dorsal view of right spermathecae (amp, ampulla; dv, diverticulum); (C) dorsal view of left prostate gland (pd, prostatic duct); (D) dorsal view of right prostate gland. Scale bar 1 mm.
Description.
External: Total length
133–151 mm
. Weight
1.78–2.69 g
. Segments numbering 131–142. Clitellum XIV–XVI, setae and dorsal pores absent, length
2.79–4.78 mm
and width
3.32–4.77 mm
. Prostomium epilobous. Setae
74–97 in
VII,
73–89 in
XX, and 16–22 between male pores in XVIII. First dorsal pore in 11/12. Spermathecal pores small, four pairs in intersegmental furrows of 5/6–8/9; distance between paired pores 0.25–0.28 body circumference ventrally apart. Genital papillae absent. Female pore single, mid-ventral in XIV. Male pores paired in XVIII, 0.22–0.29 body circumference ventrally apart, each inconspicuous on a round, slightly elevated porophore (
Fig. 4
A). Genital papillae absent. Preserved specimens grayish brown in color with dark to light brown clitellum.
Internal:
Septa
5/6–7/8 and
10/11–13/14
thick and muscular,
8/9/10
absent. Nephridial tufts on anterior faces of 5/6/7. Gizzard large in VIII–X. Intestine enlarged from XV or XVI. Intestinal caeca paired in XXVII, each simple, long, extending anteriorly to XXI–XXIII, or bent in XXIV. Esophageal hearts in X–XIII. Spermathecae four pairs in VI–IX (
Fig. 4
B), ampulla round or elongated oval-shaped, surface wrinkled,
0.77–2.28 mm
long and
0.46–1.25 mm
wide, spermathecal stalk stout,
0.26–0.94 mm
in length. Diverticulum long, proximal part slender and slightly enlarged toward distal end, but no specially enlarged seminal chamber,
1.03–3.78 mm
in total length. Accessory glands absent. Holandric, testes large, oval, two pairs in ventrally joined sacs in X and XI. Seminal vesicles small, two pairs in XI and XII, anterior pair occupying half to full segmental compartment and posterior pair vestigial, occupying half segment, each vesicle with a round or elongated oval dorsal lobe. Prostate glands large, occupying four to nine segments in XVI–XXIV (
Figs. 4
C, D), racemose, divided into several lobules by grooves. Prostatic duct stout, C- or S-shaped in XVIII or XVIII–XIX. Accessory glands absent.
Etymology.
The name
taiwumontis
is given to this species with reference to its
type
locality (elevation
207 m
) at Mt. Taiwu in Kinmen.
Remarks.
On the main island of Kinmen,
Amynthas taiwumontis
sp. nov.
was only found in areas around Mt. Taiwu. It is octothecal, and has simple male pore structure and no genital papillae or genital markings. These characters are similar to
Amynthas fornicatus
(
Gates, 1935
)
from the west border of Sichuan,
China
. However, the two species can be easily distinguished by the external characters.
A. fornicatus
is smaller (length
80–94 mm
and segments 90–105) and has much lower setal number than
A. taiwumontis
with 43–52 setae in VI–VIII and 45–55 setae in XXV for the former (
Chen 1936
) and 74–97 setae in VII and 73–89 setae in XX for the latter.
Amynthas marenzelleri
(
Cognetti, 1906
)
from
Japan
is octothecal and also has a simple male pore structure and no genital markings. It is different from
A. taiwumontis
by the larger body size (length
160–190 mm
and diameter
6–7 mm
) and lower setal number (36–43 setae in VII and 50–54 setae in XXIV) (
Cognetti 1906
;
Kobayashi 1938
). In addition,
A. marenzelleri
has small prostate glands confined in XVIII and small spermathecae without diverticulum, whereas
A. taiwumontis
has large prostate glands occupying four to nine segments in XVI–XXIV and spermathecae with long diverticulum.
Amynthas sinabunganus
(
Michaelsen, 1923
)
from Sumatra and
Amynthas tertiadamae
(
Michaelsen, 1934
)
from Gulf of
Siam
are also octothecal with simple male pore structure and without genital markings. However, the two species are distinguishable specifically from
A. taiwumontis
simply by their much smaller body size and lower setal number. Both are
52 mm
long and
2–3 mm
wide, with 104 segments for
A. sinabunganus
(
Michaelsen 1923
)
and 120 segments for
A. tertiadamae
(
Michaelsen 1934
)
. Setal numbers range from 23 to 40 per segment for
A. tertiadamae
(
Michaelsen 1934
)
and about 50 per segment for
A. sinabunganus
(
Michaelsen 1923
)
.