New species of earthworms belonging to the Metaphire formosae species group (Clitellata: Megascolecidae) in TaiwanAuthorChang, Chih-HanAuthorChuang, Shu-ChunAuthorWu, Jia HsingAuthorChen, Jiun-HongtextZootaxa201437744324332journal article4627810.11646/zootaxa.3774.4.22383d3fd-3ec2-4af2-8d97-94d35629f4791175-53262259881E9E30D8-392F-454B-B6F6-68E2276B35F9Metaphire taiwanensis tsaiissp. nov.
Chang and Chen
(
Fig. 3
)
Metaphire taiwanensis
(part): Chang
et al.
2008: 958, 967,
Figs. 1
, 4,
Tables 1
, 3–4; Chang & Chen 2008: 46–48,
Fig. 1
L,
Table 1
;
Chang
et al.
2009
: 6,
Fig.
2
L. [Chang & Chen (2008) cited the taxon as ‘
Metaphire taiwanensis
subsp.’].
Type
specimens.
Holotype
:
MZNTU
14-05614 (mature), collected
24 Nov 2002
from Fushan Botanical Research Station, Ilan County,
Taiwan
by C.-H. Chang.
Paratypes
:
MZNTU
14-00033 (mature), collected
1 September 1994
from Fushan Botanical Research Station, Ilan County,
Taiwan
by S.-S. Lu;
MZNTU
14-03883 (mature), collected
18 May 2002
from Jiaosi, Ilan County,
Taiwan
by I-H. Chen;
MZNTU
14-00028 (mature), collected
15 November 1994
from Fushan Botanical Research Station, Ilan County,
Taiwan
by S.-S. Lu.
Other material examined.
Four mature specimens.
MZNTU
14-00026,
8 December 1994
from Fushan Botanical Research Station, Ilan County,
Taiwan
by S.-H. Lu;
MZNTU
14-00029, collected
16 November 1994
from Fushan Botanical Research Station, Ilan County,
Taiwan
by S.-H. Lu;
MZNTU
14-05319, collected
24 January 2002
from Fushan Botanical Research Station, Ilan County,
Taiwan
by C.-H. Chang;
MZNTU
14-05903, collected
14 April 2003
from Yuanshan, Ilan County,
Taiwan
by W.-M. Lee.
Distribution.
Northern
Taiwan
. Recorded in Fushan Botanical Research Station and the surrounding regions in the Ilan County.
Etymology.
Noun in the genitive case, after Taiwanese earthworm taxonomist Dr. Chu-Fa Tsai.
DNA
barcodes of
type
material.
Available for
MZNTU
14-05614 (
Table 1
)
Diagnosis.
Pheretimoids with lengths
248–343 mm
, clitellum width
10–12 mm
. Copulatory pouches present with an anterior oval pad similar in size to the porophore. Spermathecae four pairs in 6–9. No genital papillae in the spermathecal pore area. Testes proandric. Prostate gland lobular. Caeca simple.
FIGURE 3.
Metaphire taiwanensis tsaiissp. nov.
A.
Ventral view of anterior body (fp, female pore; mp, male pore; cl, clitellum).
B.
Spermatheca (amp, ampulla; dv, diverticulum).
C.
Male pore area (op, oval pad).
D.
prostate gland with prostatic duct. Drawing of B, C, and D based on photographs from Fig. 26 in Chang & Chen 2008.
Morphology.
External characters.
Length (mature)
248–343 mm
, clitellum width
10–12 mm
, segment number 152–188. Number of annuli per segment three in 5–9, five in 10–13, three in body segments behind 17. Prostomium prolobous. Setae
121–164 in7, 132–135 in
20, 22–28 between male pores. First dorsal pore in 12/13. Clitellum 14–16, annular, smooth, length
10–11 mm
, dorsal pore absent, setae absent. Preserved specimens bluish brown on dorsum, light brown on ventrum. Clitellum dark bluish brown on dorsum, greyish brown on ventrum. Spermathecal pores four pairs in 5/6-8/9, minute, invisible externally, distance between the paired pores about 0.4– 0.5 body circumference apart ventrally. No genital papillae in the spermathecal pore region. Female pore single, mid-ventral in 14. Male pores paired in 18, small, latero-ventral, in a slightly C-shaped copulatory pouch, bordered laterally by a thick skin surrounded by circular folds. Porophore circular, tuberculated. An oval pad situated anteriorly to the porophore, with size similar to the porophore. Circular folds surrounding porophore and oval pad, extending anteriorly to 17/18 and posteriorly to 18/19. Genital papillae absent in the male pore area.
Internal characters.Septa
5/6–7/8 and
10/11–13/14
thickened, 8/9 membranous, 9/10 absent. Gizzard in 8. Intestine enlarged from 15. Intestinal caeca paired in 27, simple, long, surface slightly wrinkled, extending anteriorly to 23. Oesophageal hearts enlarged in 10–13. Spermathecae four pairs in 6–9. Ampulla elliptical, about
3–5 mm
in length, with a short stalk about
2 mm
long. Diverticulum small, with an oval, smooth seminal chamber and a short coiled or twisted stalk, reaching the basal 1/3 of the ampulla. Meronephridia tufted, attached to the anterior face of septa 5/6 and 6/7. Ovaries paired in 13, medio-ventral, close to the 12/13 septum. Testis sacs paired in 10, oval, smooth, medio-ventral in front of 10/11. Seminal vesicles paired in 11, large, surface tuberculated, with a large dorsal lobe. Prostate glands paired in 18, large, oval, extending to 17 and 19.
