枝腺科吸虫一新亚种(吸虫纲:复殖目)

本文记述了寄生于蛙类的枝腺科吸虫一新亚种——柔弱似侧殖吸虫四川亚种Pleurogenoides tener sichuanensis subsp.nov,。新亚种肠支伸至睾丸之前;卵巢近圆形;子宫经虫体左侧前伸,并在肠管、食道和口吸盘区域形成盘曲;生殖孔位于食道水平等特征而不同于指名亚种Pleurogenoides tener tener。新亚种具有食道和子宫末段,睾丸并列,生殖孔位于食道水平等特征而区别于近似种Pleurogenoides ifranensis。     

关于牛首科吸虫的分类地位(吸虫纲:复殖目:牛首科)

关于牛首科（即腹口类）吸虫的分类地位,一直存在着意见分歧,一种观点认为牛首科所代表的腹口类与前口类应作为两个分别独立而并列的分类单元,另一种观点认为腹口类在分类上应归于前口类中的某一分类单元。本文通过对牛首科吸虫的特征分析以及与前口类吸虫的比较,发现牛首科吸虫在成虫,毛蚴,胞蚴,尾蚴,宿主类型,染色体等方面都与前口类有显著差别,因而支持前一种分类观点,不应将牛首科放入前口类中。     

湖南鸣禽的滑口吸虫研究(复殖目:短咽科)

对湖南省鸣禽寄生虫调查中检获短咽科滑口吸虫属Ｇｌａｐｈｙｒｏｓｔｏｍｕｍ虫种５个,其中有３个新种,画眉滑口吸虫Ｇｌａｐｈｙｒｏｓｔｏｍｕｍ ｇａｒｒｕｌｕｍ ｓｐ．ｎｏｖ。,两吸盘约等大,睾丸偏于体右侧,卵黄腺始于腹吸盘水平;湖南滑口吸虫虫体较短小,体表在腹吸盘前被小棘,口腹吸盘比约１．０：１．５,睾丸偏体左侧,卵黄腺起始于口吸盘后缘至咽水平,小型滑口吸虫Ｇ．ｍｉｎｏｒ ｓｐ．ｎｏｖ虫体较小,体表     

双盘属吸虫一新种记述(复殖目:微茎科)

微茎类吸虫中的双盘属Diacetabulum Belopolskaia,1952是在苏联剖检灰鹬Tringa incana brevipes的肠中获得并建属定种。迄今本属在世界上除在美国的翻石鹬Arenaria interpres morinella肠内获得另一种利氏双盘吸虫D.riggini(Dery,1958)外,未见有其他虫种及地区的报道。作者在汕头市剖检鸟类获得双盘属的一个新种,定名为汕头双盘     

短咽属吸虫一新种的研究(复殖目:短咽科)

本文记述寄生于四川省雅安市四川短尾鼩肠道内的短咽科吸虫一新种——雅安短咽吸虫(Brochylaima yaanensis sp.nov.).模式标本保存于四川省雅安地区卫生防疫站。     

马蹄属一新种及其囊蚴在体外的培养(吸虫纲:微茎科)

1986年6—7月间,作者于吉林省敦化市检查东北(虫刺)蛄Cambaroides dauricus时,于其鳃及肝内查得马蹄属Maritrema Nicoll., 1907吸虫囊蚴,经感染雏鸭、大白鼠、犬及人工体外培养,结果仅于雏鸭及体外培养获得成虫。检查当地家鸭Anas platyrhynchos domestica亦获得成虫,经鉴定认为是一新种,定名为吉林马蹄吸虫,新种Maritrema jilinensis sp.nov.。现将结果报道于下。文内量度以mm为单位。模式标本保存于长春白求恩医科大学寄生虫学教研室。     

中国微茎类吸虫的研究——Ⅹ.云南省两新种的报道(复殖目:微茎科)

