Morphological and genetic characterization of Kudoa whippsi (Myxosporea: Multivalvulida) from Cheilodactylus zonatus in the western Pacific Ocean off Japan, and two new Kudoa spp. (K. akihitoi n. sp. and K. empressmichikoae n. sp.) from Acanthogobius hasta in the Sea of Ariake, Japan

Abstract

Molecular genetic characterization using the ribosomal RNA (rDNA) gene accrues a wealth of knowledge regarding the true nature of species diversity of Kudoa Meglitsch, 1947 (Myxozoa: Myxosporea: Multivalvulida) and the biogeographical relationships of isolates from different host fish and sea areas. In the present study, we characterized morphologically and genetically three Kudoa spp. with four shell valves and polar capsules (SV/PC), forming pseudocysts in the myofiber of trunk muscles of Cheilodactylus zonatus or Acanthogobius hasta in the natural seawater around Japan. Myxospores from C. zonatus fished in the western Pacific Ocean off Kochi, Japan, were unequal quadrangular pyramids with one large and three smaller SV/PC, morphologically closest to Kudoa whippsi recorded in various pomacentrid and apogonid fish from the Australian Coral Sea. The 18S and 28S rDNA nucleotide sequences of the Japanese isolate were highly similar to some Australian K. whippsi isolates, but also displayed less similarity to other K. whippsi isolates from the same sea mainly due to instability of nucleotides at certain base positions and/or segments of different isolates. All the K. whippsi isolates including the present Japanese isolate, however, were distinct from Kudoa gunterae, K. whippsi's closest kudoid species in morphology, molecular phylogeny, and biogeography. Our detection of K. whippsi from C. zonatus in the natural seawater around Japan is a new host and geographical record. Kudoid myxospores from A. hasta from the Sea of Ariake, a deep bay of the western part of Japan, exhibited two morphotypes, one resembling K. whippsi and the other Kudoa quadricornis with distinct posteriolateral SV projections. However, rDNA nucleotide sequencing revealed that these two Kudoa spp. were distinct from any known congeners; thus, Kudoa akihitoi n. sp. and Kudoa empressmichikoae n. sp. were erected. The morphological differentiation of K. akihitoi n. sp. from multiple Kudoa spp. with scalene stellate myxospores containing one large and three smaller SV/PC was difficult, whereas K. empressmichikoae n. sp. with spherical spore bodies extending small posteriolateral SV projections was distinct from known congeners with similar but elongated spore bodies and PC, i.e., K. quadricornis and Kudoa paraquadricornis, found in the trunk muscle of carangid fish from the Australian Coral Sea.

Morphological and Molecular Characteristics of Kudoa viseuensis n. sp. (Myxosporea: Multivalvulida), Found in the Muscle of Batrachoides surinamensis (Teleostei: Batrachoididae) in the Brazilian Amazon Region

“…The new parasite is clearly aligned with other Kudoa species, although this is the first kudoid species from a Brazilian estuary for which molecular data have been obtained. Infection by this new parasite is characterised by the formation of a pseudocyst in the musculature of its host (Yokoyama et al 2012;Kasai et al 2016, Kasai et al 2017Sakai et al 2018). The infection of Kudoa species presents muscle tissue tropism, as observed in the present study, with Kudoa viseuensis n. sp.…”

“…Although the morphology of the spores is essential for the taxonomic classification of species, the phenotypic similarities among kudoid species and the intraspecific variation found in many cases hampers the reliable diagnosis of species based solely on morphology (Urawa et al 2009, Burger and Adlard 2010, Heiniger and Adlard 2012, Heiniger et al 2013. Phylogenetic analyses have provided a better understanding of the diversity and biogeographic relationships among these parasites and their hosts (Urawa et al 2011, Kasai et al 2017, Sakai et al 2018.…”

Immunohistochemical Study of Four Fish Tumors

“…Thus, differential diagnoses involved hyperplastic, hypertrophic, and neoplastic conditions, such as lymphocystis disease (Essbauer and Ahne ), histozoic myxosporidian infections (Kasai et al. ), papilloma, fibroma, neurofibroma, leiomyoma (Oryan et al. ), rhabdomyoma, angioleiomyoma (Marino et al.…”

Morphometric and molecular characterization of Kudoa encrasicoli n. sp. (Myxozoa: Myxosporea) from the European anchovy, Engraulis encrasicolus (L.) (Clupeiformes: Engraulidae)

“…Moran et al, 1999 andEiras et al, 2014). Something similar occurs in the case of K. empressmichikoae Kasai, Setsuda & Sato, 2017, the myxospores of which have furthermore a spherical body with posterolateral SV projections (Kasai et al, 2017). Regarding species with myxospores exhibiting 4 PCs unequal in size, K. (Whipps et al, 2003a;Yokoyama et al, 2004;Whipps & Kent 2006;Burger & Adlard 2010;Heiniger et al, 2013;Eiras et al, 2014;Kasai et al, 2016bKasai et al, , 2017, and from K. valamugili Kalavati & Anuradha, 1993 which has quadrate myxospores in apical view and SVs with curved edges (morphology reviewed by Eiras et al, 2014).…”

“…(from Mugil cephalus), which have myxospores with 2 SVs and PCs, have led to amend the genus Kudoa to include myxospores having 2-13 (mostly 4) SVs and PCs (Casal et al, 2019). It comprises more than 100 nominal species, most of them being histozoic myxozoans typically infecting the musculature of a large range of fish species (Moran et al, 1999;Eiras et al, 2014;Kristmundsson & Freeman 2014;Mansour et al, 2014Mansour et al, , 2015Shirakashi et al, 2014;Yokoyama et al, 2014;Abdel-Baki et al, 2016;Azevedo et al, 2016;Shin et al, 2016;Kasai et al, 2016aKasai et al, , 2016bKasai et al, , 2017. Some of these species (e. g. K. thyrsites (Gilchrist, 1923) and others) are economically important because they can form macroscopic cysts in the host's muscle tissues and/or cause the ''soft flesh'', ''milky flesh'' or ''jelly flesh'' syndrome, a postmortem myoliquefactive degeneration negatively affecting the flesh texture of certain severely infected species (Moran et al, 1999;Levsen et al, 2008;Henning & Manley 2012;Eiras et al, 2014;Marshall et al, 2016).…”