Zemao Gu

Myxobolus turpisrotundus (Myxosporea: Bivalvulida) spores with caudal appendages: investigating the validity of the genus Henneguya with morphological and molecular evidence

Spores of the myxozoan parasite Myxobolus turpisrotundus Zhang 2009 were observed for the first time bearing caudal appendages. Most spores had the typical Myxobolus spp. morphology, but approximately 10% of spores possessed a spore body that was slightly elongated with a short tail projecting from the spore valve. In other spores, the tail was much more clearly visible and elongate. The spore body of these unusual spores is consistent in morphology and dimension to the normal spores of M. turpisrotundus. Both spore types were found within individual cysts, and the small subunit ribosomal RNA (ssrRNA) gene sequence from parasite cysts of this type was nearly identical to the previously published sequence of M. turpisrotundus from allogynogenetic gibel carp Carassius auratus gibelio (Bloch). The phenomenon of Myxobolus spores with caudal appendages provides additional evidence that the use of this character to separate Myxobolus and Henneguya into distinct genera is not reflective of an evolutionarily accurate classification scheme. Phylogenetic analysis of ssrDNA sequence from Myxobolus and Henneguya species showed clustering of species in some locations of the tree, but ultimately these genera are intermixed. The use of a single character to delineate species in the two most species-rich myxozoan genera has been consistently challenged where DNA analyses are used. The present finding of a single species bearing both Myxobolus-type and Henneguya-type spores emphasizes the inadequacy of this classification scheme, and highlights the need for careful consideration of these variable characteristics when describing myxozoan species.

Haematopoietic necrosis of cultured Prussian carp, Carassius gibelio (Bloch), associated with Cyprinid herpesvirus 2

The members of the Alloherpesviridae are widespread among fish and frogs and have been grouped into four genera: Batrachovirus, Cyprinivirus, Ictalurivirus and Salmonivirus (Davison et al. 2009). Among them, the members of the Cyprinivirus can cause devastating diseases in fish culture. There are four known species in Cyprinivirus, named Anguillid herpesvirus 1 (AngHV-1) in European eel, Anguilla anguilla of the, Cyprinid herpesvirus 1 (CyHV-1) and Cyprinid herpesvirus 3 (CyHV-3) in common carp, Cyprinus carpio L., and koi carp (a variety of Cyprinus carpio), and Cyprinid herpesvirus 2 (CyHV-2) in goldfish, Carassius auratus (L.) (Hanson, Dishon & Kotler 2011). Recently, complete genomes of CyHV-1, CyHV-2 and CyHV-3 have been determined, and the structures of the genomes have been compared in detail (Davison et al. 2013). Besides the differences of the genomic structures, the three cyprinid herpesviruses also differ in the host range and clinical signs (Waltzek et al. 2005; Davison et al. 2013). Although both CyHV-1 and CyHV-3 infect common carp and koi carp, in comparison with waxy epidermal growth on the CyHV-1-infected carp, CyHV-3 infection results in carp nephritis and gill necrosis (Davison et al. 2013). Interestingly, common carp and koi carp are not susceptible to CyHV-2, which infects goldfish and produces herpesviral haematopoietic necrosis disease with lesions occurring in haematopoietic tissues, including kidney and spleen (Jung & Miyazaki 1995). In 1995, CyHV-2 was first reported as a severe pathogen of goldfish in Japan (Jung & Miyazaki 1995); thereafter, there have been a number of outbreaks in goldfish in other countries and areas, including USA (Groff et al. 1998; Goodwin et al. 2006a), Taiwan (Chang et al. 1999), Australia (Stephens, Raidal & Jones 2004) and the UK (Jeffery et al. 2007). Recently, our surveillance of CyHV-2 in goldfish cultured in China suggested that CyHV-2 has a wide geographic distribution in China (Li et al. 2013). Besides goldfish, most recently it has been reported that CyHV-2 caused massive mortality of wild-ranging Prussian carp, Carassius gibelio (Bloch), in the Elbe River in the Czech Republic (Danek et al. 2012). Despite many outbreaks of herpesviral haematopoietic necrosis diseases, there is no report in domestic cultured Prussian carp. Here, we report that CyHV-2 infection can cause massive mortality of Prussian carp cultured in domestic ponds in China. Prussian carp is an important commercial fish species, which has been cultured for more than 30 years in China. Its annual product has increased to more than 2 billion kg in China (Gui & Zhou 2010; Wang et al. 2011). During May to June 2012, the first epizootic was observed in Prussian carp cultured together with silver carp, Hypophthalmichthys molitrix (Valenciennes), and bighead carp, Aristichthys nobilis Correspondence L J Li, Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China (e-mail: lilijuan@mail.hzau.edu.cn) and J F Yuan, Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China (e-mail: jfyuan@mail.hzau.edu.cn)