微茎类吸虫的囊蚴及成虫广泛寄生于咸、淡水领域的甲壳类及各种动物体内,广东及广西等地虫种很丰富。云南省地处我国西南高原,位处边境,山高林密溪河纵横,地形复杂,甲壳类及动物种类繁多。但过去有关微茎类吸虫仅钟惠澜等,1975论及当地淡水蟹体内有微茎类吸虫囊蚴寄生,但未有进一步作动物饲喂感染或体外培养以获得成虫。故云南省有关该类虫种的材料极贫乏。作者近年曾到云南省进行调查采集,初步整理出微茎科吸虫中两个属内的两个新种。     

四川鱼类寄生吸虫Ⅱ.尾孔科、孔肠科和鳞肉科一新属四新种(吸虫纲:复殖目)

本文描述了采自四川鱼类肠道的复殖吸虫一新属四新种,它们是:1.(鱼兆)尾孔吸虫,新种Urotrema glyptothoraci sp.nov.,2.裂腹鱼斜孔吸虫,新种Plagioporus(Plagioporus)schizothoraci sp.nov.,3.异巢斜孔吸虫,新种Plagioporus(Plagioporus)allovaris sp.nov.,4.类宫殖属,新属Hysterogonoidet gen.nov.及模式种——双囊类宫殖吸虫,新种Hysterogonoldes disaccus sp.nov.。这些新属新种分别隶于尾孔科Urotrematidae、孔肠科Opecoelidae和鳞肉科Lepocreadiidae。     

Discovery of Maritrema obstipum (Digenea: Microphallidae) from migratory birds in Korea

Adults of Maritrema obstipum (Digenea: Microphallidae) were found in the intestines of 4 species of migratory birds, including the sanderling (Crocethia alba), Kentish plover (Charadrius alexandrines), Mongolian plover (Charadrius mongolus), and red-necked stint (Calidris ruficollis), collected from Yubu Island, Chungcheongnam-do, Korea. The worms of were 451 × 265 μm in size, and were easily identifiable as Maritrema species by the presence of the cirrus sac, and the ring-like distribution of the vitellaria. More specifically, the ejaculatory duct curved posteromedially, and the 2 parts of vitelline follicles were found to be distinct at the posterior end. The eggs were brown-colored, and 19.8 × 12.3 μm in size. All these findings implicated M. obstipum as the pertinent species of the worms. Beside these, adult worms of Gynaecotyla squatarolae, Parvatrema duboisi, and Acanthoparyphium sp. were also discovered. This is the first report establishing migratory birds as the natural definitive hosts for M. obstipum.     

Clonal diversity of the marine trematode Maritrema novaezealandensis within intermediate hosts: the molecular ecology of parasite life cycles

We quantified the clonal diversity of the New Zealand marine trematode Maritrema novaezealandensis (n = 1250) within Zeacumantus subcarinatus snail (n = 25) and Macrophthalmus hirtipes crab (n = 25) intermediate hosts using four to six microsatellite loci, and investigated the potential biological and physical factors responsible for the observed genetic patterns. Individual snails harboured one to five trematode genotypes and 48% of snails were infected by multiple parasite genotypes. Overall, the number of parasite genotypes did not increase with snail size, but was highest in intermediate-sized snails. Significantly larger numbers of parasite genotypes were detected in crabs (relative to snails; P < 0.001), with 16-25 genotypes recovered from individual crabs. Although crabs are typically infected by small numbers of cercariae sourced from many snails, they are occasionally infected by large numbers of cercariae sourced from single snails. The latter cases explain the significant genetic differentiation of trematode populations detected among their crab hosts (F(ST) = 0.009, P < 0.001). Our results suggest that the timing of infection and/or intraspecific competition among parasite clones within snails determine(s) the diversity of parasite clones that snails harbour. The presence of a large number of infected snails and tidal mixing of cercariae prior to infection results in crabs potentially harbouring hundreds of parasite genotypes despite the crabs' territorial behaviour.     

