Abstract：
West Indian manatees (Trichechus manatus) harbor a variety of endoparasites, including the nasal trematode Pulmonicola cochleotrema, which infects the respiratory tract, especially the nasal passages. Previous studies have described and identified this digenean using morphological data only. This study presents the first molecular identification of P. cochleotrema in West Indian manatees from Puerto Rico and Florida. Samples of the trematode were collected from seven manatees found stranded dead at both locations. The small subunit ribosomal DNA (18S rDNA) was amplified from each sample using universal primers for different regions of the gene, resulting in a consensus sequence of 1871 base pairs. The phylogenetic reconstruction was carried out using DNA sequences of other species of digenean parasites from other hosts, including a trematode of the same taxonomic family from another sirenian species. Specimens collected from both locations show the same molecular identity using SSU rDNA sequence data. The identity of P. cochleotrema was confirmed using the Basic Local Alignment Search Tool from the National Center for Biotechnology Information database, yielding a high similarity of 98.8 % with Opisthotrema dujonis and 98.2 % with Lankatrema mannarense located in the same clade in our analysis. The latter two digeneans belong to the Opisthotrematidae as does P. cochleotrema and previous studies reported them infecting the Eustachian tubes, esophagus, and digestive tract in dugongs (Dugong dugon). These findings evidence that the nasal trematode of manatees in Florida and Puerto Rico and the dugong, all inhabiting and feeding in marine environments, will have a marine mollusk as an intermediate host, probably a gastropod. The question remains, which species of nasal trematode are harbored by lotic-dwelling manatees in other parts of their distribution like South America.
摘要：
西印度海牛（Trichechusmanatus）藏有各种体内寄生虫，包括鼻吸虫Pulmonicola耳蜗,会感染呼吸道，尤其是鼻腔.以前的研究仅使用形态学数据来描述和识别这种双基因。这项研究首次对波多黎各和佛罗里达州的西印度海牛中的P.cochleotrema进行了分子鉴定。从在两个位置都被发现死的七只海牛中收集了吸虫的样本。使用基因不同区域的通用引物从每个样品中扩增小亚基核糖体DNA（18SrDNA），产生1871个碱基对的共有序列。系统发育重建是使用来自其他宿主的其他双基因寄生虫物种的DNA序列进行的，包括来自另一个西列尼物种的同一分类科的吸虫。使用SSUrDNA序列数据,从两个位置收集的样本显示相同的分子同一性。使用国家生物技术信息中心数据库的基本局部比对搜索工具确认了P.cochleotrema的身份。在我们的分析中，与Opisthotremadujonis的相似性高达98.8％，与Lankatremamannarense的相似性高达98.2％。后两个同系物和耳蜗P.一样属于视神经科，以前的研究报道它们感染咽鼓管，食道,和消化道在儒艮（Dugongdugon）。这些发现证明了佛罗里达州和波多黎各的海牛和儒艮的鼻吸虫，都在海洋环境中居住和觅食，将有一只海洋软体动物作为中间宿主，可能是腹足动物.问题仍然存在，在南美等分布的其他地区，居住在野外的海牛都有哪些鼻吸虫。