Supplemental diagnosis of a myxozoan parasite from common carp Cyprinus carpio: Synonymy of Thelohanellus xinyangensis with Thelohanellus kitauei

Thelohanellus kitauei Egusa et Nakajima, 1981, was described from common carp Cyprinus carpio L. in Japan. In China, a myxosporean infecting the intestinal tissue of the same host species was described as Thelohanellus xinyangensis Xie, Gong, Xiao, Guo, Li et Guo, 2000, despite many similarities to T. kitauei. To examine the potential conspecificity of these species, a morphological and molecular investigation of T. xinyangensis was conducted. Comparing myxospore morphology, the mean spore length and width of each species is not identical between species, but ranges of dimensions overlap. These data are more suggestive of intraspecific variation than distinct species. Comparison of relative ratios of spore length to polar capsule length and spore width to polar capsule width of T. xinyangensis and T. kitauei reveal no differences and scanning electron microscopy reveals a smooth spore surface of T. xinyangensis, which is consistent with that of T. kitauei. Most convincingly, DNA sequences of the small subunit ribosomal RNA (ssrRNA) gene of the two species were identical. From the morphological and molecular biological data, we propose T. xinyangensis from the intestine of common carp is not a distinct species and is synonymous with T. kitauei.

Saprolegnia brachydanis, A New Oomycete Isolated from Zebra Fish

Saprolegnia brachydanis is described from zebra fish (Brachydanio rerio) in Wuhan, Hubei Province, China. The species is illustrated and compared with other species of the genus. The distinctive characteristics of S.brachydanis are the production of glomerulate oogonia wrapped around by predominantly monoclinous antheridia which can be up to eight in one oogonium. The oogonial stalks are short, straight, or curved and the antheridia, twisted, can enwind one or more oogonia. The oospores cannot mature or easily abort. Morphological features of the oomycete and the ITS sequence of its rDNA as well as the comparison with related species are discussed in this article.

First report of two Balantidium species from the Chinese giant salamander, Andrias davidianus: Balantidium sinensis Nie 1935 and Balantidium andianusis n. sp.

Two ciliated protozoa, Balantidium sinensis Nie 1935 and Balantidium andianusi n. sp., were isolated from the feces of a wild Chinese giant salamander (Andrias davidianus) captured from the mountainous area of Shiyan, Hubei Province, Central China in October 2006. It is the first report of Balantidium species inhabiting Cryptobranchoidea amphibians. The occurrence of B. sinensis in A. davidianus should be a new record because the type specimens were first discovered and named by Nie in 1935 from Rana nigromaculata and Rana plancyi. For the lack of enough descriptions of taxonomic features in the previous report, it was re-described in detail and compared with Nie’s type specimens and B. giganteum to complete the morphological descriptions in the present work. B. andianusi n. sp. was considered to be a new species based on its unique morphological characteristics, especially the high length/width ratio of the vestibulum (8:1). Comparisons were also made among Balantidium species that were found from urodele amphibians.

Study of Apiosoma piscicola (Blanchard 1885) occurring on fry of freshwater fishes in Hongze, China with consideration of the genus Apiosoma

Apiosoma piscicola (Blanchard 1885) was reported from fry of Carassius auratus (Var. pengze) and Ctenopharyngodon idella during parasite surveys in May 2005 and June 2006 at Hongze Lake Fish Hatchery, Jiangsu province, China. Twelve morphometric parameters were used to describe this peritrich in detail in the present study and comparisons were made with other reports. Its synonyms, Glossatella cylindriformis (Chen 1955) and Apiosoma magna (Banina 1968), were clarified based on reliable data. A. piscicola was still considered somewhat host-specific by us, especially to cyprinids, although it shows a quite wide limit of host variability. The telotroch was also observed, and its structures were described herein. Besides, the difficulties of the generic taxonomy were discussed and some suggestions were given.