Ribosomal DNA sequence characterization of Maritrema cf. eroliae Yamaguti, 1939 (Digenea: Microphallidae) and its life cycle

The microphallid Maritrema eroliae parasitizes shore birds in marine ecosystems while its larval stages infect mud snails and crustacean hosts. Because it is difficult to morphologically distinguish between larvae of M. eroliae and other microphallids co-occurring in the same habitat, partial nucleotide sequences of the ribosomal DNA (rDNA), including the 28S and 18S in addition to complete sequences of ITS1 and ITS2, were scrutinized. This analysis was used to establish the snail-crab link in the life cycle of M. cf. eroliae . The rDNA 28S, 18S, and ITS sequences of metacercariae from the crab Xantho exaratus and sporocysts from the snail Clypeomorus bifasciata were compared. Sequence alignment demonstrated that the sporocyst and metacercaria may belong to M. eroliae and suggested a new second intermediate host for M. eroliae , the crab X. exaratus . The phylogenetic positions of the larval stages were determined by comparing the 28S, 18S, and ITS sequences with those of other trematodes available in GenBank. The phylogenetic trees confirmed the position of M. cf. eroliae within the Microphallidae and found it to be closely related to Maritrema heardi and Maritrema neomi. The present study represents the first molecular study correlating the larval stages in the life cycle of M. cf. eroliae using partial sequences of 28S and 18S in addition to complete ITS1 and ITS2 sequences. Furthermore, the sequences elucidated the evolutionary relationship of M. cf. eroliae to other microphallids.     

Discovery of Maritrema jebuensis n. sp. (Digenea: Microphallidae) from the Asian Shore Crab, Hemigrapsus sanguineus, in Korea

Maritrema spp. (Digenea: Microphallidae) are parasites of birds, but have not been found in the Republic of Korea. In this study, metacercariae of Maritrema sp. were discovered in the Asian shore crab, Hemigrapsus sanguineus, caught in the mud-flats of Jebu-do, Hwasung-gun, Gyeonggi-do, and the adult flukes were confirmed by experimental infection into mice. Based on the symmetric ribbon-like vitellarium, adult flukes of Maritrema sp. were identified, but did not belong to previously described species in terms of the following morphologic characteristics: ceca reaching to the lateral wall at the anterior border of the ovary; ventral sucker larger than oral sucker; a prominent metraterm; and vitellarium forming a complete ring. Hence, we named this microphallid M. jebuensis n. sp. after the island where the second intermediate hosts were collected. From this study, it has been shown that Maritrema sp. is distributed in Korea and transmitted by the Asian shore crab, H. sanguineus.     

In vitro excystment of the metacercaria of Maritrema arenaria (Digenea: Microphallidae)

Metacercarial cysts of Mantrema arenaria were subjected to a solution containing trypsin and bile salts at 41°C. This treatment induced intense metacercarial activity and after 15 min metacercariae burst through their cyst walls and emerged. Electron microscopy demonstrated that during the process of excystment the inner layer of the cyst wall changed from a compact to a loose fibrous state. Experiments showed that only cysts containing viable metacercariae underwent this change whereas cysts which had been forcibly vacated before treatment did not. This indicated that the structural change of the inner layer of the cyst wall could not be attributed to the excystment medium. Also there was much less acid phosphatase activity in and on the surface of newly excysted metacercariae compared with encapsulated specimens. It was concluded that the excystment medium induced physical activity in, and the release of enzymic material by, the metacercariae. Together these activities rendered the cyst wall soft and susceptible to rupture by physical pressure.     

Vertical distribution of trematode cercariae Cryptocotyle concavum (Heterophyidae) and Maritrema subdolum (Microphallidae) in the water column

The effect of gravity and light on vertical distribution of Cryptocotyle concavum (Heterophyidae) and Maritrema subdolum (Microphallidae) cercariae in the water column was experimentally studied. Maximal larvae concentration was found in zones where the highest probability of contact with potential host is considered.     

