Fauna Ryukyuana
ISSN 2187-6657
http://w3.u-ryukyu.ac.jp/naruse/lab/Fauna_Ryukyuana.html
First record of a gill parasite, Dactylogyrus extensus (Monogenea: Dactylogyridae)
co-introduced with common carp into Okinawa-jima Island, southern Japan
1
Masato Nitta1, 2 & Kazuya Nagasawa1
Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima,
Hiroshima 739-8528, Japan
2
Corresponding author ([email protected])
Abstract. Dactylogyrus extensus (Monogenea:
Dactylogyridae) is described from the gills of the
common carp, Cyprinus carpio, from the Hija River,
Okinawa-jima Island, Okinawa Prefecture, southern
Japan. This monogenean is undoubtedly an alien
species introduced along with C. carpio to the island
from an unknown locality.
Introduction
Currently, about 20 species of alien freshwater fishes
have been established on Okinawa-jima Island, one
of the Ryukyu Islands, southern Japan (Shimadzu
2011). Parasites have also been co-introduced along
with such aliens to this island, with the following
four monogenean species known to have been
established: Cichlidogyrus halli (Price & Kirk, 1967),
C. sclerosus Paperna & Thurston, 1969, C. tilapiae
Paperna, 1960, and Heteropriapulus heterotylus
(Jogunoori, Kritsky & Venkatanarasaiah, 2004)
(Maneepitaksanti & Nagasawa 2012; Nitta &
Nagasawa 2013). The common carp (Cyprinus
carpio Linnaeus, 1758) is one species of freshwater
fish introduced to Okinawa-jima Island (Kochi
2003). During a survey of freshwater fish parasites
of this island, the dactylogyrid monogenean,
Dactylogyrus extensus Mueller & Van Cleave, 1932,
was collected from a river-caught specimen of C.
carpio. The present note reports on this monogenean
as a new record from Okinawa-jima Island.
Material and methods
One common carp (191 mm in standard length [SL])
was collected using a cast net from the Hija River at
Misato, Okinawa City, Okinawa-jima Island,
Okinawa Prefecture, Japan on 26 January 2013. The
fish was brought alive to the laboratory of the
Ryukyu University Museum (Fujukan) and
examined for ectoparasites under a dissecting
microscope. One dactylogyrid specimen was
collected from the gill and fixed in ammonium
picrate glycerin under coverslip pressure (Lim 1991).
At the laboratory of Hiroshima University, this
specimen’s whole-body morphology was observed,
then dehydrated through a graded ethanol series,
cleared in xylene, and mounted in Canada balsam.
Drawings were made with the aid of a drawing tube
fitted on an Olympus BX51 light microscope. Axes
of measurements of sclerotized parts are presented in
Fig. 1. The male copulatory organ and accessory
piece lengths were measured from images taken by
an Olympus DP20 microscope digital camera at a
magnification of ×1,000 using ImageJ software
(version 1.48i). The numbering of marginal hook
pairs follows Llewellyn (1963). The voucher
specimen is deposited in the Platyhelminthes
collection of the National Museum of Nature and
Science, Tsukuba City, Ibaraki Prefecture, Japan
(NSMT-Pl).
Species account
Dactylogyrus extensus Mueller & Van Cleave,
1932
(Fig. 2)
Host.
Cyprinus
carpio
Linnaeus,
1758
(Cypriniformes: Cyprinidae).
Locality. Hija River (26°21'11"N, 127°48'28"E),
Misato, Okinawa City, Okinawa Prefecture.
Material. One specimen (NSMT-Pl 6169).
Site of infection. Gill.
Description. Body (Fig. 2A) length 1678 µm,
median width 219 µm. Three pairs of head organs.
Two pairs of eye-spots with some dissociated eyes.
Pharynx length 113 µm, width 105 µm. Esophagus
absent, bifurcate intestine with branches confluent
just posterior to testis. Testis pyriform, postovarian.
Vas deferens arising from anterior region of testis,
looped around left intestinal caeca dorsoventrally.
Seminal vesicle expanded before entering into male
copulatory organ. Two prostatic reservoirs both
saccate. Vesicle reported in Ogawa & Egusa (1979)
not observed. Male copulatory organ (Fig. 2K) tubelike, slender, length 86 µm. Sclerotized accessory
piece (Fig. 2K) rod-shaped, top brash-shaped, length
54 µm. Ovary in mid-body. Vaginal armament
unsclerotized; vaginal pore located on right body
surface, vaginal duct connected right side of oviduct.
1
2
Fauna Ryukyuana, 26: 1–4.
Oviduct arising from anterior side of ovary,
continuous to oötype and uterus. Mehlis’ gland
connected to top of oviduct. Vitelline system coextensive with intestinal caeca.