Morphological and molecular characterization of Thelohanellus macrovacuolaris n. sp. (Myxosporea: Bivalvulida) infecting the palate in the mouth of common carp Cyprinus carpio L. in China

Thelohanellus macrovacuolaris n. sp. is described during a survey on myxozoan diversity of common carp Cyprinus carpio L. in China. It is characterized by the presence of round or ellipsoidal plasmodium in the palate in the mouth of host. Mature spores were pyriform in frontal view, lemon shaped in lateral view, measuring 21.6±0.9 (19.3-23.8) long, 12.5±0.7 (10.3-13.6) wide, and 10.2±0.4 (9.8-11.8) thick. Most spores were surrounded by the membrane sheath. Single polar capsule was round with an apophysis at its top end presented close to apex of spore, measuring 9.1±0.6 (8.0-10.0) in length, 8.6±0.5 (7.8-9.6) in width. Polar filaments coiled, with 7 to 8 turns. A large, round iodinophilous vacuole was present, with 5.8-7.5 in diameter. The present species is morphologically distinct from all other Thelohanellus species. The BLAST search indicated that the newly obtained small subunit ribosomal RNA (ssrRNA) gene sequence of T. macrovacuolaris n. sp. did not match any available sequences in GenBank. Phylogenetically, T. macrovacuolaris n. sp. was placed sister to Thelohanellus wangi in the Thelohanellus clade. Both morphology and ssrRNA gene sequence data revealed that the present parasite is a new species of genus Thelohanellus.

New type of pathogenicity of Thelohanellus kitauei Egusa & Nakajima, 1981 infecting the skin of common carp Cyprinus carpio L.

Thelohanellus kitauei Egusa & Nakajima, 1981 is a common parasite infecting the intestine of common carp Cyprinus carpio L., resulting in mass mortality or loss of economic value of cultured carp. In the present study, T. kitauei infecting host skin was detected. The morphological, molecular and histological data of this parasite in the new organ record are presented. Morphological analysis showed the current specimen morphologically similar to T. kitauei from the intestine. Despite the spore length and polar capsule length of the current specimen larger than those of T. kitauei from the intestine, ranges of dimensions overlap, which is more suggestive of intraspecific variation than distinct species. BLAST search revealed that the present small subunit ribosomal DNA gene sequence is identical to those of T. kitauei. Histologically, most of spores distributed in the stratum spongiosum of dermis, and some spores in the strata compactum of host skin were also observed. Above all, both morphology and molecular analysis indicated that the current species from the skin of common carp is conspecific with T. kitauei from the intestine of carp and organ habitats transfer of T. kitauei from host intestine to skin may have occurred.

First report of Mucor circinelloides occurring on yellow catfish (Pelteobagrus fulvidraco) from China

Infected yellow catfish (Pelteobagrus fulvidraco) were sent from Niushan Lake Fishery, Hubei Province, China, to our laboratory for diagnosis. Macroscopic daffodil yellow mold was observed on the heads and fins of the fish and one Mucor species was isolated. Based on the morphological and molecular analysis, the species was identified as Mucor circinelloides. Its optimum growth temperature was 30 degrees C and it could not grow at 40 degrees C. The infectivity results showed wound infection could cause 100% cumulative mortalities at all experimental CFU (10(6), 10(7) and 10(8)). The cumulative mortalities of the intraperitoneal infection increased along with the sporangiospore concentrations; the highest mortality was 90% with 10(8) CFU. Histopathological studies showed M. circinelloides could cause a series of pathological changes in the host tissues and they disseminated in different viscera, perhaps by the blood. This is the first report of M. circinelloides infection in yellow catfish.

Description of a New Freshwater Ciliate Epistylis wuhanensis n. sp. (Ciliophora, Peritrichia) from China, with a Focus on Phylogenetic Relationships within Family Epistylididae

Two populations of Epistylis wuhanensis n. sp., a new freshwater peritrich ciliate, were isolated from different freshwater ponds located in Hubei, China. Their morphological characteristics were investigated using live observation, protargol impregnation, and scanning electron microscopy (SEM). Specimens from the two populations showed identical arrangement of the infraciliature and identical small subunit ribosomal RNA (SSU rRNA) gene and ITS1‐5.8S‐ITS2 sequences. The zooids present bell‐shaped and 90–175 × 27–54 μm in vivo. Macronucleus is variable in shape and located in the middle of cell. Pellicle is usually smooth with 139–154 and 97–105 striations above and below the trochal band, respectively. SSU rRNA gene and ITS1‐5.8S‐ITS2 sequences of E. wuhanensis n. sp. did not match any available sequences in GenBank. Phylogenetically, E. wuhanensis n. sp. clusters with the other Epistylis within the family Epistylididae, but is distinct from the major clades of Epistylis. Above all, the morphological characteristics and molecular analyses support that the present Epistylis is a new species. Expanded phylogenetic analyses of sessilids based on both SSU rRNA gene sequences and ITS1‐5.8S‐ITS2 sequences reveal that the genus Epistylis consists of Epistylis morphospecies and taxonomic revision of the genus is needed.