Cercaria caribbea LVIII Cable, 1963 (Digenea: Cyathocotylidae) in the Republic of Korea and its surface ultrastructure

Cercaria caribbea LVIII Cable, 1963 (Digenea: Cyathocotylidae) was detected from a brackish water gastropod species (Cerithideopsilla cingulata) in a coatal area of Shinan-gun, Jeollanam-do (Province), the Republic of Korea, and its surface ultrastructure was studied using a scanning electron microscope. The cercariae were found freely swimming or enveloped within daughter sporocysts when the snail host was mechanically broken. They were morphologically characterized by a linguiform and ventrally concave body, a long and bifurcated tail, and the presence of a holdfast (=tribocytic) organ posterior to the ventral sucker. On the whole ventral and dorsal surfaces, peg-like tegumental spines were densely distributed. Around the oral sucker, several sensory papillae, each with a short cilium, were distributed, and on the tail, sensory papillae, each with an extensively long cilium, were observed. This is the first record describing a cyathocotylid cercaria from a brackish water gastropod in the Republic of Korea.     

Parvatrema duboisi (Digenea: Gymnophallidae) Life Cycle Stages in Manila Clams,Ruditapes philippinarum,from Aphae-do (Island), Shinan-gun,Korea

Life cycle stages, including daughter sporocysts, cercariae, and metacercariae, of Parvatrema duboisi (Dollfus, 1923) Bartoli, 1974 (Digenea: Gymnophallidae) have been found in the Manila clam Ruditapes philippinarum from Aphae-do (Island), Shinan-gun, Jeollanam-do, Korea. The daughter sporocysts were elongated sac-like and 307–570 (av. 395) μm long and 101–213 (av. 157) μm wide. Most of the daughter sporocysts contained 15–20 furcocercous cercariae each. The cercariae measured 112–146 (av. 134) μm in total length and 35–46 (av. 40) μm in width, with 69–92 (av. 85) μm long body and 39–54 (av. 49) μm long tail. The metacercariae were 210–250 (av. 231) μm in length and 170–195 (av. 185) μm in width, and characterized by having a large oral sucker, genital pore some distance anterior to the ventral sucker, no ventral pit, and 1 compact or slightly lobed vitellarium, strongly suggesting P. duboisi. The metacercariae were experimentally infected to ICR mice, and adults were recovered at day 7 post-infection. The adult flukes were morphologically similar to the metacercariae except in the presence of up to 20 eggs in the uterus. The daughter sporocysts and metacercariae were molecularly (ITS1–5.8S rDNA-ITS2) analyzed to confirm the species, and the results showed 99.8–99.9% identity with P. duboisi reported from Kyushu, Japan and Gochang, Korea. These results confirmed the presence of various life cycle stages of P. duboisi in the Manila clam, R. philippinarum, playing the role of the first as well as the second intermediate host, on Aphae-do (Island), Shinan-gun, Korea.     

Impact of microphallid trematodes on the survivorship, growth, and reproduction of an isopod (Cyathura carinata)

Crustaceans are second intermediate hosts to several microphallid species (Trematoda). Some of these parasites are potentially pathogenic or manipulative. A laboratory experiment was performed to assess the impact of microphallids on the survival, growth and fecundity of Cyathura carinata, a protogynous hermaphroditic isopod, widespread within European estuaries. For nearly 12 weeks, experimental populations of infected and non-infected isopods were kept at 25 °C. C. carinata carrying microphallid cysts showed higher mortality rates than non-infected specimens and were not able to produce embryos. The reduced fecundity of infected isopods could be caused by parasite-induced castration and/or by mating failure due to behavioural modifications in one of the sexes. It might also be associated with lower growth rates and lower moulting frequencies, since infected C. carinata were significantly smaller than the non-infected after 9 weeks. This may imply a setback for the isopods to achieve sexual maturity (which may also affect the population sex ratio) and for females to lay their eggs in the marsupia. Regardless of the mechanisms involved, microphallids may have severe consequences for their host populations, through negative effects on survival, growth and fecundity. For species with direct development, such as C. carinata, parasite-induced reproduction failure may contribute to temporal fluctuations of abundance. Based on the present results, it is recommended to include parasites as an important factor influencing host populations from shallow-water ecosystems.