First molecular identification of the trematode Pulmonicola cochleotrema (Platyhelminthes: Opisthotrematidae) in West Indian manatees (Trichechus manatus, Sirenia: Trichechidae) from Puerto Rico and Florida.

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.