Haptor length 178 µm, width 193 µm. Single pair
of anchors (Fig. 2B), total length 84 µm, length to
notch 73 µm, outer root length 16 µm, inner root
length 27 µm, point length 19 µm. Dorsal bar (Fig.
2C), total length 47 µm, total width 14 µm, median
width 10 µm. Ventral bar absent. Marginal hooks 7
pairs; hook lengths: pair I (Fig. 2D) 32 µm; pair II
(Fig. 2E) 34 µm; pair III (Fig. 2F) 36 µm; pair IV
(Fig. 2G) 34 µm; pair V (Fig. 2H) 35 µm, pair VI
(Fig. 2I) 33 µm; pair VII (Fig. 2J) 34 µm. Pair of
needles (Fig. 2L) located near tip of second hook,
length 10 µm.
Remarks. The morphology and measurements of
sclerotized structures of the present specimen agree
with the original and subsequent descriptions of D.
extensus Mueller & Van Cleave, 1932 (e.g. Mueller
& Van Cleave 1932, Ogawa & Egusa 1979, Long
2000, Gussev et al. 2010). The vesicle reported by
Ogawa & Egusa (1979) could not be observed
because the specimen was not stained.
Dactylogyrus extensus is a gill parasite of C.
carpio, being widely distributed in Europe, Asia, and
North America (Gussev et al. 2010). In Japan, this
monogenean is known to occur in 10 prefectures
including Hokkaidō, Nīgata, Nagano, Gunma,
Ibaraki, Chiba, Shizuoka, Tōkyō, Shiga, and
Hiroshima (Imada et al. 1976, Nakatsugawa &
Muroga 1977, Ogawa & Egusa 1979, 1982, Ogawa
1994), and this paper represents the first record of the
monogenean from Okinawa Prefecture. Eight
species of Dactylogyrus, i.e., D. anchoratus
(Dujardin, 1845), D. biwaensis Ogawa & Egusa
1982, D. extensus, D. falciformis Achmerow, 1952,
D. minutus Kulwieć, 1927, D. mrazeki Ergens &
Dulmaa, 1969, D. sahuensis Ling, 1973, and D.
takahashii Ogawa & Egusa 1982, have been
recorded from common carp in Japan (Imada et al.
1976, Nakatsugawa & Muroga 1977, Ogawa &
Egusa 1977, 1979, 1982, Ogawa 1994). Only one
specimen of D. extensus was collected from the
common carp examined in this study.
Cyprinus carpio is not native to Okinawa-jima
Island but is believed to have been introduced before
the 19th century (Kochi 2003). Recently, common
carp including koi carp are widely distributed on
Okinawa-jima Island (Shimadzu 2011). The origin
of the introduced carp is unknown, but since the
native host of D. extensus is C. carpio (Gussev et al.
2010), this monogenean is undoubtedly an
introduced species on Okinawa-jima Island.
Acknowledgments
We thank Daisuke Uyeno, Kagoshima University,
for help with fish sampling. We are also grateful to
Takeshi Sasaki, University Museum Fujukan,
University of the Ryukyus (UR), for providing
laboratory facilities. This study was partially
supported by JSPS KAKENHI grants (no. 15J05777
to M. N. and no. 15K07527 to K. N.). Thanks are due
to Pavel I. Gerasev, Russian Academy of Sciences,
Kazuo Ogawa, Meguro Parasitological Museum, and
Tohru Naruse, UR, for useful comments on the
manuscript.
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Fig. 1. Dactylogyrus extensus Mueller & Van Cleave, 1932. NSMT-Pl 6169. A, whole mount (dorsal view); B, anchor; C,
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1.
Dactylogyrus extensus Mueller & Van Cleave, 1932. NSMT-Pl 6169. A,
(
); B,
; C,
; D,
1 ; E,
2 ; F,
3 ; G,
4 ; H,
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6 ; J,
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; L,
.
: apl,
; atl,
;
bmw,
; btl,
; btw,
; cl,
; hl,
; irl,
; ltn,
;
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; orl,
; pl,
.
[Report] Nitta & Nagasawa: Dactylogyrus extensus from Okinawa-jima Island
3
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比謝川で採集された外来魚コイに寄生してい
た外来単生類コイユビガタムシ (単生類: ユビ
ガタムシ科): 沖縄県初記録
新田理人
1, 2
·長澤和也
1
〒739-8528 広島県東広島市鏡山1-4-4 広島大学
大学院生物圏科学研究科
2
通信著者 ([email protected])
1
.
carpio Linnaeus, 1758
Cyprinus
2 (
Dactylogyrus extensus
Mueller & Van Cleave, 1932
)
2 (
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