Alejandra G. Jaramillo
Jacob E. Ashford
Stephen W. Feist
Kevin D. Lafferty
Michael L. Kent
Justin L. Sanders
2015
<p><span>Two myxozoan species were observed in the kidney of topsmelt, </span><i><span class="genus-species">Atherinops affinis</span></i><span>, during a survey of parasites of estuarine fishes in the Carpinteria Salt Marsh Reserve, California. Fish collected on 3 dates in 2012 and 2013 were sectioned and examined histologically. Large extrasporogonic stages occurred in the renal interstitium of several fish from the first 2 collections (5/8, 11/20, respectively) and, in some fish, these replaced over 80% of the kidney. In addition, presporogonic and polysporogonic stages occurred in the lumen of the renal tubules, collecting ducts, and mesonephric ducts. The latter contained subspherical spores with up to 4 polar capsules, consistent with the genus </span><i>Chloromyxum</i><span>. For the third collection (15 May 2013, n = 30), we portioned kidneys for examination by histology, wet mount, and DNA extraction for small subunit ribosomal (SSU rDNA) gene sequencing. Histology showed the large extrasporogonic forms in the kidney interstitium of 3 fish and showed 2 other fish with subspherical myxospores in the lumen of the renal tubules with smooth valves and 2 spherical polar capsules consistent with the genus </span><i>Sphaerospora. Chloromyxum</i><span>-type myxospores were observed in the renal tubules of 1 fish by wet mount. Sequencing of the kidney tissue from this fish yielded a partial SSU rDNA sequence of 1,769 base pairs (bp). Phylogenetic reconstruction suggested this organism to be a novel species of </span><i>Chloromyxum</i><span>, most similar to </span><i>Chloromyxum careni</i><span> (84% similarity). In addition, subspherical myxospores with smooth valves and 2 spherical polar capsules consistent with the genus </span><i>Sphaerospora</i><span> were observed in wet mounts of 2 fish. Sequencing of the kidney tissue from 1 fish yielded a partial SSU rDNA sequence of 1,937 bp. Phylogenetic reconstruction suggests this organism to be a novel species of </span><i>Sphaerospora</i><span> most closely related to </span><i>Sphaerospora epinepheli</i><span> (93%). We conclude that these organisms represent novel species of the genera </span><i>Chloromyxum</i><span> and </span><i>Sphaerospora</i><span> based on host, location, and SSU rDNA sequence. We further conclude that the formation of large, histozoic extrasporogonic stages in the renal interstitium represents developmental stages of </span><i>Chloromyxum</i><span> species for the following reasons: (1) Large extrasporogonic stages were only observed in fish with </span><i>Chloromyxum</i><span>-type spores developing within the renal tubules, (2) a DNA sequence consistent with the </span><i><span class="genus-species">Chloromyxum</span></i><span> sp. was only detected in fish with the large extrasporogonic stages, and (3) several </span><i>Sphaerospora</i><span> species have extrasporogonic forms, but they are considerably smaller and are composed of far fewer cells.</span></p>
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10.1645/15-726
en
American Society of Parasitologists
Two myxozoans from the urinary tract of topsmelt, Atherinops affinis
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