Remarks.M. taiwanensis tsaiissp. nov.
corresponds to clade E2 of
M. taiwanensis
in Chang
et al.
(2008). The two subspecies,
M. taiwanensis taiwanensis
and
M. taiwanensis tsaii
, have an allopatric distribution. They diverged by 5.7% in the COI gene (Chang
et al.
2008). Morphologically,
M. taiwanensis taiwanensis
is much larger than
M. taiwanensis tsaii
. The two subspecies also show different levels of allometric growth on their male pore areas compared to their body size: the male pore areas of the two subspecies are almost the same in size, but compared to their body size, the male pore area of
M. taiwanensis taiwanensis
is relatively smaller. It is also smoother and flatter with circular folds almost restricted to the ventral surface, whereas that of
M. taiwanensis tsaii
is more three-dimensional, with circular folds extending to the lateral side of the body.
TABLE 1.
GenBank accession numbers of DNA barcode sequences from type specimens of the
Metaphire formosae
species group.
Species MZNTU cat. GenBank accession nos.
Types
References nos.
M. feijani
14-07095
AY960809holotype
Chang
et al.
2008 14-07099
AY962162paratype
Chang
et al.
2008
M. tengjhihensis
sp.
nov.
14-05901
AY960801holotype
Chang
et al.
2008 14-07175
AY962164paratype
Chang
et al.
2008
M. nanaoensis truku
ssp.
nov.
14-07228
AY962150paratype
Chang
et al.
2008 14-05342
AY960805paratype
Chang
et al.
2008
M. tahanmonta
14-03993
AY962115holotype
Chang
et al.
2008 14-05898
AY739335paratype
Chang & Chen 2005 The assignment of the
formosae
species group to either
Metaphire
or
Amynthas
has recently been highly debated. The two genera are distinguished by only one character, the copulatory pouch, a structure present in
Metaphire
and absent in
Amynthas
(
Sims & Easton 1972
)
. However, there are two distinguishable forms of copulatory pouches that seem to be non-homologous (James
et al.
2005), and each of them has various degrees of reduction or “degradation”, which makes it difficult in some cases to decide between presence or absence of that character. James prefers to restrict
Metaphire
to species with well-developed copulatory pouches (James 2005; James
et al.
2005) and assigns species with "degraded" pouches to
Amynthas
, while Blakemore (2010) prefers to restrict
Amynthas
to species with superficial male pores, arguing that all species with the derivative character state of nonsuperficial male pores should belong to
Metaphire
. As a result, species in the
formosae
species group were assigned to
Amynthas
and
Metaphire
by James and Blakemore, respectively. We follow the conventional practice of assigning species in the
formosae
species group to
Metaphire
(
Chang & Chen 2004
,
2005a
,
b
;
Tsai et al. 2000
,
2003
,
2004
), but recognize the different forms of copulatory pouches presented by
Easton (1979)
and James (James 2005; James
et al.
2005), particularly the intramural and intracoelomic ones. Furthermore, we doubt that the assignment of species with the intramural form and the various “degradations” of both forms to either
Amynthas
or
Metaphire
is satisfying regarding preserving information of character states and evolution. Recent molecular phylogenetic studies strongly suggest that
Metaphire
is not monophyletic (Chang
et al.
2008; James 2005); it is indeed polyphyletic (unpublished data) regardless of difference in opinions on the definition of
Metaphire
or
Amynthas
. Considering this nature and the viewpoints already discussed by the above authors, any further arguments on the
Amynthas
-or-
Metaphire
issue seem meaningless before someone takes on the task of revising the whole group.
14-05899
AY960800
paratype Chang
et al.
2008
M. taiwanensis tsaiissp. nov.
14-05614
AY962157
holotype Chang
et al.
2008
Discussion
Hypotheses regarding synonyms of earthworms can usually be tested by comparing DNA barcodes. Blakemore
et al.
(2010) further recommended that any new earthworm taxa described should be accompanied by DNA barcodes from
types
to meet current standards. Although some of the DNA barcodes published by Chang and Chen and their coauthors (
Chang & Chen 2005b
; Chang
et al.
2008) are from
type
specimens of the
M. formosae
species group, this connection has never been established either explicitly or implicitly until the present study (
Table 1
). DNA barcodes from non-type specimens are also available for all species and subspecies in the
M. formosae
species group (see Chang
et al.
2008). These genetic data, together with all the published morphological descriptions, enable unambiguous identification.
Drawing a line between intraspecific and interspecific morphological variations is sometimes difficult in
Amynthas
and
Metaphire
. The studies regarding the
M. formosae
species group published after 2000 (as cited in this study) have collectively demonstrated an integrative taxonomic approach through which hypotheses regarding species are tested using morphological, molecular, biogeographical and, to some extent, ecological data. Considering the complexity of morphological variations and the huge numbers of described (and undescribed) species in
Amynthas
and
Metaphire
, and in order to prevent interminable arguments about synonyms, we strongly suggest preserving DNA-friendly samples on a regular basis and using an integrative taxonomic approach that combines morphological and molecular data when it comes to describing a new species of
Amynthas
or
Metaphire
that may raise debates about synonyms.